1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
|
// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
/*
// encParams are not really used, just here for reference.
type encParams struct {
// largest match distance : larger == more compression, more memory needed during decompression
windowLog uint8
// fully searched segment : larger == more compression, slower, more memory (useless for fast)
chainLog uint8
// dispatch table : larger == faster, more memory
hashLog uint8
// < nb of searches : larger == more compression, slower
searchLog uint8
// < match length searched : larger == faster decompression, sometimes less compression
minMatch uint8
// acceptable match size for optimal parser (only) : larger == more compression, slower
targetLength uint32
// see ZSTD_strategy definition above
strategy strategy
}
// strategy defines the algorithm to use when generating sequences.
type strategy uint8
const (
// Compression strategies, listed from fastest to strongest
strategyFast strategy = iota + 1
strategyDfast
strategyGreedy
strategyLazy
strategyLazy2
strategyBtlazy2
strategyBtopt
strategyBtultra
strategyBtultra2
// note : new strategies _might_ be added in the future.
// Only the order (from fast to strong) is guaranteed
)
var defEncParams = [4][]encParams{
{ // "default" - for any srcSize > 256 KB
// W, C, H, S, L, TL, strat
{19, 12, 13, 1, 6, 1, strategyFast}, // base for negative levels
{19, 13, 14, 1, 7, 0, strategyFast}, // level 1
{20, 15, 16, 1, 6, 0, strategyFast}, // level 2
{21, 16, 17, 1, 5, 1, strategyDfast}, // level 3
{21, 18, 18, 1, 5, 1, strategyDfast}, // level 4
{21, 18, 19, 2, 5, 2, strategyGreedy}, // level 5
{21, 19, 19, 3, 5, 4, strategyGreedy}, // level 6
{21, 19, 19, 3, 5, 8, strategyLazy}, // level 7
{21, 19, 19, 3, 5, 16, strategyLazy2}, // level 8
{21, 19, 20, 4, 5, 16, strategyLazy2}, // level 9
{22, 20, 21, 4, 5, 16, strategyLazy2}, // level 10
{22, 21, 22, 4, 5, 16, strategyLazy2}, // level 11
{22, 21, 22, 5, 5, 16, strategyLazy2}, // level 12
{22, 21, 22, 5, 5, 32, strategyBtlazy2}, // level 13
{22, 22, 23, 5, 5, 32, strategyBtlazy2}, // level 14
{22, 23, 23, 6, 5, 32, strategyBtlazy2}, // level 15
{22, 22, 22, 5, 5, 48, strategyBtopt}, // level 16
{23, 23, 22, 5, 4, 64, strategyBtopt}, // level 17
{23, 23, 22, 6, 3, 64, strategyBtultra}, // level 18
{23, 24, 22, 7, 3, 256, strategyBtultra2}, // level 19
{25, 25, 23, 7, 3, 256, strategyBtultra2}, // level 20
{26, 26, 24, 7, 3, 512, strategyBtultra2}, // level 21
{27, 27, 25, 9, 3, 999, strategyBtultra2}, // level 22
},
{ // for srcSize <= 256 KB
// W, C, H, S, L, T, strat
{18, 12, 13, 1, 5, 1, strategyFast}, // base for negative levels
{18, 13, 14, 1, 6, 0, strategyFast}, // level 1
{18, 14, 14, 1, 5, 1, strategyDfast}, // level 2
{18, 16, 16, 1, 4, 1, strategyDfast}, // level 3
{18, 16, 17, 2, 5, 2, strategyGreedy}, // level 4.
{18, 18, 18, 3, 5, 2, strategyGreedy}, // level 5.
{18, 18, 19, 3, 5, 4, strategyLazy}, // level 6.
{18, 18, 19, 4, 4, 4, strategyLazy}, // level 7
{18, 18, 19, 4, 4, 8, strategyLazy2}, // level 8
{18, 18, 19, 5, 4, 8, strategyLazy2}, // level 9
{18, 18, 19, 6, 4, 8, strategyLazy2}, // level 10
{18, 18, 19, 5, 4, 12, strategyBtlazy2}, // level 11.
{18, 19, 19, 7, 4, 12, strategyBtlazy2}, // level 12.
{18, 18, 19, 4, 4, 16, strategyBtopt}, // level 13
{18, 18, 19, 4, 3, 32, strategyBtopt}, // level 14.
{18, 18, 19, 6, 3, 128, strategyBtopt}, // level 15.
{18, 19, 19, 6, 3, 128, strategyBtultra}, // level 16.
{18, 19, 19, 8, 3, 256, strategyBtultra}, // level 17.
{18, 19, 19, 6, 3, 128, strategyBtultra2}, // level 18.
{18, 19, 19, 8, 3, 256, strategyBtultra2}, // level 19.
{18, 19, 19, 10, 3, 512, strategyBtultra2}, // level 20.
{18, 19, 19, 12, 3, 512, strategyBtultra2}, // level 21.
{18, 19, 19, 13, 3, 999, strategyBtultra2}, // level 22.
},
{ // for srcSize <= 128 KB
// W, C, H, S, L, T, strat
{17, 12, 12, 1, 5, 1, strategyFast}, // base for negative levels
{17, 12, 13, 1, 6, 0, strategyFast}, // level 1
{17, 13, 15, 1, 5, 0, strategyFast}, // level 2
{17, 15, 16, 2, 5, 1, strategyDfast}, // level 3
{17, 17, 17, 2, 4, 1, strategyDfast}, // level 4
{17, 16, 17, 3, 4, 2, strategyGreedy}, // level 5
{17, 17, 17, 3, 4, 4, strategyLazy}, // level 6
{17, 17, 17, 3, 4, 8, strategyLazy2}, // level 7
{17, 17, 17, 4, 4, 8, strategyLazy2}, // level 8
{17, 17, 17, 5, 4, 8, strategyLazy2}, // level 9
{17, 17, 17, 6, 4, 8, strategyLazy2}, // level 10
{17, 17, 17, 5, 4, 8, strategyBtlazy2}, // level 11
{17, 18, 17, 7, 4, 12, strategyBtlazy2}, // level 12
{17, 18, 17, 3, 4, 12, strategyBtopt}, // level 13.
{17, 18, 17, 4, 3, 32, strategyBtopt}, // level 14.
{17, 18, 17, 6, 3, 256, strategyBtopt}, // level 15.
{17, 18, 17, 6, 3, 128, strategyBtultra}, // level 16.
{17, 18, 17, 8, 3, 256, strategyBtultra}, // level 17.
{17, 18, 17, 10, 3, 512, strategyBtultra}, // level 18.
{17, 18, 17, 5, 3, 256, strategyBtultra2}, // level 19.
{17, 18, 17, 7, 3, 512, strategyBtultra2}, // level 20.
{17, 18, 17, 9, 3, 512, strategyBtultra2}, // level 21.
{17, 18, 17, 11, 3, 999, strategyBtultra2}, // level 22.
},
{ // for srcSize <= 16 KB
// W, C, H, S, L, T, strat
{14, 12, 13, 1, 5, 1, strategyFast}, // base for negative levels
{14, 14, 15, 1, 5, 0, strategyFast}, // level 1
{14, 14, 15, 1, 4, 0, strategyFast}, // level 2
{14, 14, 15, 2, 4, 1, strategyDfast}, // level 3
{14, 14, 14, 4, 4, 2, strategyGreedy}, // level 4
{14, 14, 14, 3, 4, 4, strategyLazy}, // level 5.
{14, 14, 14, 4, 4, 8, strategyLazy2}, // level 6
{14, 14, 14, 6, 4, 8, strategyLazy2}, // level 7
{14, 14, 14, 8, 4, 8, strategyLazy2}, // level 8.
{14, 15, 14, 5, 4, 8, strategyBtlazy2}, // level 9.
{14, 15, 14, 9, 4, 8, strategyBtlazy2}, // level 10.
{14, 15, 14, 3, 4, 12, strategyBtopt}, // level 11.
{14, 15, 14, 4, 3, 24, strategyBtopt}, // level 12.
{14, 15, 14, 5, 3, 32, strategyBtultra}, // level 13.
{14, 15, 15, 6, 3, 64, strategyBtultra}, // level 14.
{14, 15, 15, 7, 3, 256, strategyBtultra}, // level 15.
{14, 15, 15, 5, 3, 48, strategyBtultra2}, // level 16.
{14, 15, 15, 6, 3, 128, strategyBtultra2}, // level 17.
{14, 15, 15, 7, 3, 256, strategyBtultra2}, // level 18.
{14, 15, 15, 8, 3, 256, strategyBtultra2}, // level 19.
{14, 15, 15, 8, 3, 512, strategyBtultra2}, // level 20.
{14, 15, 15, 9, 3, 512, strategyBtultra2}, // level 21.
{14, 15, 15, 10, 3, 999, strategyBtultra2}, // level 22.
},
}
*/
|
