769 строки
19 KiB
C
769 строки
19 KiB
C
/*
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* LZ4 HC - High Compression Mode of LZ4
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* Copyright (C) 2011-2015, Yann Collet.
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*
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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/module.h>
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#include <linux/kernel.h>
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#include <linux/string.h> /* memset */
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/* *************************************
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* Local Constants and types
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***************************************/
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#define OPTIMAL_ML (int)((ML_MASK - 1) + MINMATCH)
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#define HASH_FUNCTION(i) (((i) * 2654435761U) \
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>> ((MINMATCH*8) - LZ4HC_HASH_LOG))
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#define DELTANEXTU16(p) chainTable[(U16)(p)] /* faster */
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static U32 LZ4HC_hashPtr(const void *ptr)
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{
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return HASH_FUNCTION(LZ4_read32(ptr));
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}
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/**************************************
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* HC Compression
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**************************************/
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static void LZ4HC_init(LZ4HC_CCtx_internal *hc4, const BYTE *start)
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{
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memset((void *)hc4->hashTable, 0, sizeof(hc4->hashTable));
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memset(hc4->chainTable, 0xFF, sizeof(hc4->chainTable));
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hc4->nextToUpdate = 64 * KB;
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hc4->base = start - 64 * KB;
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hc4->end = start;
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hc4->dictBase = start - 64 * KB;
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hc4->dictLimit = 64 * KB;
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hc4->lowLimit = 64 * KB;
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}
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/* Update chains up to ip (excluded) */
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static FORCE_INLINE void LZ4HC_Insert(LZ4HC_CCtx_internal *hc4,
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const BYTE *ip)
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{
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U16 * const chainTable = hc4->chainTable;
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U32 * const hashTable = hc4->hashTable;
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const BYTE * const base = hc4->base;
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U32 const target = (U32)(ip - base);
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U32 idx = hc4->nextToUpdate;
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while (idx < target) {
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U32 const h = LZ4HC_hashPtr(base + idx);
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size_t delta = idx - hashTable[h];
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if (delta > MAX_DISTANCE)
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delta = MAX_DISTANCE;
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DELTANEXTU16(idx) = (U16)delta;
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hashTable[h] = idx;
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idx++;
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}
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hc4->nextToUpdate = target;
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}
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static FORCE_INLINE int LZ4HC_InsertAndFindBestMatch(
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LZ4HC_CCtx_internal *hc4, /* Index table will be updated */
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const BYTE *ip,
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const BYTE * const iLimit,
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const BYTE **matchpos,
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const int maxNbAttempts)
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{
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U16 * const chainTable = hc4->chainTable;
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U32 * const HashTable = hc4->hashTable;
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const BYTE * const base = hc4->base;
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const BYTE * const dictBase = hc4->dictBase;
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const U32 dictLimit = hc4->dictLimit;
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const U32 lowLimit = (hc4->lowLimit + 64 * KB > (U32)(ip - base))
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? hc4->lowLimit
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: (U32)(ip - base) - (64 * KB - 1);
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U32 matchIndex;
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int nbAttempts = maxNbAttempts;
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size_t ml = 0;
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/* HC4 match finder */
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LZ4HC_Insert(hc4, ip);
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matchIndex = HashTable[LZ4HC_hashPtr(ip)];
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while ((matchIndex >= lowLimit)
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&& (nbAttempts)) {
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nbAttempts--;
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if (matchIndex >= dictLimit) {
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const BYTE * const match = base + matchIndex;
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if (*(match + ml) == *(ip + ml)
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&& (LZ4_read32(match) == LZ4_read32(ip))) {
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size_t const mlt = LZ4_count(ip + MINMATCH,
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match + MINMATCH, iLimit) + MINMATCH;
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if (mlt > ml) {
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ml = mlt;
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*matchpos = match;
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}
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}
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} else {
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const BYTE * const match = dictBase + matchIndex;
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if (LZ4_read32(match) == LZ4_read32(ip)) {
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size_t mlt;
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const BYTE *vLimit = ip
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+ (dictLimit - matchIndex);
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if (vLimit > iLimit)
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vLimit = iLimit;
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mlt = LZ4_count(ip + MINMATCH,
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match + MINMATCH, vLimit) + MINMATCH;
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if ((ip + mlt == vLimit)
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&& (vLimit < iLimit))
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mlt += LZ4_count(ip + mlt,
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base + dictLimit,
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iLimit);
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if (mlt > ml) {
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/* virtual matchpos */
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ml = mlt;
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*matchpos = base + matchIndex;
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}
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}
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}
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matchIndex -= DELTANEXTU16(matchIndex);
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}
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return (int)ml;
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}
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static FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch(
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LZ4HC_CCtx_internal *hc4,
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const BYTE * const ip,
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const BYTE * const iLowLimit,
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const BYTE * const iHighLimit,
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int longest,
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const BYTE **matchpos,
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const BYTE **startpos,
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const int maxNbAttempts)
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{
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U16 * const chainTable = hc4->chainTable;
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U32 * const HashTable = hc4->hashTable;
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const BYTE * const base = hc4->base;
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const U32 dictLimit = hc4->dictLimit;
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const BYTE * const lowPrefixPtr = base + dictLimit;
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const U32 lowLimit = (hc4->lowLimit + 64 * KB > (U32)(ip - base))
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? hc4->lowLimit
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: (U32)(ip - base) - (64 * KB - 1);
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const BYTE * const dictBase = hc4->dictBase;
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U32 matchIndex;
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int nbAttempts = maxNbAttempts;
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int delta = (int)(ip - iLowLimit);
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/* First Match */
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LZ4HC_Insert(hc4, ip);
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matchIndex = HashTable[LZ4HC_hashPtr(ip)];
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while ((matchIndex >= lowLimit)
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&& (nbAttempts)) {
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nbAttempts--;
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if (matchIndex >= dictLimit) {
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const BYTE *matchPtr = base + matchIndex;
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if (*(iLowLimit + longest)
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== *(matchPtr - delta + longest)) {
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if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
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int mlt = MINMATCH + LZ4_count(
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ip + MINMATCH,
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matchPtr + MINMATCH,
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iHighLimit);
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int back = 0;
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while ((ip + back > iLowLimit)
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&& (matchPtr + back > lowPrefixPtr)
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&& (ip[back - 1] == matchPtr[back - 1]))
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back--;
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mlt -= back;
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if (mlt > longest) {
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longest = (int)mlt;
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*matchpos = matchPtr + back;
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*startpos = ip + back;
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}
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}
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}
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} else {
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const BYTE * const matchPtr = dictBase + matchIndex;
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if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
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size_t mlt;
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int back = 0;
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const BYTE *vLimit = ip + (dictLimit - matchIndex);
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if (vLimit > iHighLimit)
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vLimit = iHighLimit;
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mlt = LZ4_count(ip + MINMATCH,
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matchPtr + MINMATCH, vLimit) + MINMATCH;
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if ((ip + mlt == vLimit) && (vLimit < iHighLimit))
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mlt += LZ4_count(ip + mlt, base + dictLimit,
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iHighLimit);
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while ((ip + back > iLowLimit)
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&& (matchIndex + back > lowLimit)
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&& (ip[back - 1] == matchPtr[back - 1]))
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back--;
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mlt -= back;
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if ((int)mlt > longest) {
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longest = (int)mlt;
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*matchpos = base + matchIndex + back;
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*startpos = ip + back;
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}
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}
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}
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matchIndex -= DELTANEXTU16(matchIndex);
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}
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return longest;
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}
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static FORCE_INLINE int LZ4HC_encodeSequence(
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const BYTE **ip,
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BYTE **op,
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const BYTE **anchor,
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int matchLength,
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const BYTE * const match,
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limitedOutput_directive limitedOutputBuffer,
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BYTE *oend)
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{
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int length;
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BYTE *token;
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/* Encode Literal length */
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length = (int)(*ip - *anchor);
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token = (*op)++;
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if ((limitedOutputBuffer)
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&& ((*op + (length>>8)
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+ length + (2 + 1 + LASTLITERALS)) > oend)) {
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/* Check output limit */
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return 1;
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}
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if (length >= (int)RUN_MASK) {
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int len;
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*token = (RUN_MASK<<ML_BITS);
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len = length - RUN_MASK;
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for (; len > 254 ; len -= 255)
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*(*op)++ = 255;
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*(*op)++ = (BYTE)len;
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} else
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*token = (BYTE)(length<<ML_BITS);
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/* Copy Literals */
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LZ4_wildCopy(*op, *anchor, (*op) + length);
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*op += length;
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/* Encode Offset */
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LZ4_writeLE16(*op, (U16)(*ip - match));
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*op += 2;
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/* Encode MatchLength */
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length = (int)(matchLength - MINMATCH);
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if ((limitedOutputBuffer)
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&& (*op + (length>>8)
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+ (1 + LASTLITERALS) > oend)) {
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/* Check output limit */
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return 1;
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}
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if (length >= (int)ML_MASK) {
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*token += ML_MASK;
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length -= ML_MASK;
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for (; length > 509 ; length -= 510) {
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*(*op)++ = 255;
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*(*op)++ = 255;
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}
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if (length > 254) {
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length -= 255;
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*(*op)++ = 255;
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}
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*(*op)++ = (BYTE)length;
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} else
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*token += (BYTE)(length);
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/* Prepare next loop */
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*ip += matchLength;
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*anchor = *ip;
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return 0;
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}
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static int LZ4HC_compress_generic(
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LZ4HC_CCtx_internal *const ctx,
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const char * const source,
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char * const dest,
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int const inputSize,
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int const maxOutputSize,
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int compressionLevel,
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limitedOutput_directive limit
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)
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{
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const BYTE *ip = (const BYTE *) source;
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const BYTE *anchor = ip;
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const BYTE * const iend = ip + inputSize;
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const BYTE * const mflimit = iend - MFLIMIT;
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const BYTE * const matchlimit = (iend - LASTLITERALS);
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BYTE *op = (BYTE *) dest;
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BYTE * const oend = op + maxOutputSize;
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unsigned int maxNbAttempts;
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int ml, ml2, ml3, ml0;
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const BYTE *ref = NULL;
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const BYTE *start2 = NULL;
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const BYTE *ref2 = NULL;
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const BYTE *start3 = NULL;
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const BYTE *ref3 = NULL;
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const BYTE *start0;
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const BYTE *ref0;
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/* init */
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if (compressionLevel > LZ4HC_MAX_CLEVEL)
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compressionLevel = LZ4HC_MAX_CLEVEL;
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if (compressionLevel < 1)
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compressionLevel = LZ4HC_DEFAULT_CLEVEL;
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maxNbAttempts = 1 << (compressionLevel - 1);
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ctx->end += inputSize;
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ip++;
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/* Main Loop */
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while (ip < mflimit) {
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ml = LZ4HC_InsertAndFindBestMatch(ctx, ip,
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matchlimit, (&ref), maxNbAttempts);
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if (!ml) {
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ip++;
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continue;
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}
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/* saved, in case we would skip too much */
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start0 = ip;
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ref0 = ref;
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ml0 = ml;
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_Search2:
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if (ip + ml < mflimit)
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ml2 = LZ4HC_InsertAndGetWiderMatch(ctx,
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ip + ml - 2, ip + 0,
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matchlimit, ml, &ref2,
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&start2, maxNbAttempts);
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else
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ml2 = ml;
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if (ml2 == ml) {
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/* No better match */
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if (LZ4HC_encodeSequence(&ip, &op,
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&anchor, ml, ref, limit, oend))
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return 0;
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continue;
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}
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if (start0 < ip) {
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if (start2 < ip + ml0) {
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/* empirical */
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ip = start0;
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ref = ref0;
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ml = ml0;
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}
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}
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/* Here, start0 == ip */
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if ((start2 - ip) < 3) {
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/* First Match too small : removed */
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ml = ml2;
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ip = start2;
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ref = ref2;
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goto _Search2;
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}
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_Search3:
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/*
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* Currently we have :
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* ml2 > ml1, and
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* ip1 + 3 <= ip2 (usually < ip1 + ml1)
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*/
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if ((start2 - ip) < OPTIMAL_ML) {
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int correction;
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int new_ml = ml;
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if (new_ml > OPTIMAL_ML)
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new_ml = OPTIMAL_ML;
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if (ip + new_ml > start2 + ml2 - MINMATCH)
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new_ml = (int)(start2 - ip) + ml2 - MINMATCH;
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correction = new_ml - (int)(start2 - ip);
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if (correction > 0) {
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start2 += correction;
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ref2 += correction;
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ml2 -= correction;
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}
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}
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/*
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* Now, we have start2 = ip + new_ml,
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* with new_ml = min(ml, OPTIMAL_ML = 18)
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*/
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if (start2 + ml2 < mflimit)
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ml3 = LZ4HC_InsertAndGetWiderMatch(ctx,
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start2 + ml2 - 3, start2,
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matchlimit, ml2, &ref3, &start3,
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maxNbAttempts);
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else
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ml3 = ml2;
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if (ml3 == ml2) {
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/* No better match : 2 sequences to encode */
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/* ip & ref are known; Now for ml */
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if (start2 < ip + ml)
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ml = (int)(start2 - ip);
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/* Now, encode 2 sequences */
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if (LZ4HC_encodeSequence(&ip, &op, &anchor,
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ml, ref, limit, oend))
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return 0;
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ip = start2;
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if (LZ4HC_encodeSequence(&ip, &op, &anchor,
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ml2, ref2, limit, oend))
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return 0;
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continue;
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}
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if (start3 < ip + ml + 3) {
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/* Not enough space for match 2 : remove it */
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if (start3 >= (ip + ml)) {
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/* can write Seq1 immediately
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* ==> Seq2 is removed,
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* so Seq3 becomes Seq1
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*/
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if (start2 < ip + ml) {
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int correction = (int)(ip + ml - start2);
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start2 += correction;
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ref2 += correction;
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ml2 -= correction;
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if (ml2 < MINMATCH) {
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start2 = start3;
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ref2 = ref3;
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ml2 = ml3;
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}
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}
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if (LZ4HC_encodeSequence(&ip, &op, &anchor,
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ml, ref, limit, oend))
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return 0;
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ip = start3;
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ref = ref3;
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ml = ml3;
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start0 = start2;
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ref0 = ref2;
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ml0 = ml2;
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goto _Search2;
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}
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start2 = start3;
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ref2 = ref3;
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ml2 = ml3;
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goto _Search3;
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}
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/*
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* OK, now we have 3 ascending matches;
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* let's write at least the first one
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* ip & ref are known; Now for ml
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*/
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if (start2 < ip + ml) {
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if ((start2 - ip) < (int)ML_MASK) {
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int correction;
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|
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if (ml > OPTIMAL_ML)
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ml = OPTIMAL_ML;
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if (ip + ml > start2 + ml2 - MINMATCH)
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ml = (int)(start2 - ip) + ml2 - MINMATCH;
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correction = ml - (int)(start2 - ip);
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if (correction > 0) {
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start2 += correction;
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ref2 += correction;
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ml2 -= correction;
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}
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} else
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ml = (int)(start2 - ip);
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}
|
|
if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml,
|
|
ref, limit, oend))
|
|
return 0;
|
|
|
|
ip = start2;
|
|
ref = ref2;
|
|
ml = ml2;
|
|
|
|
start2 = start3;
|
|
ref2 = ref3;
|
|
ml2 = ml3;
|
|
|
|
goto _Search3;
|
|
}
|
|
|
|
/* Encode Last Literals */
|
|
{
|
|
int lastRun = (int)(iend - anchor);
|
|
|
|
if ((limit)
|
|
&& (((char *)op - dest) + lastRun + 1
|
|
+ ((lastRun + 255 - RUN_MASK)/255)
|
|
> (U32)maxOutputSize)) {
|
|
/* Check output limit */
|
|
return 0;
|
|
}
|
|
if (lastRun >= (int)RUN_MASK) {
|
|
*op++ = (RUN_MASK<<ML_BITS);
|
|
lastRun -= RUN_MASK;
|
|
for (; lastRun > 254 ; lastRun -= 255)
|
|
*op++ = 255;
|
|
*op++ = (BYTE) lastRun;
|
|
} else
|
|
*op++ = (BYTE)(lastRun<<ML_BITS);
|
|
LZ4_memcpy(op, anchor, iend - anchor);
|
|
op += iend - anchor;
|
|
}
|
|
|
|
/* End */
|
|
return (int) (((char *)op) - dest);
|
|
}
|
|
|
|
static int LZ4_compress_HC_extStateHC(
|
|
void *state,
|
|
const char *src,
|
|
char *dst,
|
|
int srcSize,
|
|
int maxDstSize,
|
|
int compressionLevel)
|
|
{
|
|
LZ4HC_CCtx_internal *ctx = &((LZ4_streamHC_t *)state)->internal_donotuse;
|
|
|
|
if (((size_t)(state)&(sizeof(void *) - 1)) != 0) {
|
|
/* Error : state is not aligned
|
|
* for pointers (32 or 64 bits)
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
LZ4HC_init(ctx, (const BYTE *)src);
|
|
|
|
if (maxDstSize < LZ4_compressBound(srcSize))
|
|
return LZ4HC_compress_generic(ctx, src, dst,
|
|
srcSize, maxDstSize, compressionLevel, limitedOutput);
|
|
else
|
|
return LZ4HC_compress_generic(ctx, src, dst,
|
|
srcSize, maxDstSize, compressionLevel, noLimit);
|
|
}
|
|
|
|
int LZ4_compress_HC(const char *src, char *dst, int srcSize,
|
|
int maxDstSize, int compressionLevel, void *wrkmem)
|
|
{
|
|
return LZ4_compress_HC_extStateHC(wrkmem, src, dst,
|
|
srcSize, maxDstSize, compressionLevel);
|
|
}
|
|
EXPORT_SYMBOL(LZ4_compress_HC);
|
|
|
|
/**************************************
|
|
* Streaming Functions
|
|
**************************************/
|
|
void LZ4_resetStreamHC(LZ4_streamHC_t *LZ4_streamHCPtr, int compressionLevel)
|
|
{
|
|
LZ4_streamHCPtr->internal_donotuse.base = NULL;
|
|
LZ4_streamHCPtr->internal_donotuse.compressionLevel = (unsigned int)compressionLevel;
|
|
}
|
|
|
|
int LZ4_loadDictHC(LZ4_streamHC_t *LZ4_streamHCPtr,
|
|
const char *dictionary,
|
|
int dictSize)
|
|
{
|
|
LZ4HC_CCtx_internal *ctxPtr = &LZ4_streamHCPtr->internal_donotuse;
|
|
|
|
if (dictSize > 64 * KB) {
|
|
dictionary += dictSize - 64 * KB;
|
|
dictSize = 64 * KB;
|
|
}
|
|
LZ4HC_init(ctxPtr, (const BYTE *)dictionary);
|
|
if (dictSize >= 4)
|
|
LZ4HC_Insert(ctxPtr, (const BYTE *)dictionary + (dictSize - 3));
|
|
ctxPtr->end = (const BYTE *)dictionary + dictSize;
|
|
return dictSize;
|
|
}
|
|
EXPORT_SYMBOL(LZ4_loadDictHC);
|
|
|
|
/* compression */
|
|
|
|
static void LZ4HC_setExternalDict(
|
|
LZ4HC_CCtx_internal *ctxPtr,
|
|
const BYTE *newBlock)
|
|
{
|
|
if (ctxPtr->end >= ctxPtr->base + 4) {
|
|
/* Referencing remaining dictionary content */
|
|
LZ4HC_Insert(ctxPtr, ctxPtr->end - 3);
|
|
}
|
|
|
|
/*
|
|
* Only one memory segment for extDict,
|
|
* so any previous extDict is lost at this stage
|
|
*/
|
|
ctxPtr->lowLimit = ctxPtr->dictLimit;
|
|
ctxPtr->dictLimit = (U32)(ctxPtr->end - ctxPtr->base);
|
|
ctxPtr->dictBase = ctxPtr->base;
|
|
ctxPtr->base = newBlock - ctxPtr->dictLimit;
|
|
ctxPtr->end = newBlock;
|
|
/* match referencing will resume from there */
|
|
ctxPtr->nextToUpdate = ctxPtr->dictLimit;
|
|
}
|
|
|
|
static int LZ4_compressHC_continue_generic(
|
|
LZ4_streamHC_t *LZ4_streamHCPtr,
|
|
const char *source,
|
|
char *dest,
|
|
int inputSize,
|
|
int maxOutputSize,
|
|
limitedOutput_directive limit)
|
|
{
|
|
LZ4HC_CCtx_internal *ctxPtr = &LZ4_streamHCPtr->internal_donotuse;
|
|
|
|
/* auto - init if forgotten */
|
|
if (ctxPtr->base == NULL)
|
|
LZ4HC_init(ctxPtr, (const BYTE *) source);
|
|
|
|
/* Check overflow */
|
|
if ((size_t)(ctxPtr->end - ctxPtr->base) > 2 * GB) {
|
|
size_t dictSize = (size_t)(ctxPtr->end - ctxPtr->base)
|
|
- ctxPtr->dictLimit;
|
|
if (dictSize > 64 * KB)
|
|
dictSize = 64 * KB;
|
|
LZ4_loadDictHC(LZ4_streamHCPtr,
|
|
(const char *)(ctxPtr->end) - dictSize, (int)dictSize);
|
|
}
|
|
|
|
/* Check if blocks follow each other */
|
|
if ((const BYTE *)source != ctxPtr->end)
|
|
LZ4HC_setExternalDict(ctxPtr, (const BYTE *)source);
|
|
|
|
/* Check overlapping input/dictionary space */
|
|
{
|
|
const BYTE *sourceEnd = (const BYTE *) source + inputSize;
|
|
const BYTE * const dictBegin = ctxPtr->dictBase + ctxPtr->lowLimit;
|
|
const BYTE * const dictEnd = ctxPtr->dictBase + ctxPtr->dictLimit;
|
|
|
|
if ((sourceEnd > dictBegin)
|
|
&& ((const BYTE *)source < dictEnd)) {
|
|
if (sourceEnd > dictEnd)
|
|
sourceEnd = dictEnd;
|
|
ctxPtr->lowLimit = (U32)(sourceEnd - ctxPtr->dictBase);
|
|
|
|
if (ctxPtr->dictLimit - ctxPtr->lowLimit < 4)
|
|
ctxPtr->lowLimit = ctxPtr->dictLimit;
|
|
}
|
|
}
|
|
|
|
return LZ4HC_compress_generic(ctxPtr, source, dest,
|
|
inputSize, maxOutputSize, ctxPtr->compressionLevel, limit);
|
|
}
|
|
|
|
int LZ4_compress_HC_continue(
|
|
LZ4_streamHC_t *LZ4_streamHCPtr,
|
|
const char *source,
|
|
char *dest,
|
|
int inputSize,
|
|
int maxOutputSize)
|
|
{
|
|
if (maxOutputSize < LZ4_compressBound(inputSize))
|
|
return LZ4_compressHC_continue_generic(LZ4_streamHCPtr,
|
|
source, dest, inputSize, maxOutputSize, limitedOutput);
|
|
else
|
|
return LZ4_compressHC_continue_generic(LZ4_streamHCPtr,
|
|
source, dest, inputSize, maxOutputSize, noLimit);
|
|
}
|
|
EXPORT_SYMBOL(LZ4_compress_HC_continue);
|
|
|
|
/* dictionary saving */
|
|
|
|
int LZ4_saveDictHC(
|
|
LZ4_streamHC_t *LZ4_streamHCPtr,
|
|
char *safeBuffer,
|
|
int dictSize)
|
|
{
|
|
LZ4HC_CCtx_internal *const streamPtr = &LZ4_streamHCPtr->internal_donotuse;
|
|
int const prefixSize = (int)(streamPtr->end
|
|
- (streamPtr->base + streamPtr->dictLimit));
|
|
|
|
if (dictSize > 64 * KB)
|
|
dictSize = 64 * KB;
|
|
if (dictSize < 4)
|
|
dictSize = 0;
|
|
if (dictSize > prefixSize)
|
|
dictSize = prefixSize;
|
|
|
|
memmove(safeBuffer, streamPtr->end - dictSize, dictSize);
|
|
|
|
{
|
|
U32 const endIndex = (U32)(streamPtr->end - streamPtr->base);
|
|
|
|
streamPtr->end = (const BYTE *)safeBuffer + dictSize;
|
|
streamPtr->base = streamPtr->end - endIndex;
|
|
streamPtr->dictLimit = endIndex - dictSize;
|
|
streamPtr->lowLimit = endIndex - dictSize;
|
|
|
|
if (streamPtr->nextToUpdate < streamPtr->dictLimit)
|
|
streamPtr->nextToUpdate = streamPtr->dictLimit;
|
|
}
|
|
return dictSize;
|
|
}
|
|
EXPORT_SYMBOL(LZ4_saveDictHC);
|
|
|
|
MODULE_LICENSE("Dual BSD/GPL");
|
|
MODULE_DESCRIPTION("LZ4 HC compressor");
|