// hevm: flattened sources of src/vox.sol
pragma solidity ^0.4.18;

////// lib/ds-guard/lib/ds-auth/src/auth.sol
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

/* pragma solidity ^0.4.13; */

contract DSAuthority {
    function canCall(
        address src, address dst, bytes4 sig
    ) public view returns (bool);
}

contract DSAuthEvents {
    event LogSetAuthority (address indexed authority);
    event LogSetOwner     (address indexed owner);
}

contract DSAuth is DSAuthEvents {
    DSAuthority  public  authority;
    address      public  owner;

    function DSAuth() public {
        owner = msg.sender;
        LogSetOwner(msg.sender);
    }

    function setOwner(address owner_)
        public
        auth
    {
        owner = owner_;
        LogSetOwner(owner);
    }

    function setAuthority(DSAuthority authority_)
        public
        auth
    {
        authority = authority_;
        LogSetAuthority(authority);
    }

    modifier auth {
        require(isAuthorized(msg.sender, msg.sig));
        _;
    }

    function isAuthorized(address src, bytes4 sig) internal view returns (bool) {
        if (src == address(this)) {
            return true;
        } else if (src == owner) {
            return true;
        } else if (authority == DSAuthority(0)) {
            return false;
        } else {
            return authority.canCall(src, this, sig);
        }
    }
}

////// lib/ds-spell/lib/ds-note/src/note.sol
/// note.sol -- the `note' modifier, for logging calls as events

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

/* pragma solidity ^0.4.13; */

contract DSNote {
    event LogNote(
        bytes4   indexed  sig,
        address  indexed  guy,
        bytes32  indexed  foo,
        bytes32  indexed  bar,
        uint              wad,
        bytes             fax
    ) anonymous;

    modifier note {
        bytes32 foo;
        bytes32 bar;

        assembly {
            foo := calldataload(4)
            bar := calldataload(36)
        }

        LogNote(msg.sig, msg.sender, foo, bar, msg.value, msg.data);

        _;
    }
}

////// lib/ds-thing/lib/ds-math/src/math.sol
/// math.sol -- mixin for inline numerical wizardry

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

/* pragma solidity ^0.4.13; */

contract DSMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x);
    }
    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x);
    }
    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x);
    }

    function min(uint x, uint y) internal pure returns (uint z) {
        return x <= y ? x : y;
    }
    function max(uint x, uint y) internal pure returns (uint z) {
        return x >= y ? x : y;
    }
    function imin(int x, int y) internal pure returns (int z) {
        return x <= y ? x : y;
    }
    function imax(int x, int y) internal pure returns (int z) {
        return x >= y ? x : y;
    }

    uint constant WAD = 10 ** 18;
    uint constant RAY = 10 ** 27;

    function wmul(uint x, uint y) internal pure returns (uint z) {
        z = add(mul(x, y), WAD / 2) / WAD;
    }
    function rmul(uint x, uint y) internal pure returns (uint z) {
        z = add(mul(x, y), RAY / 2) / RAY;
    }
    function wdiv(uint x, uint y) internal pure returns (uint z) {
        z = add(mul(x, WAD), y / 2) / y;
    }
    function rdiv(uint x, uint y) internal pure returns (uint z) {
        z = add(mul(x, RAY), y / 2) / y;
    }

    // This famous algorithm is called "exponentiation by squaring"
    // and calculates x^n with x as fixed-point and n as regular unsigned.
    //
    // It's O(log n), instead of O(n) for naive repeated multiplication.
    //
    // These facts are why it works:
    //
    //  If n is even, then x^n = (x^2)^(n/2).
    //  If n is odd,  then x^n = x * x^(n-1),
    //   and applying the equation for even x gives
    //    x^n = x * (x^2)^((n-1) / 2).
    //
    //  Also, EVM division is flooring and
    //    floor[(n-1) / 2] = floor[n / 2].
    //
    function rpow(uint x, uint n) internal pure returns (uint z) {
        z = n % 2 != 0 ? x : RAY;

        for (n /= 2; n != 0; n /= 2) {
            x = rmul(x, x);

            if (n % 2 != 0) {
                z = rmul(z, x);
            }
        }
    }
}

////// lib/ds-thing/src/thing.sol
// thing.sol - `auth` with handy mixins. your things should be DSThings

// Copyright (C) 2017  DappHub, LLC

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

/* pragma solidity ^0.4.13; */

/* import 'ds-auth/auth.sol'; */
/* import 'ds-note/note.sol'; */
/* import 'ds-math/math.sol'; */

contract DSThing is DSAuth, DSNote, DSMath {

    function S(string s) internal pure returns (bytes4) {
        return bytes4(keccak256(s));
    }

}

////// src/vox.sol
/// vox.sol -- target price feed

// Copyright (C) 2016, 2017  Nikolai Mushegian <nikolai@dapphub.com>
// Copyright (C) 2016, 2017  Daniel Brockman <daniel@dapphub.com>
// Copyright (C) 2017        Rain Break <rainbreak@riseup.net>

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

/* pragma solidity ^0.4.18; */

/* import "ds-thing/thing.sol"; */

contract SaiVox is DSThing {
    uint256  _par;
    uint256  _way;

    uint256  public  fix;
    uint256  public  how;
    uint256  public  tau;

    function SaiVox(uint par_) public {
        _par = fix = par_;
        _way = RAY;
        tau  = era();
    }

    function era() public view returns (uint) {
        return block.timestamp;
    }

    function mold(bytes32 param, uint val) public note auth {
        if (param == 'way') _way = val;
    }

    // Dai Target Price (ref per dai)
    function par() public returns (uint) {
        prod();
        return _par;
    }
    function way() public returns (uint) {
        prod();
        return _way;
    }

    function tell(uint256 ray) public note auth {
        fix = ray;
    }
    function tune(uint256 ray) public note auth {
        how = ray;
    }

    function prod() public note {
        var age = era() - tau;
        if (age == 0) return;  // optimised
        tau = era();

        if (_way != RAY) _par = rmul(_par, rpow(_way, age));  // optimised

        if (how == 0) return;  // optimised
        var wag = int128(how * age);
        _way = inj(prj(_way) + (fix < _par ? wag : -wag));
    }

    function inj(int128 x) internal pure returns (uint256) {
        return x >= 0 ? uint256(x) + RAY
            : rdiv(RAY, RAY + uint256(-x));
    }
    function prj(uint256 x) internal pure returns (int128) {
        return x >= RAY ? int128(x - RAY)
            : int128(RAY) - int128(rdiv(RAY, x));
    }
}