xref: /freebsd/sys/contrib/zstd/lib/compress/zstd_double_fast.c (revision d3d381b2b194b4d24853e92eecef55f262688d1a)
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 
15 void 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 
48 FORCE_INLINE_TEMPLATE
49 size_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 
161 size_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 
181 static 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 
310 size_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