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state.go
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state.go
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package brotli
import "io"
/* Copyright 2015 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
/* Brotli state for partial streaming decoding. */
const (
stateUninited = iota
stateLargeWindowBits
stateInitialize
stateMetablockBegin
stateMetablockHeader
stateMetablockHeader2
stateContextModes
stateCommandBegin
stateCommandInner
stateCommandPostDecodeLiterals
stateCommandPostWrapCopy
stateUncompressed
stateMetadata
stateCommandInnerWrite
stateMetablockDone
stateCommandPostWrite1
stateCommandPostWrite2
stateHuffmanCode0
stateHuffmanCode1
stateHuffmanCode2
stateHuffmanCode3
stateContextMap1
stateContextMap2
stateTreeGroup
stateDone
)
const (
stateMetablockHeaderNone = iota
stateMetablockHeaderEmpty
stateMetablockHeaderNibbles
stateMetablockHeaderSize
stateMetablockHeaderUncompressed
stateMetablockHeaderReserved
stateMetablockHeaderBytes
stateMetablockHeaderMetadata
)
const (
stateUncompressedNone = iota
stateUncompressedWrite
)
const (
stateTreeGroupNone = iota
stateTreeGroupLoop
)
const (
stateContextMapNone = iota
stateContextMapReadPrefix
stateContextMapHuffman
stateContextMapDecode
stateContextMapTransform
)
const (
stateHuffmanNone = iota
stateHuffmanSimpleSize
stateHuffmanSimpleRead
stateHuffmanSimpleBuild
stateHuffmanComplex
stateHuffmanLengthSymbols
)
const (
stateDecodeUint8None = iota
stateDecodeUint8Short
stateDecodeUint8Long
)
const (
stateReadBlockLengthNone = iota
stateReadBlockLengthSuffix
)
type Reader struct {
src io.Reader
buf []byte // scratch space for reading from src
in []byte // current chunk to decode; usually aliases buf
state int
loop_counter int
br bitReader
buffer struct {
u64 uint64
u8 [8]byte
}
buffer_length uint32
pos int
max_backward_distance int
max_distance int
ringbuffer_size int
ringbuffer_mask int
dist_rb_idx int
dist_rb [4]int
error_code int
sub_loop_counter uint32
ringbuffer []byte
ringbuffer_end []byte
htree_command []huffmanCode
context_lookup []byte
context_map_slice []byte
dist_context_map_slice []byte
literal_hgroup huffmanTreeGroup
insert_copy_hgroup huffmanTreeGroup
distance_hgroup huffmanTreeGroup
block_type_trees []huffmanCode
block_len_trees []huffmanCode
trivial_literal_context int
distance_context int
meta_block_remaining_len int
block_length_index uint32
block_length [3]uint32
num_block_types [3]uint32
block_type_rb [6]uint32
distance_postfix_bits uint32
num_direct_distance_codes uint32
distance_postfix_mask int
num_dist_htrees uint32
dist_context_map []byte
literal_htree []huffmanCode
dist_htree_index byte
repeat_code_len uint32
prev_code_len uint32
copy_length int
distance_code int
rb_roundtrips uint
partial_pos_out uint
symbol uint32
repeat uint32
space uint32
table [32]huffmanCode
symbol_lists symbolList
symbols_lists_array [huffmanMaxCodeLength + 1 + numCommandSymbols]uint16
next_symbol [32]int
code_length_code_lengths [codeLengthCodes]byte
code_length_histo [16]uint16
htree_index int
next []huffmanCode
context_index uint32
max_run_length_prefix uint32
code uint32
context_map_table [huffmanMaxSize272]huffmanCode
substate_metablock_header int
substate_tree_group int
substate_context_map int
substate_uncompressed int
substate_huffman int
substate_decode_uint8 int
substate_read_block_length int
is_last_metablock uint
is_uncompressed uint
is_metadata uint
should_wrap_ringbuffer uint
canny_ringbuffer_allocation uint
large_window bool
size_nibbles uint
window_bits uint32
new_ringbuffer_size int
num_literal_htrees uint32
context_map []byte
context_modes []byte
dictionary *dictionary
transforms *transforms
trivial_literal_contexts [8]uint32
}
func decoderStateInit(s *Reader) bool {
s.error_code = 0 /* BROTLI_DECODER_NO_ERROR */
initBitReader(&s.br)
s.state = stateUninited
s.large_window = false
s.substate_metablock_header = stateMetablockHeaderNone
s.substate_tree_group = stateTreeGroupNone
s.substate_context_map = stateContextMapNone
s.substate_uncompressed = stateUncompressedNone
s.substate_huffman = stateHuffmanNone
s.substate_decode_uint8 = stateDecodeUint8None
s.substate_read_block_length = stateReadBlockLengthNone
s.buffer_length = 0
s.loop_counter = 0
s.pos = 0
s.rb_roundtrips = 0
s.partial_pos_out = 0
s.block_type_trees = nil
s.block_len_trees = nil
s.ringbuffer_size = 0
s.new_ringbuffer_size = 0
s.ringbuffer_mask = 0
s.context_map = nil
s.context_modes = nil
s.dist_context_map = nil
s.context_map_slice = nil
s.dist_context_map_slice = nil
s.sub_loop_counter = 0
s.literal_hgroup.codes = nil
s.literal_hgroup.htrees = nil
s.insert_copy_hgroup.codes = nil
s.insert_copy_hgroup.htrees = nil
s.distance_hgroup.codes = nil
s.distance_hgroup.htrees = nil
s.is_last_metablock = 0
s.is_uncompressed = 0
s.is_metadata = 0
s.should_wrap_ringbuffer = 0
s.canny_ringbuffer_allocation = 1
s.window_bits = 0
s.max_distance = 0
s.dist_rb[0] = 16
s.dist_rb[1] = 15
s.dist_rb[2] = 11
s.dist_rb[3] = 4
s.dist_rb_idx = 0
s.block_type_trees = nil
s.block_len_trees = nil
s.symbol_lists.storage = s.symbols_lists_array[:]
s.symbol_lists.offset = huffmanMaxCodeLength + 1
s.dictionary = getDictionary()
s.transforms = getTransforms()
return true
}
func decoderStateMetablockBegin(s *Reader) {
s.meta_block_remaining_len = 0
s.block_length[0] = 1 << 24
s.block_length[1] = 1 << 24
s.block_length[2] = 1 << 24
s.num_block_types[0] = 1
s.num_block_types[1] = 1
s.num_block_types[2] = 1
s.block_type_rb[0] = 1
s.block_type_rb[1] = 0
s.block_type_rb[2] = 1
s.block_type_rb[3] = 0
s.block_type_rb[4] = 1
s.block_type_rb[5] = 0
s.context_map = nil
s.context_modes = nil
s.dist_context_map = nil
s.context_map_slice = nil
s.literal_htree = nil
s.dist_context_map_slice = nil
s.dist_htree_index = 0
s.context_lookup = nil
s.literal_hgroup.codes = nil
s.literal_hgroup.htrees = nil
s.insert_copy_hgroup.codes = nil
s.insert_copy_hgroup.htrees = nil
s.distance_hgroup.codes = nil
s.distance_hgroup.htrees = nil
}
func decoderStateCleanupAfterMetablock(s *Reader) {
s.context_modes = nil
s.context_map = nil
s.dist_context_map = nil
s.literal_hgroup.htrees = nil
s.insert_copy_hgroup.htrees = nil
s.distance_hgroup.htrees = nil
}
func decoderHuffmanTreeGroupInit(s *Reader, group *huffmanTreeGroup, alphabet_size uint32, max_symbol uint32, ntrees uint32) bool {
var max_table_size uint = uint(kMaxHuffmanTableSize[(alphabet_size+31)>>5])
group.alphabet_size = uint16(alphabet_size)
group.max_symbol = uint16(max_symbol)
group.num_htrees = uint16(ntrees)
group.htrees = make([][]huffmanCode, ntrees)
group.codes = make([]huffmanCode, (uint(ntrees) * max_table_size))
return !(group.codes == nil)
}