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
15void 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
41FORCE_INLINE_TEMPLATE
42size_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
125size_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
147static 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
240size_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}
260