mirror of https://git.tukaani.org/xz.git
56 lines
1.2 KiB
C
56 lines
1.2 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file crc32_init.c
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/// \brief CRC32 table initialization
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//
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// This code is based on various public domain sources.
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// This code has been put into the public domain.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifdef HAVE_CONFIG_H
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# include "check.h"
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#endif
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#ifdef WORDS_BIGENDIAN
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# include "check_byteswap.h"
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#endif
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uint32_t lzma_crc32_table[8][256];
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extern void
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lzma_crc32_init(void)
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{
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static const uint32_t poly32 = UINT32_C(0xEDB88320);
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for (size_t s = 0; s < 8; ++s) {
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for (size_t b = 0; b < 256; ++b) {
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uint32_t r = s == 0 ? b : lzma_crc32_table[s - 1][b];
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for (size_t i = 0; i < 8; ++i) {
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if (r & 1)
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r = (r >> 1) ^ poly32;
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else
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r >>= 1;
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}
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lzma_crc32_table[s][b] = r;
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}
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}
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#ifdef WORDS_BIGENDIAN
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for (size_t s = 0; s < 8; ++s)
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for (size_t b = 0; b < 256; ++b)
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lzma_crc32_table[s][b]
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= bswap_32(lzma_crc32_table[s][b]);
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#endif
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return;
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}
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