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Updates to Brotli compression format, decoder and encoder

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This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last month. Most important changes:

   * Fixes to the spec.
   * Change of code length code order.
   * Use a 2-level Huffman lookup table in the decoder.
   * Faster uncompressed meta-block decoding.
   * Optimized encoding of the Huffman code.
   * Detection of UTF-8 input encoding.
   * UTF-8 based literal cost modeling for improved
     backward reference selection.
This commit is contained in:
Zoltan Szabadka
2014-02-14 15:04:23 +01:00
parent dfc5a9f215
commit cbd5cb55f4
16 changed files with 912 additions and 635 deletions
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brotli/dec/bit_reader.h
+15 -16
View File
@@ -31,7 +31,7 @@ extern "C" {
#define BROTLI_IBUF_SIZE (2 * BROTLI_READ_SIZE + 32)
#define BROTLI_IBUF_MASK (2 * BROTLI_READ_SIZE - 1)
#define UNALIGNED_COPY64(dst, src) *(uint64_t*)(dst) = *(const uint64_t*)(src)
#define UNALIGNED_COPY64(dst, src) memcpy(dst, src, 8)
static const uint32_t kBitMask[BROTLI_MAX_NUM_BIT_READ] = {
0, 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767,
@@ -42,13 +42,13 @@ typedef struct {
/* Input byte buffer, consist of a ringbuffer and a "slack" region where */
/* bytes from the start of the ringbuffer are copied. */
uint8_t buf_[BROTLI_IBUF_SIZE];
uint8_t* buf_ptr_; /* next input will write here */
BrotliInput input_; /* input callback */
uint64_t val_; /* pre-fetched bits */
uint32_t pos_; /* byte position in stream */
uint32_t bit_pos_; /* current bit-reading position in val_ */
uint32_t bits_left_; /* how many valid bits left */
int eos_; /* input stream is finished */
uint8_t* buf_ptr_; /* next input will write here */
BrotliInput input_; /* input callback */
uint64_t val_; /* pre-fetched bits */
uint32_t pos_; /* byte position in stream */
uint32_t bit_pos_; /* current bit-reading position in val_ */
uint32_t bit_end_pos_; /* bit-reading end position from LSB of val_ */
int eos_; /* input stream is finished */
} BrotliBitReader;
int BrotliInitBitReader(BrotliBitReader* const br, BrotliInput input);
@@ -65,7 +65,7 @@ static BROTLI_INLINE void BrotliSetBitPos(BrotliBitReader* const br,
#ifdef BROTLI_DECODE_DEBUG
uint32_t n_bits = val - br->bit_pos_;
const uint32_t bval = (uint32_t)(br->val_ >> br->bit_pos_) & kBitMask[n_bits];
printf("[BrotliReadBits] %010ld %2d val: %6x\n",
printf("[BrotliReadBits] %010d %2d val: %6x\n",
(br->pos_ << 3) + br->bit_pos_ - 64, n_bits, bval);
#endif
br->bit_pos_ = val;
@@ -78,7 +78,7 @@ static BROTLI_INLINE void ShiftBytes(BrotliBitReader* const br) {
br->val_ |= ((uint64_t)br->buf_[br->pos_ & BROTLI_IBUF_MASK]) << 56;
++br->pos_;
br->bit_pos_ -= 8;
br->bits_left_ -= 8;
br->bit_end_pos_ -= 8;
}
}
@@ -95,10 +95,10 @@ static BROTLI_INLINE void ShiftBytes(BrotliBitReader* const br) {
every 32 bytes of input is read.
*/
static BROTLI_INLINE int BrotliReadMoreInput(BrotliBitReader* const br) {
if (br->bits_left_ > 320) {
if (br->bit_end_pos_ > 256) {
return 1;
} else if (br->eos_) {
return br->bit_pos_ <= br->bits_left_;
return br->bit_pos_ <= br->bit_end_pos_;
} else {
uint8_t* dst = br->buf_ptr_;
int bytes_read = BrotliRead(br->input_, dst, BROTLI_READ_SIZE);
@@ -131,7 +131,7 @@ static BROTLI_INLINE int BrotliReadMoreInput(BrotliBitReader* const br) {
} else {
br->buf_ptr_ = br->buf_;
}
br->bits_left_ += ((uint32_t)bytes_read << 3);
br->bit_end_pos_ += ((uint32_t)bytes_read << 3);
return 1;
}
}
@@ -147,7 +147,7 @@ static BROTLI_INLINE void BrotliFillBitWindow(BrotliBitReader* const br) {
br->buf_ + (br->pos_ & BROTLI_IBUF_MASK)) << 24;
br->pos_ += 5;
br->bit_pos_ -= 40;
br->bits_left_ -= 40;
br->bit_end_pos_ -= 40;
#else
ShiftBytes(br);
#endif
@@ -155,14 +155,13 @@ static BROTLI_INLINE void BrotliFillBitWindow(BrotliBitReader* const br) {
}
/* Reads the specified number of bits from Read Buffer. */
/* Requires that n_bits is positive. */
static BROTLI_INLINE uint32_t BrotliReadBits(
BrotliBitReader* const br, int n_bits) {
uint32_t val;
BrotliFillBitWindow(br);
val = (uint32_t)(br->val_ >> br->bit_pos_) & kBitMask[n_bits];
#ifdef BROTLI_DECODE_DEBUG
printf("[BrotliReadBits] %010ld %2d val: %6x\n",
printf("[BrotliReadBits] %010d %2d val: %6x\n",
(br->pos_ << 3) + br->bit_pos_ - 64, n_bits, val);
#endif
br->bit_pos_ += (uint32_t)n_bits;