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Add brotli decompressor

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This commit is for the decoder for brotli compression format.
Brotli is a generic byte-level compression algorithm.
This commit is contained in:
Zoltan Szabadka 2013-10-11 10:26:07 +02:00
commit 8f30907d0f
13 changed files with 1935 additions and 0 deletions
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This directory holds the decoder for brotli compression format.
Brotli is proposed to be used at the byte-compression level in WOFF 2.0 format.

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Bit reading helpers
#include <assert.h>
#include "./bit_reader.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#define MAX_NUM_BIT_READ 25
#define LBITS 64 // Number of bits prefetched.
#define WBITS 32 // Minimum number of bytes needed after
// BrotliFillBitWindow.
#define LOG8_WBITS 4 // Number of bytes needed to store WBITS bits.
static const uint32_t kBitMask[MAX_NUM_BIT_READ] = {
0, 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767,
65535, 131071, 262143, 524287, 1048575, 2097151, 4194303, 8388607, 16777215
};
void BrotliInitBitReader(BrotliBitReader* const br,
const uint8_t* const start,
size_t length) {
size_t i;
assert(br != NULL);
assert(start != NULL);
assert(length < 0xfffffff8u); // can't happen with a RIFF chunk.
br->buf_ = start;
br->len_ = length;
br->val_ = 0;
br->pos_ = 0;
br->bit_pos_ = 0;
br->eos_ = 0;
br->error_ = 0;
for (i = 0; i < sizeof(br->val_) && i < br->len_; ++i) {
br->val_ |= ((uint64_t)br->buf_[br->pos_]) << (8 * i);
++br->pos_;
}
}
void BrotliBitReaderSetBuffer(BrotliBitReader* const br,
const uint8_t* const buf, size_t len) {
assert(br != NULL);
assert(buf != NULL);
assert(len < 0xfffffff8u); // can't happen with a RIFF chunk.
br->eos_ = (br->pos_ >= len);
br->buf_ = buf;
br->len_ = len;
}
// If not at EOS, reload up to LBITS byte-by-byte
static void ShiftBytes(BrotliBitReader* const br) {
while (br->bit_pos_ >= 8 && br->pos_ < br->len_) {
br->val_ >>= 8;
br->val_ |= ((uint64_t)br->buf_[br->pos_]) << (LBITS - 8);
++br->pos_;
br->bit_pos_ -= 8;
}
}
void BrotliFillBitWindow(BrotliBitReader* const br) {
if (br->bit_pos_ >= WBITS) {
#if (defined(__x86_64__) || defined(_M_X64))
if (br->pos_ + sizeof(br->val_) < br->len_) {
br->val_ >>= WBITS;
br->bit_pos_ -= WBITS;
// The expression below needs a little-endian arch to work correctly.
// This gives a large speedup for decoding speed.
br->val_ |= *(const uint64_t*)(br->buf_ + br->pos_) << (LBITS - WBITS);
br->pos_ += LOG8_WBITS;
return;
}
#endif
ShiftBytes(br); // Slow path.
if (br->pos_ == br->len_ && br->bit_pos_ == LBITS) {
br->eos_ = 1;
}
}
}
uint32_t BrotliReadBits(BrotliBitReader* const br, int n_bits) {
assert(n_bits >= 0);
// Flag an error if end_of_stream or n_bits is more than allowed limit.
if (n_bits == 0 || (!br->eos_ && n_bits < MAX_NUM_BIT_READ)) {
const uint32_t val =
(uint32_t)(br->val_ >> br->bit_pos_) & kBitMask[n_bits];
const int new_bits = br->bit_pos_ + n_bits;
br->bit_pos_ = new_bits;
// If this read is going to cross the read buffer, set the eos flag.
if (br->pos_ == br->len_) {
if (new_bits >= LBITS) {
br->eos_ = 1;
}
}
ShiftBytes(br);
return val;
} else {
br->error_ = 1;
return 0;
}
}
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Bit reading helpers
#ifndef BROTLI_DEC_BIT_READER_H_
#define BROTLI_DEC_BIT_READER_H_
#include "./types.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
typedef struct {
uint64_t val_; // pre-fetched bits
const uint8_t* buf_; // input byte buffer
size_t len_; // buffer length
size_t pos_; // byte position in buf_
int bit_pos_; // current bit-reading position in val_
int eos_; // bitstream is finished
int error_; // an error occurred (buffer overflow attempt...)
} BrotliBitReader;
void BrotliInitBitReader(BrotliBitReader* const br,
const uint8_t* const start,
size_t length);
// Sets a new data buffer.
void BrotliBitReaderSetBuffer(BrotliBitReader* const br,
const uint8_t* const buffer, size_t length);
// Reads the specified number of bits from Read Buffer.
// Flags an error in case end_of_stream or n_bits is more than allowed limit.
// Flags eos if this read attempt is going to cross the read buffer.
uint32_t BrotliReadBits(BrotliBitReader* const br, int n_bits);
// Return the prefetched bits, so they can be looked up.
static BROTLI_INLINE uint32_t BrotliPrefetchBits(BrotliBitReader* const br) {
return (uint32_t)(br->val_ >> br->bit_pos_);
}
// For jumping over a number of bits in the bit stream when accessed with
// BrotliPrefetchBits and BrotliFillBitWindow.
static BROTLI_INLINE void BrotliSetBitPos(BrotliBitReader* const br, int val) {
br->bit_pos_ = val;
}
// Advances the Read buffer by 4 bytes to make room for reading next 32 bits.
void BrotliFillBitWindow(BrotliBitReader* const br);
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif
#endif // BROTLI_DEC_BIT_READER_H_

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Lookup tables to map the previous one to three bytes to a context id.
#ifndef BROTLI_DEC_CONTEXT_H_
#define BROTLI_DEC_CONTEXT_H_
#include "./types.h"
static const int kSigned2BitContextLookup[] = {
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3,
};
static const int kSigned3BitContextLookup[] = {
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7,
};
static const int kSigned4BitContextLookup[] = {
0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 14, 15,
};
enum ContextType {
CONTEXT_FULL = 0,
CONTEXT_MSB7 = 1,
CONTEXT_MSB6 = 2,
CONTEXT_MSB5 = 3,
CONTEXT_MSB4 = 4,
CONTEXT_MSB3 = 5,
CONTEXT_MSB2 = 6,
CONTEXT_MSB1 = 7,
CONTEXT_IS_ZERO = 8,
CONTEXT_SIGNED_2BIT = 9,
CONTEXT_SIGNED_3BIT = 10,
CONTEXT_SIGNED_4BIT = 11,
CONTEXT_SIGNED_MIXED_3BYTE = 12,
};
static const int kContextSize[] = {
256, 128, 64, 32, 16, 8, 4, 2, 2, 4, 8, 16, 64,
};
static BROTLI_INLINE int NumContexts(int mode) {
return kContextSize[mode];
}
static BROTLI_INLINE uint8_t Context(uint8_t prev_byte, uint8_t prev_byte2,
uint8_t prev_byte3, int mode) {
switch (mode) {
case CONTEXT_IS_ZERO:
return prev_byte == 0 ? 0 : 1;
case CONTEXT_SIGNED_2BIT:
return kSigned2BitContextLookup[prev_byte];
case CONTEXT_SIGNED_3BIT:
return kSigned3BitContextLookup[prev_byte];
case CONTEXT_SIGNED_4BIT:
return kSigned4BitContextLookup[prev_byte];
case CONTEXT_SIGNED_MIXED_3BYTE:
return ((kSigned3BitContextLookup[prev_byte] << 3) +
(kSigned2BitContextLookup[prev_byte2] << 1) +
(prev_byte3 == 0 ? 0 : 1));
default:
return prev_byte >> mode;
}
}
#endif // BROTLI_DEC_CONTEXT_H_

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "./bit_reader.h"
#include "./context.h"
#include "./decode.h"
#include "./huffman.h"
#include "./prefix.h"
#include "./safe_malloc.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#ifdef BROTLI_DECODE_DEBUG
#define BROTLI_LOG_UINT(name) \
printf("[%s] %s = %zd\n", __func__, #name, (size_t)name)
#define BROTLI_LOG_ARRAY_INDEX(array_name, idx) \
printf("[%s] %s[%zd] = %zd\n", __func__, #array_name, \
(size_t)idx, (size_t)array_name[idx])
#else
#define BROTLI_LOG_UINT(name)
#define BROTLI_LOG_ARRAY_INDEX(array_name, idx)
#endif
static const int kDefaultCodeLength = 8;
static const int kCodeLengthLiterals = 16;
static const int kCodeLengthRepeatCode = 16;
static const int kCodeLengthExtraBits[3] = { 2, 3, 7 };
static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 };
static const int kNumLiteralCodes = 256;
static const int kNumInsertAndCopyCodes = 704;
static const int kNumBlockLengthCodes = 26;
#define CODE_LENGTH_CODES 19
static const uint8_t kCodeLengthCodeOrder[CODE_LENGTH_CODES] = {
17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
};
#define NUM_DISTANCE_SHORT_CODES 16
static const int kDistanceShortCodeIndexOffset[NUM_DISTANCE_SHORT_CODES] = {
3, 2, 1, 0, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2
};
static const int kDistanceShortCodeValueOffset[NUM_DISTANCE_SHORT_CODES] = {
0, 0, 0, 0, -1, 1, -2, 2, -3, 3, -1, 1, -2, 2, -3, 3
};
static int DecodeSize(BrotliBitReader* br, size_t* len) {
int size_bytes = BrotliReadBits(br, 3);
*len = 0;
int i = 0;
for (; i < size_bytes; ++i) {
*len |= BrotliReadBits(br, 8) << (i * 8);
}
return !br->error_;
}
static int DecodeMetaBlockLength(int input_size_bits,
size_t remaining_length,
BrotliBitReader* br,
size_t* meta_block_length) {
if (BrotliReadBits(br, 1)) {
*meta_block_length = remaining_length;
return 1;
}
*meta_block_length = 0;
int shift = 0;
while (input_size_bits > 0) {
*meta_block_length |= BrotliReadBits(br, 8) << shift;
input_size_bits -= 8;
shift += 8;
}
if (input_size_bits > 0) {
*meta_block_length |= BrotliReadBits(br, input_size_bits) << shift;
}
++(*meta_block_length);
return !br->error_;
}
// Decodes the next Huffman code from bit-stream.
// FillBitWindow(br) needs to be called at minimum every second call
// to ReadSymbol, in order to pre-fetch enough bits.
static BROTLI_INLINE int ReadSymbol(const HuffmanTree* tree,
BrotliBitReader* br) {
if (tree->fixed_bit_length_ > 0) {
return BrotliReadBits(br, tree->fixed_bit_length_);
}
const HuffmanTreeNode* node = tree->root_;
uint32_t bits = BrotliPrefetchBits(br);
int bitpos = br->bit_pos_;
// Check if we find the bit combination from the Huffman lookup table.
const int lut_ix = bits & (HUFF_LUT - 1);
const int lut_bits = tree->lut_bits_[lut_ix];
if (lut_bits <= HUFF_LUT_BITS) {
BrotliSetBitPos(br, bitpos + lut_bits);
return tree->lut_symbol_[lut_ix];
}
node += tree->lut_jump_[lut_ix];
bitpos += HUFF_LUT_BITS;
bits >>= HUFF_LUT_BITS;
// Decode the value from a binary tree.
assert(node != NULL);
do {
node = HuffmanTreeNextNode(node, bits & 1);
bits >>= 1;
++bitpos;
} while (HuffmanTreeNodeIsNotLeaf(node));
BrotliSetBitPos(br, bitpos);
return node->symbol_;
}
static void PrintIntVector(const int* v, int len) {
while (len-- > 0) printf(" %d", *v++);
printf("\n");
}
static int ReadHuffmanCodeLengths(
const int* code_length_code_lengths,
int num_symbols, int* code_lengths,
BrotliBitReader* br) {
int ok = 0;
int symbol;
int max_symbol;
int prev_code_len = kDefaultCodeLength;
HuffmanTree tree;
if (!HuffmanTreeBuildImplicit(&tree, code_length_code_lengths,
CODE_LENGTH_CODES)) {
printf("[ReadHuffmanCodeLengths] Building code length tree failed: ");
PrintIntVector(code_length_code_lengths, CODE_LENGTH_CODES);
return 0;
}
int use_length = BrotliReadBits(br, 1);
BROTLI_LOG_UINT(use_length);
if (use_length) {
const int length_nbits = 2 + 2 * BrotliReadBits(br, 3);
max_symbol = 2 + BrotliReadBits(br, length_nbits);
BROTLI_LOG_UINT(length_nbits);
if (max_symbol > num_symbols) {
printf("[ReadHuffmanCodeLengths] max_symbol > num_symbols (%d vs %d)\n",
max_symbol, num_symbols);
goto End;
}
} else {
max_symbol = num_symbols;
}
BROTLI_LOG_UINT(max_symbol);
symbol = 0;
while (symbol < num_symbols) {
int code_len;
if (max_symbol-- == 0) break;
BrotliFillBitWindow(br);
code_len = ReadSymbol(&tree, br);
BROTLI_LOG_UINT(symbol);
BROTLI_LOG_UINT(code_len);
if (code_len < kCodeLengthLiterals) {
code_lengths[symbol++] = code_len;
if (code_len != 0) prev_code_len = code_len;
} else {
const int use_prev = (code_len == kCodeLengthRepeatCode);
const int slot = code_len - kCodeLengthLiterals;
const int extra_bits = kCodeLengthExtraBits[slot];
const int repeat_offset = kCodeLengthRepeatOffsets[slot];
const int length = use_prev ? prev_code_len : 0;
int repeat = BrotliReadBits(br, extra_bits) + repeat_offset;
BROTLI_LOG_UINT(repeat);
BROTLI_LOG_UINT(length);
if (symbol + repeat > num_symbols) {
printf("[ReadHuffmanCodeLengths] symbol + repeat > num_symbols "
"(%d + %d vs %d)\n", symbol, repeat, num_symbols);
goto End;
} else {
while (repeat-- > 0) {
code_lengths[symbol++] = length;
}
}
}
}
while (symbol < num_symbols) code_lengths[symbol++] = 0;
ok = 1;
End:
HuffmanTreeRelease(&tree);
return ok;
}
static const int64_t kUnitInterval = 1LL<<30;
static int RepairHuffmanCodeLengths(int num_symbols, int* code_lengths) {
int i;
int64_t space = kUnitInterval;
int max_length = 0;
for(i = 0; i < num_symbols; i++)
if (code_lengths[i] != 0) {
if (code_lengths[i] > max_length)
max_length = code_lengths[i];
space -= kUnitInterval >> code_lengths[i];
}
// The code which contains one symbol of length one cannot be made optimal.
if (max_length == 1)
return 1;
if (space < 0) {
int count_longest = 0;
for(i = 0; i < num_symbols; i++) {
if (code_lengths[i] == max_length)
count_longest++;
}
// Substitute all longest codes with sufficiently longer ones, so that all
// code words fit into the unit interval. Leftover space will be
// redistributed later.
space += count_longest * (kUnitInterval >> max_length);
if (space < 0)
return 0;
int new_length = max_length;
while (space < count_longest * (kUnitInterval >> new_length))
new_length++;
space -= count_longest * (kUnitInterval >> new_length);
for(i = 0; i < num_symbols; i++) {
if (code_lengths[i] == max_length)
code_lengths[i] = new_length;
}
}
while (space > 0) {
// Redistribute leftover space in an approximation of a uniform fashion.
for(i = 0; i < num_symbols; i++) {
if (code_lengths[i] > 1 && space >= (kUnitInterval >> code_lengths[i])) {
space -= kUnitInterval >> code_lengths[i];
code_lengths[i]--;
}
if (space == 0)
break;
}
}
return 1;
}
static int ReadHuffmanCode(int alphabet_size,
HuffmanTree* tree,
BrotliBitReader* br) {
int ok = 0;
const int simple_code = BrotliReadBits(br, 1);
BROTLI_LOG_UINT(simple_code);
if (simple_code) { // Read symbols, codes & code lengths directly.
int symbols[2] = { 0 };
int codes[2];
int code_lengths[2];
const int num_symbols = BrotliReadBits(br, 1) + 1;
const int first_symbol_len_code = BrotliReadBits(br, 1);
// The first code is either 1 bit or 8 bit code.
symbols[0] = BrotliReadBits(br, (first_symbol_len_code == 0) ? 1 : 8);
codes[0] = 0;
code_lengths[0] = num_symbols - 1;
// The second code (if present), is always 8 bit long.
if (num_symbols == 2) {
symbols[1] = BrotliReadBits(br, 8);
codes[1] = 1;
code_lengths[1] = num_symbols - 1;
}
BROTLI_LOG_UINT(num_symbols);
BROTLI_LOG_UINT(first_symbol_len_code);
BROTLI_LOG_UINT(symbols[0]);
BROTLI_LOG_UINT(symbols[1]);
ok = HuffmanTreeBuildExplicit(tree, code_lengths, codes, symbols,
alphabet_size, num_symbols);
if (!ok) {
printf("[ReadHuffmanCode] HuffmanTreeBuildExplicit failed: ");
PrintIntVector(code_lengths, num_symbols);
}
} else { // Decode Huffman-coded code lengths.
int* code_lengths = NULL;
int i;
int code_length_code_lengths[CODE_LENGTH_CODES] = { 0 };
const int num_codes = BrotliReadBits(br, 4) + 4;
BROTLI_LOG_UINT(num_codes);
if (num_codes > CODE_LENGTH_CODES) {
return 0;
}
code_lengths =
(int*)BrotliSafeMalloc((uint64_t)alphabet_size, sizeof(*code_lengths));
if (code_lengths == NULL) {
return 0;
}
for (i = 0; i < num_codes; ++i) {
int code_len_idx = kCodeLengthCodeOrder[i];
code_length_code_lengths[code_len_idx] = BrotliReadBits(br, 3);
BROTLI_LOG_ARRAY_INDEX(code_length_code_lengths, code_len_idx);
}
ok = ReadHuffmanCodeLengths(code_length_code_lengths, alphabet_size,
code_lengths, br) &&
RepairHuffmanCodeLengths(alphabet_size, code_lengths);
if (ok) {
ok = HuffmanTreeBuildImplicit(tree, code_lengths, alphabet_size);
if (!ok) {
printf("[ReadHuffmanCode] HuffmanTreeBuildImplicit failed: ");
PrintIntVector(code_lengths, alphabet_size);
}
}
free(code_lengths);
}
ok = ok && !br->error_;
if (!ok) {
return 0;
}
return 1;
}
static int ReadCopyDistance(const HuffmanTree* tree,
int num_direct_codes,
int postfix_bits,
uint32_t postfix_mask,
BrotliBitReader* br) {
BrotliFillBitWindow(br);
int code = ReadSymbol(tree, br);
if (code < num_direct_codes) {
return code;
}
code -= num_direct_codes;
int postfix = code & postfix_mask;
code >>= postfix_bits;
int nbits = (code >> 1) + 1;
int offset = ((2 + (code & 1)) << nbits) - 4;
return (num_direct_codes +
((offset + BrotliReadBits(br, nbits)) << postfix_bits) +
postfix);
}
static int ReadBlockLength(const HuffmanTree* tree, BrotliBitReader* br) {
BrotliFillBitWindow(br);
int code = ReadSymbol(tree, br);
int nbits = kBlockLengthPrefixCode[code].nbits;
return kBlockLengthPrefixCode[code].offset + BrotliReadBits(br, nbits);
}
static void ReadInsertAndCopy(const HuffmanTree* tree,
int* insert_len,
int* copy_len,
int* copy_dist,
BrotliBitReader* br) {
BrotliFillBitWindow(br);
int code = ReadSymbol(tree, br);
int range_idx = code >> 6;
if (range_idx >= 2) {
range_idx -= 2;
*copy_dist = -1;
} else {
*copy_dist = 0;
}
int insert_code = (kInsertRangeLut[range_idx] << 3) + ((code >> 3) & 7);
int copy_code = (kCopyRangeLut[range_idx] << 3) + (code & 7);
*insert_len =
kInsertLengthPrefixCode[insert_code].offset +
BrotliReadBits(br, kInsertLengthPrefixCode[insert_code].nbits);
*copy_len =
kCopyLengthPrefixCode[copy_code].offset +
BrotliReadBits(br, kCopyLengthPrefixCode[copy_code].nbits);
}
static int TranslateShortCodes(int code, int* ringbuffer, size_t* index) {
int val;
if (code < NUM_DISTANCE_SHORT_CODES) {
val = code;
int index_offset = kDistanceShortCodeIndexOffset[val];
int value_offset = kDistanceShortCodeValueOffset[val];
val = ringbuffer[(*index + index_offset) & 3] + value_offset;
} else {
val = code - NUM_DISTANCE_SHORT_CODES + 1;
}
if (code > 0) {
ringbuffer[*index & 3] = val;
++(*index);
}
return val;
}
static void MoveToFront(uint8_t* v, uint8_t index) {
uint8_t value = v[index];
uint8_t i = index;
for (; i; --i) v[i] = v[i - 1];
v[0] = value;
}
static void InverseMoveToFrontTransform(uint8_t* v, int v_len) {
uint8_t mtf[256];
int i;
for (i = 0; i < 256; ++i) {
mtf[i] = i;
}
for (i = 0; i < v_len; ++i) {
uint8_t index = v[i];
v[i] = mtf[index];
if (index) MoveToFront(mtf, index);
}
}
// Contains a collection of huffman trees with the same alphabet size.
typedef struct {
int alphabet_size;
int num_htrees;
HuffmanTree* htrees;
} HuffmanTreeGroup;
void HuffmanTreeGroupInit(HuffmanTreeGroup* group, int alphabet_size,
int ntrees) {
group->alphabet_size = alphabet_size;
group->num_htrees = ntrees;
group->htrees = (HuffmanTree*)malloc(sizeof(HuffmanTree) * ntrees);
}
void HuffmanTreeGroupRelease(HuffmanTreeGroup* group) {
int i;
for (i = 0; i < group->num_htrees; ++i) {
HuffmanTreeRelease(&group->htrees[i]);
}
free(group->htrees);
}
int HuffmanTreeGroupDecode(HuffmanTreeGroup* group, BrotliBitReader* br) {
int i;
for (i = 0; i < group->num_htrees; ++i) {
ReadHuffmanCode(group->alphabet_size, &group->htrees[i], br);
}
return 1;
}
int DecodeContextMap(int num_block_types,
int stream_type,
int* context_mode,
int* contexts_per_block,
int* num_htrees,
uint8_t** context_map,
BrotliBitReader* br) {
int use_context = BrotliReadBits(br, 1);
if (!use_context) {
*context_mode = 0;
*contexts_per_block = 1;
*context_map = NULL;
*num_htrees = num_block_types;
return 1;
}
switch (stream_type) {
case 0:
*context_mode = BrotliReadBits(br, 4);
*contexts_per_block = NumContexts(*context_mode);
break;
case 2:
*context_mode = 1;
*contexts_per_block = 4;
break;
}
int context_map_size = *contexts_per_block * num_block_types;
*num_htrees = BrotliReadBits(br, 8) + 1;
BROTLI_LOG_UINT(*context_mode);
BROTLI_LOG_UINT(context_map_size);
BROTLI_LOG_UINT(*num_htrees);
*context_map = (uint8_t*)malloc(context_map_size);
if (*num_htrees <= 1) {
memset(*context_map, 0, context_map_size);
return 1;
}
int i;
if (*num_htrees == context_map_size) {
for (i = 0; i < context_map_size; ++i) {
(*context_map)[i] = i;
}
return 1;
}
int use_rle_for_zeros = BrotliReadBits(br, 1);
int max_run_length_prefix = 0;
if (use_rle_for_zeros) {
max_run_length_prefix = BrotliReadBits(br, 4) + 1;
}
HuffmanTree tree_index_htree;
ReadHuffmanCode(*num_htrees + max_run_length_prefix,
&tree_index_htree, br);
if (use_rle_for_zeros) {
for (i = 0; i < context_map_size;) {
BrotliFillBitWindow(br);
int code = ReadSymbol(&tree_index_htree, br);
if (code == 0) {
(*context_map)[i] = 0;
++i;
} else if (code <= max_run_length_prefix) {
int reps = 1 + (1 << code) + BrotliReadBits(br, code);
while (--reps) {
(*context_map)[i] = 0;
++i;
}
} else {
(*context_map)[i] = code - max_run_length_prefix;
++i;
}
}
} else {
for (i = 0; i < context_map_size; ++i) {
BrotliFillBitWindow(br);
(*context_map)[i] = ReadSymbol(&tree_index_htree, br);
}
}
HuffmanTreeRelease(&tree_index_htree);
if (BrotliReadBits(br, 1)) {
InverseMoveToFrontTransform(*context_map, context_map_size);
}
return 1;
}
static BROTLI_INLINE void DecodeBlockType(const HuffmanTree* trees,
int tree_type,
int* block_types,
int* ringbuffers,
size_t* indexes,
BrotliBitReader* br) {
int* ringbuffer = ringbuffers + tree_type * 2;
size_t* index = indexes + tree_type;
int type_code = ReadSymbol(trees + tree_type, br);
int block_type;
if (type_code == 0) {
block_type = ringbuffer[*index & 1];
} else if (type_code == 1) {
block_type = ringbuffer[(*index - 1) & 1] + 1;
} else {
block_type = type_code - 2;
}
block_types[tree_type] = block_type;
ringbuffer[(*index) & 1] = block_type;
++(*index);
}
int BrotliDecompressedSize(size_t encoded_size,
const uint8_t* encoded_buffer,
size_t* decoded_size) {
BrotliBitReader br;
BrotliInitBitReader(&br, encoded_buffer, encoded_size);
return DecodeSize(&br, decoded_size);
}
int BrotliDecompressBuffer(size_t encoded_size,
const uint8_t* encoded_buffer,
size_t* decoded_size,
uint8_t* decoded_buffer) {
BrotliBitReader br;
BrotliInitBitReader(&br, encoded_buffer, encoded_size);
int ok = DecodeSize(&br, decoded_size);
if (!ok) return 0;
if (*decoded_size == 0) {
return 1;
}
size_t n = *decoded_size;
int input_size_bits = (n == (n &~ (n - 1))) ? -1 : 0;
while (n) {
++input_size_bits;
n >>= 1;
}
BROTLI_LOG_UINT(*decoded_size);
BROTLI_LOG_UINT(input_size_bits);
int i;
size_t pos = 0;
const size_t end = *decoded_size;
uint8_t* data = decoded_buffer;
// This ring buffer holds a few past copy distances that will be used by
// some special distance codes.
int dist_rb[4] = { 4, 11, 15, 16 };
size_t dist_rb_idx = 0;
HuffmanTreeGroup hgroup[3];
while (pos < end && ok) {
BROTLI_LOG_UINT(pos);
size_t meta_block_len = 0;
if (!DecodeMetaBlockLength(input_size_bits, end - pos,
&br, &meta_block_len)) {
printf("Could not decode meta-block length.\n");
ok = 0;
goto End;
}
BROTLI_LOG_UINT(meta_block_len);
size_t meta_block_end = pos + meta_block_len;
size_t block_length[3] = { 0 };
int block_type[3] = { 0 };
int num_block_types[3] = { 0 };
int block_type_rb[6] = { 0, 1, 0, 1, 0, 1 };
size_t block_type_rb_index[3] = { 0 };
HuffmanTree block_type_trees[3];
HuffmanTree block_len_trees[3];
for (i = 0; i < 3; ++i) {
block_type_trees[i].root_ = NULL;
block_len_trees[i].root_ = NULL;
if (BrotliReadBits(&br, 1)) {
num_block_types[i] = BrotliReadBits(&br, 8) + 1;
ReadHuffmanCode(num_block_types[i] + 2, &block_type_trees[i], &br);
ReadHuffmanCode(kNumBlockLengthCodes, &block_len_trees[i], &br);
block_length[i] = ReadBlockLength(&block_len_trees[i], &br);
block_type_rb_index[i] = 1;
} else {
num_block_types[i] = 1;
block_length[i] = meta_block_len;
}
}
BROTLI_LOG_UINT(num_block_types[0]);
BROTLI_LOG_UINT(num_block_types[1]);
BROTLI_LOG_UINT(num_block_types[2]);
BROTLI_LOG_UINT(block_length[0]);
BROTLI_LOG_UINT(block_length[1]);
BROTLI_LOG_UINT(block_length[2]);
int distance_postfix_bits = BrotliReadBits(&br, 2);
int num_direct_distance_codes =
NUM_DISTANCE_SHORT_CODES +
(BrotliReadBits(&br, 4) << distance_postfix_bits);
uint32_t distance_postfix_mask = (1 << distance_postfix_bits) - 1;
int num_distance_codes = (num_direct_distance_codes +
(48 << distance_postfix_bits));
BROTLI_LOG_UINT(num_direct_distance_codes);
BROTLI_LOG_UINT(distance_postfix_bits);
uint8_t* context_map;
int context_mode;
int contexts_per_block;
int num_literal_htrees;
DecodeContextMap(num_block_types[0], 0, &context_mode, &contexts_per_block,
&num_literal_htrees, &context_map, &br);
uint8_t* dist_context_map;
int dist_context_mode;
int dist_contexts_per_block;
int num_dist_htrees;
DecodeContextMap(num_block_types[2], 2, &dist_context_mode,
&dist_contexts_per_block,
&num_dist_htrees, &dist_context_map, &br);
HuffmanTreeGroupInit(&hgroup[0], kNumLiteralCodes, num_literal_htrees);
HuffmanTreeGroupInit(&hgroup[1], kNumInsertAndCopyCodes,
num_block_types[1]);
HuffmanTreeGroupInit(&hgroup[2], num_distance_codes, num_dist_htrees);
for (i = 0; i < 3; ++i) {
HuffmanTreeGroupDecode(&hgroup[i], &br);
}
HuffmanTree* literal_htrees = hgroup[0].htrees;
int context_offset = 0;
uint8_t* context_map_slice = context_map;
uint8_t literal_htree_index = 0;
int dist_context_offset = 0;
uint8_t* dist_context_map_slice = dist_context_map;
uint8_t dist_htree_index = 0;
while (pos < meta_block_end) {
if (block_length[1] == 0) {
DecodeBlockType(block_type_trees, 1, block_type, block_type_rb,
block_type_rb_index, &br);
block_length[1] = ReadBlockLength(&block_len_trees[1], &br);
}
--block_length[1];
int insert_length;
int copy_length;
int distance_code;
ReadInsertAndCopy(&hgroup[1].htrees[block_type[1]],
&insert_length, &copy_length, &distance_code, &br);
BROTLI_LOG_UINT(insert_length);
BROTLI_LOG_UINT(copy_length);
BROTLI_LOG_UINT(distance_code);
int j;
for (j = 0; j < insert_length; ++j) {
if (block_length[0] == 0) {
DecodeBlockType(block_type_trees, 0, block_type, block_type_rb,
block_type_rb_index, &br);
block_length[0] = ReadBlockLength(&block_len_trees[0], &br);
literal_htree_index = block_type[0];
context_offset = block_type[0] * contexts_per_block;
context_map_slice = context_map + context_offset;
}
--block_length[0];
BrotliFillBitWindow(&br);
// Figure out htree
if (contexts_per_block > 1) {
uint8_t prev_byte = pos > 0 ? data[pos - 1] : 0;
uint8_t prev_byte2 = pos > 1 ? data[pos - 2] : 0;
uint8_t prev_byte3 = pos > 2 ? data[pos - 3] : 0;
uint8_t context = Context(prev_byte, prev_byte2, prev_byte3,
context_mode);
BROTLI_LOG_UINT(context);
literal_htree_index = context_map_slice[context];
}
data[pos] = ReadSymbol(&literal_htrees[literal_htree_index], &br);
BROTLI_LOG_UINT(literal_htree_index);
BROTLI_LOG_ARRAY_INDEX(data, pos);
++pos;
}
if (br.error_) {
printf("Read error after decoding literal sequence.\n");
ok = 0;
goto End;
}
if (pos == meta_block_end) break;
if (distance_code < 0) {
if (block_length[2] == 0) {
DecodeBlockType(block_type_trees, 2, block_type, block_type_rb,
block_type_rb_index, &br);
block_length[2] = ReadBlockLength(&block_len_trees[2], &br);
dist_htree_index = block_type[2];
dist_context_offset = block_type[2] * dist_contexts_per_block;
dist_context_map_slice = dist_context_map + dist_context_offset;
}
--block_length[2];
if (dist_contexts_per_block > 1) {
uint8_t context = copy_length > 4 ? 3 : copy_length - 2;
dist_htree_index = dist_context_map_slice[context];
}
distance_code = ReadCopyDistance(&hgroup[2].htrees[dist_htree_index],
num_direct_distance_codes,
distance_postfix_bits,
distance_postfix_mask,
&br);
if (br.error_) {
printf("Could not read copy distance.\n");
ok = 0;
goto End;
}
}
// Convert the distance code to the actual distance by possibly looking
// up past distnaces from the ringbuffer.
int dist = TranslateShortCodes(distance_code, dist_rb, &dist_rb_idx);
BROTLI_LOG_UINT(dist);
// Do the actual copy if it is valid.
if (pos >= dist && pos + copy_length <= end) {
int j;
for (j = 0; j < copy_length; ++j) {
data[pos + j] = data[pos + j - dist];
}
pos += copy_length;
} else {
printf("Invalid backward reference. pos: %zd dist: %d "
"len: %d end:%zd\n",
pos, dist, copy_length, end);
ok = 0;
goto End;
}
}
End:
free(context_map);
free(dist_context_map);
for (i = 0; i < 3; ++i) {
HuffmanTreeGroupRelease(&hgroup[i]);
HuffmanTreeRelease(&block_type_trees[i]);
HuffmanTreeRelease(&block_len_trees[i]);
}
}
return ok;
}
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// API for Brotli decompression
#ifndef BROTLI_DEC_DECODE_H_
#define BROTLI_DEC_DECODE_H_
#include "./types.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
// Sets *decoded_size to the decompressed size of the given encoded stream.
// Returns 1 on success, 0 on failure.
int BrotliDecompressedSize(size_t encoded_size,
const uint8_t* encoded_buffer,
size_t* decoded_size);
// Decompresses the data in encoded_buffer into decoded_buffer, and sets
// *decoded_size to the decompressed length.
// Returns 0 if there was either a bit stream error or memory allocation error,
// and 1 otherwise.
// If decoded size is zero, returns 1 and keeps decoded_buffer unchanged.
int BrotliDecompressBuffer(size_t encoded_size,
const uint8_t* encoded_buffer,
size_t* decoded_size,
uint8_t* decoded_buffer);
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif
#endif // BROTLI_DEC_DECODE_H_

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Utilities for building and looking up Huffman trees.
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "./huffman.h"
#include "./safe_malloc.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
// Uncomment the following to use look-up table for ReverseBits()
// (might be faster on some platform)
// #define USE_LUT_REVERSE_BITS
#define NON_EXISTENT_SYMBOL (-1)
#define MAX_ALLOWED_CODE_LENGTH 15
static void TreeNodeInit(HuffmanTreeNode* const node) {
node->children_ = -1; // means: 'unassigned so far'
}
static int NodeIsEmpty(const HuffmanTreeNode* const node) {
return (node->children_ < 0);
}
static int IsFull(const HuffmanTree* const tree) {
return (tree->num_nodes_ == tree->max_nodes_);
}
static void AssignChildren(HuffmanTree* const tree,
HuffmanTreeNode* const node) {
HuffmanTreeNode* const children = tree->root_ + tree->num_nodes_;
node->children_ = (int)(children - node);
assert(children - node == (int)(children - node));
tree->num_nodes_ += 2;
TreeNodeInit(children + 0);
TreeNodeInit(children + 1);
}
static int TreeInit(HuffmanTree* const tree, int num_leaves) {
assert(tree != NULL);
tree->fixed_bit_length_ = 0;
if (num_leaves == 0) return 0;
// We allocate maximum possible nodes in the tree at once.
// Note that a Huffman tree is a full binary tree; and in a full binary tree
// with L leaves, the total number of nodes N = 2 * L - 1.
tree->max_nodes_ = 2 * num_leaves - 1;
assert(tree->max_nodes_ < (1 << 16)); // limit for the lut_jump_ table
tree->root_ = (HuffmanTreeNode*)BrotliSafeMalloc((uint64_t)tree->max_nodes_,
sizeof(*tree->root_));
if (tree->root_ == NULL) return 0;
TreeNodeInit(tree->root_); // Initialize root.
tree->num_nodes_ = 1;
memset(tree->lut_bits_, 255, sizeof(tree->lut_bits_));
memset(tree->lut_jump_, 0, sizeof(tree->lut_jump_));
return 1;
}
void HuffmanTreeRelease(HuffmanTree* const tree) {
if (tree != NULL) {
free(tree->root_);
tree->root_ = NULL;
tree->max_nodes_ = 0;
tree->num_nodes_ = 0;
}
}
int HuffmanCodeLengthsToCodes(const int* const code_lengths,
int code_lengths_size, int* const huff_codes) {
int symbol;
int code_len;
int code_length_hist[MAX_ALLOWED_CODE_LENGTH + 1] = { 0 };
int curr_code;
int next_codes[MAX_ALLOWED_CODE_LENGTH + 1] = { 0 };
int max_code_length = 0;
assert(code_lengths != NULL);
assert(code_lengths_size > 0);
assert(huff_codes != NULL);
// Calculate max code length.
for (symbol = 0; symbol < code_lengths_size; ++symbol) {
if (code_lengths[symbol] > max_code_length) {
max_code_length = code_lengths[symbol];
}
}
if (max_code_length > MAX_ALLOWED_CODE_LENGTH) return 0;
// Calculate code length histogram.
for (symbol = 0; symbol < code_lengths_size; ++symbol) {
++code_length_hist[code_lengths[symbol]];
}
code_length_hist[0] = 0;
// Calculate the initial values of 'next_codes' for each code length.
// next_codes[code_len] denotes the code to be assigned to the next symbol
// of code length 'code_len'.
curr_code = 0;
next_codes[0] = -1; // Unused, as code length = 0 implies code doesn't exist.
for (code_len = 1; code_len <= max_code_length; ++code_len) {
curr_code = (curr_code + code_length_hist[code_len - 1]) << 1;
next_codes[code_len] = curr_code;
}
// Get symbols.
for (symbol = 0; symbol < code_lengths_size; ++symbol) {
if (code_lengths[symbol] > 0) {
huff_codes[symbol] = next_codes[code_lengths[symbol]]++;
} else {
huff_codes[symbol] = NON_EXISTENT_SYMBOL;
}
}
return 1;
}
#ifndef USE_LUT_REVERSE_BITS
static int ReverseBitsShort(int bits, int num_bits) {
int retval = 0;
int i;
assert(num_bits <= 8); // Not a hard requirement, just for coherency.
for (i = 0; i < num_bits; ++i) {
retval <<= 1;
retval |= bits & 1;
bits >>= 1;
}
return retval;
}
#else
static const uint8_t kReversedBits[16] = { // Pre-reversed 4-bit values.
0x0, 0x8, 0x4, 0xc, 0x2, 0xa, 0x6, 0xe,
0x1, 0x9, 0x5, 0xd, 0x3, 0xb, 0x7, 0xf
};
static int ReverseBitsShort(int bits, int num_bits) {
const uint8_t v = (kReversedBits[bits & 0xf] << 4) | kReversedBits[bits >> 4];
assert(num_bits <= 8);
return v >> (8 - num_bits);
}
#endif
static int TreeAddSymbol(HuffmanTree* const tree,
int symbol, int code, int code_length) {
int step = HUFF_LUT_BITS;
int base_code;
HuffmanTreeNode* node = tree->root_;
const HuffmanTreeNode* const max_node = tree->root_ + tree->max_nodes_;
assert(symbol == (int16_t)symbol);
if (code_length <= HUFF_LUT_BITS) {
int i;
base_code = ReverseBitsShort(code, code_length);
for (i = 0; i < (1 << (HUFF_LUT_BITS - code_length)); ++i) {
const int idx = base_code | (i << code_length);
tree->lut_symbol_[idx] = (int16_t)symbol;
tree->lut_bits_[idx] = code_length;
}
} else {
base_code = ReverseBitsShort((code >> (code_length - HUFF_LUT_BITS)),
HUFF_LUT_BITS);
}
while (code_length-- > 0) {
if (node >= max_node) {
return 0;
}
if (NodeIsEmpty(node)) {
if (IsFull(tree)) return 0; // error: too many symbols.
AssignChildren(tree, node);
} else if (!HuffmanTreeNodeIsNotLeaf(node)) {
return 0; // leaf is already occupied.
}
node += node->children_ + ((code >> code_length) & 1);
if (--step == 0) {
tree->lut_jump_[base_code] = (int16_t)(node - tree->root_);
}
}
if (NodeIsEmpty(node)) {
node->children_ = 0; // turn newly created node into a leaf.
} else if (HuffmanTreeNodeIsNotLeaf(node)) {
return 0; // trying to assign a symbol to already used code.
}
node->symbol_ = symbol; // Add symbol in this node.
return 1;
}
int HuffmanTreeBuildImplicit(HuffmanTree* const tree,
const int* const code_lengths,
int code_lengths_size) {
int symbol;
int num_symbols = 0;
int root_symbol = 0;
assert(tree != NULL);
assert(code_lengths != NULL);
// Find out number of symbols and the root symbol.
for (symbol = 0; symbol < code_lengths_size; ++symbol) {
if (code_lengths[symbol] > 0) {
// Note: code length = 0 indicates non-existent symbol.
++num_symbols;
root_symbol = symbol;
}
}
// Initialize the tree. Will fail for num_symbols = 0
if (!TreeInit(tree, num_symbols)) return 0;
// Build tree.
if (num_symbols == 1) { // Trivial case.
const int max_symbol = code_lengths_size;
if (root_symbol < 0 || root_symbol >= max_symbol) {
HuffmanTreeRelease(tree);
return 0;
}
return TreeAddSymbol(tree, root_symbol, 0, 0);
} else { // Normal case.
int ok = 0;
// Get Huffman codes from the code lengths.
int* const codes =
(int*)BrotliSafeMalloc((uint64_t)code_lengths_size, sizeof(*codes));
if (codes == NULL) goto End;
if (!HuffmanCodeLengthsToCodes(code_lengths, code_lengths_size, codes)) {
goto End;
}
// Add symbols one-by-one.
for (symbol = 0; symbol < code_lengths_size; ++symbol) {
if (code_lengths[symbol] > 0) {
if (!TreeAddSymbol(tree, symbol, codes[symbol], code_lengths[symbol])) {
goto End;
}
}
}
ok = 1;
End:
free(codes);
ok = ok && IsFull(tree);
if (!ok) HuffmanTreeRelease(tree);
return ok;
}
}
int HuffmanTreeBuildExplicit(HuffmanTree* const tree,
const int* const code_lengths,
const int* const codes,
const int* const symbols, int max_symbol,
int num_symbols) {
int ok = 0;
int i;
assert(tree != NULL);
assert(code_lengths != NULL);
assert(codes != NULL);
assert(symbols != NULL);
// Initialize the tree. Will fail if num_symbols = 0.
if (!TreeInit(tree, num_symbols)) return 0;
// Add symbols one-by-one.
for (i = 0; i < num_symbols; ++i) {
if (codes[i] != NON_EXISTENT_SYMBOL) {
if (symbols[i] < 0 || symbols[i] >= max_symbol) {
goto End;
}
if (!TreeAddSymbol(tree, symbols[i], codes[i], code_lengths[i])) {
goto End;
}
}
}
ok = 1;
End:
ok = ok && IsFull(tree);
if (!ok) HuffmanTreeRelease(tree);
return ok;
}
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Utilities for building and looking up Huffman trees.
#ifndef BROTLI_DEC_HUFFMAN_H_
#define BROTLI_DEC_HUFFMAN_H_
#include <assert.h>
#include "./types.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
// A node of a Huffman tree.
typedef struct {
int symbol_;
int children_; // delta offset to both children (contiguous) or 0 if leaf.
} HuffmanTreeNode;
// Huffman Tree.
#define HUFF_LUT_BITS 7
#define HUFF_LUT (1U << HUFF_LUT_BITS)
typedef struct HuffmanTree HuffmanTree;
struct HuffmanTree {
// Fast lookup for short bit lengths.
uint8_t lut_bits_[HUFF_LUT];
int16_t lut_symbol_[HUFF_LUT];
int16_t lut_jump_[HUFF_LUT];
// Complete tree for lookups.
HuffmanTreeNode* root_; // all the nodes, starting at root.
int max_nodes_; // max number of nodes
int num_nodes_; // number of currently occupied nodes
int fixed_bit_length_; // If non-zero, uses fixed length coding
};
// Returns true if the given node is not a leaf of the Huffman tree.
static BROTLI_INLINE int HuffmanTreeNodeIsNotLeaf(
const HuffmanTreeNode* const node) {
return node->children_;
}
// Go down one level. Most critical function. 'right_child' must be 0 or 1.
static BROTLI_INLINE const HuffmanTreeNode* HuffmanTreeNextNode(
const HuffmanTreeNode* node, int right_child) {
return node + node->children_ + right_child;
}
// Releases the nodes of the Huffman tree.
// Note: It does NOT free 'tree' itself.
void HuffmanTreeRelease(HuffmanTree* const tree);
// Builds Huffman tree assuming code lengths are implicitly in symbol order.
// Returns false in case of error (invalid tree or memory error).
int HuffmanTreeBuildImplicit(HuffmanTree* const tree,
const int* const code_lengths,
int code_lengths_size);
// Build a Huffman tree with explicitly given lists of code lengths, codes
// and symbols. Verifies that all symbols added are smaller than max_symbol.
// Returns false in case of an invalid symbol, invalid tree or memory error.
int HuffmanTreeBuildExplicit(HuffmanTree* const tree,
const int* const code_lengths,
const int* const codes,
const int* const symbols, int max_symbol,
int num_symbols);
// Utility: converts Huffman code lengths to corresponding Huffman codes.
// 'huff_codes' should be pre-allocated.
// Returns false in case of error (memory allocation, invalid codes).
int HuffmanCodeLengthsToCodes(const int* const code_lengths,
int code_lengths_size, int* const huff_codes);
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif
#endif // BROTLI_DEC_HUFFMAN_H_

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Lookup tables to map prefix codes to value ranges. This is used during
// decoding of the block lengths, literal insertion lengths and copy lengths.
#ifndef BROTLI_DEC_PREFIX_H_
#define BROTLI_DEC_PREFIX_H_
// Represents the range of values belonging to a prefix code:
// [offset, offset + 2^nbits)
struct PrefixCodeRange {
int offset;
int nbits;
};
static const struct PrefixCodeRange kBlockLengthPrefixCode[] = {
{ 1, 2}, { 5, 2}, { 9, 2}, { 13, 2},
{ 17, 3}, { 25, 3}, { 33, 3}, { 41, 3},
{ 49, 4}, { 65, 4}, { 81, 4}, { 97, 4},
{ 113, 5}, { 145, 5}, { 177, 5}, { 209, 5},
{ 241, 6}, { 305, 6}, { 369, 7}, { 497, 8},
{ 753, 9}, { 1265, 10}, {2289, 11}, {4337, 12},
{8433, 13}, {16625, 24}
};
static const struct PrefixCodeRange kInsertLengthPrefixCode[] = {
{ 0, 0}, { 1, 0}, { 2, 0}, { 3, 0},
{ 4, 0}, { 5, 0}, { 6, 1}, { 8, 1},
{ 10, 2}, { 14, 2}, { 18, 3}, { 26, 3},
{ 34, 4}, { 50, 4}, { 66, 5}, { 98, 5},
{ 130, 6}, { 194, 7}, { 322, 8}, { 578, 9},
{1090, 10}, {2114, 12}, {6210, 14}, {22594, 24},
};
static const struct PrefixCodeRange kCopyLengthPrefixCode[] = {
{ 2, 0}, { 3, 0}, { 4, 0}, { 5, 0},
{ 6, 0}, { 7, 0}, { 8, 0}, { 9, 0},
{ 10, 1}, { 12, 1}, { 14, 2}, { 18, 2},
{ 22, 3}, { 30, 3}, { 38, 4}, { 54, 4},
{ 70, 5}, { 102, 5}, { 134, 6}, { 198, 7},
{326, 8}, { 582, 9}, {1094, 10}, {2118, 24},
};
static const int kInsertAndCopyRangeLut[9] = {
0, 1, 4, 2, 3, 6, 5, 7, 8,
};
static const int kInsertRangeLut[9] = {
0, 0, 1, 1, 0, 2, 1, 2, 2,
};
static const int kCopyRangeLut[9] = {
0, 1, 0, 1, 2, 0, 2, 1, 2,
};
#endif // BROTLI_DEC_PREFIX_H_

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Size-checked memory allocation.
#include <stdlib.h>
#include "./safe_malloc.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
// Returns 0 in case of overflow of nmemb * size.
static int CheckSizeArgumentsOverflow(uint64_t nmemb, size_t size) {
const uint64_t total_size = nmemb * size;
if (nmemb == 0) return 1;
if ((uint64_t)size > BROTLI_MAX_ALLOCABLE_MEMORY / nmemb) return 0;
if (total_size != (size_t)total_size) return 0;
return 1;
}
void* BrotliSafeMalloc(uint64_t nmemb, size_t size) {
if (!CheckSizeArgumentsOverflow(nmemb, size)) return NULL;
assert(nmemb * size > 0);
return malloc((size_t)(nmemb * size));
}
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Size-checked memory allocation.
#ifndef BROTLI_UTILS_UTILS_H_
#define BROTLI_UTILS_UTILS_H_
#include <assert.h>
#include "./types.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
// This is the maximum memory amount that we will ever try to allocate.
#define BROTLI_MAX_ALLOCABLE_MEMORY (1ULL << 40)
// size-checking safe malloc/calloc: verify that the requested size is not too
// large, or return NULL. You don't need to call these for constructs like
// malloc(sizeof(foo)), but only if there's font-dependent size involved
// somewhere (like: malloc(decoded_size * sizeof(*something))). That's why this
// safe malloc() borrows the signature from calloc(), pointing at the dangerous
// underlying multiply involved.
void* BrotliSafeMalloc(uint64_t nmemb, size_t size);
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif
#endif /* BROTLI_UTILS_UTILS_H_ */

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Common types
#ifndef BROTLI_DEC_TYPES_H_
#define BROTLI_DEC_TYPES_H_
#include <stddef.h> // for size_t
#ifndef _MSC_VER
#include <inttypes.h>
#ifdef __STRICT_ANSI__
#define BROTLI_INLINE
#else /* __STRICT_ANSI__ */
#define BROTLI_INLINE inline
#endif
#else
typedef signed char int8_t;
typedef unsigned char uint8_t;
typedef signed short int16_t;
typedef unsigned short uint16_t;
typedef signed int int32_t;
typedef unsigned int uint32_t;
typedef unsigned long long int uint64_t;
typedef long long int int64_t;
#define BROTLI_INLINE __forceinline
#endif /* _MSC_VER */
#endif // BROTLI_DEC_TYPES_H_