kopia lustrzana https://github.com/micropython/micropython
64 wiersze
1.9 KiB
C
64 wiersze
1.9 KiB
C
/*
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* CRC32 checksum
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*
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* Copyright (c) 1998-2003 by Joergen Ibsen / Jibz
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* All Rights Reserved
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*
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* http://www.ibsensoftware.com/
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*
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* This software is provided 'as-is', without any express
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* or implied warranty. In no event will the authors be
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* held liable for any damages arising from the use of
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* this software.
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*
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* Permission is granted to anyone to use this software
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* for any purpose, including commercial applications,
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* and to alter it and redistribute it freely, subject to
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* the following restrictions:
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*
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* 1. The origin of this software must not be
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* misrepresented; you must not claim that you
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* wrote the original software. If you use this
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* software in a product, an acknowledgment in
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* the product documentation would be appreciated
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* but is not required.
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*
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* 2. Altered source versions must be plainly marked
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* as such, and must not be misrepresented as
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* being the original software.
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*
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* 3. This notice may not be removed or altered from
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* any source distribution.
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*/
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/*
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* CRC32 algorithm taken from the zlib source, which is
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* Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler
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*/
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#include "uzlib.h"
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static const unsigned int tinf_crc32tab[16] = {
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0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac, 0x76dc4190,
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0x6b6b51f4, 0x4db26158, 0x5005713c, 0xedb88320, 0xf00f9344,
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0xd6d6a3e8, 0xcb61b38c, 0x9b64c2b0, 0x86d3d2d4, 0xa00ae278,
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0xbdbdf21c
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};
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/* crc is previous value for incremental computation, 0xffffffff initially */
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uint32_t uzlib_crc32(const void *data, unsigned int length, uint32_t crc)
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{
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const unsigned char *buf = (const unsigned char *)data;
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unsigned int i;
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for (i = 0; i < length; ++i)
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{
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crc ^= buf[i];
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crc = tinf_crc32tab[crc & 0x0f] ^ (crc >> 4);
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crc = tinf_crc32tab[crc & 0x0f] ^ (crc >> 4);
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}
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// return value suitable for passing in next time, for final value invert it
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return crc/* ^ 0xffffffff*/;
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}
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