648db22b |
1 | /* |
2 | * Copyright (c) Yann Collet, Meta Platforms, 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 "external_matchfinder.h" |
12 | #include <string.h> |
13 | #include "zstd_compress_internal.h" |
14 | |
15 | #define HSIZE 1024 |
16 | static U32 const HLOG = 10; |
17 | static U32 const MLS = 4; |
18 | static U32 const BADIDX = 0xffffffff; |
19 | |
20 | static size_t simpleSequenceProducer( |
21 | void* sequenceProducerState, |
22 | ZSTD_Sequence* outSeqs, size_t outSeqsCapacity, |
23 | const void* src, size_t srcSize, |
24 | const void* dict, size_t dictSize, |
25 | int compressionLevel, |
26 | size_t windowSize |
27 | ) { |
28 | const BYTE* const istart = (const BYTE*)src; |
29 | const BYTE* const iend = istart + srcSize; |
30 | const BYTE* ip = istart; |
31 | const BYTE* anchor = istart; |
32 | size_t seqCount = 0; |
33 | U32 hashTable[HSIZE]; |
34 | |
35 | (void)sequenceProducerState; |
36 | (void)dict; |
37 | (void)dictSize; |
38 | (void)outSeqsCapacity; |
39 | (void)compressionLevel; |
40 | |
41 | { int i; |
42 | for (i=0; i < HSIZE; i++) { |
43 | hashTable[i] = BADIDX; |
44 | } } |
45 | |
46 | while (ip + MLS < iend) { |
47 | size_t const hash = ZSTD_hashPtr(ip, HLOG, MLS); |
48 | U32 const matchIndex = hashTable[hash]; |
49 | hashTable[hash] = (U32)(ip - istart); |
50 | |
51 | if (matchIndex != BADIDX) { |
52 | const BYTE* const match = istart + matchIndex; |
53 | U32 const matchLen = (U32)ZSTD_count(ip, match, iend); |
54 | if (matchLen >= ZSTD_MINMATCH_MIN) { |
55 | U32 const litLen = (U32)(ip - anchor); |
56 | U32 const offset = (U32)(ip - match); |
57 | ZSTD_Sequence const seq = { |
58 | offset, litLen, matchLen, 0 |
59 | }; |
60 | |
61 | /* Note: it's crucial to stay within the window size! */ |
62 | if (offset <= windowSize) { |
63 | outSeqs[seqCount++] = seq; |
64 | ip += matchLen; |
65 | anchor = ip; |
66 | continue; |
67 | } |
68 | } |
69 | } |
70 | |
71 | ip++; |
72 | } |
73 | |
74 | { ZSTD_Sequence const finalSeq = { |
75 | 0, (U32)(iend - anchor), 0, 0 |
76 | }; |
77 | outSeqs[seqCount++] = finalSeq; |
78 | } |
79 | |
80 | return seqCount; |
81 | } |
82 | |
83 | size_t zstreamSequenceProducer( |
84 | void* sequenceProducerState, |
85 | ZSTD_Sequence* outSeqs, size_t outSeqsCapacity, |
86 | const void* src, size_t srcSize, |
87 | const void* dict, size_t dictSize, |
88 | int compressionLevel, |
89 | size_t windowSize |
90 | ) { |
91 | EMF_testCase const testCase = *((EMF_testCase*)sequenceProducerState); |
92 | memset(outSeqs, 0, outSeqsCapacity); |
93 | |
94 | switch (testCase) { |
95 | case EMF_ZERO_SEQS: |
96 | return 0; |
97 | case EMF_ONE_BIG_SEQ: |
98 | outSeqs[0].offset = 0; |
99 | outSeqs[0].matchLength = 0; |
100 | outSeqs[0].litLength = (U32)(srcSize); |
101 | return 1; |
102 | case EMF_LOTS_OF_SEQS: |
103 | return simpleSequenceProducer( |
104 | sequenceProducerState, |
105 | outSeqs, outSeqsCapacity, |
106 | src, srcSize, |
107 | dict, dictSize, |
108 | compressionLevel, |
109 | windowSize |
110 | ); |
111 | case EMF_INVALID_OFFSET: |
112 | outSeqs[0].offset = 1 << 20; |
113 | outSeqs[0].matchLength = 4; |
114 | outSeqs[0].litLength = (U32)(srcSize - 4); |
115 | return 1; |
116 | case EMF_INVALID_MATCHLEN: |
117 | outSeqs[0].offset = 1; |
118 | outSeqs[0].matchLength = (U32)(srcSize); |
119 | outSeqs[0].litLength = 1; |
120 | return 1; |
121 | case EMF_INVALID_LITLEN: |
122 | outSeqs[0].offset = 0; |
123 | outSeqs[0].matchLength = 0; |
124 | outSeqs[0].litLength = (U32)(srcSize + 1); |
125 | return 1; |
126 | case EMF_INVALID_LAST_LITS: |
127 | outSeqs[0].offset = 1; |
128 | outSeqs[0].matchLength = 1; |
129 | outSeqs[0].litLength = 1; |
130 | outSeqs[1].offset = 0; |
131 | outSeqs[1].matchLength = 0; |
132 | outSeqs[1].litLength = (U32)(srcSize - 1); |
133 | return 2; |
134 | case EMF_SMALL_ERROR: |
135 | return outSeqsCapacity + 1; |
136 | case EMF_BIG_ERROR: |
137 | default: |
138 | return ZSTD_SEQUENCE_PRODUCER_ERROR; |
139 | } |
140 | } |