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brotli/c/enc/brotli_bit_stream.c
Eugene Kliuchnikov 223d80cfbe
Update (#826) 
* IMPORTANT: decoder: fix potential overflow when input chunk is >2GiB
 * simplify max Huffman table size calculation
 * eliminate symbol duplicates (static arrays in .h files)
 * minor combing in research/ code
2020-08-26 12:32:27 +02:00

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/* Copyright 2014 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
/* Brotli bit stream functions to support the low level format. There are no
compression algorithms here, just the right ordering of bits to match the
specs. */
#include "./brotli_bit_stream.h"
#include <string.h> /* memcpy, memset */
#include "../common/constants.h"
#include "../common/context.h"
#include "../common/platform.h"
#include <brotli/types.h>
#include "./entropy_encode.h"
#include "./entropy_encode_static.h"
#include "./fast_log.h"
#include "./histogram.h"
#include "./memory.h"
#include "./write_bits.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#define MAX_HUFFMAN_TREE_SIZE (2 * BROTLI_NUM_COMMAND_SYMBOLS + 1)
/* The maximum size of Huffman dictionary for distances assuming that
NPOSTFIX = 0 and NDIRECT = 0. */
#define MAX_SIMPLE_DISTANCE_ALPHABET_SIZE \
BROTLI_DISTANCE_ALPHABET_SIZE(0, 0, BROTLI_LARGE_MAX_DISTANCE_BITS)
/* MAX_SIMPLE_DISTANCE_ALPHABET_SIZE == 140 */
static BROTLI_INLINE uint32_t BlockLengthPrefixCode(uint32_t len) {
uint32_t code = (len >= 177) ? (len >= 753 ? 20 : 14) : (len >= 41 ? 7 : 0);
while (code < (BROTLI_NUM_BLOCK_LEN_SYMBOLS - 1) &&
len >= _kBrotliPrefixCodeRanges[code + 1].offset) ++code;
return code;
}
static BROTLI_INLINE void GetBlockLengthPrefixCode(uint32_t len, size_t* code,
uint32_t* n_extra, uint32_t* extra) {
*code = BlockLengthPrefixCode(len);
*n_extra = _kBrotliPrefixCodeRanges[*code].nbits;
*extra = len - _kBrotliPrefixCodeRanges[*code].offset;
}
typedef struct BlockTypeCodeCalculator {
size_t last_type;
size_t second_last_type;
} BlockTypeCodeCalculator;
static void InitBlockTypeCodeCalculator(BlockTypeCodeCalculator* self) {
self->last_type = 1;
self->second_last_type = 0;
}
static BROTLI_INLINE size_t NextBlockTypeCode(
BlockTypeCodeCalculator* calculator, uint8_t type) {
size_t type_code = (type == calculator->last_type + 1) ? 1u :
(type == calculator->second_last_type) ? 0u : type + 2u;
calculator->second_last_type = calculator->last_type;
calculator->last_type = type;
return type_code;
}
/* |nibblesbits| represents the 2 bits to encode MNIBBLES (0-3)
REQUIRES: length > 0
REQUIRES: length <= (1 << 24) */
static void BrotliEncodeMlen(size_t length, uint64_t* bits,
size_t* numbits, uint64_t* nibblesbits) {
size_t lg = (length == 1) ? 1 : Log2FloorNonZero((uint32_t)(length - 1)) + 1;
size_t mnibbles = (lg < 16 ? 16 : (lg + 3)) / 4;
BROTLI_DCHECK(length > 0);
BROTLI_DCHECK(length <= (1 << 24));
BROTLI_DCHECK(lg <= 24);
*nibblesbits = mnibbles - 4;
*numbits = mnibbles * 4;
*bits = length - 1;
}
static BROTLI_INLINE void StoreCommandExtra(
const Command* cmd, size_t* storage_ix, uint8_t* storage) {
uint32_t copylen_code = CommandCopyLenCode(cmd);
uint16_t inscode = GetInsertLengthCode(cmd->insert_len_);
uint16_t copycode = GetCopyLengthCode(copylen_code);
uint32_t insnumextra = GetInsertExtra(inscode);
uint64_t insextraval = cmd->insert_len_ - GetInsertBase(inscode);
uint64_t copyextraval = copylen_code - GetCopyBase(copycode);
uint64_t bits = (copyextraval << insnumextra) | insextraval;
BrotliWriteBits(
insnumextra + GetCopyExtra(copycode), bits, storage_ix, storage);
}
/* Data structure that stores almost everything that is needed to encode each
block switch command. */
typedef struct BlockSplitCode {
BlockTypeCodeCalculator type_code_calculator;
uint8_t type_depths[BROTLI_MAX_BLOCK_TYPE_SYMBOLS];
uint16_t type_bits[BROTLI_MAX_BLOCK_TYPE_SYMBOLS];
uint8_t length_depths[BROTLI_NUM_BLOCK_LEN_SYMBOLS];
uint16_t length_bits[BROTLI_NUM_BLOCK_LEN_SYMBOLS];
} BlockSplitCode;
/* Stores a number between 0 and 255. */
static void StoreVarLenUint8(size_t n, size_t* storage_ix, uint8_t* storage) {
if (n == 0) {
BrotliWriteBits(1, 0, storage_ix, storage);
} else {
size_t nbits = Log2FloorNonZero(n);
BrotliWriteBits(1, 1, storage_ix, storage);
BrotliWriteBits(3, nbits, storage_ix, storage);
BrotliWriteBits(nbits, n - ((size_t)1 << nbits), storage_ix, storage);
}
}
/* Stores the compressed meta-block header.
REQUIRES: length > 0
REQUIRES: length <= (1 << 24) */
static void StoreCompressedMetaBlockHeader(BROTLI_BOOL is_final_block,
size_t length,
size_t* storage_ix,
uint8_t* storage) {
uint64_t lenbits;
size_t nlenbits;
uint64_t nibblesbits;
/* Write ISLAST bit. */
BrotliWriteBits(1, (uint64_t)is_final_block, storage_ix, storage);
/* Write ISEMPTY bit. */
if (is_final_block) {
BrotliWriteBits(1, 0, storage_ix, storage);
}
BrotliEncodeMlen(length, &lenbits, &nlenbits, &nibblesbits);
BrotliWriteBits(2, nibblesbits, storage_ix, storage);
BrotliWriteBits(nlenbits, lenbits, storage_ix, storage);
if (!is_final_block) {
/* Write ISUNCOMPRESSED bit. */
BrotliWriteBits(1, 0, storage_ix, storage);
}
}
/* Stores the uncompressed meta-block header.
REQUIRES: length > 0
REQUIRES: length <= (1 << 24) */
static void BrotliStoreUncompressedMetaBlockHeader(size_t length,
size_t* storage_ix,
uint8_t* storage) {
uint64_t lenbits;
size_t nlenbits;
uint64_t nibblesbits;
/* Write ISLAST bit.
Uncompressed block cannot be the last one, so set to 0. */
BrotliWriteBits(1, 0, storage_ix, storage);
BrotliEncodeMlen(length, &lenbits, &nlenbits, &nibblesbits);
BrotliWriteBits(2, nibblesbits, storage_ix, storage);
BrotliWriteBits(nlenbits, lenbits, storage_ix, storage);
/* Write ISUNCOMPRESSED bit. */
BrotliWriteBits(1, 1, storage_ix, storage);
}
static void BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(
const int num_codes, const uint8_t* code_length_bitdepth,
size_t* storage_ix, uint8_t* storage) {
static const uint8_t kStorageOrder[BROTLI_CODE_LENGTH_CODES] = {
1, 2, 3, 4, 0, 5, 17, 6, 16, 7, 8, 9, 10, 11, 12, 13, 14, 15
};
/* The bit lengths of the Huffman code over the code length alphabet
are compressed with the following static Huffman code:
Symbol Code
------ ----
0 00
1 1110
2 110
3 01
4 10
5 1111 */
static const uint8_t kHuffmanBitLengthHuffmanCodeSymbols[6] = {
0, 7, 3, 2, 1, 15
};
static const uint8_t kHuffmanBitLengthHuffmanCodeBitLengths[6] = {
2, 4, 3, 2, 2, 4
};
size_t skip_some = 0; /* skips none. */
/* Throw away trailing zeros: */
size_t codes_to_store = BROTLI_CODE_LENGTH_CODES;
if (num_codes > 1) {
for (; codes_to_store > 0; --codes_to_store) {
if (code_length_bitdepth[kStorageOrder[codes_to_store - 1]] != 0) {
break;
}
}
}
if (code_length_bitdepth[kStorageOrder[0]] == 0 &&
code_length_bitdepth[kStorageOrder[1]] == 0) {
skip_some = 2; /* skips two. */
if (code_length_bitdepth[kStorageOrder[2]] == 0) {
skip_some = 3; /* skips three. */
}
}
BrotliWriteBits(2, skip_some, storage_ix, storage);
{
size_t i;
for (i = skip_some; i < codes_to_store; ++i) {
size_t l = code_length_bitdepth[kStorageOrder[i]];
BrotliWriteBits(kHuffmanBitLengthHuffmanCodeBitLengths[l],
kHuffmanBitLengthHuffmanCodeSymbols[l], storage_ix, storage);
}
}
}
static void BrotliStoreHuffmanTreeToBitMask(
const size_t huffman_tree_size, const uint8_t* huffman_tree,
const uint8_t* huffman_tree_extra_bits, const uint8_t* code_length_bitdepth,
const uint16_t* code_length_bitdepth_symbols,
size_t* BROTLI_RESTRICT storage_ix, uint8_t* BROTLI_RESTRICT storage) {
size_t i;
for (i = 0; i < huffman_tree_size; ++i) {
size_t ix = huffman_tree[i];
BrotliWriteBits(code_length_bitdepth[ix], code_length_bitdepth_symbols[ix],
storage_ix, storage);
/* Extra bits */
switch (ix) {
case BROTLI_REPEAT_PREVIOUS_CODE_LENGTH:
BrotliWriteBits(2, huffman_tree_extra_bits[i], storage_ix, storage);
break;
case BROTLI_REPEAT_ZERO_CODE_LENGTH:
BrotliWriteBits(3, huffman_tree_extra_bits[i], storage_ix, storage);
break;
}
}
}
static void StoreSimpleHuffmanTree(const uint8_t* depths,
size_t symbols[4],
size_t num_symbols,
size_t max_bits,
size_t* storage_ix, uint8_t* storage) {
/* value of 1 indicates a simple Huffman code */
BrotliWriteBits(2, 1, storage_ix, storage);
BrotliWriteBits(2, num_symbols - 1, storage_ix, storage); /* NSYM - 1 */
{
/* Sort */
size_t i;
for (i = 0; i < num_symbols; i++) {
size_t j;
for (j = i + 1; j < num_symbols; j++) {
if (depths[symbols[j]] < depths[symbols[i]]) {
BROTLI_SWAP(size_t, symbols, j, i);
}
}
}
}
if (num_symbols == 2) {
BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
} else if (num_symbols == 3) {
BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
} else {
BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[3], storage_ix, storage);
/* tree-select */
BrotliWriteBits(1, depths[symbols[0]] == 1 ? 1 : 0, storage_ix, storage);
}
}
/* num = alphabet size
depths = symbol depths */
void BrotliStoreHuffmanTree(const uint8_t* depths, size_t num,
HuffmanTree* tree,
size_t* storage_ix, uint8_t* storage) {
/* Write the Huffman tree into the brotli-representation.
The command alphabet is the largest, so this allocation will fit all
alphabets. */
uint8_t huffman_tree[BROTLI_NUM_COMMAND_SYMBOLS];
uint8_t huffman_tree_extra_bits[BROTLI_NUM_COMMAND_SYMBOLS];
size_t huffman_tree_size = 0;
uint8_t code_length_bitdepth[BROTLI_CODE_LENGTH_CODES] = { 0 };
uint16_t code_length_bitdepth_symbols[BROTLI_CODE_LENGTH_CODES];
uint32_t huffman_tree_histogram[BROTLI_CODE_LENGTH_CODES] = { 0 };
size_t i;
int num_codes = 0;
size_t code = 0;
BROTLI_DCHECK(num <= BROTLI_NUM_COMMAND_SYMBOLS);
BrotliWriteHuffmanTree(depths, num, &huffman_tree_size, huffman_tree,
huffman_tree_extra_bits);
/* Calculate the statistics of the Huffman tree in brotli-representation. */
for (i = 0; i < huffman_tree_size; ++i) {
++huffman_tree_histogram[huffman_tree[i]];
}
for (i = 0; i < BROTLI_CODE_LENGTH_CODES; ++i) {
if (huffman_tree_histogram[i]) {
if (num_codes == 0) {
code = i;
num_codes = 1;
} else if (num_codes == 1) {
num_codes = 2;
break;
}
}
}
/* Calculate another Huffman tree to use for compressing both the
earlier Huffman tree with. */
BrotliCreateHuffmanTree(huffman_tree_histogram, BROTLI_CODE_LENGTH_CODES,
5, tree, code_length_bitdepth);
BrotliConvertBitDepthsToSymbols(code_length_bitdepth,
BROTLI_CODE_LENGTH_CODES,
code_length_bitdepth_symbols);
/* Now, we have all the data, let's start storing it */
BrotliStoreHuffmanTreeOfHuffmanTreeToBitMask(num_codes, code_length_bitdepth,
storage_ix, storage);
if (num_codes == 1) {
code_length_bitdepth[code] = 0;
}
/* Store the real Huffman tree now. */
BrotliStoreHuffmanTreeToBitMask(huffman_tree_size,
huffman_tree,
huffman_tree_extra_bits,
code_length_bitdepth,
code_length_bitdepth_symbols,
storage_ix, storage);
}
/* Builds a Huffman tree from histogram[0:length] into depth[0:length] and
bits[0:length] and stores the encoded tree to the bit stream. */
static void BuildAndStoreHuffmanTree(const uint32_t* histogram,
const size_t histogram_length,
const size_t alphabet_size,
HuffmanTree* tree,
uint8_t* depth,
uint16_t* bits,
size_t* storage_ix,
uint8_t* storage) {
size_t count = 0;
size_t s4[4] = { 0 };
size_t i;
size_t max_bits = 0;
for (i = 0; i < histogram_length; i++) {
if (histogram[i]) {
if (count < 4) {
s4[count] = i;
} else if (count > 4) {
break;
}
count++;
}
}
{
size_t max_bits_counter = alphabet_size - 1;
while (max_bits_counter) {
max_bits_counter >>= 1;
++max_bits;
}
}
if (count <= 1) {
BrotliWriteBits(4, 1, storage_ix, storage);
BrotliWriteBits(max_bits, s4[0], storage_ix, storage);
depth[s4[0]] = 0;
bits[s4[0]] = 0;
return;
}
memset(depth, 0, histogram_length * sizeof(depth[0]));
BrotliCreateHuffmanTree(histogram, histogram_length, 15, tree, depth);
BrotliConvertBitDepthsToSymbols(depth, histogram_length, bits);
if (count <= 4) {
StoreSimpleHuffmanTree(depth, s4, count, max_bits, storage_ix, storage);
} else {
BrotliStoreHuffmanTree(depth, histogram_length, tree, storage_ix, storage);
}
}
static BROTLI_INLINE BROTLI_BOOL SortHuffmanTree(
const HuffmanTree* v0, const HuffmanTree* v1) {
return TO_BROTLI_BOOL(v0->total_count_ < v1->total_count_);
}
void BrotliBuildAndStoreHuffmanTreeFast(MemoryManager* m,
const uint32_t* histogram,
const size_t histogram_total,
const size_t max_bits,
uint8_t* depth, uint16_t* bits,
size_t* storage_ix,
uint8_t* storage) {
size_t count = 0;
size_t symbols[4] = { 0 };
size_t length = 0;
size_t total = histogram_total;
while (total != 0) {
if (histogram[length]) {
if (count < 4) {
symbols[count] = length;
}
++count;
total -= histogram[length];
}
++length;
}
if (count <= 1) {
BrotliWriteBits(4, 1, storage_ix, storage);
BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
depth[symbols[0]] = 0;
bits[symbols[0]] = 0;
return;
}
memset(depth, 0, length * sizeof(depth[0]));
{
const size_t max_tree_size = 2 * length + 1;
HuffmanTree* tree = BROTLI_ALLOC(m, HuffmanTree, max_tree_size);
uint32_t count_limit;
if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(tree)) return;
for (count_limit = 1; ; count_limit *= 2) {
HuffmanTree* node = tree;
size_t l;
for (l = length; l != 0;) {
--l;
if (histogram[l]) {
if (BROTLI_PREDICT_TRUE(histogram[l] >= count_limit)) {
InitHuffmanTree(node, histogram[l], -1, (int16_t)l);
} else {
InitHuffmanTree(node, count_limit, -1, (int16_t)l);
}
++node;
}
}
{
const int n = (int)(node - tree);
HuffmanTree sentinel;
int i = 0; /* Points to the next leaf node. */
int j = n + 1; /* Points to the next non-leaf node. */
int k;
SortHuffmanTreeItems(tree, (size_t)n, SortHuffmanTree);
/* The nodes are:
[0, n): the sorted leaf nodes that we start with.
[n]: we add a sentinel here.
[n + 1, 2n): new parent nodes are added here, starting from
(n+1). These are naturally in ascending order.
[2n]: we add a sentinel at the end as well.
There will be (2n+1) elements at the end. */
InitHuffmanTree(&sentinel, BROTLI_UINT32_MAX, -1, -1);
*node++ = sentinel;
*node++ = sentinel;
for (k = n - 1; k > 0; --k) {
int left, right;
if (tree[i].total_count_ <= tree[j].total_count_) {
left = i;
++i;
} else {
left = j;
++j;
}
if (tree[i].total_count_ <= tree[j].total_count_) {
right = i;
++i;
} else {
right = j;
++j;
}
/* The sentinel node becomes the parent node. */
node[-1].total_count_ =
tree[left].total_count_ + tree[right].total_count_;
node[-1].index_left_ = (int16_t)left;
node[-1].index_right_or_value_ = (int16_t)right;
/* Add back the last sentinel node. */
*node++ = sentinel;
}
if (BrotliSetDepth(2 * n - 1, tree, depth, 14)) {
/* We need to pack the Huffman tree in 14 bits. If this was not
successful, add fake entities to the lowest values and retry. */
break;
}
}
}
BROTLI_FREE(m, tree);
}
BrotliConvertBitDepthsToSymbols(depth, length, bits);
if (count <= 4) {
size_t i;
/* value of 1 indicates a simple Huffman code */
BrotliWriteBits(2, 1, storage_ix, storage);
BrotliWriteBits(2, count - 1, storage_ix, storage); /* NSYM - 1 */
/* Sort */
for (i = 0; i < count; i++) {
size_t j;
for (j = i + 1; j < count; j++) {
if (depth[symbols[j]] < depth[symbols[i]]) {
BROTLI_SWAP(size_t, symbols, j, i);
}
}
}
if (count == 2) {
BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
} else if (count == 3) {
BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
} else {
BrotliWriteBits(max_bits, symbols[0], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[1], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[2], storage_ix, storage);
BrotliWriteBits(max_bits, symbols[3], storage_ix, storage);
/* tree-select */
BrotliWriteBits(1, depth[symbols[0]] == 1 ? 1 : 0, storage_ix, storage);
}
} else {
uint8_t previous_value = 8;
size_t i;
/* Complex Huffman Tree */
StoreStaticCodeLengthCode(storage_ix, storage);
/* Actual RLE coding. */
for (i = 0; i < length;) {
const uint8_t value = depth[i];
size_t reps = 1;
size_t k;
for (k = i + 1; k < length && depth[k] == value; ++k) {
++reps;
}
i += reps;
if (value == 0) {
BrotliWriteBits(kZeroRepsDepth[reps], kZeroRepsBits[reps],
storage_ix, storage);
} else {
if (previous_value != value) {
BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value],
storage_ix, storage);
--reps;
}
if (reps < 3) {
while (reps != 0) {
reps--;
BrotliWriteBits(kCodeLengthDepth[value], kCodeLengthBits[value],
storage_ix, storage);
}
} else {
reps -= 3;
BrotliWriteBits(kNonZeroRepsDepth[reps], kNonZeroRepsBits[reps],
storage_ix, storage);
}
previous_value = value;
}
}
}
}
static size_t IndexOf(const uint8_t* v, size_t v_size, uint8_t value) {
size_t i = 0;
for (; i < v_size; ++i) {
if (v[i] == value) return i;
}
return i;
}
static void MoveToFront(uint8_t* v, size_t index) {
uint8_t value = v[index];
size_t i;
for (i = index; i != 0; --i) {
v[i] = v[i - 1];
}
v[0] = value;
}
static void MoveToFrontTransform(const uint32_t* BROTLI_RESTRICT v_in,
const size_t v_size,
uint32_t* v_out) {
size_t i;
uint8_t mtf[256];
uint32_t max_value;
if (v_size == 0) {
return;
}
max_value = v_in[0];
for (i = 1; i < v_size; ++i) {
if (v_in[i] > max_value) max_value = v_in[i];
}
BROTLI_DCHECK(max_value < 256u);
for (i = 0; i <= max_value; ++i) {
mtf[i] = (uint8_t)i;
}
{
size_t mtf_size = max_value + 1;
for (i = 0; i < v_size; ++i) {
size_t index = IndexOf(mtf, mtf_size, (uint8_t)v_in[i]);
BROTLI_DCHECK(index < mtf_size);
v_out[i] = (uint32_t)index;
MoveToFront(mtf, index);
}
}
}
/* Finds runs of zeros in v[0..in_size) and replaces them with a prefix code of
the run length plus extra bits (lower 9 bits is the prefix code and the rest
are the extra bits). Non-zero values in v[] are shifted by
*max_length_prefix. Will not create prefix codes bigger than the initial
value of *max_run_length_prefix. The prefix code of run length L is simply
Log2Floor(L) and the number of extra bits is the same as the prefix code. */
static void RunLengthCodeZeros(const size_t in_size,
uint32_t* BROTLI_RESTRICT v, size_t* BROTLI_RESTRICT out_size,
uint32_t* BROTLI_RESTRICT max_run_length_prefix) {
uint32_t max_reps = 0;
size_t i;
uint32_t max_prefix;
for (i = 0; i < in_size;) {
uint32_t reps = 0;
for (; i < in_size && v[i] != 0; ++i) ;
for (; i < in_size && v[i] == 0; ++i) {
++reps;
}
max_reps = BROTLI_MAX(uint32_t, reps, max_reps);
}
max_prefix = max_reps > 0 ? Log2FloorNonZero(max_reps) : 0;
max_prefix = BROTLI_MIN(uint32_t, max_prefix, *max_run_length_prefix);
*max_run_length_prefix = max_prefix;
*out_size = 0;
for (i = 0; i < in_size;) {
BROTLI_DCHECK(*out_size <= i);
if (v[i] != 0) {
v[*out_size] = v[i] + *max_run_length_prefix;
++i;
++(*out_size);
} else {
uint32_t reps = 1;
size_t k;
for (k = i + 1; k < in_size && v[k] == 0; ++k) {
++reps;
}
i += reps;
while (reps != 0) {
if (reps < (2u << max_prefix)) {
uint32_t run_length_prefix = Log2FloorNonZero(reps);
const uint32_t extra_bits = reps - (1u << run_length_prefix);
v[*out_size] = run_length_prefix + (extra_bits << 9);
++(*out_size);
break;
} else {
const uint32_t extra_bits = (1u << max_prefix) - 1u;
v[*out_size] = max_prefix + (extra_bits << 9);
reps -= (2u << max_prefix) - 1u;
++(*out_size);
}
}
}
}
}
#define SYMBOL_BITS 9
static void EncodeContextMap(MemoryManager* m,
const uint32_t* context_map,
size_t context_map_size,
size_t num_clusters,
HuffmanTree* tree,
size_t* storage_ix, uint8_t* storage) {
size_t i;
uint32_t* rle_symbols;
uint32_t max_run_length_prefix = 6;
size_t num_rle_symbols = 0;
uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
static const uint32_t kSymbolMask = (1u << SYMBOL_BITS) - 1u;
uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
StoreVarLenUint8(num_clusters - 1, storage_ix, storage);
if (num_clusters == 1) {
return;
}
rle_symbols = BROTLI_ALLOC(m, uint32_t, context_map_size);
if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(rle_symbols)) return;
MoveToFrontTransform(context_map, context_map_size, rle_symbols);
RunLengthCodeZeros(context_map_size, rle_symbols,
&num_rle_symbols, &max_run_length_prefix);
memset(histogram, 0, sizeof(histogram));
for (i = 0; i < num_rle_symbols; ++i) {
++histogram[rle_symbols[i] & kSymbolMask];
}
{
BROTLI_BOOL use_rle = TO_BROTLI_BOOL(max_run_length_prefix > 0);
BrotliWriteBits(1, (uint64_t)use_rle, storage_ix, storage);
if (use_rle) {
BrotliWriteBits(4, max_run_length_prefix - 1, storage_ix, storage);
}
}
BuildAndStoreHuffmanTree(histogram, num_clusters + max_run_length_prefix,
num_clusters + max_run_length_prefix,
tree, depths, bits, storage_ix, storage);
for (i = 0; i < num_rle_symbols; ++i) {
const uint32_t rle_symbol = rle_symbols[i] & kSymbolMask;
const uint32_t extra_bits_val = rle_symbols[i] >> SYMBOL_BITS;
BrotliWriteBits(depths[rle_symbol], bits[rle_symbol], storage_ix, storage);
if (rle_symbol > 0 && rle_symbol <= max_run_length_prefix) {
BrotliWriteBits(rle_symbol, extra_bits_val, storage_ix, storage);
}
}
BrotliWriteBits(1, 1, storage_ix, storage); /* use move-to-front */
BROTLI_FREE(m, rle_symbols);
}
/* Stores the block switch command with index block_ix to the bit stream. */
static BROTLI_INLINE void StoreBlockSwitch(BlockSplitCode* code,
const uint32_t block_len,
const uint8_t block_type,
BROTLI_BOOL is_first_block,
size_t* storage_ix,
uint8_t* storage) {
size_t typecode = NextBlockTypeCode(&code->type_code_calculator, block_type);
size_t lencode;
uint32_t len_nextra;
uint32_t len_extra;
if (!is_first_block) {
BrotliWriteBits(code->type_depths[typecode], code->type_bits[typecode],
storage_ix, storage);
}
GetBlockLengthPrefixCode(block_len, &lencode, &len_nextra, &len_extra);
BrotliWriteBits(code->length_depths[lencode], code->length_bits[lencode],
storage_ix, storage);
BrotliWriteBits(len_nextra, len_extra, storage_ix, storage);
}
/* Builds a BlockSplitCode data structure from the block split given by the
vector of block types and block lengths and stores it to the bit stream. */
static void BuildAndStoreBlockSplitCode(const uint8_t* types,
const uint32_t* lengths,
const size_t num_blocks,
const size_t num_types,
HuffmanTree* tree,
BlockSplitCode* code,
size_t* storage_ix,
uint8_t* storage) {
uint32_t type_histo[BROTLI_MAX_BLOCK_TYPE_SYMBOLS];
uint32_t length_histo[BROTLI_NUM_BLOCK_LEN_SYMBOLS];
size_t i;
BlockTypeCodeCalculator type_code_calculator;
memset(type_histo, 0, (num_types + 2) * sizeof(type_histo[0]));
memset(length_histo, 0, sizeof(length_histo));
InitBlockTypeCodeCalculator(&type_code_calculator);
for (i = 0; i < num_blocks; ++i) {
size_t type_code = NextBlockTypeCode(&type_code_calculator, types[i]);
if (i != 0) ++type_histo[type_code];
++length_histo[BlockLengthPrefixCode(lengths[i])];
}
StoreVarLenUint8(num_types - 1, storage_ix, storage);
if (num_types > 1) { /* TODO: else? could StoreBlockSwitch occur? */
BuildAndStoreHuffmanTree(&type_histo[0], num_types + 2, num_types + 2, tree,
&code->type_depths[0], &code->type_bits[0],
storage_ix, storage);
BuildAndStoreHuffmanTree(&length_histo[0], BROTLI_NUM_BLOCK_LEN_SYMBOLS,
BROTLI_NUM_BLOCK_LEN_SYMBOLS,
tree, &code->length_depths[0],
&code->length_bits[0], storage_ix, storage);
StoreBlockSwitch(code, lengths[0], types[0], 1, storage_ix, storage);
}
}
/* Stores a context map where the histogram type is always the block type. */
static void StoreTrivialContextMap(size_t num_types,
size_t context_bits,
HuffmanTree* tree,
size_t* storage_ix,
uint8_t* storage) {
StoreVarLenUint8(num_types - 1, storage_ix, storage);
if (num_types > 1) {
size_t repeat_code = context_bits - 1u;
size_t repeat_bits = (1u << repeat_code) - 1u;
size_t alphabet_size = num_types + repeat_code;
uint32_t histogram[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
uint8_t depths[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
uint16_t bits[BROTLI_MAX_CONTEXT_MAP_SYMBOLS];
size_t i;
memset(histogram, 0, alphabet_size * sizeof(histogram[0]));
/* Write RLEMAX. */
BrotliWriteBits(1, 1, storage_ix, storage);
BrotliWriteBits(4, repeat_code - 1, storage_ix, storage);
histogram[repeat_code] = (uint32_t)num_types;
histogram[0] = 1;
for (i = context_bits; i < alphabet_size; ++i) {
histogram[i] = 1;
}
BuildAndStoreHuffmanTree(histogram, alphabet_size, alphabet_size,
tree, depths, bits, storage_ix, storage);
for (i = 0; i < num_types; ++i) {
size_t code = (i == 0 ? 0 : i + context_bits - 1);
BrotliWriteBits(depths[code], bits[code], storage_ix, storage);
BrotliWriteBits(
depths[repeat_code], bits[repeat_code], storage_ix, storage);
BrotliWriteBits(repeat_code, repeat_bits, storage_ix, storage);
}
/* Write IMTF (inverse-move-to-front) bit. */
BrotliWriteBits(1, 1, storage_ix, storage);
}
}
/* Manages the encoding of one block category (literal, command or distance). */
typedef struct BlockEncoder {
size_t histogram_length_;
size_t num_block_types_;
const uint8_t* block_types_; /* Not owned. */
const uint32_t* block_lengths_; /* Not owned. */
size_t num_blocks_;
BlockSplitCode block_split_code_;
size_t block_ix_;
size_t block_len_;
size_t entropy_ix_;
uint8_t* depths_;
uint16_t* bits_;
} BlockEncoder;
static void InitBlockEncoder(BlockEncoder* self, size_t histogram_length,
size_t num_block_types, const uint8_t* block_types,
const uint32_t* block_lengths, const size_t num_blocks) {
self->histogram_length_ = histogram_length;
self->num_block_types_ = num_block_types;
self->block_types_ = block_types;
self->block_lengths_ = block_lengths;
self->num_blocks_ = num_blocks;
InitBlockTypeCodeCalculator(&self->block_split_code_.type_code_calculator);
self->block_ix_ = 0;
self->block_len_ = num_blocks == 0 ? 0 : block_lengths[0];
self->entropy_ix_ = 0;
self->depths_ = 0;
self->bits_ = 0;
}
static void CleanupBlockEncoder(MemoryManager* m, BlockEncoder* self) {
BROTLI_FREE(m, self->depths_);
BROTLI_FREE(m, self->bits_);
}
/* Creates entropy codes of block lengths and block types and stores them
to the bit stream. */
static void BuildAndStoreBlockSwitchEntropyCodes(BlockEncoder* self,
HuffmanTree* tree, size_t* storage_ix, uint8_t* storage) {
BuildAndStoreBlockSplitCode(self->block_types_, self->block_lengths_,
self->num_blocks_, self->num_block_types_, tree, &self->block_split_code_,
storage_ix, storage);
}
/* Stores the next symbol with the entropy code of the current block type.
Updates the block type and block length at block boundaries. */
static void StoreSymbol(BlockEncoder* self, size_t symbol, size_t* storage_ix,
uint8_t* storage) {
if (self->block_len_ == 0) {
size_t block_ix = ++self->block_ix_;
uint32_t block_len = self->block_lengths_[block_ix];
uint8_t block_type = self->block_types_[block_ix];
self->block_len_ = block_len;
self->entropy_ix_ = block_type * self->histogram_length_;
StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0,
storage_ix, storage);
}
--self->block_len_;
{
size_t ix = self->entropy_ix_ + symbol;
BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage);
}
}
/* Stores the next symbol with the entropy code of the current block type and
context value.
Updates the block type and block length at block boundaries. */
static void StoreSymbolWithContext(BlockEncoder* self, size_t symbol,
size_t context, const uint32_t* context_map, size_t* storage_ix,
uint8_t* storage, const size_t context_bits) {
if (self->block_len_ == 0) {
size_t block_ix = ++self->block_ix_;
uint32_t block_len = self->block_lengths_[block_ix];
uint8_t block_type = self->block_types_[block_ix];
self->block_len_ = block_len;
self->entropy_ix_ = (size_t)block_type << context_bits;
StoreBlockSwitch(&self->block_split_code_, block_len, block_type, 0,
storage_ix, storage);
}
--self->block_len_;
{
size_t histo_ix = context_map[self->entropy_ix_ + context];
size_t ix = histo_ix * self->histogram_length_ + symbol;
BrotliWriteBits(self->depths_[ix], self->bits_[ix], storage_ix, storage);
}
}
#define FN(X) X ## Literal
/* NOLINTNEXTLINE(build/include) */
#include "./block_encoder_inc.h"
#undef FN
#define FN(X) X ## Command
/* NOLINTNEXTLINE(build/include) */
#include "./block_encoder_inc.h"
#undef FN
#define FN(X) X ## Distance
/* NOLINTNEXTLINE(build/include) */
#include "./block_encoder_inc.h"
#undef FN
static void JumpToByteBoundary(size_t* storage_ix, uint8_t* storage) {
*storage_ix = (*storage_ix + 7u) & ~7u;
storage[*storage_ix >> 3] = 0;
}
void BrotliStoreMetaBlock(MemoryManager* m,
const uint8_t* input, size_t start_pos, size_t length, size_t mask,
uint8_t prev_byte, uint8_t prev_byte2, BROTLI_BOOL is_last,
const BrotliEncoderParams* params, ContextType literal_context_mode,
const Command* commands, size_t n_commands, const MetaBlockSplit* mb,
size_t* storage_ix, uint8_t* storage) {
size_t pos = start_pos;
size_t i;
uint32_t num_distance_symbols = params->dist.alphabet_size_max;
uint32_t num_effective_distance_symbols = params->dist.alphabet_size_limit;
HuffmanTree* tree;
ContextLut literal_context_lut = BROTLI_CONTEXT_LUT(literal_context_mode);
BlockEncoder literal_enc;
BlockEncoder command_enc;
BlockEncoder distance_enc;
const BrotliDistanceParams* dist = &params->dist;
BROTLI_DCHECK(
num_effective_distance_symbols <= BROTLI_NUM_HISTOGRAM_DISTANCE_SYMBOLS);
StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
tree = BROTLI_ALLOC(m, HuffmanTree, MAX_HUFFMAN_TREE_SIZE);
if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(tree)) return;
InitBlockEncoder(&literal_enc, BROTLI_NUM_LITERAL_SYMBOLS,
mb->literal_split.num_types, mb->literal_split.types,
mb->literal_split.lengths, mb->literal_split.num_blocks);
InitBlockEncoder(&command_enc, BROTLI_NUM_COMMAND_SYMBOLS,
mb->command_split.num_types, mb->command_split.types,
mb->command_split.lengths, mb->command_split.num_blocks);
InitBlockEncoder(&distance_enc, num_effective_distance_symbols,
mb->distance_split.num_types, mb->distance_split.types,
mb->distance_split.lengths, mb->distance_split.num_blocks);
BuildAndStoreBlockSwitchEntropyCodes(&literal_enc, tree, storage_ix, storage);
BuildAndStoreBlockSwitchEntropyCodes(&command_enc, tree, storage_ix, storage);
BuildAndStoreBlockSwitchEntropyCodes(
&distance_enc, tree, storage_ix, storage);
BrotliWriteBits(2, dist->distance_postfix_bits, storage_ix, storage);
BrotliWriteBits(
4, dist->num_direct_distance_codes >> dist->distance_postfix_bits,
storage_ix, storage);
for (i = 0; i < mb->literal_split.num_types; ++i) {
BrotliWriteBits(2, literal_context_mode, storage_ix, storage);
}
if (mb->literal_context_map_size == 0) {
StoreTrivialContextMap(mb->literal_histograms_size,
BROTLI_LITERAL_CONTEXT_BITS, tree, storage_ix, storage);
} else {
EncodeContextMap(m,
mb->literal_context_map, mb->literal_context_map_size,
mb->literal_histograms_size, tree, storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
}
if (mb->distance_context_map_size == 0) {
StoreTrivialContextMap(mb->distance_histograms_size,
BROTLI_DISTANCE_CONTEXT_BITS, tree, storage_ix, storage);
} else {
EncodeContextMap(m,
mb->distance_context_map, mb->distance_context_map_size,
mb->distance_histograms_size, tree, storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
}
BuildAndStoreEntropyCodesLiteral(m, &literal_enc, mb->literal_histograms,
mb->literal_histograms_size, BROTLI_NUM_LITERAL_SYMBOLS, tree,
storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
BuildAndStoreEntropyCodesCommand(m, &command_enc, mb->command_histograms,
mb->command_histograms_size, BROTLI_NUM_COMMAND_SYMBOLS, tree,
storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
BuildAndStoreEntropyCodesDistance(m, &distance_enc, mb->distance_histograms,
mb->distance_histograms_size, num_distance_symbols, tree,
storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
BROTLI_FREE(m, tree);
for (i = 0; i < n_commands; ++i) {
const Command cmd = commands[i];
size_t cmd_code = cmd.cmd_prefix_;
StoreSymbol(&command_enc, cmd_code, storage_ix, storage);
StoreCommandExtra(&cmd, storage_ix, storage);
if (mb->literal_context_map_size == 0) {
size_t j;
for (j = cmd.insert_len_; j != 0; --j) {
StoreSymbol(&literal_enc, input[pos & mask], storage_ix, storage);
++pos;
}
} else {
size_t j;
for (j = cmd.insert_len_; j != 0; --j) {
size_t context =
BROTLI_CONTEXT(prev_byte, prev_byte2, literal_context_lut);
uint8_t literal = input[pos & mask];
StoreSymbolWithContext(&literal_enc, literal, context,
mb->literal_context_map, storage_ix, storage,
BROTLI_LITERAL_CONTEXT_BITS);
prev_byte2 = prev_byte;
prev_byte = literal;
++pos;
}
}
pos += CommandCopyLen(&cmd);
if (CommandCopyLen(&cmd)) {
prev_byte2 = input[(pos - 2) & mask];
prev_byte = input[(pos - 1) & mask];
if (cmd.cmd_prefix_ >= 128) {
size_t dist_code = cmd.dist_prefix_ & 0x3FF;
uint32_t distnumextra = cmd.dist_prefix_ >> 10;
uint64_t distextra = cmd.dist_extra_;
if (mb->distance_context_map_size == 0) {
StoreSymbol(&distance_enc, dist_code, storage_ix, storage);
} else {
size_t context = CommandDistanceContext(&cmd);
StoreSymbolWithContext(&distance_enc, dist_code, context,
mb->distance_context_map, storage_ix, storage,
BROTLI_DISTANCE_CONTEXT_BITS);
}
BrotliWriteBits(distnumextra, distextra, storage_ix, storage);
}
}
}
CleanupBlockEncoder(m, &distance_enc);
CleanupBlockEncoder(m, &command_enc);
CleanupBlockEncoder(m, &literal_enc);
if (is_last) {
JumpToByteBoundary(storage_ix, storage);
}
}
static void BuildHistograms(const uint8_t* input,
size_t start_pos,
size_t mask,
const Command* commands,
size_t n_commands,
HistogramLiteral* lit_histo,
HistogramCommand* cmd_histo,
HistogramDistance* dist_histo) {
size_t pos = start_pos;
size_t i;
for (i = 0; i < n_commands; ++i) {
const Command cmd = commands[i];
size_t j;
HistogramAddCommand(cmd_histo, cmd.cmd_prefix_);
for (j = cmd.insert_len_; j != 0; --j) {
HistogramAddLiteral(lit_histo, input[pos & mask]);
++pos;
}
pos += CommandCopyLen(&cmd);
if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) {
HistogramAddDistance(dist_histo, cmd.dist_prefix_ & 0x3FF);
}
}
}
static void StoreDataWithHuffmanCodes(const uint8_t* input,
size_t start_pos,
size_t mask,
const Command* commands,
size_t n_commands,
const uint8_t* lit_depth,
const uint16_t* lit_bits,
const uint8_t* cmd_depth,
const uint16_t* cmd_bits,
const uint8_t* dist_depth,
const uint16_t* dist_bits,
size_t* storage_ix,
uint8_t* storage) {
size_t pos = start_pos;
size_t i;
for (i = 0; i < n_commands; ++i) {
const Command cmd = commands[i];
const size_t cmd_code = cmd.cmd_prefix_;
size_t j;
BrotliWriteBits(
cmd_depth[cmd_code], cmd_bits[cmd_code], storage_ix, storage);
StoreCommandExtra(&cmd, storage_ix, storage);
for (j = cmd.insert_len_; j != 0; --j) {
const uint8_t literal = input[pos & mask];
BrotliWriteBits(
lit_depth[literal], lit_bits[literal], storage_ix, storage);
++pos;
}
pos += CommandCopyLen(&cmd);
if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) {
const size_t dist_code = cmd.dist_prefix_ & 0x3FF;
const uint32_t distnumextra = cmd.dist_prefix_ >> 10;
const uint32_t distextra = cmd.dist_extra_;
BrotliWriteBits(dist_depth[dist_code], dist_bits[dist_code],
storage_ix, storage);
BrotliWriteBits(distnumextra, distextra, storage_ix, storage);
}
}
}
void BrotliStoreMetaBlockTrivial(MemoryManager* m,
const uint8_t* input, size_t start_pos, size_t length, size_t mask,
BROTLI_BOOL is_last, const BrotliEncoderParams* params,
const Command* commands, size_t n_commands,
size_t* storage_ix, uint8_t* storage) {
HistogramLiteral lit_histo;
HistogramCommand cmd_histo;
HistogramDistance dist_histo;
uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS];
uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS];
uint8_t dist_depth[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
uint16_t dist_bits[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
HuffmanTree* tree;
uint32_t num_distance_symbols = params->dist.alphabet_size_max;
StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
HistogramClearLiteral(&lit_histo);
HistogramClearCommand(&cmd_histo);
HistogramClearDistance(&dist_histo);
BuildHistograms(input, start_pos, mask, commands, n_commands,
&lit_histo, &cmd_histo, &dist_histo);
BrotliWriteBits(13, 0, storage_ix, storage);
tree = BROTLI_ALLOC(m, HuffmanTree, MAX_HUFFMAN_TREE_SIZE);
if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(tree)) return;
BuildAndStoreHuffmanTree(lit_histo.data_, BROTLI_NUM_LITERAL_SYMBOLS,
BROTLI_NUM_LITERAL_SYMBOLS, tree,
lit_depth, lit_bits,
storage_ix, storage);
BuildAndStoreHuffmanTree(cmd_histo.data_, BROTLI_NUM_COMMAND_SYMBOLS,
BROTLI_NUM_COMMAND_SYMBOLS, tree,
cmd_depth, cmd_bits,
storage_ix, storage);
BuildAndStoreHuffmanTree(dist_histo.data_, MAX_SIMPLE_DISTANCE_ALPHABET_SIZE,
num_distance_symbols, tree,
dist_depth, dist_bits,
storage_ix, storage);
BROTLI_FREE(m, tree);
StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
n_commands, lit_depth, lit_bits,
cmd_depth, cmd_bits,
dist_depth, dist_bits,
storage_ix, storage);
if (is_last) {
JumpToByteBoundary(storage_ix, storage);
}
}
void BrotliStoreMetaBlockFast(MemoryManager* m,
const uint8_t* input, size_t start_pos, size_t length, size_t mask,
BROTLI_BOOL is_last, const BrotliEncoderParams* params,
const Command* commands, size_t n_commands,
size_t* storage_ix, uint8_t* storage) {
uint32_t num_distance_symbols = params->dist.alphabet_size_max;
uint32_t distance_alphabet_bits =
Log2FloorNonZero(num_distance_symbols - 1) + 1;
StoreCompressedMetaBlockHeader(is_last, length, storage_ix, storage);
BrotliWriteBits(13, 0, storage_ix, storage);
if (n_commands <= 128) {
uint32_t histogram[BROTLI_NUM_LITERAL_SYMBOLS] = { 0 };
size_t pos = start_pos;
size_t num_literals = 0;
size_t i;
uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
for (i = 0; i < n_commands; ++i) {
const Command cmd = commands[i];
size_t j;
for (j = cmd.insert_len_; j != 0; --j) {
++histogram[input[pos & mask]];
++pos;
}
num_literals += cmd.insert_len_;
pos += CommandCopyLen(&cmd);
}
BrotliBuildAndStoreHuffmanTreeFast(m, histogram, num_literals,
/* max_bits = */ 8,
lit_depth, lit_bits,
storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
StoreStaticCommandHuffmanTree(storage_ix, storage);
StoreStaticDistanceHuffmanTree(storage_ix, storage);
StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
n_commands, lit_depth, lit_bits,
kStaticCommandCodeDepth,
kStaticCommandCodeBits,
kStaticDistanceCodeDepth,
kStaticDistanceCodeBits,
storage_ix, storage);
} else {
HistogramLiteral lit_histo;
HistogramCommand cmd_histo;
HistogramDistance dist_histo;
uint8_t lit_depth[BROTLI_NUM_LITERAL_SYMBOLS];
uint16_t lit_bits[BROTLI_NUM_LITERAL_SYMBOLS];
uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS];
uint16_t cmd_bits[BROTLI_NUM_COMMAND_SYMBOLS];
uint8_t dist_depth[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
uint16_t dist_bits[MAX_SIMPLE_DISTANCE_ALPHABET_SIZE];
HistogramClearLiteral(&lit_histo);
HistogramClearCommand(&cmd_histo);
HistogramClearDistance(&dist_histo);
BuildHistograms(input, start_pos, mask, commands, n_commands,
&lit_histo, &cmd_histo, &dist_histo);
BrotliBuildAndStoreHuffmanTreeFast(m, lit_histo.data_,
lit_histo.total_count_,
/* max_bits = */ 8,
lit_depth, lit_bits,
storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
BrotliBuildAndStoreHuffmanTreeFast(m, cmd_histo.data_,
cmd_histo.total_count_,
/* max_bits = */ 10,
cmd_depth, cmd_bits,
storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
BrotliBuildAndStoreHuffmanTreeFast(m, dist_histo.data_,
dist_histo.total_count_,
/* max_bits = */
distance_alphabet_bits,
dist_depth, dist_bits,
storage_ix, storage);
if (BROTLI_IS_OOM(m)) return;
StoreDataWithHuffmanCodes(input, start_pos, mask, commands,
n_commands, lit_depth, lit_bits,
cmd_depth, cmd_bits,
dist_depth, dist_bits,
storage_ix, storage);
}
if (is_last) {
JumpToByteBoundary(storage_ix, storage);
}
}
/* This is for storing uncompressed blocks (simple raw storage of
bytes-as-bytes). */
void BrotliStoreUncompressedMetaBlock(BROTLI_BOOL is_final_block,
const uint8_t* BROTLI_RESTRICT input,
size_t position, size_t mask,
size_t len,
size_t* BROTLI_RESTRICT storage_ix,
uint8_t* BROTLI_RESTRICT storage) {
size_t masked_pos = position & mask;
BrotliStoreUncompressedMetaBlockHeader(len, storage_ix, storage);
JumpToByteBoundary(storage_ix, storage);
if (masked_pos + len > mask + 1) {
size_t len1 = mask + 1 - masked_pos;
memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len1);
*storage_ix += len1 << 3;
len -= len1;
masked_pos = 0;
}
memcpy(&storage[*storage_ix >> 3], &input[masked_pos], len);
*storage_ix += len << 3;
/* We need to clear the next 4 bytes to continue to be
compatible with BrotliWriteBits. */
BrotliWriteBitsPrepareStorage(*storage_ix, storage);
/* Since the uncompressed block itself may not be the final block, add an
empty one after this. */
if (is_final_block) {
BrotliWriteBits(1, 1, storage_ix, storage); /* islast */
BrotliWriteBits(1, 1, storage_ix, storage); /* isempty */
JumpToByteBoundary(storage_ix, storage);
}
}
#if defined(__cplusplus) || defined(c_plusplus)
} /* extern "C" */
#endif
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