| #----------------------------------------------------------------------------- |
| # Low level CRC functions for use by crcmod. This version is implemented in |
| # Python for a couple of reasons. 1) Provide a reference implememtation. |
| # 2) Provide a version that can be used on systems where a C compiler is not |
| # available for building extension modules. |
| # |
| # Copyright (c) 2009 Raymond L. Buvel |
| # Copyright (c) 2010 Craig McQueen |
| # |
| # Permission is hereby granted, free of charge, to any person obtaining a copy |
| # of this software and associated documentation files (the "Software"), to deal |
| # in the Software without restriction, including without limitation the rights |
| # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| # copies of the Software, and to permit persons to whom the Software is |
| # furnished to do so, subject to the following conditions: |
| # |
| # The above copyright notice and this permission notice shall be included in |
| # all copies or substantial portions of the Software. |
| # |
| # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| # SOFTWARE. |
| #----------------------------------------------------------------------------- |
| |
| def _get_buffer_view(in_obj): |
| if isinstance(in_obj, str): |
| raise TypeError('Unicode-objects must be encoded before calculating a CRC') |
| mv = memoryview(in_obj) |
| if mv.ndim > 1: |
| raise BufferError('Buffer must be single dimension') |
| return mv |
| |
| |
| def _crc8(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFF |
| for x in mv.tobytes(): |
| crc = table[x ^ crc] |
| return crc |
| |
| def _crc8r(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFF |
| for x in mv.tobytes(): |
| crc = table[x ^ crc] |
| return crc |
| |
| def _crc16(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFFFF |
| for x in mv.tobytes(): |
| crc = table[x ^ ((crc>>8) & 0xFF)] ^ ((crc << 8) & 0xFF00) |
| return crc |
| |
| def _crc16r(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFFFF |
| for x in mv.tobytes(): |
| crc = table[x ^ (crc & 0xFF)] ^ (crc >> 8) |
| return crc |
| |
| def _crc24(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFFFFFF |
| for x in mv.tobytes(): |
| crc = table[x ^ (crc>>16 & 0xFF)] ^ ((crc << 8) & 0xFFFF00) |
| return crc |
| |
| def _crc24r(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFFFFFF |
| for x in mv.tobytes(): |
| crc = table[x ^ (crc & 0xFF)] ^ (crc >> 8) |
| return crc |
| |
| def _crc32(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFFFFFFFF |
| for x in mv.tobytes(): |
| crc = table[x ^ ((crc>>24) & 0xFF)] ^ ((crc << 8) & 0xFFFFFF00) |
| return crc |
| |
| def _crc32r(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFFFFFFFF |
| for x in mv.tobytes(): |
| crc = table[x ^ (crc & 0xFF)] ^ (crc >> 8) |
| return crc |
| |
| def _crc64(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFFFFFFFFFFFFFFFF |
| for x in mv.tobytes(): |
| crc = table[x ^ ((crc>>56) & 0xFF)] ^ ((crc << 8) & 0xFFFFFFFFFFFFFF00) |
| return crc |
| |
| def _crc64r(data, crc, table): |
| mv = _get_buffer_view(data) |
| crc = crc & 0xFFFFFFFFFFFFFFFF |
| for x in mv.tobytes(): |
| crc = table[x ^ (crc & 0xFF)] ^ (crc >> 8) |
| return crc |
| |
