145 lines
3.5 KiB
C
145 lines
3.5 KiB
C
/*
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* This file is a part of Pcompress, a chunked parallel multi-
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* algorithm lossless compression and decompression program.
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*
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* Copyright (C) 2012-2013 Moinak Ghosh. All rights reserved.
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* Use is subject to license terms.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 3 of the License, or (at your option) any later version.
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*
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* This program 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. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program.
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* If not, see <http://www.gnu.org/licenses/>.
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*
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* moinakg@belenix.org, http://moinakg.wordpress.com/
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*
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*/
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///////////////////////////////////////////////////////////////////////////////
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//
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/// \file crc64.c
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/// \brief CRC64 calculation
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///
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/// Calculate the CRC64 using the slice-by-four algorithm. This is the same
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/// idea that is used in crc32_fast.c, but for CRC64 we use only four tables
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/// instead of eight to avoid increasing CPU cache usage.
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//
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// Author: Lasse Collin
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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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///////////////////////////////////////////////////////////////////////////////
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#include <crc_macros.h>
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#ifdef WORDS_BIGENDIAN
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# define A1(x) ((x) >> 56)
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#else
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# define A1 A
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#endif
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extern const uint64_t lzma_crc64_table[4][256];
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// See the comments in crc32_fast.c. They aren't duplicated here.
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extern uint64_t
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lzma_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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#ifdef WORDS_BIGENDIAN
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crc = bswap64(crc);
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#endif
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if (size > 4) {
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while ((uintptr_t)(buf) & 3) {
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crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
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--size;
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}
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const uint8_t *const limit = buf + (size & ~(size_t)(3));
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size &= (size_t)(3);
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while (buf < limit) {
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#ifdef WORDS_BIGENDIAN
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const uint32_t tmp = (crc >> 32)
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^ *(const uint32_t *)(buf);
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#else
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const uint32_t tmp = crc ^ *(const uint32_t *)(buf);
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#endif
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buf += 4;
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crc = lzma_crc64_table[3][A(tmp)]
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^ lzma_crc64_table[2][B(tmp)]
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^ S32(crc)
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^ lzma_crc64_table[1][C(tmp)]
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^ lzma_crc64_table[0][D(tmp)];
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}
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}
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while (size-- != 0)
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crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
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#ifdef WORDS_BIGENDIAN
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crc = bswap64(crc);
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#endif
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return ~crc;
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}
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extern uint64_t
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lzma_crc64_8bchk(const uint8_t *buf, size_t size, uint64_t crc, uint64_t *cnt)
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{
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crc = ~crc;
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uint64_t cnt1 = 0;
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#ifdef WORDS_BIGENDIAN
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crc = bswap64(crc);
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#endif
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if (size > 4) {
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while ((uintptr_t)(buf) & 3) {
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crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
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--size;
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}
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const uint8_t *const limit = buf + (size & ~(size_t)(3));
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size &= (size_t)(3);
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while (buf < limit) {
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uint32_t val = *(const uint32_t *)(buf);
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#ifdef WORDS_BIGENDIAN
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const uint32_t tmp = (crc >> 32) ^ val;
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#else
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const uint32_t tmp = crc ^ val;
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#endif
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buf += 4;
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val >>= 7; cnt1 += (val & 1);
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val >>= 8; cnt1 += (val & 1);
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crc = lzma_crc64_table[3][A(tmp)]
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^ lzma_crc64_table[2][B(tmp)]
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^ S32(crc)
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^ lzma_crc64_table[1][C(tmp)]
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^ lzma_crc64_table[0][D(tmp)];
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}
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}
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while (size-- != 0)
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crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
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#ifdef WORDS_BIGENDIAN
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crc = bswap64(crc);
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#endif
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*cnt = cnt1;
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return ~crc;
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}
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