| /* |
| * Copyright (c) Yann Collet, Facebook, Inc. |
| * All rights reserved. |
| * |
| * This source code is licensed under both the BSD-style license (found in the |
| * LICENSE file in the root directory of this source tree) and the GPLv2 (found |
| * in the COPYING file in the root directory of this source tree). |
| * You may select, at your option, one of the above-listed licenses. |
| */ |
| |
| #include "zstd_compress_internal.h" /* ZSTD_hashPtr, ZSTD_count, ZSTD_storeSeq */ |
| #include "zstd_fast.h" |
| |
| |
| void ZSTD_fillHashTable(ZSTD_matchState_t* ms, |
| const void* const end, |
| ZSTD_dictTableLoadMethod_e dtlm) |
| { |
| const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| U32* const hashTable = ms->hashTable; |
| U32 const hBits = cParams->hashLog; |
| U32 const mls = cParams->minMatch; |
| const BYTE* const base = ms->window.base; |
| const BYTE* ip = base + ms->nextToUpdate; |
| const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE; |
| const U32 fastHashFillStep = 3; |
| |
| /* Always insert every fastHashFillStep position into the hash table. |
| * Insert the other positions if their hash entry is empty. |
| */ |
| for ( ; ip + fastHashFillStep < iend + 2; ip += fastHashFillStep) { |
| U32 const curr = (U32)(ip - base); |
| size_t const hash0 = ZSTD_hashPtr(ip, hBits, mls); |
| hashTable[hash0] = curr; |
| if (dtlm == ZSTD_dtlm_fast) continue; |
| /* Only load extra positions for ZSTD_dtlm_full */ |
| { U32 p; |
| for (p = 1; p < fastHashFillStep; ++p) { |
| size_t const hash = ZSTD_hashPtr(ip + p, hBits, mls); |
| if (hashTable[hash] == 0) { /* not yet filled */ |
| hashTable[hash] = curr + p; |
| } } } } |
| } |
| |
| |
| /** |
| * If you squint hard enough (and ignore repcodes), the search operation at any |
| * given position is broken into 4 stages: |
| * |
| * 1. Hash (map position to hash value via input read) |
| * 2. Lookup (map hash val to index via hashtable read) |
| * 3. Load (map index to value at that position via input read) |
| * 4. Compare |
| * |
| * Each of these steps involves a memory read at an address which is computed |
| * from the previous step. This means these steps must be sequenced and their |
| * latencies are cumulative. |
| * |
| * Rather than do 1->2->3->4 sequentially for a single position before moving |
| * onto the next, this implementation interleaves these operations across the |
| * next few positions: |
| * |
| * R = Repcode Read & Compare |
| * H = Hash |
| * T = Table Lookup |
| * M = Match Read & Compare |
| * |
| * Pos | Time --> |
| * ----+------------------- |
| * N | ... M |
| * N+1 | ... TM |
| * N+2 | R H T M |
| * N+3 | H TM |
| * N+4 | R H T M |
| * N+5 | H ... |
| * N+6 | R ... |
| * |
| * This is very much analogous to the pipelining of execution in a CPU. And just |
| * like a CPU, we have to dump the pipeline when we find a match (i.e., take a |
| * branch). |
| * |
| * When this happens, we throw away our current state, and do the following prep |
| * to re-enter the loop: |
| * |
| * Pos | Time --> |
| * ----+------------------- |
| * N | H T |
| * N+1 | H |
| * |
| * This is also the work we do at the beginning to enter the loop initially. |
| */ |
| FORCE_INLINE_TEMPLATE size_t |
| ZSTD_compressBlock_fast_noDict_generic( |
| ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| void const* src, size_t srcSize, |
| U32 const mls, U32 const hasStep) |
| { |
| const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| U32* const hashTable = ms->hashTable; |
| U32 const hlog = cParams->hashLog; |
| /* support stepSize of 0 */ |
| size_t const stepSize = hasStep ? (cParams->targetLength + !(cParams->targetLength) + 1) : 2; |
| const BYTE* const base = ms->window.base; |
| const BYTE* const istart = (const BYTE*)src; |
| const U32 endIndex = (U32)((size_t)(istart - base) + srcSize); |
| const U32 prefixStartIndex = ZSTD_getLowestPrefixIndex(ms, endIndex, cParams->windowLog); |
| const BYTE* const prefixStart = base + prefixStartIndex; |
| const BYTE* const iend = istart + srcSize; |
| const BYTE* const ilimit = iend - HASH_READ_SIZE; |
| |
| const BYTE* anchor = istart; |
| const BYTE* ip0 = istart; |
| const BYTE* ip1; |
| const BYTE* ip2; |
| const BYTE* ip3; |
| U32 current0; |
| |
| U32 rep_offset1 = rep[0]; |
| U32 rep_offset2 = rep[1]; |
| U32 offsetSaved = 0; |
| |
| size_t hash0; /* hash for ip0 */ |
| size_t hash1; /* hash for ip1 */ |
| U32 idx; /* match idx for ip0 */ |
| U32 mval; /* src value at match idx */ |
| |
| U32 offcode; |
| const BYTE* match0; |
| size_t mLength; |
| |
| /* ip0 and ip1 are always adjacent. The targetLength skipping and |
| * uncompressibility acceleration is applied to every other position, |
| * matching the behavior of #1562. step therefore represents the gap |
| * between pairs of positions, from ip0 to ip2 or ip1 to ip3. */ |
| size_t step; |
| const BYTE* nextStep; |
| const size_t kStepIncr = (1 << (kSearchStrength - 1)); |
| |
| DEBUGLOG(5, "ZSTD_compressBlock_fast_generic"); |
| ip0 += (ip0 == prefixStart); |
| { U32 const curr = (U32)(ip0 - base); |
| U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, cParams->windowLog); |
| U32 const maxRep = curr - windowLow; |
| if (rep_offset2 > maxRep) offsetSaved = rep_offset2, rep_offset2 = 0; |
| if (rep_offset1 > maxRep) offsetSaved = rep_offset1, rep_offset1 = 0; |
| } |
| |
| /* start each op */ |
| _start: /* Requires: ip0 */ |
| |
| step = stepSize; |
| nextStep = ip0 + kStepIncr; |
| |
| /* calculate positions, ip0 - anchor == 0, so we skip step calc */ |
| ip1 = ip0 + 1; |
| ip2 = ip0 + step; |
| ip3 = ip2 + 1; |
| |
| if (ip3 >= ilimit) { |
| goto _cleanup; |
| } |
| |
| hash0 = ZSTD_hashPtr(ip0, hlog, mls); |
| hash1 = ZSTD_hashPtr(ip1, hlog, mls); |
| |
| idx = hashTable[hash0]; |
| |
| do { |
| /* load repcode match for ip[2]*/ |
| const U32 rval = MEM_read32(ip2 - rep_offset1); |
| |
| /* write back hash table entry */ |
| current0 = (U32)(ip0 - base); |
| hashTable[hash0] = current0; |
| |
| /* check repcode at ip[2] */ |
| if ((MEM_read32(ip2) == rval) & (rep_offset1 > 0)) { |
| ip0 = ip2; |
| match0 = ip0 - rep_offset1; |
| mLength = ip0[-1] == match0[-1]; |
| ip0 -= mLength; |
| match0 -= mLength; |
| offcode = 0; |
| mLength += 4; |
| goto _match; |
| } |
| |
| /* load match for ip[0] */ |
| if (idx >= prefixStartIndex) { |
| mval = MEM_read32(base + idx); |
| } else { |
| mval = MEM_read32(ip0) ^ 1; /* guaranteed to not match. */ |
| } |
| |
| /* check match at ip[0] */ |
| if (MEM_read32(ip0) == mval) { |
| /* found a match! */ |
| goto _offset; |
| } |
| |
| /* lookup ip[1] */ |
| idx = hashTable[hash1]; |
| |
| /* hash ip[2] */ |
| hash0 = hash1; |
| hash1 = ZSTD_hashPtr(ip2, hlog, mls); |
| |
| /* advance to next positions */ |
| ip0 = ip1; |
| ip1 = ip2; |
| ip2 = ip3; |
| |
| /* write back hash table entry */ |
| current0 = (U32)(ip0 - base); |
| hashTable[hash0] = current0; |
| |
| /* load match for ip[0] */ |
| if (idx >= prefixStartIndex) { |
| mval = MEM_read32(base + idx); |
| } else { |
| mval = MEM_read32(ip0) ^ 1; /* guaranteed to not match. */ |
| } |
| |
| /* check match at ip[0] */ |
| if (MEM_read32(ip0) == mval) { |
| /* found a match! */ |
| goto _offset; |
| } |
| |
| /* lookup ip[1] */ |
| idx = hashTable[hash1]; |
| |
| /* hash ip[2] */ |
| hash0 = hash1; |
| hash1 = ZSTD_hashPtr(ip2, hlog, mls); |
| |
| /* advance to next positions */ |
| ip0 = ip1; |
| ip1 = ip2; |
| ip2 = ip0 + step; |
| ip3 = ip1 + step; |
| |
| /* calculate step */ |
| if (ip2 >= nextStep) { |
| step++; |
| PREFETCH_L1(ip1 + 64); |
| PREFETCH_L1(ip1 + 128); |
| nextStep += kStepIncr; |
| } |
| } while (ip3 < ilimit); |
| |
| _cleanup: |
| /* Note that there are probably still a couple positions we could search. |
| * However, it seems to be a meaningful performance hit to try to search |
| * them. So let's not. */ |
| |
| /* save reps for next block */ |
| rep[0] = rep_offset1 ? rep_offset1 : offsetSaved; |
| rep[1] = rep_offset2 ? rep_offset2 : offsetSaved; |
| |
| /* Return the last literals size */ |
| return (size_t)(iend - anchor); |
| |
| _offset: /* Requires: ip0, idx */ |
| |
| /* Compute the offset code. */ |
| match0 = base + idx; |
| rep_offset2 = rep_offset1; |
| rep_offset1 = (U32)(ip0-match0); |
| offcode = rep_offset1 + ZSTD_REP_MOVE; |
| mLength = 4; |
| |
| /* Count the backwards match length. */ |
| while (((ip0>anchor) & (match0>prefixStart)) && (ip0[-1] == match0[-1])) { |
| ip0--; |
| match0--; |
| mLength++; |
| } |
| |
| _match: /* Requires: ip0, match0, offcode */ |
| |
| /* Count the forward length. */ |
| mLength += ZSTD_count(ip0 + mLength, match0 + mLength, iend); |
| |
| ZSTD_storeSeq(seqStore, (size_t)(ip0 - anchor), anchor, iend, offcode, mLength - MINMATCH); |
| |
| ip0 += mLength; |
| anchor = ip0; |
| |
| /* write next hash table entry */ |
| if (ip1 < ip0) { |
| hashTable[hash1] = (U32)(ip1 - base); |
| } |
| |
| /* Fill table and check for immediate repcode. */ |
| if (ip0 <= ilimit) { |
| /* Fill Table */ |
| assert(base+current0+2 > istart); /* check base overflow */ |
| hashTable[ZSTD_hashPtr(base+current0+2, hlog, mls)] = current0+2; /* here because current+2 could be > iend-8 */ |
| hashTable[ZSTD_hashPtr(ip0-2, hlog, mls)] = (U32)(ip0-2-base); |
| |
| if (rep_offset2 > 0) { /* rep_offset2==0 means rep_offset2 is invalidated */ |
| while ( (ip0 <= ilimit) && (MEM_read32(ip0) == MEM_read32(ip0 - rep_offset2)) ) { |
| /* store sequence */ |
| size_t const rLength = ZSTD_count(ip0+4, ip0+4-rep_offset2, iend) + 4; |
| { U32 const tmpOff = rep_offset2; rep_offset2 = rep_offset1; rep_offset1 = tmpOff; } /* swap rep_offset2 <=> rep_offset1 */ |
| hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = (U32)(ip0-base); |
| ip0 += rLength; |
| ZSTD_storeSeq(seqStore, 0 /*litLen*/, anchor, iend, 0 /*offCode*/, rLength-MINMATCH); |
| anchor = ip0; |
| continue; /* faster when present (confirmed on gcc-8) ... (?) */ |
| } } } |
| |
| goto _start; |
| } |
| |
| #define ZSTD_GEN_FAST_FN(dictMode, mls, step) \ |
| static size_t ZSTD_compressBlock_fast_##dictMode##_##mls##_##step( \ |
| ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], \ |
| void const* src, size_t srcSize) \ |
| { \ |
| return ZSTD_compressBlock_fast_##dictMode##_generic(ms, seqStore, rep, src, srcSize, mls, step); \ |
| } |
| |
| ZSTD_GEN_FAST_FN(noDict, 4, 1) |
| ZSTD_GEN_FAST_FN(noDict, 5, 1) |
| ZSTD_GEN_FAST_FN(noDict, 6, 1) |
| ZSTD_GEN_FAST_FN(noDict, 7, 1) |
| |
| ZSTD_GEN_FAST_FN(noDict, 4, 0) |
| ZSTD_GEN_FAST_FN(noDict, 5, 0) |
| ZSTD_GEN_FAST_FN(noDict, 6, 0) |
| ZSTD_GEN_FAST_FN(noDict, 7, 0) |
| |
| size_t ZSTD_compressBlock_fast( |
| ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| void const* src, size_t srcSize) |
| { |
| U32 const mls = ms->cParams.minMatch; |
| assert(ms->dictMatchState == NULL); |
| if (ms->cParams.targetLength > 1) { |
| switch(mls) |
| { |
| default: /* includes case 3 */ |
| case 4 : |
| return ZSTD_compressBlock_fast_noDict_4_1(ms, seqStore, rep, src, srcSize); |
| case 5 : |
| return ZSTD_compressBlock_fast_noDict_5_1(ms, seqStore, rep, src, srcSize); |
| case 6 : |
| return ZSTD_compressBlock_fast_noDict_6_1(ms, seqStore, rep, src, srcSize); |
| case 7 : |
| return ZSTD_compressBlock_fast_noDict_7_1(ms, seqStore, rep, src, srcSize); |
| } |
| } else { |
| switch(mls) |
| { |
| default: /* includes case 3 */ |
| case 4 : |
| return ZSTD_compressBlock_fast_noDict_4_0(ms, seqStore, rep, src, srcSize); |
| case 5 : |
| return ZSTD_compressBlock_fast_noDict_5_0(ms, seqStore, rep, src, srcSize); |
| case 6 : |
| return ZSTD_compressBlock_fast_noDict_6_0(ms, seqStore, rep, src, srcSize); |
| case 7 : |
| return ZSTD_compressBlock_fast_noDict_7_0(ms, seqStore, rep, src, srcSize); |
| } |
| |
| } |
| } |
| |
| FORCE_INLINE_TEMPLATE |
| size_t ZSTD_compressBlock_fast_dictMatchState_generic( |
| ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| void const* src, size_t srcSize, U32 const mls, U32 const hasStep) |
| { |
| const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| U32* const hashTable = ms->hashTable; |
| U32 const hlog = cParams->hashLog; |
| /* support stepSize of 0 */ |
| U32 const stepSize = cParams->targetLength + !(cParams->targetLength); |
| const BYTE* const base = ms->window.base; |
| const BYTE* const istart = (const BYTE*)src; |
| const BYTE* ip = istart; |
| const BYTE* anchor = istart; |
| const U32 prefixStartIndex = ms->window.dictLimit; |
| const BYTE* const prefixStart = base + prefixStartIndex; |
| const BYTE* const iend = istart + srcSize; |
| const BYTE* const ilimit = iend - HASH_READ_SIZE; |
| U32 offset_1=rep[0], offset_2=rep[1]; |
| U32 offsetSaved = 0; |
| |
| const ZSTD_matchState_t* const dms = ms->dictMatchState; |
| const ZSTD_compressionParameters* const dictCParams = &dms->cParams ; |
| const U32* const dictHashTable = dms->hashTable; |
| const U32 dictStartIndex = dms->window.dictLimit; |
| const BYTE* const dictBase = dms->window.base; |
| const BYTE* const dictStart = dictBase + dictStartIndex; |
| const BYTE* const dictEnd = dms->window.nextSrc; |
| const U32 dictIndexDelta = prefixStartIndex - (U32)(dictEnd - dictBase); |
| const U32 dictAndPrefixLength = (U32)(ip - prefixStart + dictEnd - dictStart); |
| const U32 dictHLog = dictCParams->hashLog; |
| |
| /* if a dictionary is still attached, it necessarily means that |
| * it is within window size. So we just check it. */ |
| const U32 maxDistance = 1U << cParams->windowLog; |
| const U32 endIndex = (U32)((size_t)(ip - base) + srcSize); |
| assert(endIndex - prefixStartIndex <= maxDistance); |
| (void)maxDistance; (void)endIndex; /* these variables are not used when assert() is disabled */ |
| |
| (void)hasStep; /* not currently specialized on whether it's accelerated */ |
| |
| /* ensure there will be no underflow |
| * when translating a dict index into a local index */ |
| assert(prefixStartIndex >= (U32)(dictEnd - dictBase)); |
| |
| /* init */ |
| DEBUGLOG(5, "ZSTD_compressBlock_fast_dictMatchState_generic"); |
| ip += (dictAndPrefixLength == 0); |
| /* dictMatchState repCode checks don't currently handle repCode == 0 |
| * disabling. */ |
| assert(offset_1 <= dictAndPrefixLength); |
| assert(offset_2 <= dictAndPrefixLength); |
| |
| /* Main Search Loop */ |
| while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */ |
| size_t mLength; |
| size_t const h = ZSTD_hashPtr(ip, hlog, mls); |
| U32 const curr = (U32)(ip-base); |
| U32 const matchIndex = hashTable[h]; |
| const BYTE* match = base + matchIndex; |
| const U32 repIndex = curr + 1 - offset_1; |
| const BYTE* repMatch = (repIndex < prefixStartIndex) ? |
| dictBase + (repIndex - dictIndexDelta) : |
| base + repIndex; |
| hashTable[h] = curr; /* update hash table */ |
| |
| if ( ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow : ensure repIndex isn't overlapping dict + prefix */ |
| && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) { |
| const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend; |
| mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4; |
| ip++; |
| ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, mLength-MINMATCH); |
| } else if ( (matchIndex <= prefixStartIndex) ) { |
| size_t const dictHash = ZSTD_hashPtr(ip, dictHLog, mls); |
| U32 const dictMatchIndex = dictHashTable[dictHash]; |
| const BYTE* dictMatch = dictBase + dictMatchIndex; |
| if (dictMatchIndex <= dictStartIndex || |
| MEM_read32(dictMatch) != MEM_read32(ip)) { |
| assert(stepSize >= 1); |
| ip += ((ip-anchor) >> kSearchStrength) + stepSize; |
| continue; |
| } else { |
| /* found a dict match */ |
| U32 const offset = (U32)(curr-dictMatchIndex-dictIndexDelta); |
| mLength = ZSTD_count_2segments(ip+4, dictMatch+4, iend, dictEnd, prefixStart) + 4; |
| while (((ip>anchor) & (dictMatch>dictStart)) |
| && (ip[-1] == dictMatch[-1])) { |
| ip--; dictMatch--; mLength++; |
| } /* catch up */ |
| offset_2 = offset_1; |
| offset_1 = offset; |
| ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH); |
| } |
| } else if (MEM_read32(match) != MEM_read32(ip)) { |
| /* it's not a match, and we're not going to check the dictionary */ |
| assert(stepSize >= 1); |
| ip += ((ip-anchor) >> kSearchStrength) + stepSize; |
| continue; |
| } else { |
| /* found a regular match */ |
| U32 const offset = (U32)(ip-match); |
| mLength = ZSTD_count(ip+4, match+4, iend) + 4; |
| while (((ip>anchor) & (match>prefixStart)) |
| && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */ |
| offset_2 = offset_1; |
| offset_1 = offset; |
| ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH); |
| } |
| |
| /* match found */ |
| ip += mLength; |
| anchor = ip; |
| |
| if (ip <= ilimit) { |
| /* Fill Table */ |
| assert(base+curr+2 > istart); /* check base overflow */ |
| hashTable[ZSTD_hashPtr(base+curr+2, hlog, mls)] = curr+2; /* here because curr+2 could be > iend-8 */ |
| hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base); |
| |
| /* check immediate repcode */ |
| while (ip <= ilimit) { |
| U32 const current2 = (U32)(ip-base); |
| U32 const repIndex2 = current2 - offset_2; |
| const BYTE* repMatch2 = repIndex2 < prefixStartIndex ? |
| dictBase - dictIndexDelta + repIndex2 : |
| base + repIndex2; |
| if ( ((U32)((prefixStartIndex-1) - (U32)repIndex2) >= 3 /* intentional overflow */) |
| && (MEM_read32(repMatch2) == MEM_read32(ip)) ) { |
| const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend; |
| size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4; |
| U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */ |
| ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, repLength2-MINMATCH); |
| hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2; |
| ip += repLength2; |
| anchor = ip; |
| continue; |
| } |
| break; |
| } |
| } |
| } |
| |
| /* save reps for next block */ |
| rep[0] = offset_1 ? offset_1 : offsetSaved; |
| rep[1] = offset_2 ? offset_2 : offsetSaved; |
| |
| /* Return the last literals size */ |
| return (size_t)(iend - anchor); |
| } |
| |
| |
| ZSTD_GEN_FAST_FN(dictMatchState, 4, 0) |
| ZSTD_GEN_FAST_FN(dictMatchState, 5, 0) |
| ZSTD_GEN_FAST_FN(dictMatchState, 6, 0) |
| ZSTD_GEN_FAST_FN(dictMatchState, 7, 0) |
| |
| size_t ZSTD_compressBlock_fast_dictMatchState( |
| ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| void const* src, size_t srcSize) |
| { |
| U32 const mls = ms->cParams.minMatch; |
| assert(ms->dictMatchState != NULL); |
| switch(mls) |
| { |
| default: /* includes case 3 */ |
| case 4 : |
| return ZSTD_compressBlock_fast_dictMatchState_4_0(ms, seqStore, rep, src, srcSize); |
| case 5 : |
| return ZSTD_compressBlock_fast_dictMatchState_5_0(ms, seqStore, rep, src, srcSize); |
| case 6 : |
| return ZSTD_compressBlock_fast_dictMatchState_6_0(ms, seqStore, rep, src, srcSize); |
| case 7 : |
| return ZSTD_compressBlock_fast_dictMatchState_7_0(ms, seqStore, rep, src, srcSize); |
| } |
| } |
| |
| |
| static size_t ZSTD_compressBlock_fast_extDict_generic( |
| ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| void const* src, size_t srcSize, U32 const mls, U32 const hasStep) |
| { |
| const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| U32* const hashTable = ms->hashTable; |
| U32 const hlog = cParams->hashLog; |
| /* support stepSize of 0 */ |
| U32 const stepSize = cParams->targetLength + !(cParams->targetLength); |
| const BYTE* const base = ms->window.base; |
| const BYTE* const dictBase = ms->window.dictBase; |
| const BYTE* const istart = (const BYTE*)src; |
| const BYTE* ip = istart; |
| const BYTE* anchor = istart; |
| const U32 endIndex = (U32)((size_t)(istart - base) + srcSize); |
| const U32 lowLimit = ZSTD_getLowestMatchIndex(ms, endIndex, cParams->windowLog); |
| const U32 dictStartIndex = lowLimit; |
| const BYTE* const dictStart = dictBase + dictStartIndex; |
| const U32 dictLimit = ms->window.dictLimit; |
| const U32 prefixStartIndex = dictLimit < lowLimit ? lowLimit : dictLimit; |
| const BYTE* const prefixStart = base + prefixStartIndex; |
| const BYTE* const dictEnd = dictBase + prefixStartIndex; |
| const BYTE* const iend = istart + srcSize; |
| const BYTE* const ilimit = iend - 8; |
| U32 offset_1=rep[0], offset_2=rep[1]; |
| |
| (void)hasStep; /* not currently specialized on whether it's accelerated */ |
| |
| DEBUGLOG(5, "ZSTD_compressBlock_fast_extDict_generic (offset_1=%u)", offset_1); |
| |
| /* switch to "regular" variant if extDict is invalidated due to maxDistance */ |
| if (prefixStartIndex == dictStartIndex) |
| return ZSTD_compressBlock_fast(ms, seqStore, rep, src, srcSize); |
| |
| /* Search Loop */ |
| while (ip < ilimit) { /* < instead of <=, because (ip+1) */ |
| const size_t h = ZSTD_hashPtr(ip, hlog, mls); |
| const U32 matchIndex = hashTable[h]; |
| const BYTE* const matchBase = matchIndex < prefixStartIndex ? dictBase : base; |
| const BYTE* match = matchBase + matchIndex; |
| const U32 curr = (U32)(ip-base); |
| const U32 repIndex = curr + 1 - offset_1; |
| const BYTE* const repBase = repIndex < prefixStartIndex ? dictBase : base; |
| const BYTE* const repMatch = repBase + repIndex; |
| hashTable[h] = curr; /* update hash table */ |
| DEBUGLOG(7, "offset_1 = %u , curr = %u", offset_1, curr); |
| |
| if ( ( ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow */ |
| & (offset_1 <= curr+1 - dictStartIndex) ) /* note: we are searching at curr+1 */ |
| && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) { |
| const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend; |
| size_t const rLength = ZSTD_count_2segments(ip+1 +4, repMatch +4, iend, repMatchEnd, prefixStart) + 4; |
| ip++; |
| ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, rLength-MINMATCH); |
| ip += rLength; |
| anchor = ip; |
| } else { |
| if ( (matchIndex < dictStartIndex) || |
| (MEM_read32(match) != MEM_read32(ip)) ) { |
| assert(stepSize >= 1); |
| ip += ((ip-anchor) >> kSearchStrength) + stepSize; |
| continue; |
| } |
| { const BYTE* const matchEnd = matchIndex < prefixStartIndex ? dictEnd : iend; |
| const BYTE* const lowMatchPtr = matchIndex < prefixStartIndex ? dictStart : prefixStart; |
| U32 const offset = curr - matchIndex; |
| size_t mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, prefixStart) + 4; |
| while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */ |
| offset_2 = offset_1; offset_1 = offset; /* update offset history */ |
| ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, offset + ZSTD_REP_MOVE, mLength-MINMATCH); |
| ip += mLength; |
| anchor = ip; |
| } } |
| |
| if (ip <= ilimit) { |
| /* Fill Table */ |
| hashTable[ZSTD_hashPtr(base+curr+2, hlog, mls)] = curr+2; |
| hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base); |
| /* check immediate repcode */ |
| while (ip <= ilimit) { |
| U32 const current2 = (U32)(ip-base); |
| U32 const repIndex2 = current2 - offset_2; |
| const BYTE* const repMatch2 = repIndex2 < prefixStartIndex ? dictBase + repIndex2 : base + repIndex2; |
| if ( (((U32)((prefixStartIndex-1) - repIndex2) >= 3) & (offset_2 <= curr - dictStartIndex)) /* intentional overflow */ |
| && (MEM_read32(repMatch2) == MEM_read32(ip)) ) { |
| const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend; |
| size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4; |
| { U32 const tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; } /* swap offset_2 <=> offset_1 */ |
| ZSTD_storeSeq(seqStore, 0 /*litlen*/, anchor, iend, 0 /*offcode*/, repLength2-MINMATCH); |
| hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2; |
| ip += repLength2; |
| anchor = ip; |
| continue; |
| } |
| break; |
| } } } |
| |
| /* save reps for next block */ |
| rep[0] = offset_1; |
| rep[1] = offset_2; |
| |
| /* Return the last literals size */ |
| return (size_t)(iend - anchor); |
| } |
| |
| ZSTD_GEN_FAST_FN(extDict, 4, 0) |
| ZSTD_GEN_FAST_FN(extDict, 5, 0) |
| ZSTD_GEN_FAST_FN(extDict, 6, 0) |
| ZSTD_GEN_FAST_FN(extDict, 7, 0) |
| |
| size_t ZSTD_compressBlock_fast_extDict( |
| ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| void const* src, size_t srcSize) |
| { |
| U32 const mls = ms->cParams.minMatch; |
| switch(mls) |
| { |
| default: /* includes case 3 */ |
| case 4 : |
| return ZSTD_compressBlock_fast_extDict_4_0(ms, seqStore, rep, src, srcSize); |
| case 5 : |
| return ZSTD_compressBlock_fast_extDict_5_0(ms, seqStore, rep, src, srcSize); |
| case 6 : |
| return ZSTD_compressBlock_fast_extDict_6_0(ms, seqStore, rep, src, srcSize); |
| case 7 : |
| return ZSTD_compressBlock_fast_extDict_7_0(ms, seqStore, rep, src, srcSize); |
| } |
| } |
