363 lines
13 KiB
C
363 lines
13 KiB
C
/*
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lz4opt.h - Optimal Mode of LZ4
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Copyright (C) 2015-2017, Przemyslaw Skibinski <inikep@gmail.com>
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Note : this file is intended to be included within lz4hc.c
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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 source repository : https://github.com/lz4/lz4
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- LZ4 public forum : https://groups.google.com/forum/#!forum/lz4c
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*/
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#define LZ4_OPT_NUM (1<<12)
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typedef struct {
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int off;
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int len;
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} LZ4HC_match_t;
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typedef struct {
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int price;
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int off;
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int mlen;
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int litlen;
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} LZ4HC_optimal_t;
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/* price in bits */
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FORCE_INLINE size_t LZ4HC_literalsPrice(size_t litlen)
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{
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size_t price = litlen;
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if (litlen >= (size_t)RUN_MASK) price += 1+(litlen-RUN_MASK)/255;
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return price;
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}
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/* requires mlen >= MINMATCH */
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FORCE_INLINE size_t LZ4HC_sequencePrice(size_t litlen, size_t mlen)
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{
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size_t price = 2 + 1; /* 16-bit offset + token */
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price += LZ4HC_literalsPrice(litlen);
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if (mlen >= (size_t)(ML_MASK+MINMATCH))
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price+= 1+(mlen-(ML_MASK+MINMATCH))/255;
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return price;
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}
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/*-*************************************
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* Binary Tree search
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***************************************/
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FORCE_INLINE int LZ4HC_BinTree_InsertAndGetAllMatches (
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LZ4HC_CCtx_internal* ctx,
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const BYTE* const ip,
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const BYTE* const iHighLimit,
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size_t best_mlen,
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LZ4HC_match_t* matches,
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int* matchNum)
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{
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U16* const chainTable = ctx->chainTable;
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U32* const HashTable = ctx->hashTable;
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const BYTE* const base = ctx->base;
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const U32 dictLimit = ctx->dictLimit;
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const U32 current = (U32)(ip - base);
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const U32 lowLimit = (ctx->lowLimit + MAX_DISTANCE > current) ? ctx->lowLimit : current - (MAX_DISTANCE - 1);
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const BYTE* const dictBase = ctx->dictBase;
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const BYTE* match;
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int nbAttempts = ctx->searchNum;
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int mnum = 0;
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U16 *ptr0, *ptr1, delta0, delta1;
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U32 matchIndex;
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size_t matchLength = 0;
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U32* HashPos;
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if (ip + MINMATCH > iHighLimit) return 1;
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/* HC4 match finder */
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HashPos = &HashTable[LZ4HC_hashPtr(ip)];
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matchIndex = *HashPos;
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*HashPos = current;
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ptr0 = &DELTANEXTMAXD(current*2+1);
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ptr1 = &DELTANEXTMAXD(current*2);
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delta0 = delta1 = (U16)(current - matchIndex);
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while ((matchIndex < current) && (matchIndex>=lowLimit) && (nbAttempts)) {
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nbAttempts--;
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if (matchIndex >= dictLimit) {
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match = base + matchIndex;
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matchLength = LZ4_count(ip, match, iHighLimit);
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} else {
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const BYTE* vLimit = ip + (dictLimit - matchIndex);
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match = dictBase + matchIndex;
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if (vLimit > iHighLimit) vLimit = iHighLimit;
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matchLength = LZ4_count(ip, match, vLimit);
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if ((ip+matchLength == vLimit) && (vLimit < iHighLimit))
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matchLength += LZ4_count(ip+matchLength, base+dictLimit, iHighLimit);
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}
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if (matchLength > best_mlen) {
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best_mlen = matchLength;
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if (matches) {
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if (matchIndex >= dictLimit)
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matches[mnum].off = (int)(ip - match);
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else
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matches[mnum].off = (int)(ip - (base + matchIndex)); /* virtual matchpos */
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matches[mnum].len = (int)matchLength;
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mnum++;
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}
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if (best_mlen > LZ4_OPT_NUM) break;
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}
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if (ip+matchLength >= iHighLimit) /* equal : no way to know if inf or sup */
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break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt the tree */
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if (*(ip+matchLength) < *(match+matchLength)) {
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*ptr0 = delta0;
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ptr0 = &DELTANEXTMAXD(matchIndex*2);
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if (*ptr0 == (U16)-1) break;
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delta0 = *ptr0;
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delta1 += delta0;
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matchIndex -= delta0;
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} else {
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*ptr1 = delta1;
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ptr1 = &DELTANEXTMAXD(matchIndex*2+1);
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if (*ptr1 == (U16)-1) break;
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delta1 = *ptr1;
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delta0 += delta1;
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matchIndex -= delta1;
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}
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}
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*ptr0 = (U16)-1;
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*ptr1 = (U16)-1;
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if (matchNum) *matchNum = mnum;
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/* if (best_mlen > 8) return best_mlen-8; */
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if (!matchNum) return 1;
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return 1;
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}
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FORCE_INLINE void LZ4HC_updateBinTree(LZ4HC_CCtx_internal* ctx, const BYTE* const ip, const BYTE* const iHighLimit)
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{
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const BYTE* const base = ctx->base;
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const U32 target = (U32)(ip - base);
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U32 idx = ctx->nextToUpdate;
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while(idx < target)
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idx += LZ4HC_BinTree_InsertAndGetAllMatches(ctx, base+idx, iHighLimit, 8, NULL, NULL);
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}
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/** Tree updater, providing best match */
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FORCE_INLINE int LZ4HC_BinTree_GetAllMatches (
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LZ4HC_CCtx_internal* ctx,
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const BYTE* const ip, const BYTE* const iHighLimit,
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size_t best_mlen, LZ4HC_match_t* matches, const int fullUpdate)
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{
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int mnum = 0;
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if (ip < ctx->base + ctx->nextToUpdate) return 0; /* skipped area */
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if (fullUpdate) LZ4HC_updateBinTree(ctx, ip, iHighLimit);
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best_mlen = LZ4HC_BinTree_InsertAndGetAllMatches(ctx, ip, iHighLimit, best_mlen, matches, &mnum);
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ctx->nextToUpdate = (U32)(ip - ctx->base + best_mlen);
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return mnum;
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}
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#define SET_PRICE(pos, ml, offset, ll, cost) \
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{ \
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while (last_pos < pos) { opt[last_pos+1].price = 1<<30; last_pos++; } \
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opt[pos].mlen = (int)ml; \
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opt[pos].off = (int)offset; \
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opt[pos].litlen = (int)ll; \
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opt[pos].price = (int)cost; \
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}
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static int LZ4HC_compress_optimal (
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LZ4HC_CCtx_internal* ctx,
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const char* const source,
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char* dest,
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int inputSize,
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int maxOutputSize,
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limitedOutput_directive limit,
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size_t sufficient_len,
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const int fullUpdate
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)
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{
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LZ4HC_optimal_t opt[LZ4_OPT_NUM + 1]; /* this uses a bit too much stack memory to my taste ... */
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LZ4HC_match_t matches[LZ4_OPT_NUM + 1];
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const BYTE *inr = NULL;
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size_t res, cur, cur2;
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size_t i, llen, litlen, mlen, best_mlen, price, offset, best_off, match_num, last_pos;
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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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/* init */
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if (sufficient_len >= LZ4_OPT_NUM) sufficient_len = LZ4_OPT_NUM-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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memset(opt, 0, sizeof(LZ4HC_optimal_t));
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last_pos = 0;
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llen = ip - anchor;
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match_num = LZ4HC_BinTree_GetAllMatches(ctx, ip, matchlimit, MINMATCH-1, matches, fullUpdate);
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if (!match_num) { ip++; continue; }
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if ((size_t)matches[match_num-1].len > sufficient_len) {
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best_mlen = matches[match_num-1].len;
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best_off = matches[match_num-1].off;
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cur = 0;
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last_pos = 1;
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goto encode;
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}
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/* set prices using matches at position = 0 */
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for (i = 0; i < match_num; i++) {
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mlen = (i>0) ? (size_t)matches[i-1].len+1 : MINMATCH;
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best_mlen = matches[i].len; /* necessarily < LZ4_OPT_NUM */
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while (mlen <= best_mlen) {
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price = LZ4HC_sequencePrice(llen, mlen) - LZ4HC_literalsPrice(llen);
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SET_PRICE(mlen, mlen, matches[i].off, 0, price); /* updates last_pos and opt[pos] */
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mlen++;
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}
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}
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if (last_pos < MINMATCH) { ip++; continue; }
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/* check further positions */
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opt[0].mlen = opt[1].mlen = 1;
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for (cur = 1; cur <= last_pos; cur++) {
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inr = ip + cur;
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if (opt[cur-1].mlen == 1) {
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litlen = opt[cur-1].litlen + 1;
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if (cur != litlen) {
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price = opt[cur - litlen].price + LZ4HC_literalsPrice(litlen);
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} else {
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price = LZ4HC_literalsPrice(llen + litlen) - LZ4HC_literalsPrice(llen);
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}
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} else {
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litlen = 1;
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price = opt[cur - 1].price + LZ4HC_literalsPrice(litlen);
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}
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mlen = 1;
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best_mlen = 0;
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if (price < (size_t)opt[cur].price)
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SET_PRICE(cur, mlen, best_mlen, litlen, price); /* note : increases last_pos */
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if (cur == last_pos || inr >= mflimit) break;
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match_num = LZ4HC_BinTree_GetAllMatches(ctx, inr, matchlimit, MINMATCH-1, matches, fullUpdate);
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if ((match_num > 0) && (size_t)matches[match_num-1].len > sufficient_len) {
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/* immediate encoding */
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best_mlen = matches[match_num-1].len;
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best_off = matches[match_num-1].off;
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last_pos = cur + 1;
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goto encode;
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}
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/* set prices using matches at position = cur */
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for (i = 0; i < match_num; i++) {
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mlen = (i>0) ? (size_t)matches[i-1].len+1 : MINMATCH;
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cur2 = cur;
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best_mlen = (cur2 + matches[i].len < LZ4_OPT_NUM) ? (size_t)matches[i].len : LZ4_OPT_NUM - cur2;
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while (mlen <= best_mlen) {
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if (opt[cur2].mlen == 1) {
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litlen = opt[cur2].litlen;
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if (cur2 != litlen)
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price = opt[cur2 - litlen].price + LZ4HC_sequencePrice(litlen, mlen);
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else
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price = LZ4HC_sequencePrice(llen + litlen, mlen) - LZ4HC_literalsPrice(llen);
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} else {
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litlen = 0;
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price = opt[cur2].price + LZ4HC_sequencePrice(litlen, mlen);
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}
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if (cur2 + mlen > last_pos || price < (size_t)opt[cur2 + mlen].price) { // || (((int)price == opt[cur2 + mlen].price) && (opt[cur2 + mlen-1].mlen == 1))) {
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SET_PRICE(cur2 + mlen, mlen, matches[i].off, litlen, price);
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}
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mlen++;
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}
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}
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} /* for (cur = 1; cur <= last_pos; cur++) */
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best_mlen = opt[last_pos].mlen;
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best_off = opt[last_pos].off;
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cur = last_pos - best_mlen;
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encode: /* cur, last_pos, best_mlen, best_off have to be set */
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opt[0].mlen = 1;
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while (1) {
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mlen = opt[cur].mlen;
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offset = opt[cur].off;
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opt[cur].mlen = (int)best_mlen;
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opt[cur].off = (int)best_off;
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best_mlen = mlen;
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best_off = offset;
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if (mlen > cur) break;
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cur -= mlen;
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}
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cur = 0;
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while (cur < last_pos) {
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mlen = opt[cur].mlen;
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if (mlen == 1) { ip++; cur++; continue; }
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offset = opt[cur].off;
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cur += mlen;
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res = LZ4HC_encodeSequence(&ip, &op, &anchor, (int)mlen, ip - offset, limit, oend);
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if (res) return 0;
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}
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}
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/* Encode Last Literals */
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{ int lastRun = (int)(iend - anchor);
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if ((limit) && (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize)) return 0; /* Check output limit */
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if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun > 254 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; }
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else *op++ = (BYTE)(lastRun<<ML_BITS);
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memcpy(op, anchor, iend - anchor);
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op += iend-anchor;
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}
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/* End */
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return (int) ((char*)op-dest);
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}
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