// File: @0x/contracts-utils/contracts/src/SafeMath.sol

pragma solidity ^0.4.24;


contract SafeMath {

    function safeMul(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(
            c / a == b,
            "UINT256_OVERFLOW"
        );
        return c;
    }

    function safeDiv(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        uint256 c = a / b;
        return c;
    }

    function safeSub(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        require(
            b <= a,
            "UINT256_UNDERFLOW"
        );
        return a - b;
    }

    function safeAdd(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        uint256 c = a + b;
        require(
            c >= a,
            "UINT256_OVERFLOW"
        );
        return c;
    }

    function max64(uint64 a, uint64 b)
        internal
        pure
        returns (uint256)
    {
        return a >= b ? a : b;
    }

    function min64(uint64 a, uint64 b)
        internal
        pure
        returns (uint256)
    {
        return a < b ? a : b;
    }

    function max256(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        return a >= b ? a : b;
    }

    function min256(uint256 a, uint256 b)
        internal
        pure
        returns (uint256)
    {
        return a < b ? a : b;
    }
}

// File: @0x/contracts-exchange-libs/contracts/src/LibFillResults.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.4.24;



contract LibFillResults is
    SafeMath
{
    struct FillResults {
        uint256 makerAssetFilledAmount;  // Total amount of makerAsset(s) filled.
        uint256 takerAssetFilledAmount;  // Total amount of takerAsset(s) filled.
        uint256 makerFeePaid;            // Total amount of ZRX paid by maker(s) to feeRecipient(s).
        uint256 takerFeePaid;            // Total amount of ZRX paid by taker to feeRecipients(s).
    }

    struct MatchedFillResults {
        FillResults left;                    // Amounts filled and fees paid of left order.
        FillResults right;                   // Amounts filled and fees paid of right order.
        uint256 leftMakerAssetSpreadAmount;  // Spread between price of left and right order, denominated in the left order's makerAsset, paid to taker.
    }

    /// @dev Adds properties of both FillResults instances.
    ///      Modifies the first FillResults instance specified.
    /// @param totalFillResults Fill results instance that will be added onto.
    /// @param singleFillResults Fill results instance that will be added to totalFillResults.
    function addFillResults(FillResults memory totalFillResults, FillResults memory singleFillResults)
        internal
        pure
    {
        totalFillResults.makerAssetFilledAmount = safeAdd(totalFillResults.makerAssetFilledAmount, singleFillResults.makerAssetFilledAmount);
        totalFillResults.takerAssetFilledAmount = safeAdd(totalFillResults.takerAssetFilledAmount, singleFillResults.takerAssetFilledAmount);
        totalFillResults.makerFeePaid = safeAdd(totalFillResults.makerFeePaid, singleFillResults.makerFeePaid);
        totalFillResults.takerFeePaid = safeAdd(totalFillResults.takerFeePaid, singleFillResults.takerFeePaid);
    }
}

// File: @0x/contracts-exchange-libs/contracts/src/LibEIP712.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.4.24;


contract LibEIP712 {

    // EIP191 header for EIP712 prefix
    string constant internal EIP191_HEADER = "\x19\x01";

    // EIP712 Domain Name value
    string constant internal EIP712_DOMAIN_NAME = "0x Protocol";

    // EIP712 Domain Version value
    string constant internal EIP712_DOMAIN_VERSION = "2";

    // Hash of the EIP712 Domain Separator Schema
    bytes32 constant internal EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(abi.encodePacked(
        "EIP712Domain(",
        "string name,",
        "string version,",
        "address verifyingContract",
        ")"
    ));

    // Hash of the EIP712 Domain Separator data
    // solhint-disable-next-line var-name-mixedcase
    bytes32 public EIP712_DOMAIN_HASH;

    constructor ()
        public
    {
        EIP712_DOMAIN_HASH = keccak256(abi.encodePacked(
            EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH,
            keccak256(bytes(EIP712_DOMAIN_NAME)),
            keccak256(bytes(EIP712_DOMAIN_VERSION)),
            bytes32(address(this))
        ));
    }

    /// @dev Calculates EIP712 encoding for a hash struct in this EIP712 Domain.
    /// @param hashStruct The EIP712 hash struct.
    /// @return EIP712 hash applied to this EIP712 Domain.
    function hashEIP712Message(bytes32 hashStruct)
        internal
        view
        returns (bytes32 result)
    {
        bytes32 eip712DomainHash = EIP712_DOMAIN_HASH;

        // Assembly for more efficient computing:
        // keccak256(abi.encodePacked(
        //     EIP191_HEADER,
        //     EIP712_DOMAIN_HASH,
        //     hashStruct    
        // ));

        assembly {
            // Load free memory pointer
            let memPtr := mload(64)

            mstore(memPtr, 0x1901000000000000000000000000000000000000000000000000000000000000)  // EIP191 header
            mstore(add(memPtr, 2), eip712DomainHash)                                            // EIP712 domain hash
            mstore(add(memPtr, 34), hashStruct)                                                 // Hash of struct

            // Compute hash
            result := keccak256(memPtr, 66)
        }
        return result;
    }
}

// File: @0x/contracts-exchange-libs/contracts/src/LibOrder.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.4.24;



contract LibOrder is
    LibEIP712
{
    // Hash for the EIP712 Order Schema
    bytes32 constant internal EIP712_ORDER_SCHEMA_HASH = keccak256(abi.encodePacked(
        "Order(",
        "address makerAddress,",
        "address takerAddress,",
        "address feeRecipientAddress,",
        "address senderAddress,",
        "uint256 makerAssetAmount,",
        "uint256 takerAssetAmount,",
        "uint256 makerFee,",
        "uint256 takerFee,",
        "uint256 expirationTimeSeconds,",
        "uint256 salt,",
        "bytes makerAssetData,",
        "bytes takerAssetData",
        ")"
    ));

    // A valid order remains fillable until it is expired, fully filled, or cancelled.
    // An order's state is unaffected by external factors, like account balances.
    enum OrderStatus {
        INVALID,                     // Default value
        INVALID_MAKER_ASSET_AMOUNT,  // Order does not have a valid maker asset amount
        INVALID_TAKER_ASSET_AMOUNT,  // Order does not have a valid taker asset amount
        FILLABLE,                    // Order is fillable
        EXPIRED,                     // Order has already expired
        FULLY_FILLED,                // Order is fully filled
        CANCELLED                    // Order has been cancelled
    }

    // solhint-disable max-line-length
    struct Order {
        address makerAddress;           // Address that created the order.      
        address takerAddress;           // Address that is allowed to fill the order. If set to 0, any address is allowed to fill the order.          
        address feeRecipientAddress;    // Address that will recieve fees when order is filled.      
        address senderAddress;          // Address that is allowed to call Exchange contract methods that affect this order. If set to 0, any address is allowed to call these methods.
        uint256 makerAssetAmount;       // Amount of makerAsset being offered by maker. Must be greater than 0.        
        uint256 takerAssetAmount;       // Amount of takerAsset being bid on by maker. Must be greater than 0.        
        uint256 makerFee;               // Amount of ZRX paid to feeRecipient by maker when order is filled. If set to 0, no transfer of ZRX from maker to feeRecipient will be attempted.
        uint256 takerFee;               // Amount of ZRX paid to feeRecipient by taker when order is filled. If set to 0, no transfer of ZRX from taker to feeRecipient will be attempted.
        uint256 expirationTimeSeconds;  // Timestamp in seconds at which order expires.          
        uint256 salt;                   // Arbitrary number to facilitate uniqueness of the order's hash.     
        bytes makerAssetData;           // Encoded data that can be decoded by a specified proxy contract when transferring makerAsset. The last byte references the id of this proxy.
        bytes takerAssetData;           // Encoded data that can be decoded by a specified proxy contract when transferring takerAsset. The last byte references the id of this proxy.
    }
    // solhint-enable max-line-length

    struct OrderInfo {
        uint8 orderStatus;                    // Status that describes order's validity and fillability.
        bytes32 orderHash;                    // EIP712 hash of the order (see LibOrder.getOrderHash).
        uint256 orderTakerAssetFilledAmount;  // Amount of order that has already been filled.
    }

    /// @dev Calculates Keccak-256 hash of the order.
    /// @param order The order structure.
    /// @return Keccak-256 EIP712 hash of the order.
    function getOrderHash(Order memory order)
        internal
        view
        returns (bytes32 orderHash)
    {
        orderHash = hashEIP712Message(hashOrder(order));
        return orderHash;
    }

    /// @dev Calculates EIP712 hash of the order.
    /// @param order The order structure.
    /// @return EIP712 hash of the order.
    function hashOrder(Order memory order)
        internal
        pure
        returns (bytes32 result)
    {
        bytes32 schemaHash = EIP712_ORDER_SCHEMA_HASH;
        bytes32 makerAssetDataHash = keccak256(order.makerAssetData);
        bytes32 takerAssetDataHash = keccak256(order.takerAssetData);

        // Assembly for more efficiently computing:
        // keccak256(abi.encodePacked(
        //     EIP712_ORDER_SCHEMA_HASH,
        //     bytes32(order.makerAddress),
        //     bytes32(order.takerAddress),
        //     bytes32(order.feeRecipientAddress),
        //     bytes32(order.senderAddress),
        //     order.makerAssetAmount,
        //     order.takerAssetAmount,
        //     order.makerFee,
        //     order.takerFee,
        //     order.expirationTimeSeconds,
        //     order.salt,
        //     keccak256(order.makerAssetData),
        //     keccak256(order.takerAssetData)
        // ));

        assembly {
            // Calculate memory addresses that will be swapped out before hashing
            let pos1 := sub(order, 32)
            let pos2 := add(order, 320)
            let pos3 := add(order, 352)

            // Backup
            let temp1 := mload(pos1)
            let temp2 := mload(pos2)
            let temp3 := mload(pos3)
            
            // Hash in place
            mstore(pos1, schemaHash)
            mstore(pos2, makerAssetDataHash)
            mstore(pos3, takerAssetDataHash)
            result := keccak256(pos1, 416)
            
            // Restore
            mstore(pos1, temp1)
            mstore(pos2, temp2)
            mstore(pos3, temp3)
        }
        return result;
    }
}

// File: @0x/contracts-exchange-libs/contracts/src/LibMath.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.4.24;



contract LibMath is
    SafeMath
{
    /// @dev Calculates partial value given a numerator and denominator rounded down.
    ///      Reverts if rounding error is >= 0.1%
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to calculate partial of.
    /// @return Partial value of target rounded down.
    function safeGetPartialAmountFloor(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    )
        internal
        pure
        returns (uint256 partialAmount)
    {
        require(
            denominator > 0,
            "DIVISION_BY_ZERO"
        );

        require(
            !isRoundingErrorFloor(
                numerator,
                denominator,
                target
            ),
            "ROUNDING_ERROR"
        );
        
        partialAmount = safeDiv(
            safeMul(numerator, target),
            denominator
        );
        return partialAmount;
    }

    /// @dev Calculates partial value given a numerator and denominator rounded down.
    ///      Reverts if rounding error is >= 0.1%
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to calculate partial of.
    /// @return Partial value of target rounded up.
    function safeGetPartialAmountCeil(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    )
        internal
        pure
        returns (uint256 partialAmount)
    {
        require(
            denominator > 0,
            "DIVISION_BY_ZERO"
        );

        require(
            !isRoundingErrorCeil(
                numerator,
                denominator,
                target
            ),
            "ROUNDING_ERROR"
        );
        
        // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
        //       ceil(a / b) = floor((a + b - 1) / b)
        // To implement `ceil(a / b)` using safeDiv.
        partialAmount = safeDiv(
            safeAdd(
                safeMul(numerator, target),
                safeSub(denominator, 1)
            ),
            denominator
        );
        return partialAmount;
    }

    /// @dev Calculates partial value given a numerator and denominator rounded down.
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to calculate partial of.
    /// @return Partial value of target rounded down.
    function getPartialAmountFloor(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    )
        internal
        pure
        returns (uint256 partialAmount)
    {
        require(
            denominator > 0,
            "DIVISION_BY_ZERO"
        );

        partialAmount = safeDiv(
            safeMul(numerator, target),
            denominator
        );
        return partialAmount;
    }
    
    /// @dev Calculates partial value given a numerator and denominator rounded down.
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to calculate partial of.
    /// @return Partial value of target rounded up.
    function getPartialAmountCeil(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    )
        internal
        pure
        returns (uint256 partialAmount)
    {
        require(
            denominator > 0,
            "DIVISION_BY_ZERO"
        );

        // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
        //       ceil(a / b) = floor((a + b - 1) / b)
        // To implement `ceil(a / b)` using safeDiv.
        partialAmount = safeDiv(
            safeAdd(
                safeMul(numerator, target),
                safeSub(denominator, 1)
            ),
            denominator
        );
        return partialAmount;
    }
    
    /// @dev Checks if rounding error >= 0.1% when rounding down.
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to multiply with numerator/denominator.
    /// @return Rounding error is present.
    function isRoundingErrorFloor(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    )
        internal
        pure
        returns (bool isError)
    {
        require(
            denominator > 0,
            "DIVISION_BY_ZERO"
        );
        
        // The absolute rounding error is the difference between the rounded
        // value and the ideal value. The relative rounding error is the
        // absolute rounding error divided by the absolute value of the
        // ideal value. This is undefined when the ideal value is zero.
        //
        // The ideal value is `numerator * target / denominator`.
        // Let's call `numerator * target % denominator` the remainder.
        // The absolute error is `remainder / denominator`.
        //
        // When the ideal value is zero, we require the absolute error to
        // be zero. Fortunately, this is always the case. The ideal value is
        // zero iff `numerator == 0` and/or `target == 0`. In this case the
        // remainder and absolute error are also zero. 
        if (target == 0 || numerator == 0) {
            return false;
        }
        
        // Otherwise, we want the relative rounding error to be strictly
        // less than 0.1%.
        // The relative error is `remainder / (numerator * target)`.
        // We want the relative error less than 1 / 1000:
        //        remainder / (numerator * denominator)  <  1 / 1000
        // or equivalently:
        //        1000 * remainder  <  numerator * target
        // so we have a rounding error iff:
        //        1000 * remainder  >=  numerator * target
        uint256 remainder = mulmod(
            target,
            numerator,
            denominator
        );
        isError = safeMul(1000, remainder) >= safeMul(numerator, target);
        return isError;
    }
    
    /// @dev Checks if rounding error >= 0.1% when rounding up.
    /// @param numerator Numerator.
    /// @param denominator Denominator.
    /// @param target Value to multiply with numerator/denominator.
    /// @return Rounding error is present.
    function isRoundingErrorCeil(
        uint256 numerator,
        uint256 denominator,
        uint256 target
    )
        internal
        pure
        returns (bool isError)
    {
        require(
            denominator > 0,
            "DIVISION_BY_ZERO"
        );
        
        // See the comments in `isRoundingError`.
        if (target == 0 || numerator == 0) {
            // When either is zero, the ideal value and rounded value are zero
            // and there is no rounding error. (Although the relative error
            // is undefined.)
            return false;
        }
        // Compute remainder as before
        uint256 remainder = mulmod(
            target,
            numerator,
            denominator
        );
        remainder = safeSub(denominator, remainder) % denominator;
        isError = safeMul(1000, remainder) >= safeMul(numerator, target);
        return isError;
    }
}

// File: contracts/exchange/interfaces/IExchangeCore.sol

/*

  Modified by Metaps Alpha Inc.

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;
pragma experimental ABIEncoderV2;


contract IExchangeCore {

    /// @dev Cancels all orders created by makerAddress with a salt less than or equal to the targetOrderEpoch
    ///      and senderAddress equal to msg.sender (or null address if msg.sender == makerAddress).
    /// @param targetOrderEpoch Orders created with a salt less or equal to this value will be cancelled.
    function cancelOrdersUpTo(uint256 targetOrderEpoch)
        external;

    /// @dev Fills the input order.
    /// @param order Order struct containing order specifications.
    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
    /// @param signature Proof that order has been created by maker.
    /// @return Amounts filled and fees paid by maker and taker.
    function fillOrder(
        LibOrder.Order memory order,
        uint256 takerAssetFillAmount,
        bytes memory signature
    )
        public
        payable
        returns (LibFillResults.FillResults memory fillResults);

    /// @dev After calling, the order can not be filled anymore.
    /// @param order Order struct containing order specifications.
    function cancelOrder(LibOrder.Order memory order)
        public;

    /// @dev Gets information about an order: status, hash, and amount filled.
    /// @param order Order to gather information on.
    /// @return OrderInfo Information about the order and its state.
    ///                   See LibOrder.OrderInfo for a complete description.
    function getOrderInfo(LibOrder.Order memory order)
        public
        view
        returns (LibOrder.OrderInfo memory orderInfo);

    /// @dev miime - Update order (Cancel order and then update deposit for new order).
    /// @param newOrderHash New orderHash for deposit.
    /// @param newOfferAmount New offer amount.
    /// @param orderToBeCanceled Order to be canceled.
    function updateOrder(
        bytes32 newOrderHash,
        uint256 newOfferAmount,
        LibOrder.Order memory orderToBeCanceled
    )
        public
        payable;
}

// File: contracts/exchange/mixins/MExchangeCore.sol

/*

  Modified by Metaps Alpha Inc.

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MExchangeCore is
    IExchangeCore
{
    // Fill event is emitted whenever an order is filled.
    event Fill(
        address indexed makerAddress,         // Address that created the order.      
        address indexed feeRecipientAddress,  // Address that received fees.
        address takerAddress,                 // Address that filled the order.
        address senderAddress,                // Address that called the Exchange contract (msg.sender).
        uint256 makerAssetFilledAmount,       // Amount of makerAsset sold by maker and bought by taker. 
        uint256 takerAssetFilledAmount,       // Amount of takerAsset sold by taker and bought by maker.
        uint256 makerFeePaid,                 // Amount of ZRX paid to feeRecipient by maker.
        uint256 takerFeePaid,                 // Amount of ZRX paid to feeRecipient by taker.
        bytes32 indexed orderHash,            // EIP712 hash of order (see LibOrder.getOrderHash).
        bytes makerAssetData,                 // Encoded data specific to makerAsset. 
        bytes takerAssetData                  // Encoded data specific to takerAsset.
    );

    // Cancel event is emitted whenever an individual order is cancelled.
    event Cancel(
        address indexed makerAddress,         // Address that created the order.      
        address indexed feeRecipientAddress,  // Address that would have recieved fees if order was filled.   
        address senderAddress,                // Address that called the Exchange contract (msg.sender).
        bytes32 indexed orderHash,            // EIP712 hash of order (see LibOrder.getOrderHash).
        bytes makerAssetData,                 // Encoded data specific to makerAsset. 
        bytes takerAssetData                  // Encoded data specific to takerAsset.
    );

    // CancelUpTo event is emitted whenever `cancelOrdersUpTo` is executed succesfully.
    event CancelUpTo(
        address indexed makerAddress,         // Orders cancelled must have been created by this address.
        address indexed senderAddress,        // Orders cancelled must have a `senderAddress` equal to this address.
        uint256 orderEpoch                    // Orders with specified makerAddress and senderAddress with a salt less than this value are considered cancelled.
    );

    // miime: Transfer event is emitted whenever `transfer` is executed succesfully.
    event Transfer(
        address indexed toAddress,
        uint256 indexed amount
    );

    /// @dev Fills the input order.
    /// @param order Order struct containing order specifications.
    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
    /// @param signature Proof that order has been created by maker.
    /// @return Amounts filled and fees paid by maker and taker.
    function fillOrderInternal(
        LibOrder.Order memory order,
        uint256 takerAssetFillAmount,
        bytes memory signature
    )
        internal
        returns (LibFillResults.FillResults memory fillResults);

    /// @dev After calling, the order can not be filled anymore.
    /// @param order Order struct containing order specifications.
    function cancelOrderInternal(LibOrder.Order memory order)
        internal
        returns (LibOrder.OrderInfo);

    /// @dev Updates state with results of a fill order.
    /// @param order that was filled.
    /// @param takerAddress Address of taker who filled the order.
    /// @param orderTakerAssetFilledAmount Amount of order already filled.
    /// @return fillResults Amounts filled and fees paid by maker and taker.
    function updateFilledState(
        LibOrder.Order memory order,
        address takerAddress,
        bytes32 orderHash,
        uint256 orderTakerAssetFilledAmount,
        LibFillResults.FillResults memory fillResults
    )
        internal;

    /// @dev Updates state with results of cancelling an order.
    ///      State is only updated if the order is currently fillable.
    ///      Otherwise, updating state would have no effect.
    /// @param order that was cancelled.
    /// @param orderHash Hash of order that was cancelled.
    function updateCancelledState(
        LibOrder.Order memory order,
        bytes32 orderHash
    )
        internal;
    
    /// @dev Validates context for fillOrder. Succeeds or throws.
    /// @param order to be filled.
    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
    /// @param takerAddress Address of order taker.
    /// @param signature Proof that the orders was created by its maker.
    function assertFillableOrder(
        LibOrder.Order memory order,
        LibOrder.OrderInfo memory orderInfo,
        address takerAddress,
        bytes memory signature
    )
        internal
        view;
    
    /// @dev Validates context for fillOrder. Succeeds or throws.
    /// @param order to be filled.
    /// @param orderInfo Status, orderHash, and amount already filled of order.
    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
    /// @param makerAssetFilledAmount Amount of makerAsset that will be transfered.
    function assertValidFill(
        LibOrder.Order memory order,
        LibOrder.OrderInfo memory orderInfo,
        uint256 takerAssetFillAmount,
        uint256 takerAssetFilledAmount,
        uint256 makerAssetFilledAmount
    )
        internal
        view;

    /// @dev Validates context for cancelOrder. Succeeds or throws.
    /// @param order to be cancelled.
    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
    function assertValidCancel(
        LibOrder.Order memory order,
        LibOrder.OrderInfo memory orderInfo
    )
        internal
        view;

    /// @dev Calculates amounts filled and fees paid by maker and taker.
    /// @param order to be filled.
    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
    /// @return fillResults Amounts filled and fees paid by maker and taker.
    function calculateFillResults(
        LibOrder.Order memory order,
        uint256 takerAssetFilledAmount
    )
        internal
        pure
        returns (LibFillResults.FillResults memory fillResults);

}

// File: contracts/exchange/interfaces/ISignatureValidator.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract ISignatureValidator {

    /// @dev Approves a hash on-chain using any valid signature type.
    ///      After presigning a hash, the preSign signature type will become valid for that hash and signer.
    /// @param signerAddress Address that should have signed the given hash.
    /// @param signature Proof that the hash has been signed by signer.
    function preSign(
        bytes32 hash,
        address signerAddress,
        bytes signature
    )
        external;
    
    /// @dev Approves/unnapproves a Validator contract to verify signatures on signer's behalf.
    /// @param validatorAddress Address of Validator contract.
    /// @param approval Approval or disapproval of  Validator contract.
    function setSignatureValidatorApproval(
        address validatorAddress,
        bool approval
    )
        external;

    /// @dev Verifies that a signature is valid.
    /// @param hash Message hash that is signed.
    /// @param signerAddress Address of signer.
    /// @param signature Proof of signing.
    /// @return Validity of order signature.
    function isValidSignature(
        bytes32 hash,
        address signerAddress,
        bytes memory signature
    )
        public
        view
        returns (bool isValid);
}

// File: contracts/exchange/mixins/MSignatureValidator.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MSignatureValidator is
    ISignatureValidator
{
    event SignatureValidatorApproval(
        address indexed signerAddress,     // Address that approves or disapproves a contract to verify signatures.
        address indexed validatorAddress,  // Address of signature validator contract.
        bool approved                      // Approval or disapproval of validator contract.
    );

    // Allowed signature types.
    enum SignatureType {
        Illegal,         // 0x00, default value
        Invalid,         // 0x01
        EIP712,          // 0x02
        EthSign,         // 0x03
        Wallet,          // 0x04
        Validator,       // 0x05
        PreSigned,       // 0x06
        NSignatureTypes  // 0x07, number of signature types. Always leave at end.
    }

    /// @dev Verifies signature using logic defined by Wallet contract.
    /// @param hash Any 32 byte hash.
    /// @param walletAddress Address that should have signed the given hash
    ///                      and defines its own signature verification method.
    /// @param signature Proof that the hash has been signed by signer.
    /// @return True if the address recovered from the provided signature matches the input signer address.
    function isValidWalletSignature(
        bytes32 hash,
        address walletAddress,
        bytes signature
    )
        internal
        view
        returns (bool isValid);

    /// @dev Verifies signature using logic defined by Validator contract.
    /// @param validatorAddress Address of validator contract.
    /// @param hash Any 32 byte hash.
    /// @param signerAddress Address that should have signed the given hash.
    /// @param signature Proof that the hash has been signed by signer.
    /// @return True if the address recovered from the provided signature matches the input signer address.
    function isValidValidatorSignature(
        address validatorAddress,
        bytes32 hash,
        address signerAddress,
        bytes signature
    )
        internal
        view
        returns (bool isValid);
}

// File: contracts/exchange/interfaces/ITransactions.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract ITransactions {

    /// @dev Executes an exchange method call in the context of signer.
    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
    /// @param signerAddress Address of transaction signer.
    /// @param data AbiV2 encoded calldata.
    /// @param signature Proof of signer transaction by signer.
    function executeTransaction(
        uint256 salt,
        address signerAddress,
        bytes data,
        bytes signature
    )
        external;
}

// File: contracts/exchange/mixins/MTransactions.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MTransactions is
    ITransactions
{
    // Hash for the EIP712 ZeroEx Transaction Schema
    bytes32 constant internal EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH = keccak256(abi.encodePacked(
        "ZeroExTransaction(",
        "uint256 salt,",
        "address signerAddress,",
        "bytes data",
        ")"
    ));

    /// @dev Calculates EIP712 hash of the Transaction.
    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
    /// @param signerAddress Address of transaction signer.
    /// @param data AbiV2 encoded calldata.
    /// @return EIP712 hash of the Transaction.
    function hashZeroExTransaction(
        uint256 salt,
        address signerAddress,
        bytes memory data
    )
        internal
        pure
        returns (bytes32 result);

    /// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
    ///      If calling a fill function, this address will represent the taker.
    ///      If calling a cancel function, this address will represent the maker.
    /// @return Signer of 0x transaction if entry point is `executeTransaction`.
    ///         `msg.sender` if entry point is any other function.
    function getCurrentContextAddress()
        internal
        view
        returns (address);
}

// File: contracts/exchange/interfaces/IAssetProxyDispatcher.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract IAssetProxyDispatcher {

    /// @dev Registers an asset proxy to its asset proxy id.
    ///      Once an asset proxy is registered, it cannot be unregistered.
    /// @param assetProxy Address of new asset proxy to register.
    function registerAssetProxy(address assetProxy)
        external;

    /// @dev Gets an asset proxy.
    /// @param assetProxyId Id of the asset proxy.
    /// @return The asset proxy registered to assetProxyId. Returns 0x0 if no proxy is registered.
    function getAssetProxy(bytes4 assetProxyId)
        external
        view
        returns (address);
}

// File: contracts/exchange/mixins/MAssetProxyDispatcher.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MAssetProxyDispatcher is
    IAssetProxyDispatcher
{
    // Logs registration of new asset proxy
    event AssetProxyRegistered(
        bytes4 id,              // Id of new registered AssetProxy.
        address assetProxy      // Address of new registered AssetProxy.
    );

    /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
    /// @param assetData Byte array encoded for the asset.
    /// @param from Address to transfer token from.
    /// @param to Address to transfer token to.
    /// @param amount Amount of token to transfer.
    function dispatchTransferFrom(
        bytes memory assetData,
        address from,
        address to,
        uint256 amount
    )
        internal;
}

// File: @0x/contracts-utils/contracts/src/ReentrancyGuard.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.4.24;


contract ReentrancyGuard {

    // Locked state of mutex
    bool private locked = false;

    /// @dev Functions with this modifer cannot be reentered. The mutex will be locked
    ///      before function execution and unlocked after.
    modifier nonReentrant() {
        // Ensure mutex is unlocked
        require(
            !locked,
            "REENTRANCY_ILLEGAL"
        );

        // Lock mutex before function call
        locked = true;

        // Perform function call
        _;

        // Unlock mutex after function call
        locked = false;
    }
}

// File: contracts/exchange/libs/Operational.sol

/*

  Copyright 2019 Metaps Alpha Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract Operational
{
    address public owner;
    address[] public withdrawOperators; // It is mainly responsible for the withdraw of deposit on cancelling.
    mapping (address => bool) public isWithdrawOperator;

    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );

    event WithdrawOperatorAdded(
        address indexed target,
        address indexed caller
    );

    event WithdrawOperatorRemoved(
        address indexed target,
        address indexed caller
    );

    constructor ()
        public
    {
        owner = msg.sender;
    }

    modifier onlyOwner() {
        require(
            msg.sender == owner,
            "ONLY_CONTRACT_OWNER"
        );
        _;
    }

    modifier withdrawable(address toAddress) {
        require(
            isWithdrawOperator[msg.sender] || toAddress == msg.sender,
            "SENDER_IS_NOT_WITHDRAWABLE"
        );
        _;
    }

    function transferOwnership(address newOwner)
        public
        onlyOwner
    {
        require(
            newOwner != address(0),
            "INVALID_OWNER"
        );
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }

    function addWithdrawOperator(address target)
        external
        onlyOwner
    {
        require(
            !isWithdrawOperator[target],
            "TARGET_IS_ALREADY_WITHDRAW_OPERATOR"
        );

        isWithdrawOperator[target] = true;
        withdrawOperators.push(target);
        emit WithdrawOperatorAdded(target, msg.sender);
    }

    function removeWithdrawOperator(address target)
        external
        onlyOwner
    {
        require(
            isWithdrawOperator[target],
            "TARGET_IS_NOT_WITHDRAW_OPERATOR"
        );

        delete isWithdrawOperator[target];
        for (uint256 i = 0; i < withdrawOperators.length; i++) {
            if (withdrawOperators[i] == target) {
                withdrawOperators[i] = withdrawOperators[withdrawOperators.length - 1];
                withdrawOperators.length -= 1;
                break;
            }
        }
        emit WithdrawOperatorRemoved(target, msg.sender);
    }
}

// File: contracts/exchange/libs/DepositManager.sol

/*

  Copyright 2019 Metaps Alpha Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract DepositManager is
    Operational,
    ReentrancyGuard,
    SafeMath
{
    // Mapping from user to deposit amount
    mapping (address => uint256) public depositAmount;
    // Mapping from order and user to deposit amount for withdraw
    mapping (bytes32 => mapping (address => uint256)) public orderToDepositAmount;

    // Deposit event is emitted whenever `deposit` is executed succesfully.
    event Deposit(
        bytes32 indexed orderHash,
        address indexed senderAddress,
        uint256 amount
    );

    // DepositChanged event is emitted whenever `updateOrder` is executed succesfully.
    event DepositChanged(
        bytes32 indexed newOrderHash,
        uint256 newAmount,
        bytes32 indexed oldOrderHash,
        uint256 oldAmount,
        address indexed senderAddress
    );

    // Withdraw event is emitted whenever `withdraw` (it may be called in `cancelOrder`) is executed succesfully.
    event Withdraw(
        bytes32 indexed orderHash,
        address indexed toAddress,
        uint256 amount
    );

    /// @dev Deposit for offer.
    /// @param orderHash orderHash of the order.
    function deposit(bytes32 orderHash)
        public
        payable
        nonReentrant
    {
        depositInternal(orderHash, msg.sender, msg.value);
    }

    /// @dev Withdraw deposit.
    /// @param orderHash orderHash of the order.
    /// @param toAddress Address to be refund.
    function withdraw(bytes32 orderHash, address toAddress)
        public
        nonReentrant
        withdrawable(toAddress)
    {
        withdrawInternal(orderHash, toAddress);
    }

    function depositInternal(bytes32 orderHash, address sender, uint256 amount)
        internal
    {
        depositAmount[sender] = safeAdd(depositAmount[sender], amount);
        orderToDepositAmount[orderHash][sender] = safeAdd(orderToDepositAmount[orderHash][sender], amount);
        emit Deposit(orderHash, sender, amount);
    }

    function withdrawInternal(bytes32 orderHash, address toAddress)
        internal
    {
        if (orderToDepositAmount[orderHash][toAddress] > 0) {
            uint256 amount = orderToDepositAmount[orderHash][toAddress];
            depositAmount[toAddress] = safeSub(depositAmount[toAddress], amount);
            delete orderToDepositAmount[orderHash][toAddress];
            toAddress.transfer(amount);
            emit Withdraw(orderHash, toAddress, amount);
        }
    }

    function changeDeposit(
        bytes32 newOrderHash,
        uint256 newOfferAmount,
        bytes32 oldOrderHash,
        uint256 oldOfferAmount,
        address sender
    )
        internal
    {
        if (msg.value > 0) {
            depositAmount[sender] = safeAdd(depositAmount[sender], msg.value);
            orderToDepositAmount[newOrderHash][sender] = safeAdd(orderToDepositAmount[newOrderHash][sender], msg.value);
        }
        uint256 oldOrderToDepositAmount = orderToDepositAmount[oldOrderHash][sender];
        moveDeposit(oldOrderHash, newOrderHash, sender);
        if (oldOrderToDepositAmount > newOfferAmount) {
            uint256 refundAmount = safeSub(orderToDepositAmount[newOrderHash][sender], newOfferAmount);
            orderToDepositAmount[newOrderHash][sender] = safeSub(orderToDepositAmount[newOrderHash][sender], refundAmount);
            depositAmount[sender] = safeSub(depositAmount[sender], refundAmount);
            sender.transfer(refundAmount);
        }
        emit DepositChanged(newOrderHash, newOfferAmount, oldOrderHash, oldOfferAmount, sender);
    }

    function moveDeposit(
        bytes32 fromOrderHash,
        bytes32 toOrderHash,
        address sender
    )
        internal
    {
        uint256 amount = orderToDepositAmount[fromOrderHash][sender];
        delete orderToDepositAmount[fromOrderHash][sender];
        orderToDepositAmount[toOrderHash][sender] = safeAdd(orderToDepositAmount[toOrderHash][sender], amount);
    }

    function deductOrderToDepositAmount(
        bytes32 orderHash,
        address target,
        uint256 amount
    )
        internal
    {
        orderToDepositAmount[orderHash][target] = safeSub(orderToDepositAmount[orderHash][target], amount);
    }
}

// File: contracts/exchange/libs/LibConstants.sol

/*

  Copyright 2019 Metaps Alpha Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


// solhint-disable max-line-length
contract LibConstants {
    // miime - The special asset data for ETH
    // ETH_ASSET_DATA = bytes4(keccak256("ERC20Token(address)")); + 0 padding
    //                = 0xf47261b00000000000000000000000000000000000000000000000000000000000000000
    bytes constant public ETH_ASSET_DATA = "\xf4\x72\x61\xb0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
    bytes32 constant public KECCAK256_ETH_ASSET_DATA = keccak256(ETH_ASSET_DATA);
    uint256 constant public TRANSFER_GAS_LIMIT = 300000; // Gas limit for ETH sending
}
// solhint-enable max-line-length

// File: contracts/exchange/MixinExchangeCore.sol

/*

  Modified by Metaps Alpha Inc.

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MixinExchangeCore is
    DepositManager,
    LibConstants,
    LibMath,
    LibOrder,
    LibFillResults,
    MAssetProxyDispatcher,
    MExchangeCore,
    MSignatureValidator,
    MTransactions
{
    // Mapping of orderHash => amount of takerAsset already bought by maker
    mapping (bytes32 => uint256) public filled;

    // Mapping of orderHash => cancelled
    mapping (bytes32 => bool) public cancelled;

    // Mapping of makerAddress => senderAddress => lowest salt an order can have in order to be fillable
    // Orders with specified senderAddress and with a salt less than their epoch are considered cancelled
    mapping (address => mapping (address => uint256)) public orderEpoch;

    /// @dev Cancels all orders created by makerAddress with a salt less than or equal to the targetOrderEpoch
    ///      and senderAddress equal to msg.sender (or null address if msg.sender == makerAddress).
    /// @param targetOrderEpoch Orders created with a salt less or equal to this value will be cancelled.
    function cancelOrdersUpTo(uint256 targetOrderEpoch)
        external
        nonReentrant
    {
        address makerAddress = getCurrentContextAddress();
        // If this function is called via `executeTransaction`, we only update the orderEpoch for the makerAddress/msg.sender combination.
        // This allows external filter contracts to add rules to how orders are cancelled via this function.
        address senderAddress = makerAddress == msg.sender ? address(0) : msg.sender;

        // orderEpoch is initialized to 0, so to cancelUpTo we need salt + 1
        uint256 newOrderEpoch = targetOrderEpoch + 1;
        uint256 oldOrderEpoch = orderEpoch[makerAddress][senderAddress];

        // Ensure orderEpoch is monotonically increasing
        require(
            newOrderEpoch > oldOrderEpoch,
            "INVALID_NEW_ORDER_EPOCH"
        );

        // Update orderEpoch
        orderEpoch[makerAddress][senderAddress] = newOrderEpoch;
        emit CancelUpTo(
            makerAddress,
            senderAddress,
            newOrderEpoch
        );
    }

    /// @dev Fills the input order.
    /// @param order Order struct containing order specifications.
    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
    /// @param signature Proof that order has been created by maker.
    /// @return Amounts filled and fees paid by maker and taker.
    function fillOrder(
        Order memory order,
        uint256 takerAssetFillAmount,
        bytes memory signature
    )
        public
        payable
        nonReentrant
        returns (FillResults memory fillResults)
    {
        fillResults = fillOrderInternal(
            order,
            takerAssetFillAmount,
            signature
        );
        return fillResults;
    }

    /// @dev After calling, the order can not be filled anymore.
    ///      Throws if order is invalid or sender does not have permission to cancel.
    /// @param order Order to cancel. Order must be OrderStatus.FILLABLE.
    function cancelOrder(Order memory order)
        public
        nonReentrant
    {
        OrderInfo memory orderInfo = cancelOrderInternal(order);
        withdrawInternal(orderInfo.orderHash, msg.sender);
    }

    /// @dev Gets information about an order: status, hash, and amount filled.
    /// @param order Order to gather information on.
    /// @return OrderInfo Information about the order and its state.
    ///         See LibOrder.OrderInfo for a complete description.
    function getOrderInfo(Order memory order)
        public
        view
        returns (OrderInfo memory orderInfo)
    {
        // Compute the order hash
        orderInfo.orderHash = getOrderHash(order);

        // Fetch filled amount
        orderInfo.orderTakerAssetFilledAmount = filled[orderInfo.orderHash];

        // If order.makerAssetAmount is zero, we also reject the order.
        // While the Exchange contract handles them correctly, they create
        // edge cases in the supporting infrastructure because they have
        // an 'infinite' price when computed by a simple division.
        if (order.makerAssetAmount == 0) {
            orderInfo.orderStatus = uint8(OrderStatus.INVALID_MAKER_ASSET_AMOUNT);
            return orderInfo;
        }

        // If order.takerAssetAmount is zero, then the order will always
        // be considered filled because 0 == takerAssetAmount == orderTakerAssetFilledAmount
        // Instead of distinguishing between unfilled and filled zero taker
        // amount orders, we choose not to support them.
        if (order.takerAssetAmount == 0) {
            orderInfo.orderStatus = uint8(OrderStatus.INVALID_TAKER_ASSET_AMOUNT);
            return orderInfo;
        }

        // Validate order availability
        if (orderInfo.orderTakerAssetFilledAmount >= order.takerAssetAmount) {
            orderInfo.orderStatus = uint8(OrderStatus.FULLY_FILLED);
            return orderInfo;
        }

        // Validate order expiration
        // solhint-disable-next-line not-rely-on-time
        if (block.timestamp >= order.expirationTimeSeconds) {
            orderInfo.orderStatus = uint8(OrderStatus.EXPIRED);
            return orderInfo;
        }

        // Check if order has been cancelled
        if (cancelled[orderInfo.orderHash]) {
            orderInfo.orderStatus = uint8(OrderStatus.CANCELLED);
            return orderInfo;
        }
        if (orderEpoch[order.makerAddress][order.senderAddress] > order.salt) {
            orderInfo.orderStatus = uint8(OrderStatus.CANCELLED);
            return orderInfo;
        }

        // All other statuses are ruled out: order is Fillable
        orderInfo.orderStatus = uint8(OrderStatus.FILLABLE);
        return orderInfo;
    }

    /// @dev miime - Cancel order and then update deposit for new order.
    /// @param newOrderHash New orderHash for deposit.
    /// @param newOfferAmount New offer amount.
    /// @param orderToBeCanceled Order to be canceled.
    function updateOrder(
        bytes32 newOrderHash,
        uint256 newOfferAmount,
        Order memory orderToBeCanceled
    )
        public
        payable
        nonReentrant
    {
        OrderInfo memory orderInfo = cancelOrderInternal(orderToBeCanceled);
        uint256 oldOfferAmount = safeAdd(orderToBeCanceled.makerAssetAmount, orderToBeCanceled.makerFee);
        changeDeposit(newOrderHash, newOfferAmount, orderInfo.orderHash, oldOfferAmount, msg.sender);
    }

    /// @dev Fills the input order.
    /// @param order Order struct containing order specifications.
    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
    /// @param signature Proof that order has been created by maker.
    /// @return Amounts filled and fees paid by maker and taker.
    function fillOrderInternal(
        Order memory order,
        uint256 takerAssetFillAmount,
        bytes memory signature
    )
        internal
        returns (FillResults memory fillResults)
    {
        // Fetch order info
        OrderInfo memory orderInfo = getOrderInfo(order);

        // Fetch taker address
        address takerAddress = getCurrentContextAddress();

        // miime: Deposit the sending ETH on buying
        // Hash calculation is expensive, so it is implemented here.
        if (msg.value > 0) {
            depositInternal(orderInfo.orderHash, takerAddress, msg.value);
        }

        // Assert that the order is fillable by taker
        assertFillableOrder(
            order,
            orderInfo,
            takerAddress,
            signature
        );

        // Get amount of takerAsset to fill
        uint256 remainingTakerAssetAmount = safeSub(order.takerAssetAmount, orderInfo.orderTakerAssetFilledAmount);
        uint256 takerAssetFilledAmount = min256(takerAssetFillAmount, remainingTakerAssetAmount);

        // Compute proportional fill amounts
        fillResults = calculateFillResults(order, takerAssetFilledAmount);

        // Validate context
        assertValidFill(
            order,
            orderInfo,
            takerAssetFillAmount,
            takerAssetFilledAmount,
            fillResults.makerAssetFilledAmount
        );

        // Update exchange internal state
        updateFilledState(
            order,
            takerAddress,
            orderInfo.orderHash,
            orderInfo.orderTakerAssetFilledAmount,
            fillResults
        );

        // Settle order
        settleOrder(
            order,
            takerAddress,
            fillResults
        );

        // miime: Deduct deposit of this order
        if (keccak256(order.makerAssetData) == KECCAK256_ETH_ASSET_DATA) {
            deductOrderToDepositAmount(
                orderInfo.orderHash,
                order.makerAddress,
                safeAdd(fillResults.makerAssetFilledAmount, fillResults.makerFeePaid)
            );
        }
        if (keccak256(order.takerAssetData) == KECCAK256_ETH_ASSET_DATA) {
            deductOrderToDepositAmount(
                orderInfo.orderHash,
                takerAddress,
                safeAdd(fillResults.takerAssetFilledAmount, fillResults.takerFeePaid)
            );
        }

        return fillResults;
    }

    /// @dev After calling, the order can not be filled anymore.
    ///      Throws if order is invalid or sender does not have permission to cancel.
    /// @param order Order to cancel. Order must be OrderStatus.FILLABLE.
    /// @return orderInfo
    function cancelOrderInternal(Order memory order)
        internal
        returns (OrderInfo)
    {
        // Fetch current order status
        OrderInfo memory orderInfo = getOrderInfo(order);

        // Validate context
        assertValidCancel(order, orderInfo);

        // Perform cancel
        updateCancelledState(order, orderInfo.orderHash);

        return orderInfo;
    }

    /// @dev Updates state with results of a fill order.
    /// @param order that was filled.
    /// @param takerAddress Address of taker who filled the order.
    /// @param orderTakerAssetFilledAmount Amount of order already filled.
    function updateFilledState(
        Order memory order,
        address takerAddress,
        bytes32 orderHash,
        uint256 orderTakerAssetFilledAmount,
        FillResults memory fillResults
    )
        internal
    {
        // Update state
        filled[orderHash] = safeAdd(orderTakerAssetFilledAmount, fillResults.takerAssetFilledAmount);

        // Log order
        emit Fill(
            order.makerAddress,
            order.feeRecipientAddress,
            takerAddress,
            msg.sender,
            fillResults.makerAssetFilledAmount,
            fillResults.takerAssetFilledAmount,
            fillResults.makerFeePaid,
            fillResults.takerFeePaid,
            orderHash,
            order.makerAssetData,
            order.takerAssetData
        );
    }

    /// @dev Updates state with results of cancelling an order.
    ///      State is only updated if the order is currently fillable.
    ///      Otherwise, updating state would have no effect.
    /// @param order that was cancelled.
    /// @param orderHash Hash of order that was cancelled.
    function updateCancelledState(
        Order memory order,
        bytes32 orderHash
    )
        internal
    {
        // Perform cancel
        cancelled[orderHash] = true;

        // Log cancel
        emit Cancel(
            order.makerAddress,
            order.feeRecipientAddress,
            msg.sender,
            orderHash,
            order.makerAssetData,
            order.takerAssetData
        );
    }

    /// @dev Validates context for fillOrder. Succeeds or throws.
    /// @param order to be filled.
    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
    /// @param takerAddress Address of order taker.
    /// @param signature Proof that the orders was created by its maker.
    function assertFillableOrder(
        Order memory order,
        OrderInfo memory orderInfo,
        address takerAddress,
        bytes memory signature
    )
        internal
        view
    {
        // An order can only be filled if its status is FILLABLE.
        require(
            orderInfo.orderStatus == uint8(OrderStatus.FILLABLE),
            "ORDER_UNFILLABLE"
        );

        // Validate sender is allowed to fill this order
        if (order.senderAddress != address(0)) {
            require(
                order.senderAddress == msg.sender,
                "INVALID_SENDER"
            );
        }

        // Validate taker is allowed to fill this order
        if (order.takerAddress != address(0)) {
            require(
                order.takerAddress == takerAddress,
                "INVALID_TAKER"
            );
        }

        // Validate Maker signature (check only if first time seen)
        if (orderInfo.orderTakerAssetFilledAmount == 0) {
            require(
                isValidSignature(
                    orderInfo.orderHash,
                    order.makerAddress,
                    signature
                ),
                "INVALID_ORDER_SIGNATURE"
            );
        }
    }

    /// @dev Validates context for fillOrder. Succeeds or throws.
    /// @param order to be filled.
    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
    /// @param makerAssetFilledAmount Amount of makerAsset that will be transfered.
    function assertValidFill(
        Order memory order,
        OrderInfo memory orderInfo,
        uint256 takerAssetFillAmount,  // TODO: use FillResults
        uint256 takerAssetFilledAmount,
        uint256 makerAssetFilledAmount
    )
        internal
        view
    {
        // Revert if fill amount is invalid
        // TODO: reconsider necessity for v2.1
        require(
            takerAssetFillAmount != 0,
            "INVALID_TAKER_AMOUNT"
        );

        // Make sure taker does not pay more than desired amount
        // NOTE: This assertion should never fail, it is here
        //       as an extra defence against potential bugs.
        require(
            takerAssetFilledAmount <= takerAssetFillAmount,
            "TAKER_OVERPAY"
        );

        // Make sure order is not overfilled
        // NOTE: This assertion should never fail, it is here
        //       as an extra defence against potential bugs.
        require(
            safeAdd(orderInfo.orderTakerAssetFilledAmount, takerAssetFilledAmount) <= order.takerAssetAmount,
            "ORDER_OVERFILL"
        );

        // Make sure order is filled at acceptable price.
        // The order has an implied price from the makers perspective:
        //    order price = order.makerAssetAmount / order.takerAssetAmount
        // i.e. the number of makerAsset maker is paying per takerAsset. The
        // maker is guaranteed to get this price or a better (lower) one. The
        // actual price maker is getting in this fill is:
        //    fill price = makerAssetFilledAmount / takerAssetFilledAmount
        // We need `fill price <= order price` for the fill to be fair to maker.
        // This amounts to:
        //     makerAssetFilledAmount        order.makerAssetAmount
        //    ------------------------  <=  -----------------------
        //     takerAssetFilledAmount        order.takerAssetAmount
        // or, equivalently:
        //     makerAssetFilledAmount * order.takerAssetAmount <=
        //     order.makerAssetAmount * takerAssetFilledAmount
        // NOTE: This assertion should never fail, it is here
        //       as an extra defence against potential bugs.
        require(
            safeMul(makerAssetFilledAmount, order.takerAssetAmount)
            <=
            safeMul(order.makerAssetAmount, takerAssetFilledAmount),
            "INVALID_FILL_PRICE"
        );
    }

    /// @dev Validates context for cancelOrder. Succeeds or throws.
    /// @param order to be cancelled.
    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
    function assertValidCancel(
        Order memory order,
        OrderInfo memory orderInfo
    )
        internal
        view
    {
        // Ensure order is valid
        // An order can only be cancelled if its status is FILLABLE.
        require(
            orderInfo.orderStatus == uint8(OrderStatus.FILLABLE),
            "ORDER_UNFILLABLE"
        );

        // Validate sender is allowed to cancel this order
        if (order.senderAddress != address(0)) {
            require(
                order.senderAddress == msg.sender,
                "INVALID_SENDER"
            );
        }

        // Validate transaction signed by maker
        address makerAddress = getCurrentContextAddress();
        require(
            order.makerAddress == makerAddress,
            "INVALID_MAKER"
        );
    }

    /// @dev Calculates amounts filled and fees paid by maker and taker.
    /// @param order to be filled.
    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
    /// @return fillResults Amounts filled and fees paid by maker and taker.
    function calculateFillResults(
        Order memory order,
        uint256 takerAssetFilledAmount
    )
        internal
        pure
        returns (FillResults memory fillResults)
    {
        // Compute proportional transfer amounts
        fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
        fillResults.makerAssetFilledAmount = safeGetPartialAmountFloor(
            takerAssetFilledAmount,
            order.takerAssetAmount,
            order.makerAssetAmount
        );
        fillResults.makerFeePaid = safeGetPartialAmountFloor(
            fillResults.makerAssetFilledAmount,
            order.makerAssetAmount,
            order.makerFee
        );
        fillResults.takerFeePaid = safeGetPartialAmountFloor(
            takerAssetFilledAmount,
            order.takerAssetAmount,
            order.takerFee
        );

        return fillResults;
    }

    /// @dev Settles an order by transferring assets between counterparties.
    /// @param order Order struct containing order specifications.
    /// @param takerAddress Address selling takerAsset and buying makerAsset.
    /// @param fillResults Amounts to be filled and fees paid by maker and taker.
    function settleOrder(
        LibOrder.Order memory order,
        address takerAddress,
        LibFillResults.FillResults memory fillResults
    )
        private
    {
        bytes memory ethAssetData = ETH_ASSET_DATA;
        dispatchTransferFrom(
            order.makerAssetData,
            order.makerAddress,
            takerAddress,
            fillResults.makerAssetFilledAmount
        );
        dispatchTransferFrom(
            order.takerAssetData,
            takerAddress,
            order.makerAddress,
            fillResults.takerAssetFilledAmount
        );
        dispatchTransferFrom(
            ethAssetData,
            order.makerAddress,
            order.feeRecipientAddress,
            fillResults.makerFeePaid
        );
        dispatchTransferFrom(
            ethAssetData,
            takerAddress,
            order.feeRecipientAddress,
            fillResults.takerFeePaid
        );
    }
}

// File: @0x/contracts-utils/contracts/src/LibBytes.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.4.24;


library LibBytes {

    using LibBytes for bytes;

    /// @dev Gets the memory address for a byte array.
    /// @param input Byte array to lookup.
    /// @return memoryAddress Memory address of byte array. This
    ///         points to the header of the byte array which contains
    ///         the length.
    function rawAddress(bytes memory input)
        internal
        pure
        returns (uint256 memoryAddress)
    {
        assembly {
            memoryAddress := input
        }
        return memoryAddress;
    }
    
    /// @dev Gets the memory address for the contents of a byte array.
    /// @param input Byte array to lookup.
    /// @return memoryAddress Memory address of the contents of the byte array.
    function contentAddress(bytes memory input)
        internal
        pure
        returns (uint256 memoryAddress)
    {
        assembly {
            memoryAddress := add(input, 32)
        }
        return memoryAddress;
    }

    /// @dev Copies `length` bytes from memory location `source` to `dest`.
    /// @param dest memory address to copy bytes to.
    /// @param source memory address to copy bytes from.
    /// @param length number of bytes to copy.
    function memCopy(
        uint256 dest,
        uint256 source,
        uint256 length
    )
        internal
        pure
    {
        if (length < 32) {
            // Handle a partial word by reading destination and masking
            // off the bits we are interested in.
            // This correctly handles overlap, zero lengths and source == dest
            assembly {
                let mask := sub(exp(256, sub(32, length)), 1)
                let s := and(mload(source), not(mask))
                let d := and(mload(dest), mask)
                mstore(dest, or(s, d))
            }
        } else {
            // Skip the O(length) loop when source == dest.
            if (source == dest) {
                return;
            }

            // For large copies we copy whole words at a time. The final
            // word is aligned to the end of the range (instead of after the
            // previous) to handle partial words. So a copy will look like this:
            //
            //  ####
            //      ####
            //          ####
            //            ####
            //
            // We handle overlap in the source and destination range by
            // changing the copying direction. This prevents us from
            // overwriting parts of source that we still need to copy.
            //
            // This correctly handles source == dest
            //
            if (source > dest) {
                assembly {
                    // We subtract 32 from `sEnd` and `dEnd` because it
                    // is easier to compare with in the loop, and these
                    // are also the addresses we need for copying the
                    // last bytes.
                    length := sub(length, 32)
                    let sEnd := add(source, length)
                    let dEnd := add(dest, length)

                    // Remember the last 32 bytes of source
                    // This needs to be done here and not after the loop
                    // because we may have overwritten the last bytes in
                    // source already due to overlap.
                    let last := mload(sEnd)

                    // Copy whole words front to back
                    // Note: the first check is always true,
                    // this could have been a do-while loop.
                    // solhint-disable-next-line no-empty-blocks
                    for {} lt(source, sEnd) {} {
                        mstore(dest, mload(source))
                        source := add(source, 32)
                        dest := add(dest, 32)
                    }
                    
                    // Write the last 32 bytes
                    mstore(dEnd, last)
                }
            } else {
                assembly {
                    // We subtract 32 from `sEnd` and `dEnd` because those
                    // are the starting points when copying a word at the end.
                    length := sub(length, 32)
                    let sEnd := add(source, length)
                    let dEnd := add(dest, length)

                    // Remember the first 32 bytes of source
                    // This needs to be done here and not after the loop
                    // because we may have overwritten the first bytes in
                    // source already due to overlap.
                    let first := mload(source)

                    // Copy whole words back to front
                    // We use a signed comparisson here to allow dEnd to become
                    // negative (happens when source and dest < 32). Valid
                    // addresses in local memory will never be larger than
                    // 2**255, so they can be safely re-interpreted as signed.
                    // Note: the first check is always true,
                    // this could have been a do-while loop.
                    // solhint-disable-next-line no-empty-blocks
                    for {} slt(dest, dEnd) {} {
                        mstore(dEnd, mload(sEnd))
                        sEnd := sub(sEnd, 32)
                        dEnd := sub(dEnd, 32)
                    }
                    
                    // Write the first 32 bytes
                    mstore(dest, first)
                }
            }
        }
    }

    /// @dev Returns a slices from a byte array.
    /// @param b The byte array to take a slice from.
    /// @param from The starting index for the slice (inclusive).
    /// @param to The final index for the slice (exclusive).
    /// @return result The slice containing bytes at indices [from, to)
    function slice(
        bytes memory b,
        uint256 from,
        uint256 to
    )
        internal
        pure
        returns (bytes memory result)
    {
        require(
            from <= to,
            "FROM_LESS_THAN_TO_REQUIRED"
        );
        require(
            to < b.length,
            "TO_LESS_THAN_LENGTH_REQUIRED"
        );
        
        // Create a new bytes structure and copy contents
        result = new bytes(to - from);
        memCopy(
            result.contentAddress(),
            b.contentAddress() + from,
            result.length
        );
        return result;
    }
    
    /// @dev Returns a slice from a byte array without preserving the input.
    /// @param b The byte array to take a slice from. Will be destroyed in the process.
    /// @param from The starting index for the slice (inclusive).
    /// @param to The final index for the slice (exclusive).
    /// @return result The slice containing bytes at indices [from, to)
    /// @dev When `from == 0`, the original array will match the slice. In other cases its state will be corrupted.
    function sliceDestructive(
        bytes memory b,
        uint256 from,
        uint256 to
    )
        internal
        pure
        returns (bytes memory result)
    {
        require(
            from <= to,
            "FROM_LESS_THAN_TO_REQUIRED"
        );
        require(
            to < b.length,
            "TO_LESS_THAN_LENGTH_REQUIRED"
        );
        
        // Create a new bytes structure around [from, to) in-place.
        assembly {
            result := add(b, from)
            mstore(result, sub(to, from))
        }
        return result;
    }

    /// @dev Pops the last byte off of a byte array by modifying its length.
    /// @param b Byte array that will be modified.
    /// @return The byte that was popped off.
    function popLastByte(bytes memory b)
        internal
        pure
        returns (bytes1 result)
    {
        require(
            b.length > 0,
            "GREATER_THAN_ZERO_LENGTH_REQUIRED"
        );

        // Store last byte.
        result = b[b.length - 1];

        assembly {
            // Decrement length of byte array.
            let newLen := sub(mload(b), 1)
            mstore(b, newLen)
        }
        return result;
    }

    /// @dev Pops the last 20 bytes off of a byte array by modifying its length.
    /// @param b Byte array that will be modified.
    /// @return The 20 byte address that was popped off.
    function popLast20Bytes(bytes memory b)
        internal
        pure
        returns (address result)
    {
        require(
            b.length >= 20,
            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
        );

        // Store last 20 bytes.
        result = readAddress(b, b.length - 20);

        assembly {
            // Subtract 20 from byte array length.
            let newLen := sub(mload(b), 20)
            mstore(b, newLen)
        }
        return result;
    }

    /// @dev Tests equality of two byte arrays.
    /// @param lhs First byte array to compare.
    /// @param rhs Second byte array to compare.
    /// @return True if arrays are the same. False otherwise.
    function equals(
        bytes memory lhs,
        bytes memory rhs
    )
        internal
        pure
        returns (bool equal)
    {
        // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
        // We early exit on unequal lengths, but keccak would also correctly
        // handle this.
        return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
    }

    /// @dev Reads an address from a position in a byte array.
    /// @param b Byte array containing an address.
    /// @param index Index in byte array of address.
    /// @return address from byte array.
    function readAddress(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (address result)
    {
        require(
            b.length >= index + 20,  // 20 is length of address
            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
        );

        // Add offset to index:
        // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
        // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
        index += 20;

        // Read address from array memory
        assembly {
            // 1. Add index to address of bytes array
            // 2. Load 32-byte word from memory
            // 3. Apply 20-byte mask to obtain address
            result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
        }
        return result;
    }

    /// @dev Writes an address into a specific position in a byte array.
    /// @param b Byte array to insert address into.
    /// @param index Index in byte array of address.
    /// @param input Address to put into byte array.
    function writeAddress(
        bytes memory b,
        uint256 index,
        address input
    )
        internal
        pure
    {
        require(
            b.length >= index + 20,  // 20 is length of address
            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
        );

        // Add offset to index:
        // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
        // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
        index += 20;

        // Store address into array memory
        assembly {
            // The address occupies 20 bytes and mstore stores 32 bytes.
            // First fetch the 32-byte word where we'll be storing the address, then
            // apply a mask so we have only the bytes in the word that the address will not occupy.
            // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.

            // 1. Add index to address of bytes array
            // 2. Load 32-byte word from memory
            // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
            let neighbors := and(
                mload(add(b, index)),
                0xffffffffffffffffffffffff0000000000000000000000000000000000000000
            )
            
            // Make sure input address is clean.
            // (Solidity does not guarantee this)
            input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)

            // Store the neighbors and address into memory
            mstore(add(b, index), xor(input, neighbors))
        }
    }

    /// @dev Reads a bytes32 value from a position in a byte array.
    /// @param b Byte array containing a bytes32 value.
    /// @param index Index in byte array of bytes32 value.
    /// @return bytes32 value from byte array.
    function readBytes32(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (bytes32 result)
    {
        require(
            b.length >= index + 32,
            "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED"
        );

        // Arrays are prefixed by a 256 bit length parameter
        index += 32;

        // Read the bytes32 from array memory
        assembly {
            result := mload(add(b, index))
        }
        return result;
    }

    /// @dev Writes a bytes32 into a specific position in a byte array.
    /// @param b Byte array to insert <input> into.
    /// @param index Index in byte array of <input>.
    /// @param input bytes32 to put into byte array.
    function writeBytes32(
        bytes memory b,
        uint256 index,
        bytes32 input
    )
        internal
        pure
    {
        require(
            b.length >= index + 32,
            "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED"
        );

        // Arrays are prefixed by a 256 bit length parameter
        index += 32;

        // Read the bytes32 from array memory
        assembly {
            mstore(add(b, index), input)
        }
    }

    /// @dev Reads a uint256 value from a position in a byte array.
    /// @param b Byte array containing a uint256 value.
    /// @param index Index in byte array of uint256 value.
    /// @return uint256 value from byte array.
    function readUint256(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (uint256 result)
    {
        result = uint256(readBytes32(b, index));
        return result;
    }

    /// @dev Writes a uint256 into a specific position in a byte array.
    /// @param b Byte array to insert <input> into.
    /// @param index Index in byte array of <input>.
    /// @param input uint256 to put into byte array.
    function writeUint256(
        bytes memory b,
        uint256 index,
        uint256 input
    )
        internal
        pure
    {
        writeBytes32(b, index, bytes32(input));
    }

    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
    /// @param b Byte array containing a bytes4 value.
    /// @param index Index in byte array of bytes4 value.
    /// @return bytes4 value from byte array.
    function readBytes4(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (bytes4 result)
    {
        require(
            b.length >= index + 4,
            "GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED"
        );

        // Arrays are prefixed by a 32 byte length field
        index += 32;

        // Read the bytes4 from array memory
        assembly {
            result := mload(add(b, index))
            // Solidity does not require us to clean the trailing bytes.
            // We do it anyway
            result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
        }
        return result;
    }

    /// @dev Reads nested bytes from a specific position.
    /// @dev NOTE: the returned value overlaps with the input value.
    ///            Both should be treated as immutable.
    /// @param b Byte array containing nested bytes.
    /// @param index Index of nested bytes.
    /// @return result Nested bytes.
    function readBytesWithLength(
        bytes memory b,
        uint256 index
    )
        internal
        pure
        returns (bytes memory result)
    {
        // Read length of nested bytes
        uint256 nestedBytesLength = readUint256(b, index);
        index += 32;

        // Assert length of <b> is valid, given
        // length of nested bytes
        require(
            b.length >= index + nestedBytesLength,
            "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED"
        );
        
        // Return a pointer to the byte array as it exists inside `b`
        assembly {
            result := add(b, index)
        }
        return result;
    }

    /// @dev Inserts bytes at a specific position in a byte array.
    /// @param b Byte array to insert <input> into.
    /// @param index Index in byte array of <input>.
    /// @param input bytes to insert.
    function writeBytesWithLength(
        bytes memory b,
        uint256 index,
        bytes memory input
    )
        internal
        pure
    {
        // Assert length of <b> is valid, given
        // length of input
        require(
            b.length >= index + 32 + input.length,  // 32 bytes to store length
            "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED"
        );

        // Copy <input> into <b>
        memCopy(
            b.contentAddress() + index,
            input.rawAddress(), // includes length of <input>
            input.length + 32   // +32 bytes to store <input> length
        );
    }

    /// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
    /// @param dest Byte array that will be overwritten with source bytes.
    /// @param source Byte array to copy onto dest bytes.
    function deepCopyBytes(
        bytes memory dest,
        bytes memory source
    )
        internal
        pure
    {
        uint256 sourceLen = source.length;
        // Dest length must be >= source length, or some bytes would not be copied.
        require(
            dest.length >= sourceLen,
            "GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED"
        );
        memCopy(
            dest.contentAddress(),
            source.contentAddress(),
            sourceLen
        );
    }
}

// File: contracts/exchange/interfaces/IWallet.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract IWallet {

    /// @dev Verifies that a signature is valid.
    /// @param hash Message hash that is signed.
    /// @param signature Proof of signing.
    /// @return Validity of order signature.
    function isValidSignature(
        bytes32 hash,
        bytes signature
    )
        external
        view
        returns (bool isValid);
}

// File: contracts/exchange/interfaces/IValidator.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract IValidator {

    /// @dev Verifies that a signature is valid.
    /// @param hash Message hash that is signed.
    /// @param signerAddress Address that should have signed the given hash.
    /// @param signature Proof of signing.
    /// @return Validity of order signature.
    function isValidSignature(
        bytes32 hash,
        address signerAddress,
        bytes signature
    )
        external
        view
        returns (bool isValid);
}

// File: contracts/exchange/MixinSignatureValidator.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MixinSignatureValidator is
    ReentrancyGuard,
    MSignatureValidator,
    MTransactions
{
    using LibBytes for bytes;

    // Mapping of hash => signer => signed
    mapping (bytes32 => mapping (address => bool)) public preSigned;

    // Mapping of signer => validator => approved
    mapping (address => mapping (address => bool)) public allowedValidators;

    /// @dev Approves a hash on-chain using any valid signature type.
    ///      After presigning a hash, the preSign signature type will become valid for that hash and signer.
    /// @param signerAddress Address that should have signed the given hash.
    /// @param signature Proof that the hash has been signed by signer.
    function preSign(
        bytes32 hash,
        address signerAddress,
        bytes signature
    )
        external
    {
        if (signerAddress != msg.sender) {
            require(
                isValidSignature(
                    hash,
                    signerAddress,
                    signature
                ),
                "INVALID_SIGNATURE"
            );
        }
        preSigned[hash][signerAddress] = true;
    }

    /// @dev Approves/unnapproves a Validator contract to verify signatures on signer's behalf.
    /// @param validatorAddress Address of Validator contract.
    /// @param approval Approval or disapproval of  Validator contract.
    function setSignatureValidatorApproval(
        address validatorAddress,
        bool approval
    )
        external
        nonReentrant
    {
        address signerAddress = getCurrentContextAddress();
        allowedValidators[signerAddress][validatorAddress] = approval;
        emit SignatureValidatorApproval(
            signerAddress,
            validatorAddress,
            approval
        );
    }

    /// @dev Verifies that a hash has been signed by the given signer.
    /// @param hash Any 32 byte hash.
    /// @param signerAddress Address that should have signed the given hash.
    /// @param signature Proof that the hash has been signed by signer.
    /// @return True if the address recovered from the provided signature matches the input signer address.
    function isValidSignature(
        bytes32 hash,
        address signerAddress,
        bytes memory signature
    )
        public
        view
        returns (bool isValid)
    {
        require(
            signature.length > 0,
            "LENGTH_GREATER_THAN_0_REQUIRED"
        );

        // Pop last byte off of signature byte array.
        uint8 signatureTypeRaw = uint8(signature.popLastByte());

        // Ensure signature is supported
        require(
            signatureTypeRaw < uint8(SignatureType.NSignatureTypes),
            "SIGNATURE_UNSUPPORTED"
        );

        SignatureType signatureType = SignatureType(signatureTypeRaw);

        // Variables are not scoped in Solidity.
        uint8 v;
        bytes32 r;
        bytes32 s;
        address recovered;

        // Always illegal signature.
        // This is always an implicit option since a signer can create a
        // signature array with invalid type or length. We may as well make
        // it an explicit option. This aids testing and analysis. It is
        // also the initialization value for the enum type.
        if (signatureType == SignatureType.Illegal) {
            revert("SIGNATURE_ILLEGAL");

        // Always invalid signature.
        // Like Illegal, this is always implicitly available and therefore
        // offered explicitly. It can be implicitly created by providing
        // a correctly formatted but incorrect signature.
        } else if (signatureType == SignatureType.Invalid) {
            require(
                signature.length == 0,
                "LENGTH_0_REQUIRED"
            );
            isValid = false;
            return isValid;

        // Signature using EIP712
        } else if (signatureType == SignatureType.EIP712) {
            require(
                signature.length == 65,
                "LENGTH_65_REQUIRED"
            );
            v = uint8(signature[0]);
            r = signature.readBytes32(1);
            s = signature.readBytes32(33);
            recovered = ecrecover(
                hash,
                v,
                r,
                s
            );
            isValid = signerAddress == recovered;
            return isValid;

        // Signed using web3.eth_sign
        } else if (signatureType == SignatureType.EthSign) {
            require(
                signature.length == 65,
                "LENGTH_65_REQUIRED"
            );
            v = uint8(signature[0]);
            r = signature.readBytes32(1);
            s = signature.readBytes32(33);
            recovered = ecrecover(
                keccak256(abi.encodePacked(
                    "\x19Ethereum Signed Message:\n32",
                    hash
                )),
                v,
                r,
                s
            );
            isValid = signerAddress == recovered;
            return isValid;

        // Signature verified by wallet contract.
        // If used with an order, the maker of the order is the wallet contract.
        } else if (signatureType == SignatureType.Wallet) {
            isValid = isValidWalletSignature(
                hash,
                signerAddress,
                signature
            );
            return isValid;

        // Signature verified by validator contract.
        // If used with an order, the maker of the order can still be an EOA.
        // A signature using this type should be encoded as:
        // | Offset   | Length | Contents                        |
        // | 0x00     | x      | Signature to validate           |
        // | 0x00 + x | 20     | Address of validator contract   |
        // | 0x14 + x | 1      | Signature type is always "\x06" |
        } else if (signatureType == SignatureType.Validator) {
            // Pop last 20 bytes off of signature byte array.
            address validatorAddress = signature.popLast20Bytes();

            // Ensure signer has approved validator.
            if (!allowedValidators[signerAddress][validatorAddress]) {
                return false;
            }
            isValid = isValidValidatorSignature(
                validatorAddress,
                hash,
                signerAddress,
                signature
            );
            return isValid;

        // Signer signed hash previously using the preSign function.
        } else if (signatureType == SignatureType.PreSigned) {
            isValid = preSigned[hash][signerAddress];
            return isValid;
        }

        // Anything else is illegal (We do not return false because
        // the signature may actually be valid, just not in a format
        // that we currently support. In this case returning false
        // may lead the caller to incorrectly believe that the
        // signature was invalid.)
        revert("SIGNATURE_UNSUPPORTED");
    }

    /// @dev Verifies signature using logic defined by Wallet contract.
    /// @param hash Any 32 byte hash.
    /// @param walletAddress Address that should have signed the given hash
    ///                      and defines its own signature verification method.
    /// @param signature Proof that the hash has been signed by signer.
    /// @return True if signature is valid for given wallet..
    function isValidWalletSignature(
        bytes32 hash,
        address walletAddress,
        bytes signature
    )
        internal
        view
        returns (bool isValid)
    {
        bytes memory calldata = abi.encodeWithSelector(
            IWallet(walletAddress).isValidSignature.selector,
            hash,
            signature
        );
        bytes32 magic_salt = bytes32(bytes4(keccak256("isValidWalletSignature(bytes32,address,bytes)")));
        assembly {
            if iszero(extcodesize(walletAddress)) {
                // Revert with `Error("WALLET_ERROR")`
                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(64, 0x0000000c57414c4c45545f4552524f5200000000000000000000000000000000)
                mstore(96, 0)
                revert(0, 100)
            }

            let cdStart := add(calldata, 32)
            let success := staticcall(
                gas,              // forward all gas
                walletAddress,    // address of Wallet contract
                cdStart,          // pointer to start of input
                mload(calldata),  // length of input
                cdStart,          // write output over input
                32                // output size is 32 bytes
            )

            if iszero(eq(returndatasize(), 32)) {
                // Revert with `Error("WALLET_ERROR")`
                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(64, 0x0000000c57414c4c45545f4552524f5200000000000000000000000000000000)
                mstore(96, 0)
                revert(0, 100)
            }

            switch success
            case 0 {
                // Revert with `Error("WALLET_ERROR")`
                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(64, 0x0000000c57414c4c45545f4552524f5200000000000000000000000000000000)
                mstore(96, 0)
                revert(0, 100)
            }
            case 1 {
                // Signature is valid if call did not revert and returned true
                isValid := eq(
                    and(mload(cdStart), 0xffffffff00000000000000000000000000000000000000000000000000000000),
                    and(magic_salt, 0xffffffff00000000000000000000000000000000000000000000000000000000)
                )
            }
        }
        return isValid;
    }

    /// @dev Verifies signature using logic defined by Validator contract.
    /// @param validatorAddress Address of validator contract.
    /// @param hash Any 32 byte hash.
    /// @param signerAddress Address that should have signed the given hash.
    /// @param signature Proof that the hash has been signed by signer.
    /// @return True if the address recovered from the provided signature matches the input signer address.
    function isValidValidatorSignature(
        address validatorAddress,
        bytes32 hash,
        address signerAddress,
        bytes signature
    )
        internal
        view
        returns (bool isValid)
    {
        bytes memory calldata = abi.encodeWithSelector(
            IValidator(signerAddress).isValidSignature.selector,
            hash,
            signerAddress,
            signature
        );
        bytes32 magic_salt = bytes32(bytes4(keccak256("isValidValidatorSignature(address,bytes32,address,bytes)")));
        assembly {
            if iszero(extcodesize(validatorAddress)) {
                // Revert with `Error("VALIDATOR_ERROR")`
                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(64, 0x0000000f56414c494441544f525f4552524f5200000000000000000000000000)
                mstore(96, 0)
                revert(0, 100)
            }

            let cdStart := add(calldata, 32)
            let success := staticcall(
                gas,               // forward all gas
                validatorAddress,  // address of Validator contract
                cdStart,           // pointer to start of input
                mload(calldata),   // length of input
                cdStart,           // write output over input
                32                 // output size is 32 bytes
            )

            if iszero(eq(returndatasize(), 32)) {
                // Revert with `Error("VALIDATOR_ERROR")`
                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(64, 0x0000000f56414c494441544f525f4552524f5200000000000000000000000000)
                mstore(96, 0)
                revert(0, 100)
            }

            switch success
            case 0 {
                // Revert with `Error("VALIDATOR_ERROR")`
                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(64, 0x0000000f56414c494441544f525f4552524f5200000000000000000000000000)
                mstore(96, 0)
                revert(0, 100)
            }
            case 1 {
                // Signature is valid if call did not revert and returned true
                isValid := eq(
                    and(mload(cdStart), 0xffffffff00000000000000000000000000000000000000000000000000000000),
                    and(magic_salt, 0xffffffff00000000000000000000000000000000000000000000000000000000)
                )
            }
        }
        return isValid;
    }
}

// File: contracts/exchange/MixinWrapperFunctions.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MixinWrapperFunctions is
    ReentrancyGuard,
    LibMath,
    MExchangeCore
{
    /// @dev Synchronously cancels multiple orders in a single transaction.
    /// @param orders Array of order specifications.
    function batchCancelOrders(LibOrder.Order[] memory orders)
        public
        nonReentrant
    {
        uint256 ordersLength = orders.length;
        for (uint256 i = 0; i != ordersLength; i++) {
            cancelOrderInternal(orders[i]);
        }
    }

    /// @dev Fetches information for all passed in orders.
    /// @param orders Array of order specifications.
    /// @return Array of OrderInfo instances that correspond to each order.
    function getOrdersInfo(LibOrder.Order[] memory orders)
        public
        view
        returns (LibOrder.OrderInfo[] memory)
    {
        uint256 ordersLength = orders.length;
        LibOrder.OrderInfo[] memory ordersInfo = new LibOrder.OrderInfo[](ordersLength);
        for (uint256 i = 0; i != ordersLength; i++) {
            ordersInfo[i] = getOrderInfo(orders[i]);
        }
        return ordersInfo;
    }

}

// File: @0x/contracts-utils/contracts/src/interfaces/IOwnable.sol

pragma solidity ^0.4.24;


contract IOwnable {

    function transferOwnership(address newOwner)
        public;
}

// File: @0x/contracts-asset-proxy/contracts/src/interfaces/IAuthorizable.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.4.24;



contract IAuthorizable is
    IOwnable
{
    /// @dev Authorizes an address.
    /// @param target Address to authorize.
    function addAuthorizedAddress(address target)
        external;

    /// @dev Removes authorizion of an address.
    /// @param target Address to remove authorization from.
    function removeAuthorizedAddress(address target)
        external;

    /// @dev Removes authorizion of an address.
    /// @param target Address to remove authorization from.
    /// @param index Index of target in authorities array.
    function removeAuthorizedAddressAtIndex(
        address target,
        uint256 index
    )
        external;
    
    /// @dev Gets all authorized addresses.
    /// @return Array of authorized addresses.
    function getAuthorizedAddresses()
        external
        view
        returns (address[] memory);
}

// File: @0x/contracts-asset-proxy/contracts/src/interfaces/IAssetProxy.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity ^0.4.24;



contract IAssetProxy is
    IAuthorizable
{
    /// @dev Transfers assets. Either succeeds or throws.
    /// @param assetData Byte array encoded for the respective asset proxy.
    /// @param from Address to transfer asset from.
    /// @param to Address to transfer asset to.
    /// @param amount Amount of asset to transfer.
    function transferFrom(
        bytes assetData,
        address from,
        address to,
        uint256 amount
    )
        external;
    
    /// @dev Gets the proxy id associated with the proxy address.
    /// @return Proxy id.
    function getProxyId()
        external
        pure
        returns (bytes4);
}

// File: contracts/exchange/MixinAssetProxyDispatcher.sol

/*

  Modified by Metaps Alpha Inc.

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MixinAssetProxyDispatcher is
    DepositManager,
    LibConstants,
    MAssetProxyDispatcher
{
    // Mapping from Asset Proxy Id's to their respective Asset Proxy
    mapping (bytes4 => IAssetProxy) public assetProxies;

    /// @dev Registers an asset proxy to its asset proxy id.
    ///      Once an asset proxy is registered, it cannot be unregistered.
    /// @param assetProxy Address of new asset proxy to register.
    function registerAssetProxy(address assetProxy)
        external
        onlyOwner
    {
        IAssetProxy assetProxyContract = IAssetProxy(assetProxy);

        // Ensure that no asset proxy exists with current id.
        bytes4 assetProxyId = assetProxyContract.getProxyId();
        address currentAssetProxy = assetProxies[assetProxyId];
        require(
            currentAssetProxy == address(0),
            "ASSET_PROXY_ALREADY_EXISTS"
        );

        // Add asset proxy and log registration.
        assetProxies[assetProxyId] = assetProxyContract;
        emit AssetProxyRegistered(
            assetProxyId,
            assetProxy
        );
    }

    /// @dev Gets an asset proxy.
    /// @param assetProxyId Id of the asset proxy.
    /// @return The asset proxy registered to assetProxyId. Returns 0x0 if no proxy is registered.
    function getAssetProxy(bytes4 assetProxyId)
        external
        view
        returns (address)
    {
        return assetProxies[assetProxyId];
    }

    /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
    /// @param assetData Byte array encoded for the asset.
    /// @param from Address to transfer token from.
    /// @param to Address to transfer token to.
    /// @param amount Amount of token to transfer.
    function dispatchTransferFrom(
        bytes memory assetData,
        address from,
        address to,
        uint256 amount
    )
        internal
    {
        // Do nothing if no amount should be transferred.
        if (amount > 0 && from != to) {
            // Ensure assetData length is valid
            require(
                assetData.length > 3,
                "LENGTH_GREATER_THAN_3_REQUIRED"
            );

            // miime - If assetData is for ETH, send ETH from deposit.
            if (keccak256(assetData) == KECCAK256_ETH_ASSET_DATA) {
                require(
                    depositAmount[from] >= amount,
                    "DEPOSIT_AMOUNT_IS_INSUFFICIENT"
                );
                uint256 afterBalance = safeSub(depositAmount[from], amount);
                depositAmount[from] = afterBalance;
                if (to != address(this)) {
                    if (!to.call.gas(TRANSFER_GAS_LIMIT).value(amount)()) {
                        revert("ETH_SENDING_FAILED");
                    }
                }
                return;
            }

            // Lookup assetProxy. We do not use `LibBytes.readBytes4` for gas efficiency reasons.
            bytes4 assetProxyId;
            assembly {
                assetProxyId := and(mload(
                    add(assetData, 32)),
                    0xFFFFFFFF00000000000000000000000000000000000000000000000000000000
                )
            }
            address assetProxy = assetProxies[assetProxyId];

            // Ensure that assetProxy exists
            require(
                assetProxy != address(0),
                "ASSET_PROXY_DOES_NOT_EXIST"
            );
            
            // We construct calldata for the `assetProxy.transferFrom` ABI.
            // The layout of this calldata is in the table below.
            // 
            // | Area     | Offset | Length  | Contents                                    |
            // | -------- |--------|---------|-------------------------------------------- |
            // | Header   | 0      | 4       | function selector                           |
            // | Params   |        | 4 * 32  | function parameters:                        |
            // |          | 4      |         |   1. offset to assetData (*)                |
            // |          | 36     |         |   2. from                                   |
            // |          | 68     |         |   3. to                                     |
            // |          | 100    |         |   4. amount                                 |
            // | Data     |        |         | assetData:                                  |
            // |          | 132    | 32      | assetData Length                            |
            // |          | 164    | **      | assetData Contents                          |

            assembly {
                /////// Setup State ///////
                // `cdStart` is the start of the calldata for `assetProxy.transferFrom` (equal to free memory ptr).
                let cdStart := mload(64)
                // `dataAreaLength` is the total number of words needed to store `assetData`
                //  As-per the ABI spec, this value is padded up to the nearest multiple of 32,
                //  and includes 32-bytes for length.
                let dataAreaLength := and(add(mload(assetData), 63), 0xFFFFFFFFFFFE0)
                // `cdEnd` is the end of the calldata for `assetProxy.transferFrom`.
                let cdEnd := add(cdStart, add(132, dataAreaLength))

                
                /////// Setup Header Area ///////
                // This area holds the 4-byte `transferFromSelector`.
                // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
                mstore(cdStart, 0xa85e59e400000000000000000000000000000000000000000000000000000000)
                
                /////// Setup Params Area ///////
                // Each parameter is padded to 32-bytes. The entire Params Area is 128 bytes.
                // Notes:
                //   1. The offset to `assetData` is the length of the Params Area (128 bytes).
                //   2. A 20-byte mask is applied to addresses to zero-out the unused bytes.
                mstore(add(cdStart, 4), 128)
                mstore(add(cdStart, 36), and(from, 0xffffffffffffffffffffffffffffffffffffffff))
                mstore(add(cdStart, 68), and(to, 0xffffffffffffffffffffffffffffffffffffffff))
                mstore(add(cdStart, 100), amount)
                
                /////// Setup Data Area ///////
                // This area holds `assetData`.
                let dataArea := add(cdStart, 132)
                // solhint-disable-next-line no-empty-blocks
                for {} lt(dataArea, cdEnd) {} {
                    mstore(dataArea, mload(assetData))
                    dataArea := add(dataArea, 32)
                    assetData := add(assetData, 32)
                }

                /////// Call `assetProxy.transferFrom` using the constructed calldata ///////
                let success := call(
                    gas,                    // forward all gas
                    assetProxy,             // call address of asset proxy
                    0,                      // don't send any ETH
                    cdStart,                // pointer to start of input
                    sub(cdEnd, cdStart),    // length of input  
                    cdStart,                // write output over input
                    512                     // reserve 512 bytes for output
                )
                if iszero(success) {
                    revert(cdStart, returndatasize())
                }
            }
        }
    }
}

// File: @0x/contracts-exchange-libs/contracts/src/LibExchangeErrors.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

// solhint-disable
pragma solidity ^0.4.24;


/// @dev This contract documents the revert reasons used in the Exchange contract.
/// This contract is intended to serve as a reference, but is not actually used for efficiency reasons.
contract LibExchangeErrors {

    /// Order validation errors ///
    string constant ORDER_UNFILLABLE = "ORDER_UNFILLABLE";                              // Order cannot be filled.
    string constant INVALID_MAKER = "INVALID_MAKER";                                    // Invalid makerAddress.
    string constant INVALID_TAKER = "INVALID_TAKER";                                    // Invalid takerAddress.
    string constant INVALID_SENDER = "INVALID_SENDER";                                  // Invalid `msg.sender`.
    string constant INVALID_ORDER_SIGNATURE = "INVALID_ORDER_SIGNATURE";                // Signature validation failed. 
    
    /// fillOrder validation errors ///
    string constant INVALID_TAKER_AMOUNT = "INVALID_TAKER_AMOUNT";                      // takerAssetFillAmount cannot equal 0.
    string constant ROUNDING_ERROR = "ROUNDING_ERROR";                                  // Rounding error greater than 0.1% of takerAssetFillAmount. 
    
    /// Signature validation errors ///
    string constant INVALID_SIGNATURE = "INVALID_SIGNATURE";                            // Signature validation failed. 
    string constant SIGNATURE_ILLEGAL = "SIGNATURE_ILLEGAL";                            // Signature type is illegal.
    string constant SIGNATURE_UNSUPPORTED = "SIGNATURE_UNSUPPORTED";                    // Signature type unsupported.
    
    /// cancelOrdersUptTo errors ///
    string constant INVALID_NEW_ORDER_EPOCH = "INVALID_NEW_ORDER_EPOCH";                // Specified salt must be greater than or equal to existing orderEpoch.

    /// fillOrKillOrder errors ///
    string constant COMPLETE_FILL_FAILED = "COMPLETE_FILL_FAILED";                      // Desired takerAssetFillAmount could not be completely filled. 

    /// matchOrders errors ///
    string constant NEGATIVE_SPREAD_REQUIRED = "NEGATIVE_SPREAD_REQUIRED";              // Matched orders must have a negative spread.

    /// Transaction errors ///
    string constant REENTRANCY_ILLEGAL = "REENTRANCY_ILLEGAL";                          // Recursive reentrancy is not allowed. 
    string constant INVALID_TX_HASH = "INVALID_TX_HASH";                                // Transaction has already been executed. 
    string constant INVALID_TX_SIGNATURE = "INVALID_TX_SIGNATURE";                      // Signature validation failed. 
    string constant FAILED_EXECUTION = "FAILED_EXECUTION";                              // Transaction execution failed. 
    
    /// registerAssetProxy errors ///
    string constant ASSET_PROXY_ALREADY_EXISTS = "ASSET_PROXY_ALREADY_EXISTS";          // AssetProxy with same id already exists.

    /// dispatchTransferFrom errors ///
    string constant ASSET_PROXY_DOES_NOT_EXIST = "ASSET_PROXY_DOES_NOT_EXIST";          // No assetProxy registered at given id.
    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                                // Asset transfer unsuccesful.

    /// Length validation errors ///
    string constant LENGTH_GREATER_THAN_0_REQUIRED = "LENGTH_GREATER_THAN_0_REQUIRED";  // Byte array must have a length greater than 0.
    string constant LENGTH_GREATER_THAN_3_REQUIRED = "LENGTH_GREATER_THAN_3_REQUIRED";  // Byte array must have a length greater than 3.
    string constant LENGTH_0_REQUIRED = "LENGTH_0_REQUIRED";                            // Byte array must have a length of 0.
    string constant LENGTH_65_REQUIRED = "LENGTH_65_REQUIRED";                          // Byte array must have a length of 65.
}

// File: contracts/exchange/MixinTransactions.sol

/*

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


contract MixinTransactions is
    LibEIP712,
    MSignatureValidator,
    MTransactions
{
    // Mapping of transaction hash => executed
    // This prevents transactions from being executed more than once.
    mapping (bytes32 => bool) public transactions;

    // Address of current transaction signer
    address public currentContextAddress;

    /// @dev Executes an exchange method call in the context of signer.
    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
    /// @param signerAddress Address of transaction signer.
    /// @param data AbiV2 encoded calldata.
    /// @param signature Proof of signer transaction by signer.
    function executeTransaction(
        uint256 salt,
        address signerAddress,
        bytes data,
        bytes signature
    )
        external
    {
        // Prevent reentrancy
        require(
            currentContextAddress == address(0),
            "REENTRANCY_ILLEGAL"
        );

        bytes32 transactionHash = hashEIP712Message(hashZeroExTransaction(
            salt,
            signerAddress,
            data
        ));

        // Validate transaction has not been executed
        require(
            !transactions[transactionHash],
            "INVALID_TX_HASH"
        );

        // Transaction always valid if signer is sender of transaction
        if (signerAddress != msg.sender) {
            // Validate signature
            require(
                isValidSignature(
                    transactionHash,
                    signerAddress,
                    signature
                ),
                "INVALID_TX_SIGNATURE"
            );

            // Set the current transaction signer
            currentContextAddress = signerAddress;
        }

        // Execute transaction
        transactions[transactionHash] = true;
        require(
            address(this).delegatecall(data),
            "FAILED_EXECUTION"
        );

        // Reset current transaction signer if it was previously updated
        if (signerAddress != msg.sender) {
            currentContextAddress = address(0);
        }
    }

    /// @dev Calculates EIP712 hash of the Transaction.
    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
    /// @param signerAddress Address of transaction signer.
    /// @param data AbiV2 encoded calldata.
    /// @return EIP712 hash of the Transaction.
    function hashZeroExTransaction(
        uint256 salt,
        address signerAddress,
        bytes memory data
    )
        internal
        pure
        returns (bytes32 result)
    {
        bytes32 schemaHash = EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH;
        bytes32 dataHash = keccak256(data);

        // Assembly for more efficiently computing:
        // keccak256(abi.encodePacked(
        //     EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH,
        //     salt,
        //     bytes32(signerAddress),
        //     keccak256(data)
        // ));

        assembly {
            // Load free memory pointer
            let memPtr := mload(64)

            mstore(memPtr, schemaHash)                                                               // hash of schema
            mstore(add(memPtr, 32), salt)                                                            // salt
            mstore(add(memPtr, 64), and(signerAddress, 0xffffffffffffffffffffffffffffffffffffffff))  // signerAddress
            mstore(add(memPtr, 96), dataHash)                                                        // hash of data

            // Compute hash
            result := keccak256(memPtr, 128)
        }
        return result;
    }

    /// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
    ///      If calling a fill function, this address will represent the taker.
    ///      If calling a cancel function, this address will represent the maker.
    /// @return Signer of 0x transaction if entry point is `executeTransaction`.
    ///         `msg.sender` if entry point is any other function.
    function getCurrentContextAddress()
        internal
        view
        returns (address)
    {
        address currentContextAddress_ = currentContextAddress;
        address contextAddress = currentContextAddress_ == address(0) ? msg.sender : currentContextAddress_;
        return contextAddress;
    }
}

// File: contracts/exchange/Exchange.sol

/*

  Modified by Metaps Alpha Inc.

  Copyright 2018 ZeroEx Intl.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

*/

pragma solidity 0.4.24;


// solhint-disable no-empty-blocks
contract Exchange is
    MixinExchangeCore,
    MixinSignatureValidator,
    MixinTransactions,
    MixinWrapperFunctions,
    MixinAssetProxyDispatcher
{
    string constant public VERSION = "2.0.1-alpha-miime";

    // Mixins are instantiated in the order they are inherited
    constructor ()
        public
        MixinExchangeCore()
        MixinSignatureValidator()
        MixinTransactions()
        MixinAssetProxyDispatcher()
        MixinWrapperFunctions()
    {}
}