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_double_fast.h"
13
14
15void ZSTD_fillDoubleHashTable(ZSTD_matchState_t* ms,
16 ZSTD_compressionParameters const* cParams,
17 void const* end)
18{
19 U32* const hashLarge = ms->hashTable;
20 U32 const hBitsL = cParams->hashLog;
21 U32 const mls = cParams->searchLength;
22 U32* const hashSmall = ms->chainTable;
23 U32 const hBitsS = cParams->chainLog;
24 const BYTE* const base = ms->window.base;
25 const BYTE* ip = base + ms->nextToUpdate;
26 const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;
27 const U32 fastHashFillStep = 3;
28
29 /* Always insert every fastHashFillStep position into the hash tables.
30 * Insert the other positions into the large hash table if their entry
31 * is empty.
32 */
33 for (; ip + fastHashFillStep - 1 <= iend; ip += fastHashFillStep) {
34 U32 const current = (U32)(ip - base);
35 U32 i;
36 for (i = 0; i < fastHashFillStep; ++i) {
37 size_t const smHash = ZSTD_hashPtr(ip + i, hBitsS, mls);
38 size_t const lgHash = ZSTD_hashPtr(ip + i, hBitsL, 8);
39 if (i == 0)
40 hashSmall[smHash] = current + i;
41 if (i == 0 || hashLarge[lgHash] == 0)
42 hashLarge[lgHash] = current + i;
43 }
44 }
45}
46
47
48FORCE_INLINE_TEMPLATE
49size_t ZSTD_compressBlock_doubleFast_generic(
50 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
51 ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize,
52 U32 const mls /* template */)
53{
54 U32* const hashLong = ms->hashTable;
55 const U32 hBitsL = cParams->hashLog;
56 U32* const hashSmall = ms->chainTable;
57 const U32 hBitsS = cParams->chainLog;
58 const BYTE* const base = ms->window.base;
59 const BYTE* const istart = (const BYTE*)src;
60 const BYTE* ip = istart;
61 const BYTE* anchor = istart;
62 const U32 lowestIndex = ms->window.dictLimit;
63 const BYTE* const lowest = base + lowestIndex;
64 const BYTE* const iend = istart + srcSize;
65 const BYTE* const ilimit = iend - HASH_READ_SIZE;
66 U32 offset_1=rep[0], offset_2=rep[1];
67 U32 offsetSaved = 0;
68
69 /* init */
70 ip += (ip==lowest);
71 { U32 const maxRep = (U32)(ip-lowest);
72 if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
73 if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
74 }
75
76 /* Main Search Loop */
77 while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */
78 size_t mLength;
79 size_t const h2 = ZSTD_hashPtr(ip, hBitsL, 8);
80 size_t const h = ZSTD_hashPtr(ip, hBitsS, mls);
81 U32 const current = (U32)(ip-base);
82 U32 const matchIndexL = hashLong[h2];
83 U32 const matchIndexS = hashSmall[h];
84 const BYTE* matchLong = base + matchIndexL;
85 const BYTE* match = base + matchIndexS;
86 hashLong[h2] = hashSmall[h] = current; /* update hash tables */
87
88 assert(offset_1 <= current); /* supposed guaranteed by construction */
89 if ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1))) {
90 /* favor repcode */
91 mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
92 ip++;
93 ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
94 } else {
95 U32 offset;
96 if ( (matchIndexL > lowestIndex) && (MEM_read64(matchLong) == MEM_read64(ip)) ) {
97 mLength = ZSTD_count(ip+8, matchLong+8, iend) + 8;
98 offset = (U32)(ip-matchLong);
99 while (((ip>anchor) & (matchLong>lowest)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */
100 } else if ( (matchIndexS > lowestIndex) && (MEM_read32(match) == MEM_read32(ip)) ) {
101 size_t const hl3 = ZSTD_hashPtr(ip+1, hBitsL, 8);
102 U32 const matchIndexL3 = hashLong[hl3];
103 const BYTE* matchL3 = base + matchIndexL3;
104 hashLong[hl3] = current + 1;
105 if ( (matchIndexL3 > lowestIndex) && (MEM_read64(matchL3) == MEM_read64(ip+1)) ) {
106 mLength = ZSTD_count(ip+9, matchL3+8, iend) + 8;
107 ip++;
108 offset = (U32)(ip-matchL3);
109 while (((ip>anchor) & (matchL3>lowest)) && (ip[-1] == matchL3[-1])) { ip--; matchL3--; mLength++; } /* catch up */
110 } else {
111 mLength = ZSTD_count(ip+4, match+4, iend) + 4;
112 offset = (U32)(ip-match);
113 while (((ip>anchor) & (match>lowest)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
114 }
115 } else {
116 ip += ((ip-anchor) >> kSearchStrength) + 1;
117 continue;
118 }
119
120 offset_2 = offset_1;
121 offset_1 = offset;
122
123 ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
124 }
125
126 /* match found */
127 ip += mLength;
128 anchor = ip;
129
130 if (ip <= ilimit) {
131 /* Fill Table */
132 hashLong[ZSTD_hashPtr(base+current+2, hBitsL, 8)] =
133 hashSmall[ZSTD_hashPtr(base+current+2, hBitsS, mls)] = current+2; /* here because current+2 could be > iend-8 */
134 hashLong[ZSTD_hashPtr(ip-2, hBitsL, 8)] =
135 hashSmall[ZSTD_hashPtr(ip-2, hBitsS, mls)] = (U32)(ip-2-base);
136
137 /* check immediate repcode */
138 while ( (ip <= ilimit)
139 && ( (offset_2>0)
140 & (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
141 /* store sequence */
142 size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
143 { U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; } /* swap offset_2 <=> offset_1 */
144 hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = (U32)(ip-base);
145 hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = (U32)(ip-base);
146 ZSTD_storeSeq(seqStore, 0, anchor, 0, rLength-MINMATCH);
147 ip += rLength;
148 anchor = ip;
149 continue; /* faster when present ... (?) */
150 } } }
151
152 /* save reps for next block */
153 rep[0] = offset_1 ? offset_1 : offsetSaved;
154 rep[1] = offset_2 ? offset_2 : offsetSaved;
155
156 /* Return the last literals size */
157 return iend - anchor;
158}
159
160
161size_t ZSTD_compressBlock_doubleFast(
162 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
163 ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
164{
165 const U32 mls = cParams->searchLength;
166 switch(mls)
167 {
168 default: /* includes case 3 */
169 case 4 :
170 return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, cParams, src, srcSize, 4);
171 case 5 :
172 return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, cParams, src, srcSize, 5);
173 case 6 :
174 return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, cParams, src, srcSize, 6);
175 case 7 :
176 return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, cParams, src, srcSize, 7);
177 }
178}
179
180
181static size_t ZSTD_compressBlock_doubleFast_extDict_generic(
182 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
183 ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize,
184 U32 const mls /* template */)
185{
186 U32* const hashLong = ms->hashTable;
187 U32 const hBitsL = cParams->hashLog;
188 U32* const hashSmall = ms->chainTable;
189 U32 const hBitsS = cParams->chainLog;
190 const BYTE* const base = ms->window.base;
191 const BYTE* const dictBase = ms->window.dictBase;
192 const BYTE* const istart = (const BYTE*)src;
193 const BYTE* ip = istart;
194 const BYTE* anchor = istart;
195 const U32 lowestIndex = ms->window.lowLimit;
196 const BYTE* const dictStart = dictBase + lowestIndex;
197 const U32 dictLimit = ms->window.dictLimit;
198 const BYTE* const lowPrefixPtr = base + dictLimit;
199 const BYTE* const dictEnd = dictBase + dictLimit;
200 const BYTE* const iend = istart + srcSize;
201 const BYTE* const ilimit = iend - 8;
202 U32 offset_1=rep[0], offset_2=rep[1];
203
204 /* Search Loop */
205 while (ip < ilimit) { /* < instead of <=, because (ip+1) */
206 const size_t hSmall = ZSTD_hashPtr(ip, hBitsS, mls);
207 const U32 matchIndex = hashSmall[hSmall];
208 const BYTE* matchBase = matchIndex < dictLimit ? dictBase : base;
209 const BYTE* match = matchBase + matchIndex;
210
211 const size_t hLong = ZSTD_hashPtr(ip, hBitsL, 8);
212 const U32 matchLongIndex = hashLong[hLong];
213 const BYTE* matchLongBase = matchLongIndex < dictLimit ? dictBase : base;
214 const BYTE* matchLong = matchLongBase + matchLongIndex;
215
216 const U32 current = (U32)(ip-base);
217 const U32 repIndex = current + 1 - offset_1; /* offset_1 expected <= current +1 */
218 const BYTE* repBase = repIndex < dictLimit ? dictBase : base;
219 const BYTE* repMatch = repBase + repIndex;
220 size_t mLength;
221 hashSmall[hSmall] = hashLong[hLong] = current; /* update hash table */
222
223 if ( (((U32)((dictLimit-1) - repIndex) >= 3) /* intentional underflow */ & (repIndex > lowestIndex))
224 && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
225 const BYTE* repMatchEnd = repIndex < dictLimit ? dictEnd : iend;
226 mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, lowPrefixPtr) + 4;
227 ip++;
228 ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
229 } else {
230 if ((matchLongIndex > lowestIndex) && (MEM_read64(matchLong) == MEM_read64(ip))) {
231 const BYTE* matchEnd = matchLongIndex < dictLimit ? dictEnd : iend;
232 const BYTE* lowMatchPtr = matchLongIndex < dictLimit ? dictStart : lowPrefixPtr;
233 U32 offset;
234 mLength = ZSTD_count_2segments(ip+8, matchLong+8, iend, matchEnd, lowPrefixPtr) + 8;
235 offset = current - matchLongIndex;
236 while (((ip>anchor) & (matchLong>lowMatchPtr)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */
237 offset_2 = offset_1;
238 offset_1 = offset;
239 ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
240
241 } else if ((matchIndex > lowestIndex) && (MEM_read32(match) == MEM_read32(ip))) {
242 size_t const h3 = ZSTD_hashPtr(ip+1, hBitsL, 8);
243 U32 const matchIndex3 = hashLong[h3];
244 const BYTE* const match3Base = matchIndex3 < dictLimit ? dictBase : base;
245 const BYTE* match3 = match3Base + matchIndex3;
246 U32 offset;
247 hashLong[h3] = current + 1;
248 if ( (matchIndex3 > lowestIndex) && (MEM_read64(match3) == MEM_read64(ip+1)) ) {
249 const BYTE* matchEnd = matchIndex3 < dictLimit ? dictEnd : iend;
250 const BYTE* lowMatchPtr = matchIndex3 < dictLimit ? dictStart : lowPrefixPtr;
251 mLength = ZSTD_count_2segments(ip+9, match3+8, iend, matchEnd, lowPrefixPtr) + 8;
252 ip++;
253 offset = current+1 - matchIndex3;
254 while (((ip>anchor) & (match3>lowMatchPtr)) && (ip[-1] == match3[-1])) { ip--; match3--; mLength++; } /* catch up */
255 } else {
256 const BYTE* matchEnd = matchIndex < dictLimit ? dictEnd : iend;
257 const BYTE* lowMatchPtr = matchIndex < dictLimit ? dictStart : lowPrefixPtr;
258 mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, lowPrefixPtr) + 4;
259 offset = current - matchIndex;
260 while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
261 }
262 offset_2 = offset_1;
263 offset_1 = offset;
264 ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
265
266 } else {
267 ip += ((ip-anchor) >> kSearchStrength) + 1;
268 continue;
269 } }
270
271 /* found a match : store it */
272 ip += mLength;
273 anchor = ip;
274
275 if (ip <= ilimit) {
276 /* Fill Table */
277 hashSmall[ZSTD_hashPtr(base+current+2, hBitsS, mls)] = current+2;
278 hashLong[ZSTD_hashPtr(base+current+2, hBitsL, 8)] = current+2;
279 hashSmall[ZSTD_hashPtr(ip-2, hBitsS, mls)] = (U32)(ip-2-base);
280 hashLong[ZSTD_hashPtr(ip-2, hBitsL, 8)] = (U32)(ip-2-base);
281 /* check immediate repcode */
282 while (ip <= ilimit) {
283 U32 const current2 = (U32)(ip-base);
284 U32 const repIndex2 = current2 - offset_2;
285 const BYTE* repMatch2 = repIndex2 < dictLimit ? dictBase + repIndex2 : base + repIndex2;
286 if ( (((U32)((dictLimit-1) - repIndex2) >= 3) & (repIndex2 > lowestIndex)) /* intentional overflow */
287 && (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
288 const BYTE* const repEnd2 = repIndex2 < dictLimit ? dictEnd : iend;
289 size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, lowPrefixPtr) + 4;
290 U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
291 ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);
292 hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = current2;
293 hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = current2;
294 ip += repLength2;
295 anchor = ip;
296 continue;
297 }
298 break;
299 } } }
300
301 /* save reps for next block */
302 rep[0] = offset_1;
303 rep[1] = offset_2;
304
305 /* Return the last literals size */
306 return iend - anchor;
307}
308
309
310size_t ZSTD_compressBlock_doubleFast_extDict(
311 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
312 ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
313{
314 U32 const mls = cParams->searchLength;
315 switch(mls)
316 {
317 default: /* includes case 3 */
318 case 4 :
319 return ZSTD_compressBlock_doubleFast_extDict_generic(ms, seqStore, rep, cParams, src, srcSize, 4);
320 case 5 :
321 return ZSTD_compressBlock_doubleFast_extDict_generic(ms, seqStore, rep, cParams, src, srcSize, 5);
322 case 6 :
323 return ZSTD_compressBlock_doubleFast_extDict_generic(ms, seqStore, rep, cParams, src, srcSize, 6);
324 case 7 :
325 return ZSTD_compressBlock_doubleFast_extDict_generic(ms, seqStore, rep, cParams, src, srcSize, 7);
326 }
327}
328