676 lines
26 KiB
C
676 lines
26 KiB
C
/*
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* Copyright (c) Yann Collet, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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*/
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#include "zstd_compress_internal.h" /* ZSTD_hashPtr, ZSTD_count, ZSTD_storeSeq */
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#include "zstd_fast.h"
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void ZSTD_fillHashTable(ZSTD_matchState_t* ms,
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const void* const end,
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ZSTD_dictTableLoadMethod_e dtlm)
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{
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const ZSTD_compressionParameters* const cParams = &ms->cParams;
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U32* const hashTable = ms->hashTable;
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U32 const hBits = cParams->hashLog;
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U32 const mls = cParams->minMatch;
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const BYTE* const base = ms->window.base;
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const BYTE* ip = base + ms->nextToUpdate;
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const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;
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const U32 fastHashFillStep = 3;
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/* Always insert every fastHashFillStep position into the hash table.
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* Insert the other positions if their hash entry is empty.
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*/
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for ( ; ip + fastHashFillStep < iend + 2; ip += fastHashFillStep) {
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U32 const curr = (U32)(ip - base);
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size_t const hash0 = ZSTD_hashPtr(ip, hBits, mls);
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hashTable[hash0] = curr;
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if (dtlm == ZSTD_dtlm_fast) continue;
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/* Only load extra positions for ZSTD_dtlm_full */
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{ U32 p;
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for (p = 1; p < fastHashFillStep; ++p) {
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size_t const hash = ZSTD_hashPtr(ip + p, hBits, mls);
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if (hashTable[hash] == 0) { /* not yet filled */
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hashTable[hash] = curr + p;
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} } } }
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}
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/**
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* If you squint hard enough (and ignore repcodes), the search operation at any
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* given position is broken into 4 stages:
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*
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* 1. Hash (map position to hash value via input read)
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* 2. Lookup (map hash val to index via hashtable read)
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* 3. Load (map index to value at that position via input read)
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* 4. Compare
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*
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* Each of these steps involves a memory read at an address which is computed
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* from the previous step. This means these steps must be sequenced and their
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* latencies are cumulative.
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*
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* Rather than do 1->2->3->4 sequentially for a single position before moving
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* onto the next, this implementation interleaves these operations across the
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* next few positions:
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*
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* R = Repcode Read & Compare
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* H = Hash
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* T = Table Lookup
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* M = Match Read & Compare
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*
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* Pos | Time -->
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* ----+-------------------
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* N | ... M
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* N+1 | ... TM
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* N+2 | R H T M
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* N+3 | H TM
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* N+4 | R H T M
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* N+5 | H ...
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* N+6 | R ...
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*
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* This is very much analogous to the pipelining of execution in a CPU. And just
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* like a CPU, we have to dump the pipeline when we find a match (i.e., take a
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* branch).
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*
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* When this happens, we throw away our current state, and do the following prep
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* to re-enter the loop:
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*
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* Pos | Time -->
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* ----+-------------------
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* N | H T
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* N+1 | H
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*
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* This is also the work we do at the beginning to enter the loop initially.
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*/
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FORCE_INLINE_TEMPLATE size_t
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ZSTD_compressBlock_fast_noDict_generic(
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ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
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void const* src, size_t srcSize,
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U32 const mls, U32 const hasStep)
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{
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const ZSTD_compressionParameters* const cParams = &ms->cParams;
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U32* const hashTable = ms->hashTable;
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U32 const hlog = cParams->hashLog;
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/* support stepSize of 0 */
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size_t const stepSize = hasStep ? (cParams->targetLength + !(cParams->targetLength) + 1) : 2;
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const BYTE* const base = ms->window.base;
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const BYTE* const istart = (const BYTE*)src;
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const U32 endIndex = (U32)((size_t)(istart - base) + srcSize);
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const U32 prefixStartIndex = ZSTD_getLowestPrefixIndex(ms, endIndex, cParams->windowLog);
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const BYTE* const prefixStart = base + prefixStartIndex;
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const BYTE* const iend = istart + srcSize;
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const BYTE* const ilimit = iend - HASH_READ_SIZE;
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const BYTE* anchor = istart;
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const BYTE* ip0 = istart;
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const BYTE* ip1;
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const BYTE* ip2;
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const BYTE* ip3;
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U32 current0;
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U32 rep_offset1 = rep[0];
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U32 rep_offset2 = rep[1];
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U32 offsetSaved = 0;
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size_t hash0; /* hash for ip0 */
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size_t hash1; /* hash for ip1 */
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U32 idx; /* match idx for ip0 */
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U32 mval; /* src value at match idx */
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U32 offcode;
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const BYTE* match0;
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size_t mLength;
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/* ip0 and ip1 are always adjacent. The targetLength skipping and
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* uncompressibility acceleration is applied to every other position,
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* matching the behavior of #1562. step therefore represents the gap
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* between pairs of positions, from ip0 to ip2 or ip1 to ip3. */
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size_t step;
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const BYTE* nextStep;
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const size_t kStepIncr = (1 << (kSearchStrength - 1));
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DEBUGLOG(5, "ZSTD_compressBlock_fast_generic");
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ip0 += (ip0 == prefixStart);
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{ U32 const curr = (U32)(ip0 - base);
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U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, cParams->windowLog);
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U32 const maxRep = curr - windowLow;
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if (rep_offset2 > maxRep) offsetSaved = rep_offset2, rep_offset2 = 0;
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if (rep_offset1 > maxRep) offsetSaved = rep_offset1, rep_offset1 = 0;
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}
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/* start each op */
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_start: /* Requires: ip0 */
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step = stepSize;
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nextStep = ip0 + kStepIncr;
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/* calculate positions, ip0 - anchor == 0, so we skip step calc */
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ip1 = ip0 + 1;
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ip2 = ip0 + step;
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ip3 = ip2 + 1;
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if (ip3 >= ilimit) {
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goto _cleanup;
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}
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hash0 = ZSTD_hashPtr(ip0, hlog, mls);
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hash1 = ZSTD_hashPtr(ip1, hlog, mls);
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idx = hashTable[hash0];
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do {
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/* load repcode match for ip[2]*/
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const U32 rval = MEM_read32(ip2 - rep_offset1);
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/* write back hash table entry */
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current0 = (U32)(ip0 - base);
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hashTable[hash0] = current0;
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/* check repcode at ip[2] */
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if ((MEM_read32(ip2) == rval) & (rep_offset1 > 0)) {
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ip0 = ip2;
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match0 = ip0 - rep_offset1;
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mLength = ip0[-1] == match0[-1];
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ip0 -= mLength;
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match0 -= mLength;
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offcode = STORE_REPCODE_1;
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mLength += 4;
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goto _match;
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}
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/* load match for ip[0] */
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if (idx >= prefixStartIndex) {
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mval = MEM_read32(base + idx);
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} else {
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mval = MEM_read32(ip0) ^ 1; /* guaranteed to not match. */
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}
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/* check match at ip[0] */
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if (MEM_read32(ip0) == mval) {
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/* found a match! */
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goto _offset;
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}
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/* lookup ip[1] */
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idx = hashTable[hash1];
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/* hash ip[2] */
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hash0 = hash1;
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hash1 = ZSTD_hashPtr(ip2, hlog, mls);
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/* advance to next positions */
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ip0 = ip1;
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ip1 = ip2;
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ip2 = ip3;
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/* write back hash table entry */
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current0 = (U32)(ip0 - base);
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hashTable[hash0] = current0;
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/* load match for ip[0] */
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if (idx >= prefixStartIndex) {
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mval = MEM_read32(base + idx);
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} else {
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mval = MEM_read32(ip0) ^ 1; /* guaranteed to not match. */
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}
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/* check match at ip[0] */
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if (MEM_read32(ip0) == mval) {
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/* found a match! */
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goto _offset;
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}
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/* lookup ip[1] */
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idx = hashTable[hash1];
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/* hash ip[2] */
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hash0 = hash1;
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hash1 = ZSTD_hashPtr(ip2, hlog, mls);
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/* advance to next positions */
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ip0 = ip1;
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ip1 = ip2;
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ip2 = ip0 + step;
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ip3 = ip1 + step;
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/* calculate step */
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if (ip2 >= nextStep) {
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step++;
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PREFETCH_L1(ip1 + 64);
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PREFETCH_L1(ip1 + 128);
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nextStep += kStepIncr;
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}
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} while (ip3 < ilimit);
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_cleanup:
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/* Note that there are probably still a couple positions we could search.
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* However, it seems to be a meaningful performance hit to try to search
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* them. So let's not. */
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/* save reps for next block */
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rep[0] = rep_offset1 ? rep_offset1 : offsetSaved;
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rep[1] = rep_offset2 ? rep_offset2 : offsetSaved;
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/* Return the last literals size */
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return (size_t)(iend - anchor);
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_offset: /* Requires: ip0, idx */
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/* Compute the offset code. */
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match0 = base + idx;
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rep_offset2 = rep_offset1;
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rep_offset1 = (U32)(ip0-match0);
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offcode = STORE_OFFSET(rep_offset1);
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mLength = 4;
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/* Count the backwards match length. */
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while (((ip0>anchor) & (match0>prefixStart)) && (ip0[-1] == match0[-1])) {
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ip0--;
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match0--;
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mLength++;
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}
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_match: /* Requires: ip0, match0, offcode */
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/* Count the forward length. */
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mLength += ZSTD_count(ip0 + mLength, match0 + mLength, iend);
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ZSTD_storeSeq(seqStore, (size_t)(ip0 - anchor), anchor, iend, offcode, mLength);
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ip0 += mLength;
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anchor = ip0;
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/* write next hash table entry */
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if (ip1 < ip0) {
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hashTable[hash1] = (U32)(ip1 - base);
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}
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/* Fill table and check for immediate repcode. */
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if (ip0 <= ilimit) {
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/* Fill Table */
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assert(base+current0+2 > istart); /* check base overflow */
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hashTable[ZSTD_hashPtr(base+current0+2, hlog, mls)] = current0+2; /* here because current+2 could be > iend-8 */
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hashTable[ZSTD_hashPtr(ip0-2, hlog, mls)] = (U32)(ip0-2-base);
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if (rep_offset2 > 0) { /* rep_offset2==0 means rep_offset2 is invalidated */
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while ( (ip0 <= ilimit) && (MEM_read32(ip0) == MEM_read32(ip0 - rep_offset2)) ) {
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/* store sequence */
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size_t const rLength = ZSTD_count(ip0+4, ip0+4-rep_offset2, iend) + 4;
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{ U32 const tmpOff = rep_offset2; rep_offset2 = rep_offset1; rep_offset1 = tmpOff; } /* swap rep_offset2 <=> rep_offset1 */
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hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = (U32)(ip0-base);
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ip0 += rLength;
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ZSTD_storeSeq(seqStore, 0 /*litLen*/, anchor, iend, STORE_REPCODE_1, rLength);
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anchor = ip0;
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continue; /* faster when present (confirmed on gcc-8) ... (?) */
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} } }
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goto _start;
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}
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#define ZSTD_GEN_FAST_FN(dictMode, mls, step) \
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static size_t ZSTD_compressBlock_fast_##dictMode##_##mls##_##step( \
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ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], \
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void const* src, size_t srcSize) \
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{ \
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return ZSTD_compressBlock_fast_##dictMode##_generic(ms, seqStore, rep, src, srcSize, mls, step); \
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}
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ZSTD_GEN_FAST_FN(noDict, 4, 1)
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ZSTD_GEN_FAST_FN(noDict, 5, 1)
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ZSTD_GEN_FAST_FN(noDict, 6, 1)
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ZSTD_GEN_FAST_FN(noDict, 7, 1)
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ZSTD_GEN_FAST_FN(noDict, 4, 0)
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ZSTD_GEN_FAST_FN(noDict, 5, 0)
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ZSTD_GEN_FAST_FN(noDict, 6, 0)
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ZSTD_GEN_FAST_FN(noDict, 7, 0)
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size_t ZSTD_compressBlock_fast(
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ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
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void const* src, size_t srcSize)
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{
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U32 const mls = ms->cParams.minMatch;
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assert(ms->dictMatchState == NULL);
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if (ms->cParams.targetLength > 1) {
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switch(mls)
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{
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default: /* includes case 3 */
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case 4 :
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return ZSTD_compressBlock_fast_noDict_4_1(ms, seqStore, rep, src, srcSize);
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case 5 :
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return ZSTD_compressBlock_fast_noDict_5_1(ms, seqStore, rep, src, srcSize);
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case 6 :
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return ZSTD_compressBlock_fast_noDict_6_1(ms, seqStore, rep, src, srcSize);
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case 7 :
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return ZSTD_compressBlock_fast_noDict_7_1(ms, seqStore, rep, src, srcSize);
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}
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} else {
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switch(mls)
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{
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default: /* includes case 3 */
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case 4 :
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return ZSTD_compressBlock_fast_noDict_4_0(ms, seqStore, rep, src, srcSize);
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case 5 :
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return ZSTD_compressBlock_fast_noDict_5_0(ms, seqStore, rep, src, srcSize);
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case 6 :
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return ZSTD_compressBlock_fast_noDict_6_0(ms, seqStore, rep, src, srcSize);
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case 7 :
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return ZSTD_compressBlock_fast_noDict_7_0(ms, seqStore, rep, src, srcSize);
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}
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}
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}
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FORCE_INLINE_TEMPLATE
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size_t ZSTD_compressBlock_fast_dictMatchState_generic(
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ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
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void const* src, size_t srcSize, U32 const mls, U32 const hasStep)
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{
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const ZSTD_compressionParameters* const cParams = &ms->cParams;
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U32* const hashTable = ms->hashTable;
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U32 const hlog = cParams->hashLog;
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/* support stepSize of 0 */
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U32 const stepSize = cParams->targetLength + !(cParams->targetLength);
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const BYTE* const base = ms->window.base;
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const BYTE* const istart = (const BYTE*)src;
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const BYTE* ip = istart;
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const BYTE* anchor = istart;
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const U32 prefixStartIndex = ms->window.dictLimit;
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const BYTE* const prefixStart = base + prefixStartIndex;
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const BYTE* const iend = istart + srcSize;
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const BYTE* const ilimit = iend - HASH_READ_SIZE;
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U32 offset_1=rep[0], offset_2=rep[1];
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U32 offsetSaved = 0;
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const ZSTD_matchState_t* const dms = ms->dictMatchState;
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const ZSTD_compressionParameters* const dictCParams = &dms->cParams ;
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const U32* const dictHashTable = dms->hashTable;
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const U32 dictStartIndex = dms->window.dictLimit;
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const BYTE* const dictBase = dms->window.base;
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const BYTE* const dictStart = dictBase + dictStartIndex;
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const BYTE* const dictEnd = dms->window.nextSrc;
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const U32 dictIndexDelta = prefixStartIndex - (U32)(dictEnd - dictBase);
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const U32 dictAndPrefixLength = (U32)(ip - prefixStart + dictEnd - dictStart);
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const U32 dictHLog = dictCParams->hashLog;
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/* if a dictionary is still attached, it necessarily means that
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* it is within window size. So we just check it. */
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const U32 maxDistance = 1U << cParams->windowLog;
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const U32 endIndex = (U32)((size_t)(ip - base) + srcSize);
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assert(endIndex - prefixStartIndex <= maxDistance);
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(void)maxDistance; (void)endIndex; /* these variables are not used when assert() is disabled */
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(void)hasStep; /* not currently specialized on whether it's accelerated */
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/* ensure there will be no underflow
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* when translating a dict index into a local index */
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assert(prefixStartIndex >= (U32)(dictEnd - dictBase));
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/* init */
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DEBUGLOG(5, "ZSTD_compressBlock_fast_dictMatchState_generic");
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ip += (dictAndPrefixLength == 0);
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/* dictMatchState repCode checks don't currently handle repCode == 0
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* disabling. */
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assert(offset_1 <= dictAndPrefixLength);
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assert(offset_2 <= dictAndPrefixLength);
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/* Main Search Loop */
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while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */
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size_t mLength;
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size_t const h = ZSTD_hashPtr(ip, hlog, mls);
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U32 const curr = (U32)(ip-base);
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U32 const matchIndex = hashTable[h];
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const BYTE* match = base + matchIndex;
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const U32 repIndex = curr + 1 - offset_1;
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const BYTE* repMatch = (repIndex < prefixStartIndex) ?
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dictBase + (repIndex - dictIndexDelta) :
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base + repIndex;
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hashTable[h] = curr; /* update hash table */
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if ( ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow : ensure repIndex isn't overlapping dict + prefix */
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&& (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
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const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
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mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
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ip++;
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ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, STORE_REPCODE_1, mLength);
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} else if ( (matchIndex <= prefixStartIndex) ) {
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size_t const dictHash = ZSTD_hashPtr(ip, dictHLog, mls);
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U32 const dictMatchIndex = dictHashTable[dictHash];
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const BYTE* dictMatch = dictBase + dictMatchIndex;
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if (dictMatchIndex <= dictStartIndex ||
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MEM_read32(dictMatch) != MEM_read32(ip)) {
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assert(stepSize >= 1);
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ip += ((ip-anchor) >> kSearchStrength) + stepSize;
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continue;
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} else {
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/* found a dict match */
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U32 const offset = (U32)(curr-dictMatchIndex-dictIndexDelta);
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|
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, STORE_OFFSET(offset), mLength);
|
|
}
|
|
} 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, STORE_OFFSET(offset), mLength);
|
|
}
|
|
|
|
/* 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, STORE_REPCODE_1, repLength2);
|
|
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, STORE_REPCODE_1, rLength);
|
|
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, STORE_OFFSET(offset), mLength);
|
|
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, STORE_REPCODE_1, repLength2);
|
|
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);
|
|
}
|
|
}
|