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| // https://github.com/aplbrain/npyjs/blob/master/LICENSE | |
| const dtypes = { | |
| '<u1': { | |
| name: 'uint8', | |
| size: 8, | |
| arrayConstructor: Uint8Array, | |
| }, | |
| '|u1': { | |
| name: 'uint8', | |
| size: 8, | |
| arrayConstructor: Uint8Array, | |
| }, | |
| '<u2': { | |
| name: 'uint16', | |
| size: 16, | |
| arrayConstructor: Uint16Array, | |
| }, | |
| '|i1': { | |
| name: 'int8', | |
| size: 8, | |
| arrayConstructor: Int8Array, | |
| }, | |
| '<i2': { | |
| name: 'int16', | |
| size: 16, | |
| arrayConstructor: Int16Array, | |
| }, | |
| '<u4': { | |
| name: 'uint32', | |
| size: 32, | |
| arrayConstructor: Int32Array, | |
| }, | |
| '<i4': { | |
| name: 'int32', | |
| size: 32, | |
| arrayConstructor: Int32Array, | |
| }, | |
| '<u8': { | |
| name: 'uint64', | |
| size: 64, | |
| arrayConstructor: BigUint64Array, | |
| }, | |
| '<i8': { | |
| name: 'int64', | |
| size: 64, | |
| arrayConstructor: BigInt64Array, | |
| }, | |
| '<f4': { | |
| name: 'float32', | |
| size: 32, | |
| arrayConstructor: Float32Array | |
| }, | |
| '<f8': { | |
| name: 'float64', | |
| size: 64, | |
| arrayConstructor: Float64Array | |
| }, | |
| }; | |
| function parse(buffer){ | |
| const buf = new Uint8Array(buffer); | |
| if (buf[6] != 1) throw 'Only npy version 1 is supported'; | |
| const headerLength = buf[8] + buf[9]*256; | |
| const offsetBytes = 10 + headerLength; | |
| const header = JSON.parse( | |
| new TextDecoder('utf-8') | |
| .decode(buf.slice(10, 10 + headerLength)) | |
| .replace(/'/g, '"') | |
| .replace('False', 'false') | |
| .replace('(', '[') | |
| .replace(/,*\),*/g, ']') | |
| ); | |
| if (header.fortan_order) throw 'Fortran-contiguous array data are not supported'; | |
| const dtype = dtypes[header.descr]; | |
| return { | |
| data: new dtype['arrayConstructor'](buf.slice(offsetBytes).buffer), | |
| shape: header.shape, | |
| dtype: dtype.name, | |
| }; | |
| } | |
| function format(typedArray, shape){ | |
| let dtype = null; | |
| for (let d in dtypes){ | |
| if (dtypes[d].arrayConstructor == typedArray.constructor) dtype = d; | |
| } | |
| if (dtype === null) throw 'Invalid typedArray'; | |
| const header = `{'descr': '${dtype}', 'fortran_order': False, 'shape': (${shape.join(',')},), }\n`; | |
| const spacepad = Array.from({length: 64 - (8 + header.length) % 64}, d => '\x20').join(''); | |
| const hl = (header + spacepad).length; | |
| return Buffer.concat([ | |
| Buffer.from('\x93NUMPY\x01\x00', 'latin1'), | |
| // convert to little-endian | |
| Buffer.from(new Uint8Array([hl % 256, hl/256 | 0])), | |
| Buffer.from(header + spacepad, 'latin1'), | |
| Buffer.from(typedArray.buffer) | |
| ]); | |
| } | |
| export default {parse, format}; | |