source: code/trunk/vendor/github.com/andybalholm/brotli/state.go@ 145

Last change on this file since 145 was 145, checked in by Izuru Yakumo, 22 months ago

Updated the Makefile and vendored depedencies

Signed-off-by: Izuru Yakumo <yakumo.izuru@…>
File size: 7.7 KB
RevLine 
[145]1package brotli
2
3import "io"
4
5/* Copyright 2015 Google Inc. All Rights Reserved.
6
7 Distributed under MIT license.
8 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
9*/
10
11/* Brotli state for partial streaming decoding. */
12const (
13 stateUninited = iota
14 stateLargeWindowBits
15 stateInitialize
16 stateMetablockBegin
17 stateMetablockHeader
18 stateMetablockHeader2
19 stateContextModes
20 stateCommandBegin
21 stateCommandInner
22 stateCommandPostDecodeLiterals
23 stateCommandPostWrapCopy
24 stateUncompressed
25 stateMetadata
26 stateCommandInnerWrite
27 stateMetablockDone
28 stateCommandPostWrite1
29 stateCommandPostWrite2
30 stateHuffmanCode0
31 stateHuffmanCode1
32 stateHuffmanCode2
33 stateHuffmanCode3
34 stateContextMap1
35 stateContextMap2
36 stateTreeGroup
37 stateDone
38)
39
40const (
41 stateMetablockHeaderNone = iota
42 stateMetablockHeaderEmpty
43 stateMetablockHeaderNibbles
44 stateMetablockHeaderSize
45 stateMetablockHeaderUncompressed
46 stateMetablockHeaderReserved
47 stateMetablockHeaderBytes
48 stateMetablockHeaderMetadata
49)
50
51const (
52 stateUncompressedNone = iota
53 stateUncompressedWrite
54)
55
56const (
57 stateTreeGroupNone = iota
58 stateTreeGroupLoop
59)
60
61const (
62 stateContextMapNone = iota
63 stateContextMapReadPrefix
64 stateContextMapHuffman
65 stateContextMapDecode
66 stateContextMapTransform
67)
68
69const (
70 stateHuffmanNone = iota
71 stateHuffmanSimpleSize
72 stateHuffmanSimpleRead
73 stateHuffmanSimpleBuild
74 stateHuffmanComplex
75 stateHuffmanLengthSymbols
76)
77
78const (
79 stateDecodeUint8None = iota
80 stateDecodeUint8Short
81 stateDecodeUint8Long
82)
83
84const (
85 stateReadBlockLengthNone = iota
86 stateReadBlockLengthSuffix
87)
88
89type Reader struct {
90 src io.Reader
91 buf []byte // scratch space for reading from src
92 in []byte // current chunk to decode; usually aliases buf
93
94 state int
95 loop_counter int
96 br bitReader
97 buffer struct {
98 u64 uint64
99 u8 [8]byte
100 }
101 buffer_length uint32
102 pos int
103 max_backward_distance int
104 max_distance int
105 ringbuffer_size int
106 ringbuffer_mask int
107 dist_rb_idx int
108 dist_rb [4]int
109 error_code int
110 sub_loop_counter uint32
111 ringbuffer []byte
112 ringbuffer_end []byte
113 htree_command []huffmanCode
114 context_lookup []byte
115 context_map_slice []byte
116 dist_context_map_slice []byte
117 literal_hgroup huffmanTreeGroup
118 insert_copy_hgroup huffmanTreeGroup
119 distance_hgroup huffmanTreeGroup
120 block_type_trees []huffmanCode
121 block_len_trees []huffmanCode
122 trivial_literal_context int
123 distance_context int
124 meta_block_remaining_len int
125 block_length_index uint32
126 block_length [3]uint32
127 num_block_types [3]uint32
128 block_type_rb [6]uint32
129 distance_postfix_bits uint32
130 num_direct_distance_codes uint32
131 distance_postfix_mask int
132 num_dist_htrees uint32
133 dist_context_map []byte
134 literal_htree []huffmanCode
135 dist_htree_index byte
136 repeat_code_len uint32
137 prev_code_len uint32
138 copy_length int
139 distance_code int
140 rb_roundtrips uint
141 partial_pos_out uint
142 symbol uint32
143 repeat uint32
144 space uint32
145 table [32]huffmanCode
146 symbol_lists symbolList
147 symbols_lists_array [huffmanMaxCodeLength + 1 + numCommandSymbols]uint16
148 next_symbol [32]int
149 code_length_code_lengths [codeLengthCodes]byte
150 code_length_histo [16]uint16
151 htree_index int
152 next []huffmanCode
153 context_index uint32
154 max_run_length_prefix uint32
155 code uint32
156 context_map_table [huffmanMaxSize272]huffmanCode
157 substate_metablock_header int
158 substate_tree_group int
159 substate_context_map int
160 substate_uncompressed int
161 substate_huffman int
162 substate_decode_uint8 int
163 substate_read_block_length int
164 is_last_metablock uint
165 is_uncompressed uint
166 is_metadata uint
167 should_wrap_ringbuffer uint
168 canny_ringbuffer_allocation uint
169 large_window bool
170 size_nibbles uint
171 window_bits uint32
172 new_ringbuffer_size int
173 num_literal_htrees uint32
174 context_map []byte
175 context_modes []byte
176 dictionary *dictionary
177 transforms *transforms
178 trivial_literal_contexts [8]uint32
179}
180
181func decoderStateInit(s *Reader) bool {
182 s.error_code = 0 /* BROTLI_DECODER_NO_ERROR */
183
184 initBitReader(&s.br)
185 s.state = stateUninited
186 s.large_window = false
187 s.substate_metablock_header = stateMetablockHeaderNone
188 s.substate_tree_group = stateTreeGroupNone
189 s.substate_context_map = stateContextMapNone
190 s.substate_uncompressed = stateUncompressedNone
191 s.substate_huffman = stateHuffmanNone
192 s.substate_decode_uint8 = stateDecodeUint8None
193 s.substate_read_block_length = stateReadBlockLengthNone
194
195 s.buffer_length = 0
196 s.loop_counter = 0
197 s.pos = 0
198 s.rb_roundtrips = 0
199 s.partial_pos_out = 0
200
201 s.block_type_trees = nil
202 s.block_len_trees = nil
203 s.ringbuffer = nil
204 s.ringbuffer_size = 0
205 s.new_ringbuffer_size = 0
206 s.ringbuffer_mask = 0
207
208 s.context_map = nil
209 s.context_modes = nil
210 s.dist_context_map = nil
211 s.context_map_slice = nil
212 s.dist_context_map_slice = nil
213
214 s.sub_loop_counter = 0
215
216 s.literal_hgroup.codes = nil
217 s.literal_hgroup.htrees = nil
218 s.insert_copy_hgroup.codes = nil
219 s.insert_copy_hgroup.htrees = nil
220 s.distance_hgroup.codes = nil
221 s.distance_hgroup.htrees = nil
222
223 s.is_last_metablock = 0
224 s.is_uncompressed = 0
225 s.is_metadata = 0
226 s.should_wrap_ringbuffer = 0
227 s.canny_ringbuffer_allocation = 1
228
229 s.window_bits = 0
230 s.max_distance = 0
231 s.dist_rb[0] = 16
232 s.dist_rb[1] = 15
233 s.dist_rb[2] = 11
234 s.dist_rb[3] = 4
235 s.dist_rb_idx = 0
236 s.block_type_trees = nil
237 s.block_len_trees = nil
238
239 s.symbol_lists.storage = s.symbols_lists_array[:]
240 s.symbol_lists.offset = huffmanMaxCodeLength + 1
241
242 s.dictionary = getDictionary()
243 s.transforms = getTransforms()
244
245 return true
246}
247
248func decoderStateMetablockBegin(s *Reader) {
249 s.meta_block_remaining_len = 0
250 s.block_length[0] = 1 << 24
251 s.block_length[1] = 1 << 24
252 s.block_length[2] = 1 << 24
253 s.num_block_types[0] = 1
254 s.num_block_types[1] = 1
255 s.num_block_types[2] = 1
256 s.block_type_rb[0] = 1
257 s.block_type_rb[1] = 0
258 s.block_type_rb[2] = 1
259 s.block_type_rb[3] = 0
260 s.block_type_rb[4] = 1
261 s.block_type_rb[5] = 0
262 s.context_map = nil
263 s.context_modes = nil
264 s.dist_context_map = nil
265 s.context_map_slice = nil
266 s.literal_htree = nil
267 s.dist_context_map_slice = nil
268 s.dist_htree_index = 0
269 s.context_lookup = nil
270 s.literal_hgroup.codes = nil
271 s.literal_hgroup.htrees = nil
272 s.insert_copy_hgroup.codes = nil
273 s.insert_copy_hgroup.htrees = nil
274 s.distance_hgroup.codes = nil
275 s.distance_hgroup.htrees = nil
276}
277
278func decoderStateCleanupAfterMetablock(s *Reader) {
279 s.context_modes = nil
280 s.context_map = nil
281 s.dist_context_map = nil
282 s.literal_hgroup.htrees = nil
283 s.insert_copy_hgroup.htrees = nil
284 s.distance_hgroup.htrees = nil
285}
286
287func decoderHuffmanTreeGroupInit(s *Reader, group *huffmanTreeGroup, alphabet_size uint32, max_symbol uint32, ntrees uint32) bool {
288 var max_table_size uint = uint(kMaxHuffmanTableSize[(alphabet_size+31)>>5])
289 group.alphabet_size = uint16(alphabet_size)
290 group.max_symbol = uint16(max_symbol)
291 group.num_htrees = uint16(ntrees)
292 group.htrees = make([][]huffmanCode, ntrees)
293 group.codes = make([]huffmanCode, (uint(ntrees) * max_table_size))
294 return !(group.codes == nil)
295}
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