Scott Baker | e7144bc | 2019-10-01 14:16:47 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * This source code is licensed under both the BSD-style license (found in the |
| 6 | * LICENSE file in the root directory of this source tree) and the GPLv2 (found |
| 7 | * in the COPYING file in the root directory of this source tree). |
| 8 | * You may select, at your option, one of the above-listed licenses. |
| 9 | */ |
| 10 | |
| 11 | #include "zstd_compress_internal.h" |
| 12 | #include "zstd_fast.h" |
| 13 | |
| 14 | |
| 15 | void ZSTD_fillHashTable(ZSTD_matchState_t* ms, |
| 16 | ZSTD_compressionParameters const* cParams, |
| 17 | void const* end) |
| 18 | { |
| 19 | U32* const hashTable = ms->hashTable; |
| 20 | U32 const hBits = cParams->hashLog; |
| 21 | U32 const mls = cParams->searchLength; |
| 22 | const BYTE* const base = ms->window.base; |
| 23 | const BYTE* ip = base + ms->nextToUpdate; |
| 24 | const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE; |
| 25 | const U32 fastHashFillStep = 3; |
| 26 | |
| 27 | /* Always insert every fastHashFillStep position into the hash table. |
| 28 | * Insert the other positions if their hash entry is empty. |
| 29 | */ |
| 30 | for (; ip + fastHashFillStep - 1 <= iend; ip += fastHashFillStep) { |
| 31 | U32 const current = (U32)(ip - base); |
| 32 | U32 i; |
| 33 | for (i = 0; i < fastHashFillStep; ++i) { |
| 34 | size_t const hash = ZSTD_hashPtr(ip + i, hBits, mls); |
| 35 | if (i == 0 || hashTable[hash] == 0) |
| 36 | hashTable[hash] = current + i; |
| 37 | } |
| 38 | } |
| 39 | } |
| 40 | |
| 41 | FORCE_INLINE_TEMPLATE |
| 42 | size_t ZSTD_compressBlock_fast_generic( |
| 43 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 44 | void const* src, size_t srcSize, |
| 45 | U32 const hlog, U32 const stepSize, U32 const mls) |
| 46 | { |
| 47 | U32* const hashTable = ms->hashTable; |
| 48 | const BYTE* const base = ms->window.base; |
| 49 | const BYTE* const istart = (const BYTE*)src; |
| 50 | const BYTE* ip = istart; |
| 51 | const BYTE* anchor = istart; |
| 52 | const U32 lowestIndex = ms->window.dictLimit; |
| 53 | const BYTE* const lowest = base + lowestIndex; |
| 54 | const BYTE* const iend = istart + srcSize; |
| 55 | const BYTE* const ilimit = iend - HASH_READ_SIZE; |
| 56 | U32 offset_1=rep[0], offset_2=rep[1]; |
| 57 | U32 offsetSaved = 0; |
| 58 | |
| 59 | /* init */ |
| 60 | ip += (ip==lowest); |
| 61 | { U32 const maxRep = (U32)(ip-lowest); |
| 62 | if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0; |
| 63 | if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0; |
| 64 | } |
| 65 | |
| 66 | /* Main Search Loop */ |
| 67 | while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */ |
| 68 | size_t mLength; |
| 69 | size_t const h = ZSTD_hashPtr(ip, hlog, mls); |
| 70 | U32 const current = (U32)(ip-base); |
| 71 | U32 const matchIndex = hashTable[h]; |
| 72 | const BYTE* match = base + matchIndex; |
| 73 | hashTable[h] = current; /* update hash table */ |
| 74 | |
| 75 | if ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1))) { |
| 76 | mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4; |
| 77 | ip++; |
| 78 | ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH); |
| 79 | } else { |
| 80 | if ( (matchIndex <= lowestIndex) |
| 81 | || (MEM_read32(match) != MEM_read32(ip)) ) { |
| 82 | assert(stepSize >= 1); |
| 83 | ip += ((ip-anchor) >> kSearchStrength) + stepSize; |
| 84 | continue; |
| 85 | } |
| 86 | mLength = ZSTD_count(ip+4, match+4, iend) + 4; |
| 87 | { U32 const offset = (U32)(ip-match); |
| 88 | while (((ip>anchor) & (match>lowest)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */ |
| 89 | offset_2 = offset_1; |
| 90 | offset_1 = offset; |
| 91 | ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); |
| 92 | } } |
| 93 | |
| 94 | /* match found */ |
| 95 | ip += mLength; |
| 96 | anchor = ip; |
| 97 | |
| 98 | if (ip <= ilimit) { |
| 99 | /* Fill Table */ |
| 100 | hashTable[ZSTD_hashPtr(base+current+2, hlog, mls)] = current+2; /* here because current+2 could be > iend-8 */ |
| 101 | hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base); |
| 102 | /* check immediate repcode */ |
| 103 | while ( (ip <= ilimit) |
| 104 | && ( (offset_2>0) |
| 105 | & (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) { |
| 106 | /* store sequence */ |
| 107 | size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4; |
| 108 | { U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; } /* swap offset_2 <=> offset_1 */ |
| 109 | hashTable[ZSTD_hashPtr(ip, hlog, mls)] = (U32)(ip-base); |
| 110 | ZSTD_storeSeq(seqStore, 0, anchor, 0, rLength-MINMATCH); |
| 111 | ip += rLength; |
| 112 | anchor = ip; |
| 113 | continue; /* faster when present ... (?) */ |
| 114 | } } } |
| 115 | |
| 116 | /* save reps for next block */ |
| 117 | rep[0] = offset_1 ? offset_1 : offsetSaved; |
| 118 | rep[1] = offset_2 ? offset_2 : offsetSaved; |
| 119 | |
| 120 | /* Return the last literals size */ |
| 121 | return iend - anchor; |
| 122 | } |
| 123 | |
| 124 | |
| 125 | size_t ZSTD_compressBlock_fast( |
| 126 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 127 | ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize) |
| 128 | { |
| 129 | U32 const hlog = cParams->hashLog; |
| 130 | U32 const mls = cParams->searchLength; |
| 131 | U32 const stepSize = cParams->targetLength; |
| 132 | switch(mls) |
| 133 | { |
| 134 | default: /* includes case 3 */ |
| 135 | case 4 : |
| 136 | return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 4); |
| 137 | case 5 : |
| 138 | return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 5); |
| 139 | case 6 : |
| 140 | return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 6); |
| 141 | case 7 : |
| 142 | return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 7); |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | |
| 147 | static size_t ZSTD_compressBlock_fast_extDict_generic( |
| 148 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 149 | void const* src, size_t srcSize, |
| 150 | U32 const hlog, U32 const stepSize, U32 const mls) |
| 151 | { |
| 152 | U32* hashTable = ms->hashTable; |
| 153 | const BYTE* const base = ms->window.base; |
| 154 | const BYTE* const dictBase = ms->window.dictBase; |
| 155 | const BYTE* const istart = (const BYTE*)src; |
| 156 | const BYTE* ip = istart; |
| 157 | const BYTE* anchor = istart; |
| 158 | const U32 lowestIndex = ms->window.lowLimit; |
| 159 | const BYTE* const dictStart = dictBase + lowestIndex; |
| 160 | const U32 dictLimit = ms->window.dictLimit; |
| 161 | const BYTE* const lowPrefixPtr = base + dictLimit; |
| 162 | const BYTE* const dictEnd = dictBase + dictLimit; |
| 163 | const BYTE* const iend = istart + srcSize; |
| 164 | const BYTE* const ilimit = iend - 8; |
| 165 | U32 offset_1=rep[0], offset_2=rep[1]; |
| 166 | |
| 167 | /* Search Loop */ |
| 168 | while (ip < ilimit) { /* < instead of <=, because (ip+1) */ |
| 169 | const size_t h = ZSTD_hashPtr(ip, hlog, mls); |
| 170 | const U32 matchIndex = hashTable[h]; |
| 171 | const BYTE* matchBase = matchIndex < dictLimit ? dictBase : base; |
| 172 | const BYTE* match = matchBase + matchIndex; |
| 173 | const U32 current = (U32)(ip-base); |
| 174 | const U32 repIndex = current + 1 - offset_1; /* offset_1 expected <= current +1 */ |
| 175 | const BYTE* repBase = repIndex < dictLimit ? dictBase : base; |
| 176 | const BYTE* repMatch = repBase + repIndex; |
| 177 | size_t mLength; |
| 178 | hashTable[h] = current; /* update hash table */ |
| 179 | |
| 180 | if ( (((U32)((dictLimit-1) - repIndex) >= 3) /* intentional underflow */ & (repIndex > lowestIndex)) |
| 181 | && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) { |
| 182 | const BYTE* repMatchEnd = repIndex < dictLimit ? dictEnd : iend; |
| 183 | mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, lowPrefixPtr) + 4; |
| 184 | ip++; |
| 185 | ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH); |
| 186 | } else { |
| 187 | if ( (matchIndex < lowestIndex) || |
| 188 | (MEM_read32(match) != MEM_read32(ip)) ) { |
| 189 | assert(stepSize >= 1); |
| 190 | ip += ((ip-anchor) >> kSearchStrength) + stepSize; |
| 191 | continue; |
| 192 | } |
| 193 | { const BYTE* matchEnd = matchIndex < dictLimit ? dictEnd : iend; |
| 194 | const BYTE* lowMatchPtr = matchIndex < dictLimit ? dictStart : lowPrefixPtr; |
| 195 | U32 offset; |
| 196 | mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, lowPrefixPtr) + 4; |
| 197 | while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */ |
| 198 | offset = current - matchIndex; |
| 199 | offset_2 = offset_1; |
| 200 | offset_1 = offset; |
| 201 | ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH); |
| 202 | } } |
| 203 | |
| 204 | /* found a match : store it */ |
| 205 | ip += mLength; |
| 206 | anchor = ip; |
| 207 | |
| 208 | if (ip <= ilimit) { |
| 209 | /* Fill Table */ |
| 210 | hashTable[ZSTD_hashPtr(base+current+2, hlog, mls)] = current+2; |
| 211 | hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base); |
| 212 | /* check immediate repcode */ |
| 213 | while (ip <= ilimit) { |
| 214 | U32 const current2 = (U32)(ip-base); |
| 215 | U32 const repIndex2 = current2 - offset_2; |
| 216 | const BYTE* repMatch2 = repIndex2 < dictLimit ? dictBase + repIndex2 : base + repIndex2; |
| 217 | if ( (((U32)((dictLimit-1) - repIndex2) >= 3) & (repIndex2 > lowestIndex)) /* intentional overflow */ |
| 218 | && (MEM_read32(repMatch2) == MEM_read32(ip)) ) { |
| 219 | const BYTE* const repEnd2 = repIndex2 < dictLimit ? dictEnd : iend; |
| 220 | size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, lowPrefixPtr) + 4; |
| 221 | U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */ |
| 222 | ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH); |
| 223 | hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2; |
| 224 | ip += repLength2; |
| 225 | anchor = ip; |
| 226 | continue; |
| 227 | } |
| 228 | break; |
| 229 | } } } |
| 230 | |
| 231 | /* save reps for next block */ |
| 232 | rep[0] = offset_1; |
| 233 | rep[1] = offset_2; |
| 234 | |
| 235 | /* Return the last literals size */ |
| 236 | return iend - anchor; |
| 237 | } |
| 238 | |
| 239 | |
| 240 | size_t ZSTD_compressBlock_fast_extDict( |
| 241 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 242 | ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize) |
| 243 | { |
| 244 | U32 const hlog = cParams->hashLog; |
| 245 | U32 const mls = cParams->searchLength; |
| 246 | U32 const stepSize = cParams->targetLength; |
| 247 | switch(mls) |
| 248 | { |
| 249 | default: /* includes case 3 */ |
| 250 | case 4 : |
| 251 | return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 4); |
| 252 | case 5 : |
| 253 | return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 5); |
| 254 | case 6 : |
| 255 | return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 6); |
| 256 | case 7 : |
| 257 | return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, hlog, stepSize, 7); |
| 258 | } |
| 259 | } |