_websocket.pyx - mozsearch

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from cpython cimport PyBytes_AsString

#from cpython cimport PyByteArray_AsString # cython still not exports that

cdef extern from "Python.h":

    char* PyByteArray_AsString(bytearray ba) except NULL

from libc.stdint cimport uint32_t, uint64_t, uintmax_t

def _websocket_mask_cython(object mask, object data):

    """Note, this function mutates its `data` argument

"""

    cdef:

        Py_ssize_t data_len, i

        # bit operations on signed integers are implementation-specific

        unsigned char * in_buf

        const unsigned char * mask_buf

        uint32_t uint32_msk

        uint64_t uint64_msk

    assert len(mask) == 4

    if not isinstance(mask, bytes):

        mask = bytes(mask)

    if isinstance(data, bytearray):

        data = <bytearray>data

    else:

        data = bytearray(data)

    data_len = len(data)

    in_buf = <unsigned char*>PyByteArray_AsString(data)

    mask_buf = <const unsigned char*>PyBytes_AsString(mask)

    uint32_msk = (<uint32_t*>mask_buf)[0]

    # TODO: align in_data ptr to achieve even faster speeds

    # does it need in python ?! malloc() always aligns to sizeof(long) bytes

    if sizeof(size_t) >= 8:

        uint64_msk = uint32_msk

        uint64_msk = (uint64_msk << 32) | uint32_msk

        while data_len >= 8:

            (<uint64_t*>in_buf)[0] ^= uint64_msk

            in_buf += 8

            data_len -= 8

    while data_len >= 4:

        (<uint32_t*>in_buf)[0] ^= uint32_msk

        in_buf += 4

        data_len -= 4

    for i in range(0, data_len):

        in_buf[i] ^= mask_buf[i]