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![Joe Perches](/assets/img/avatar_default.png)
This operation was intentional, but tools such as smatch will warn that it might not have been. Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Yann Collet <cyan@fb.com> Cc: Vasily Averin <vvs@virtuozzo.com> Cc: Gao Xiang <hsiangkao@aol.com> Link: http://lkml.kernel.org/r/3bf931c6ea0cae3e23f3485801986859851b4f04.camel@perches.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
712 lines
20 KiB
C
712 lines
20 KiB
C
/*
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* LZ4 - Fast LZ compression algorithm
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* Copyright (C) 2011 - 2016, Yann Collet.
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* BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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* You can contact the author at :
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* - LZ4 homepage : http://www.lz4.org
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* - LZ4 source repository : https://github.com/lz4/lz4
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*
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* Changed for kernel usage by:
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* Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
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*/
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/*-************************************
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* Dependencies
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**************************************/
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#include <linux/lz4.h>
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#include "lz4defs.h"
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <asm/unaligned.h>
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/*-*****************************
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* Decompression functions
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*******************************/
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#define DEBUGLOG(l, ...) {} /* disabled */
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#ifndef assert
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#define assert(condition) ((void)0)
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#endif
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/*
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* LZ4_decompress_generic() :
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* This generic decompression function covers all use cases.
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* It shall be instantiated several times, using different sets of directives.
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* Note that it is important for performance that this function really get inlined,
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* in order to remove useless branches during compilation optimization.
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*/
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static FORCE_INLINE int LZ4_decompress_generic(
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const char * const src,
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char * const dst,
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int srcSize,
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/*
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* If endOnInput == endOnInputSize,
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* this value is `dstCapacity`
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*/
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int outputSize,
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/* endOnOutputSize, endOnInputSize */
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endCondition_directive endOnInput,
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/* full, partial */
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earlyEnd_directive partialDecoding,
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/* noDict, withPrefix64k, usingExtDict */
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dict_directive dict,
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/* always <= dst, == dst when no prefix */
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const BYTE * const lowPrefix,
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/* only if dict == usingExtDict */
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const BYTE * const dictStart,
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/* note : = 0 if noDict */
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const size_t dictSize
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)
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{
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const BYTE *ip = (const BYTE *) src;
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const BYTE * const iend = ip + srcSize;
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BYTE *op = (BYTE *) dst;
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BYTE * const oend = op + outputSize;
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BYTE *cpy;
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const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize;
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static const unsigned int inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4};
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static const int dec64table[8] = {0, 0, 0, -1, -4, 1, 2, 3};
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const int safeDecode = (endOnInput == endOnInputSize);
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const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB)));
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/* Set up the "end" pointers for the shortcut. */
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const BYTE *const shortiend = iend -
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(endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/;
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const BYTE *const shortoend = oend -
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(endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/;
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DEBUGLOG(5, "%s (srcSize:%i, dstSize:%i)", __func__,
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srcSize, outputSize);
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/* Special cases */
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assert(lowPrefix <= op);
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assert(src != NULL);
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/* Empty output buffer */
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if ((endOnInput) && (unlikely(outputSize == 0)))
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return ((srcSize == 1) && (*ip == 0)) ? 0 : -1;
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if ((!endOnInput) && (unlikely(outputSize == 0)))
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return (*ip == 0 ? 1 : -1);
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if ((endOnInput) && unlikely(srcSize == 0))
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return -1;
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/* Main Loop : decode sequences */
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while (1) {
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size_t length;
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const BYTE *match;
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size_t offset;
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/* get literal length */
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unsigned int const token = *ip++;
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length = token>>ML_BITS;
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/* ip < iend before the increment */
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assert(!endOnInput || ip <= iend);
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/*
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* A two-stage shortcut for the most common case:
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* 1) If the literal length is 0..14, and there is enough
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* space, enter the shortcut and copy 16 bytes on behalf
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* of the literals (in the fast mode, only 8 bytes can be
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* safely copied this way).
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* 2) Further if the match length is 4..18, copy 18 bytes
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* in a similar manner; but we ensure that there's enough
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* space in the output for those 18 bytes earlier, upon
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* entering the shortcut (in other words, there is a
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* combined check for both stages).
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*
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* The & in the likely() below is intentionally not && so that
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* some compilers can produce better parallelized runtime code
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*/
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if ((endOnInput ? length != RUN_MASK : length <= 8)
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/*
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* strictly "less than" on input, to re-enter
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* the loop with at least one byte
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*/
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&& likely((endOnInput ? ip < shortiend : 1) &
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(op <= shortoend))) {
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/* Copy the literals */
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memcpy(op, ip, endOnInput ? 16 : 8);
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op += length; ip += length;
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/*
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* The second stage:
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* prepare for match copying, decode full info.
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* If it doesn't work out, the info won't be wasted.
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*/
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length = token & ML_MASK; /* match length */
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offset = LZ4_readLE16(ip);
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ip += 2;
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match = op - offset;
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assert(match <= op); /* check overflow */
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/* Do not deal with overlapping matches. */
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if ((length != ML_MASK) &&
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(offset >= 8) &&
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(dict == withPrefix64k || match >= lowPrefix)) {
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/* Copy the match. */
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memcpy(op + 0, match + 0, 8);
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memcpy(op + 8, match + 8, 8);
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memcpy(op + 16, match + 16, 2);
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op += length + MINMATCH;
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/* Both stages worked, load the next token. */
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continue;
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}
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/*
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* The second stage didn't work out, but the info
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* is ready. Propel it right to the point of match
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* copying.
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*/
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goto _copy_match;
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}
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/* decode literal length */
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if (length == RUN_MASK) {
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unsigned int s;
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if (unlikely(endOnInput ? ip >= iend - RUN_MASK : 0)) {
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/* overflow detection */
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goto _output_error;
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}
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do {
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s = *ip++;
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length += s;
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} while (likely(endOnInput
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? ip < iend - RUN_MASK
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: 1) & (s == 255));
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if ((safeDecode)
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&& unlikely((uptrval)(op) +
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length < (uptrval)(op))) {
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/* overflow detection */
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goto _output_error;
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}
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if ((safeDecode)
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&& unlikely((uptrval)(ip) +
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length < (uptrval)(ip))) {
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/* overflow detection */
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goto _output_error;
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}
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}
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/* copy literals */
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cpy = op + length;
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LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH);
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if (((endOnInput) && ((cpy > oend - MFLIMIT)
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|| (ip + length > iend - (2 + 1 + LASTLITERALS))))
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|| ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) {
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if (partialDecoding) {
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if (cpy > oend) {
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/*
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* Partial decoding :
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* stop in the middle of literal segment
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*/
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cpy = oend;
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length = oend - op;
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}
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if ((endOnInput)
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&& (ip + length > iend)) {
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/*
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* Error :
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* read attempt beyond
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* end of input buffer
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*/
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goto _output_error;
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}
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} else {
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if ((!endOnInput)
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&& (cpy != oend)) {
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/*
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* Error :
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* block decoding must
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* stop exactly there
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*/
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goto _output_error;
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}
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if ((endOnInput)
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&& ((ip + length != iend)
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|| (cpy > oend))) {
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/*
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* Error :
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* input must be consumed
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*/
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goto _output_error;
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}
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}
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memcpy(op, ip, length);
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ip += length;
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op += length;
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/* Necessarily EOF, due to parsing restrictions */
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if (!partialDecoding || (cpy == oend))
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break;
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} else {
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/* may overwrite up to WILDCOPYLENGTH beyond cpy */
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LZ4_wildCopy(op, ip, cpy);
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ip += length;
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op = cpy;
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}
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/* get offset */
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offset = LZ4_readLE16(ip);
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ip += 2;
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match = op - offset;
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/* get matchlength */
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length = token & ML_MASK;
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_copy_match:
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if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) {
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/* Error : offset outside buffers */
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goto _output_error;
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}
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/* costs ~1%; silence an msan warning when offset == 0 */
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/*
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* note : when partialDecoding, there is no guarantee that
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* at least 4 bytes remain available in output buffer
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*/
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if (!partialDecoding) {
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assert(oend > op);
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assert(oend - op >= 4);
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LZ4_write32(op, (U32)offset);
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}
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if (length == ML_MASK) {
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unsigned int s;
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do {
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s = *ip++;
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if ((endOnInput) && (ip > iend - LASTLITERALS))
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goto _output_error;
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length += s;
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} while (s == 255);
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if ((safeDecode)
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&& unlikely(
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(uptrval)(op) + length < (uptrval)op)) {
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/* overflow detection */
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goto _output_error;
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}
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}
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length += MINMATCH;
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/* match starting within external dictionary */
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if ((dict == usingExtDict) && (match < lowPrefix)) {
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if (unlikely(op + length > oend - LASTLITERALS)) {
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/* doesn't respect parsing restriction */
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if (!partialDecoding)
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goto _output_error;
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length = min(length, (size_t)(oend - op));
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}
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if (length <= (size_t)(lowPrefix - match)) {
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/*
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* match fits entirely within external
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* dictionary : just copy
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*/
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memmove(op, dictEnd - (lowPrefix - match),
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length);
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op += length;
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} else {
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/*
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* match stretches into both external
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* dictionary and current block
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*/
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size_t const copySize = (size_t)(lowPrefix - match);
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size_t const restSize = length - copySize;
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memcpy(op, dictEnd - copySize, copySize);
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op += copySize;
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if (restSize > (size_t)(op - lowPrefix)) {
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/* overlap copy */
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BYTE * const endOfMatch = op + restSize;
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const BYTE *copyFrom = lowPrefix;
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while (op < endOfMatch)
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*op++ = *copyFrom++;
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} else {
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memcpy(op, lowPrefix, restSize);
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op += restSize;
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}
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}
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continue;
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}
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/* copy match within block */
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cpy = op + length;
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/*
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* partialDecoding :
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* may not respect endBlock parsing restrictions
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*/
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assert(op <= oend);
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if (partialDecoding &&
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(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
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size_t const mlen = min(length, (size_t)(oend - op));
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const BYTE * const matchEnd = match + mlen;
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BYTE * const copyEnd = op + mlen;
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if (matchEnd > op) {
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/* overlap copy */
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while (op < copyEnd)
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*op++ = *match++;
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} else {
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memcpy(op, match, mlen);
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}
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op = copyEnd;
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if (op == oend)
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break;
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continue;
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}
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if (unlikely(offset < 8)) {
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op[0] = match[0];
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op[1] = match[1];
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op[2] = match[2];
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op[3] = match[3];
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match += inc32table[offset];
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memcpy(op + 4, match, 4);
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match -= dec64table[offset];
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} else {
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LZ4_copy8(op, match);
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match += 8;
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}
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op += 8;
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if (unlikely(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
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BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
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if (cpy > oend - LASTLITERALS) {
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/*
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* Error : last LASTLITERALS bytes
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* must be literals (uncompressed)
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*/
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goto _output_error;
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}
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if (op < oCopyLimit) {
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LZ4_wildCopy(op, match, oCopyLimit);
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match += oCopyLimit - op;
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op = oCopyLimit;
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}
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while (op < cpy)
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*op++ = *match++;
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} else {
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LZ4_copy8(op, match);
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if (length > 16)
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LZ4_wildCopy(op + 8, match + 8, cpy);
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}
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op = cpy; /* wildcopy correction */
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}
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/* end of decoding */
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if (endOnInput) {
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/* Nb of output bytes decoded */
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return (int) (((char *)op) - dst);
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} else {
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/* Nb of input bytes read */
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return (int) (((const char *)ip) - src);
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}
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/* Overflow error detected */
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_output_error:
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return (int) (-(((const char *)ip) - src)) - 1;
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}
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int LZ4_decompress_safe(const char *source, char *dest,
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int compressedSize, int maxDecompressedSize)
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{
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return LZ4_decompress_generic(source, dest,
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compressedSize, maxDecompressedSize,
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endOnInputSize, decode_full_block,
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noDict, (BYTE *)dest, NULL, 0);
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}
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int LZ4_decompress_safe_partial(const char *src, char *dst,
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int compressedSize, int targetOutputSize, int dstCapacity)
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{
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dstCapacity = min(targetOutputSize, dstCapacity);
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return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity,
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endOnInputSize, partial_decode,
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noDict, (BYTE *)dst, NULL, 0);
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}
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int LZ4_decompress_fast(const char *source, char *dest, int originalSize)
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{
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return LZ4_decompress_generic(source, dest, 0, originalSize,
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endOnOutputSize, decode_full_block,
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withPrefix64k,
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(BYTE *)dest - 64 * KB, NULL, 0);
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}
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/* ===== Instantiate a few more decoding cases, used more than once. ===== */
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int LZ4_decompress_safe_withPrefix64k(const char *source, char *dest,
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int compressedSize, int maxOutputSize)
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{
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return LZ4_decompress_generic(source, dest,
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compressedSize, maxOutputSize,
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endOnInputSize, decode_full_block,
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withPrefix64k,
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(BYTE *)dest - 64 * KB, NULL, 0);
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}
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static int LZ4_decompress_safe_withSmallPrefix(const char *source, char *dest,
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int compressedSize,
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int maxOutputSize,
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size_t prefixSize)
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{
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return LZ4_decompress_generic(source, dest,
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compressedSize, maxOutputSize,
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endOnInputSize, decode_full_block,
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noDict,
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(BYTE *)dest - prefixSize, NULL, 0);
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}
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int LZ4_decompress_safe_forceExtDict(const char *source, char *dest,
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int compressedSize, int maxOutputSize,
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const void *dictStart, size_t dictSize)
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{
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return LZ4_decompress_generic(source, dest,
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compressedSize, maxOutputSize,
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endOnInputSize, decode_full_block,
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usingExtDict, (BYTE *)dest,
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(const BYTE *)dictStart, dictSize);
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}
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static int LZ4_decompress_fast_extDict(const char *source, char *dest,
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int originalSize,
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const void *dictStart, size_t dictSize)
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{
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return LZ4_decompress_generic(source, dest,
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0, originalSize,
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endOnOutputSize, decode_full_block,
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usingExtDict, (BYTE *)dest,
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(const BYTE *)dictStart, dictSize);
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}
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/*
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* The "double dictionary" mode, for use with e.g. ring buffers: the first part
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* of the dictionary is passed as prefix, and the second via dictStart + dictSize.
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* These routines are used only once, in LZ4_decompress_*_continue().
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|
*/
|
|
static FORCE_INLINE
|
|
int LZ4_decompress_safe_doubleDict(const char *source, char *dest,
|
|
int compressedSize, int maxOutputSize,
|
|
size_t prefixSize,
|
|
const void *dictStart, size_t dictSize)
|
|
{
|
|
return LZ4_decompress_generic(source, dest,
|
|
compressedSize, maxOutputSize,
|
|
endOnInputSize, decode_full_block,
|
|
usingExtDict, (BYTE *)dest - prefixSize,
|
|
(const BYTE *)dictStart, dictSize);
|
|
}
|
|
|
|
static FORCE_INLINE
|
|
int LZ4_decompress_fast_doubleDict(const char *source, char *dest,
|
|
int originalSize, size_t prefixSize,
|
|
const void *dictStart, size_t dictSize)
|
|
{
|
|
return LZ4_decompress_generic(source, dest,
|
|
0, originalSize,
|
|
endOnOutputSize, decode_full_block,
|
|
usingExtDict, (BYTE *)dest - prefixSize,
|
|
(const BYTE *)dictStart, dictSize);
|
|
}
|
|
|
|
/* ===== streaming decompression functions ===== */
|
|
|
|
int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
|
|
const char *dictionary, int dictSize)
|
|
{
|
|
LZ4_streamDecode_t_internal *lz4sd =
|
|
&LZ4_streamDecode->internal_donotuse;
|
|
|
|
lz4sd->prefixSize = (size_t) dictSize;
|
|
lz4sd->prefixEnd = (const BYTE *) dictionary + dictSize;
|
|
lz4sd->externalDict = NULL;
|
|
lz4sd->extDictSize = 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* *_continue() :
|
|
* These decoding functions allow decompression of multiple blocks
|
|
* in "streaming" mode.
|
|
* Previously decoded blocks must still be available at the memory
|
|
* position where they were decoded.
|
|
* If it's not possible, save the relevant part of
|
|
* decoded data into a safe buffer,
|
|
* and indicate where it stands using LZ4_setStreamDecode()
|
|
*/
|
|
int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
|
|
const char *source, char *dest, int compressedSize, int maxOutputSize)
|
|
{
|
|
LZ4_streamDecode_t_internal *lz4sd =
|
|
&LZ4_streamDecode->internal_donotuse;
|
|
int result;
|
|
|
|
if (lz4sd->prefixSize == 0) {
|
|
/* The first call, no dictionary yet. */
|
|
assert(lz4sd->extDictSize == 0);
|
|
result = LZ4_decompress_safe(source, dest,
|
|
compressedSize, maxOutputSize);
|
|
if (result <= 0)
|
|
return result;
|
|
lz4sd->prefixSize = result;
|
|
lz4sd->prefixEnd = (BYTE *)dest + result;
|
|
} else if (lz4sd->prefixEnd == (BYTE *)dest) {
|
|
/* They're rolling the current segment. */
|
|
if (lz4sd->prefixSize >= 64 * KB - 1)
|
|
result = LZ4_decompress_safe_withPrefix64k(source, dest,
|
|
compressedSize, maxOutputSize);
|
|
else if (lz4sd->extDictSize == 0)
|
|
result = LZ4_decompress_safe_withSmallPrefix(source,
|
|
dest, compressedSize, maxOutputSize,
|
|
lz4sd->prefixSize);
|
|
else
|
|
result = LZ4_decompress_safe_doubleDict(source, dest,
|
|
compressedSize, maxOutputSize,
|
|
lz4sd->prefixSize,
|
|
lz4sd->externalDict, lz4sd->extDictSize);
|
|
if (result <= 0)
|
|
return result;
|
|
lz4sd->prefixSize += result;
|
|
lz4sd->prefixEnd += result;
|
|
} else {
|
|
/*
|
|
* The buffer wraps around, or they're
|
|
* switching to another buffer.
|
|
*/
|
|
lz4sd->extDictSize = lz4sd->prefixSize;
|
|
lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
|
|
result = LZ4_decompress_safe_forceExtDict(source, dest,
|
|
compressedSize, maxOutputSize,
|
|
lz4sd->externalDict, lz4sd->extDictSize);
|
|
if (result <= 0)
|
|
return result;
|
|
lz4sd->prefixSize = result;
|
|
lz4sd->prefixEnd = (BYTE *)dest + result;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
|
|
const char *source, char *dest, int originalSize)
|
|
{
|
|
LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
|
|
int result;
|
|
|
|
if (lz4sd->prefixSize == 0) {
|
|
assert(lz4sd->extDictSize == 0);
|
|
result = LZ4_decompress_fast(source, dest, originalSize);
|
|
if (result <= 0)
|
|
return result;
|
|
lz4sd->prefixSize = originalSize;
|
|
lz4sd->prefixEnd = (BYTE *)dest + originalSize;
|
|
} else if (lz4sd->prefixEnd == (BYTE *)dest) {
|
|
if (lz4sd->prefixSize >= 64 * KB - 1 ||
|
|
lz4sd->extDictSize == 0)
|
|
result = LZ4_decompress_fast(source, dest,
|
|
originalSize);
|
|
else
|
|
result = LZ4_decompress_fast_doubleDict(source, dest,
|
|
originalSize, lz4sd->prefixSize,
|
|
lz4sd->externalDict, lz4sd->extDictSize);
|
|
if (result <= 0)
|
|
return result;
|
|
lz4sd->prefixSize += originalSize;
|
|
lz4sd->prefixEnd += originalSize;
|
|
} else {
|
|
lz4sd->extDictSize = lz4sd->prefixSize;
|
|
lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
|
|
result = LZ4_decompress_fast_extDict(source, dest,
|
|
originalSize, lz4sd->externalDict, lz4sd->extDictSize);
|
|
if (result <= 0)
|
|
return result;
|
|
lz4sd->prefixSize = originalSize;
|
|
lz4sd->prefixEnd = (BYTE *)dest + originalSize;
|
|
}
|
|
return result;
|
|
}
|
|
|
|
int LZ4_decompress_safe_usingDict(const char *source, char *dest,
|
|
int compressedSize, int maxOutputSize,
|
|
const char *dictStart, int dictSize)
|
|
{
|
|
if (dictSize == 0)
|
|
return LZ4_decompress_safe(source, dest,
|
|
compressedSize, maxOutputSize);
|
|
if (dictStart+dictSize == dest) {
|
|
if (dictSize >= 64 * KB - 1)
|
|
return LZ4_decompress_safe_withPrefix64k(source, dest,
|
|
compressedSize, maxOutputSize);
|
|
return LZ4_decompress_safe_withSmallPrefix(source, dest,
|
|
compressedSize, maxOutputSize, dictSize);
|
|
}
|
|
return LZ4_decompress_safe_forceExtDict(source, dest,
|
|
compressedSize, maxOutputSize, dictStart, dictSize);
|
|
}
|
|
|
|
int LZ4_decompress_fast_usingDict(const char *source, char *dest,
|
|
int originalSize,
|
|
const char *dictStart, int dictSize)
|
|
{
|
|
if (dictSize == 0 || dictStart + dictSize == dest)
|
|
return LZ4_decompress_fast(source, dest, originalSize);
|
|
|
|
return LZ4_decompress_fast_extDict(source, dest, originalSize,
|
|
dictStart, dictSize);
|
|
}
|
|
|
|
#ifndef STATIC
|
|
EXPORT_SYMBOL(LZ4_decompress_safe);
|
|
EXPORT_SYMBOL(LZ4_decompress_safe_partial);
|
|
EXPORT_SYMBOL(LZ4_decompress_fast);
|
|
EXPORT_SYMBOL(LZ4_setStreamDecode);
|
|
EXPORT_SYMBOL(LZ4_decompress_safe_continue);
|
|
EXPORT_SYMBOL(LZ4_decompress_fast_continue);
|
|
EXPORT_SYMBOL(LZ4_decompress_safe_usingDict);
|
|
EXPORT_SYMBOL(LZ4_decompress_fast_usingDict);
|
|
|
|
MODULE_LICENSE("Dual BSD/GPL");
|
|
MODULE_DESCRIPTION("LZ4 decompressor");
|
|
#endif
|