53 lines
1002 B
C
53 lines
1002 B
C
/*
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* CRC64 using the polynomial from ECMA-182
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*
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* This file is similar to xz_crc32.c. See the comments there.
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*
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* Authors: Lasse Collin <lasse.collin@tukaani.org>
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* Igor Pavlov <http://7-zip.org/>
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*
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* This file has been put into the public domain.
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* You can do whatever you want with this file.
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*/
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#include "xz_private.h"
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#ifndef STATIC_RW_DATA
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#define STATIC_RW_DATA static
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#endif
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STATIC_RW_DATA uint64_t xz_crc64_table[256];
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XZ_EXTERN void xz_crc64_init(void)
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{
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const uint64_t poly = 0xC96C5795D7870F42;
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uint32_t i;
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uint32_t j;
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uint64_t r;
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for (i = 0; i < 256; ++i)
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{
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r = i;
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for (j = 0; j < 8; ++j)
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r = (r >> 1) ^ (poly & ~((r & 1) - 1));
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xz_crc64_table[i] = r;
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}
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return;
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}
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XZ_EXTERN uint64_t xz_crc64(const uint8_t *buf, size_t size, uint64_t crc)
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{
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crc = ~crc;
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while (size != 0)
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{
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crc = xz_crc64_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
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--size;
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}
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return ~crc;
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}
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