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