| /* |
| lz4opt.h - Optimal Mode of LZ4 |
| Copyright (C) 2015-2017, Przemyslaw Skibinski <inikep@gmail.com> |
| Note : this file is intended to be included within lz4hc.c |
| |
| BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php) |
| |
| Redistribution and use in source and binary forms, with or without |
| modification, are permitted provided that the following conditions are |
| met: |
| |
| * Redistributions of source code must retain the above copyright |
| notice, this list of conditions and the following disclaimer. |
| * Redistributions in binary form must reproduce the above |
| copyright notice, this list of conditions and the following disclaimer |
| in the documentation and/or other materials provided with the |
| distribution. |
| |
| THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| You can contact the author at : |
| - LZ4 source repository : https://github.com/lz4/lz4 |
| - LZ4 public forum : https://groups.google.com/forum/#!forum/lz4c |
| */ |
| |
| #define LZ4_OPT_NUM (1<<12) |
| |
| |
| typedef struct { |
| int off; |
| int len; |
| } LZ4HC_match_t; |
| |
| typedef struct { |
| int price; |
| int off; |
| int mlen; |
| int litlen; |
| } LZ4HC_optimal_t; |
| |
| |
| /* price in bytes */ |
| FORCE_INLINE size_t LZ4HC_literalsPrice(size_t litlen) |
| { |
| size_t price = litlen; |
| if (litlen >= (size_t)RUN_MASK) |
| price += 1 + (litlen-RUN_MASK)/255; |
| return price; |
| } |
| |
| |
| /* requires mlen >= MINMATCH */ |
| FORCE_INLINE size_t LZ4HC_sequencePrice(size_t litlen, size_t mlen) |
| { |
| size_t price = 2 + 1; /* 16-bit offset + token */ |
| |
| price += LZ4HC_literalsPrice(litlen); |
| |
| if (mlen >= (size_t)(ML_MASK+MINMATCH)) |
| price+= 1 + (mlen-(ML_MASK+MINMATCH))/255; |
| |
| return price; |
| } |
| |
| |
| /*-************************************* |
| * Binary Tree search |
| ***************************************/ |
| FORCE_INLINE int LZ4HC_BinTree_InsertAndGetAllMatches ( |
| LZ4HC_CCtx_internal* ctx, |
| const BYTE* const ip, |
| const BYTE* const iHighLimit, |
| size_t best_mlen, |
| LZ4HC_match_t* matches, |
| int* matchNum) |
| { |
| U16* const chainTable = ctx->chainTable; |
| U32* const HashTable = ctx->hashTable; |
| const BYTE* const base = ctx->base; |
| const U32 dictLimit = ctx->dictLimit; |
| const U32 current = (U32)(ip - base); |
| const U32 lowLimit = (ctx->lowLimit + MAX_DISTANCE > current) ? ctx->lowLimit : current - (MAX_DISTANCE - 1); |
| const BYTE* const dictBase = ctx->dictBase; |
| const BYTE* match; |
| int nbAttempts = ctx->searchNum; |
| int mnum = 0; |
| U16 *ptr0, *ptr1, delta0, delta1; |
| U32 matchIndex; |
| size_t matchLength = 0; |
| U32* HashPos; |
| |
| if (ip + MINMATCH > iHighLimit) return 1; |
| |
| /* HC4 match finder */ |
| HashPos = &HashTable[LZ4HC_hashPtr(ip)]; |
| matchIndex = *HashPos; |
| *HashPos = current; |
| |
| ptr0 = &DELTANEXTMAXD(current*2+1); |
| ptr1 = &DELTANEXTMAXD(current*2); |
| delta0 = delta1 = (U16)(current - matchIndex); |
| |
| while ((matchIndex < current) && (matchIndex>=lowLimit) && (nbAttempts)) { |
| nbAttempts--; |
| if (matchIndex >= dictLimit) { |
| match = base + matchIndex; |
| matchLength = LZ4_count(ip, match, iHighLimit); |
| } else { |
| const BYTE* vLimit = ip + (dictLimit - matchIndex); |
| match = dictBase + matchIndex; |
| if (vLimit > iHighLimit) vLimit = iHighLimit; |
| matchLength = LZ4_count(ip, match, vLimit); |
| if ((ip+matchLength == vLimit) && (vLimit < iHighLimit)) |
| matchLength += LZ4_count(ip+matchLength, base+dictLimit, iHighLimit); |
| } |
| |
| if (matchLength > best_mlen) { |
| best_mlen = matchLength; |
| if (matches) { |
| if (matchIndex >= dictLimit) |
| matches[mnum].off = (int)(ip - match); |
| else |
| matches[mnum].off = (int)(ip - (base + matchIndex)); /* virtual matchpos */ |
| matches[mnum].len = (int)matchLength; |
| mnum++; |
| } |
| if (best_mlen > LZ4_OPT_NUM) break; |
| } |
| |
| if (ip+matchLength >= iHighLimit) /* equal : no way to know if inf or sup */ |
| break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt the tree */ |
| |
| if (*(ip+matchLength) < *(match+matchLength)) { |
| *ptr0 = delta0; |
| ptr0 = &DELTANEXTMAXD(matchIndex*2); |
| if (*ptr0 == (U16)-1) break; |
| delta0 = *ptr0; |
| delta1 += delta0; |
| matchIndex -= delta0; |
| } else { |
| *ptr1 = delta1; |
| ptr1 = &DELTANEXTMAXD(matchIndex*2+1); |
| if (*ptr1 == (U16)-1) break; |
| delta1 = *ptr1; |
| delta0 += delta1; |
| matchIndex -= delta1; |
| } |
| } |
| |
| *ptr0 = (U16)-1; |
| *ptr1 = (U16)-1; |
| if (matchNum) *matchNum = mnum; |
| /* if (best_mlen > 8) return best_mlen-8; */ |
| if (!matchNum) return 1; |
| return 1; |
| } |
| |
| |
| FORCE_INLINE void LZ4HC_updateBinTree(LZ4HC_CCtx_internal* ctx, const BYTE* const ip, const BYTE* const iHighLimit) |
| { |
| const BYTE* const base = ctx->base; |
| const U32 target = (U32)(ip - base); |
| U32 idx = ctx->nextToUpdate; |
| while(idx < target) |
| idx += LZ4HC_BinTree_InsertAndGetAllMatches(ctx, base+idx, iHighLimit, 8, NULL, NULL); |
| } |
| |
| |
| /** Tree updater, providing best match */ |
| FORCE_INLINE int LZ4HC_BinTree_GetAllMatches ( |
| LZ4HC_CCtx_internal* ctx, |
| const BYTE* const ip, const BYTE* const iHighLimit, |
| size_t best_mlen, LZ4HC_match_t* matches, const int fullUpdate) |
| { |
| int mnum = 0; |
| if (ip < ctx->base + ctx->nextToUpdate) return 0; /* skipped area */ |
| if (fullUpdate) LZ4HC_updateBinTree(ctx, ip, iHighLimit); |
| best_mlen = LZ4HC_BinTree_InsertAndGetAllMatches(ctx, ip, iHighLimit, best_mlen, matches, &mnum); |
| ctx->nextToUpdate = (U32)(ip - ctx->base + best_mlen); |
| return mnum; |
| } |
| |
| |
| #define SET_PRICE(pos, ml, offset, ll, cost) \ |
| { \ |
| while (last_pos < pos) { opt[last_pos+1].price = 1<<30; last_pos++; } \ |
| opt[pos].mlen = (int)ml; \ |
| opt[pos].off = (int)offset; \ |
| opt[pos].litlen = (int)ll; \ |
| opt[pos].price = (int)cost; \ |
| } |
| |
| |
| static int LZ4HC_compress_optimal ( |
| LZ4HC_CCtx_internal* ctx, |
| const char* const source, |
| char* dest, |
| int inputSize, |
| int maxOutputSize, |
| limitedOutput_directive limit, |
| size_t sufficient_len, |
| const int fullUpdate |
| ) |
| { |
| LZ4HC_optimal_t opt[LZ4_OPT_NUM + 1]; /* this uses a bit too much stack memory to my taste ... */ |
| LZ4HC_match_t matches[LZ4_OPT_NUM + 1]; |
| |
| const BYTE* ip = (const BYTE*) source; |
| const BYTE* anchor = ip; |
| const BYTE* const iend = ip + inputSize; |
| const BYTE* const mflimit = iend - MFLIMIT; |
| const BYTE* const matchlimit = (iend - LASTLITERALS); |
| BYTE* op = (BYTE*) dest; |
| BYTE* const oend = op + maxOutputSize; |
| |
| /* init */ |
| if (sufficient_len >= LZ4_OPT_NUM) sufficient_len = LZ4_OPT_NUM-1; |
| ctx->end += inputSize; |
| ip++; |
| |
| /* Main Loop */ |
| while (ip < mflimit) { |
| size_t const llen = ip - anchor; |
| size_t last_pos = 0; |
| size_t match_num, cur, best_mlen, best_off; |
| memset(opt, 0, sizeof(LZ4HC_optimal_t)); /* memset only the first one */ |
| |
| match_num = LZ4HC_BinTree_GetAllMatches(ctx, ip, matchlimit, MINMATCH-1, matches, fullUpdate); |
| if (!match_num) { ip++; continue; } |
| |
| if ((size_t)matches[match_num-1].len > sufficient_len) { |
| /* good enough solution : immediate encoding */ |
| best_mlen = matches[match_num-1].len; |
| best_off = matches[match_num-1].off; |
| cur = 0; |
| last_pos = 1; |
| goto encode; |
| } |
| |
| /* set prices using matches at position = 0 */ |
| { size_t matchNb; |
| for (matchNb = 0; matchNb < match_num; matchNb++) { |
| size_t mlen = (matchNb>0) ? (size_t)matches[matchNb-1].len+1 : MINMATCH; |
| best_mlen = matches[matchNb].len; /* necessarily < sufficient_len < LZ4_OPT_NUM */ |
| for ( ; mlen <= best_mlen ; mlen++) { |
| size_t const cost = LZ4HC_sequencePrice(llen, mlen) - LZ4HC_literalsPrice(llen); |
| SET_PRICE(mlen, mlen, matches[matchNb].off, 0, cost); /* updates last_pos and opt[pos] */ |
| } } } |
| |
| if (last_pos < MINMATCH) { ip++; continue; } /* note : on clang at least, this test improves performance */ |
| |
| /* check further positions */ |
| opt[0].mlen = opt[1].mlen = 1; |
| for (cur = 1; cur <= last_pos; cur++) { |
| const BYTE* const curPtr = ip + cur; |
| |
| /* establish baseline price if cur is literal */ |
| { size_t price, litlen; |
| if (opt[cur-1].mlen == 1) { |
| /* no match at previous position */ |
| litlen = opt[cur-1].litlen + 1; |
| if (cur > litlen) { |
| price = opt[cur - litlen].price + LZ4HC_literalsPrice(litlen); |
| } else { |
| price = LZ4HC_literalsPrice(llen + litlen) - LZ4HC_literalsPrice(llen); |
| } |
| } else { |
| litlen = 1; |
| price = opt[cur - 1].price + LZ4HC_literalsPrice(1); |
| } |
| |
| if (price < (size_t)opt[cur].price) |
| SET_PRICE(cur, 1 /*mlen*/, 0 /*off*/, litlen, price); /* note : increases last_pos */ |
| } |
| |
| if (cur == last_pos || curPtr >= mflimit) break; |
| |
| match_num = LZ4HC_BinTree_GetAllMatches(ctx, curPtr, matchlimit, MINMATCH-1, matches, fullUpdate); |
| if ((match_num > 0) && (size_t)matches[match_num-1].len > sufficient_len) { |
| /* immediate encoding */ |
| best_mlen = matches[match_num-1].len; |
| best_off = matches[match_num-1].off; |
| last_pos = cur + 1; |
| goto encode; |
| } |
| |
| /* set prices using matches at position = cur */ |
| { size_t matchNb; |
| for (matchNb = 0; matchNb < match_num; matchNb++) { |
| size_t ml = (matchNb>0) ? (size_t)matches[matchNb-1].len+1 : MINMATCH; |
| best_mlen = (cur + matches[matchNb].len < LZ4_OPT_NUM) ? |
| (size_t)matches[matchNb].len : LZ4_OPT_NUM - cur; |
| |
| for ( ; ml <= best_mlen ; ml++) { |
| size_t ll, price; |
| if (opt[cur].mlen == 1) { |
| ll = opt[cur].litlen; |
| if (cur > ll) |
| price = opt[cur - ll].price + LZ4HC_sequencePrice(ll, ml); |
| else |
| price = LZ4HC_sequencePrice(llen + ll, ml) - LZ4HC_literalsPrice(llen); |
| } else { |
| ll = 0; |
| price = opt[cur].price + LZ4HC_sequencePrice(0, ml); |
| } |
| |
| if (cur + ml > last_pos || price < (size_t)opt[cur + ml].price) { |
| SET_PRICE(cur + ml, ml, matches[matchNb].off, ll, price); |
| } } } } |
| } /* for (cur = 1; cur <= last_pos; cur++) */ |
| |
| best_mlen = opt[last_pos].mlen; |
| best_off = opt[last_pos].off; |
| cur = last_pos - best_mlen; |
| |
| encode: /* cur, last_pos, best_mlen, best_off must be set */ |
| opt[0].mlen = 1; |
| while (1) { /* from end to beginning */ |
| size_t const ml = opt[cur].mlen; |
| int const offset = opt[cur].off; |
| opt[cur].mlen = (int)best_mlen; |
| opt[cur].off = (int)best_off; |
| best_mlen = ml; |
| best_off = offset; |
| if (ml > cur) break; /* can this happen ? */ |
| cur -= ml; |
| } |
| |
| /* encode all recorded sequences */ |
| cur = 0; |
| while (cur < last_pos) { |
| int const ml = opt[cur].mlen; |
| int const offset = opt[cur].off; |
| if (ml == 1) { ip++; cur++; continue; } |
| cur += ml; |
| if ( LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ip - offset, limit, oend) ) return 0; |
| } |
| } /* while (ip < mflimit) */ |
| |
| /* Encode Last Literals */ |
| { int lastRun = (int)(iend - anchor); |
| if ((limit) && (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize)) return 0; /* Check output limit */ |
| 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); |
| memcpy(op, anchor, iend - anchor); |
| op += iend-anchor; |
| } |
| |
| /* End */ |
| return (int) ((char*)op-dest); |
| } |