mirror of https://github.com/opencv/opencv.git
Open Source Computer Vision Library
https://opencv.org/
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
214 lines
6.9 KiB
214 lines
6.9 KiB
// Copyright 2010 Google Inc. All Rights Reserved. |
|
// |
|
// Use of this source code is governed by a BSD-style license |
|
// that can be found in the COPYING file in the root of the source |
|
// tree. An additional intellectual property rights grant can be found |
|
// in the file PATENTS. All contributing project authors may |
|
// be found in the AUTHORS file in the root of the source tree. |
|
// ----------------------------------------------------------------------------- |
|
// |
|
// Boolean decoder |
|
// |
|
// Author: Skal (pascal.massimino@gmail.com) |
|
|
|
#include "./bit_reader.h" |
|
|
|
#if defined(__cplusplus) || defined(c_plusplus) |
|
extern "C" { |
|
#endif |
|
|
|
#ifndef USE_RIGHT_JUSTIFY |
|
#define MK(X) (((range_t)(X) << (BITS)) | (MASK)) |
|
#else |
|
#define MK(X) ((range_t)(X)) |
|
#endif |
|
|
|
//------------------------------------------------------------------------------ |
|
// VP8BitReader |
|
|
|
void VP8InitBitReader(VP8BitReader* const br, |
|
const uint8_t* const start, const uint8_t* const end) { |
|
assert(br != NULL); |
|
assert(start != NULL); |
|
assert(start <= end); |
|
br->range_ = MK(255 - 1); |
|
br->buf_ = start; |
|
br->buf_end_ = end; |
|
br->value_ = 0; |
|
br->bits_ = -8; // to load the very first 8bits |
|
br->eof_ = 0; |
|
} |
|
|
|
const uint8_t kVP8Log2Range[128] = { |
|
7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, |
|
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, |
|
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, |
|
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, |
|
0 |
|
}; |
|
|
|
// range = (range << kVP8Log2Range[range]) + trailing 1's |
|
const range_t kVP8NewRange[128] = { |
|
MK(127), MK(127), MK(191), MK(127), MK(159), MK(191), MK(223), MK(127), |
|
MK(143), MK(159), MK(175), MK(191), MK(207), MK(223), MK(239), MK(127), |
|
MK(135), MK(143), MK(151), MK(159), MK(167), MK(175), MK(183), MK(191), |
|
MK(199), MK(207), MK(215), MK(223), MK(231), MK(239), MK(247), MK(127), |
|
MK(131), MK(135), MK(139), MK(143), MK(147), MK(151), MK(155), MK(159), |
|
MK(163), MK(167), MK(171), MK(175), MK(179), MK(183), MK(187), MK(191), |
|
MK(195), MK(199), MK(203), MK(207), MK(211), MK(215), MK(219), MK(223), |
|
MK(227), MK(231), MK(235), MK(239), MK(243), MK(247), MK(251), MK(127), |
|
MK(129), MK(131), MK(133), MK(135), MK(137), MK(139), MK(141), MK(143), |
|
MK(145), MK(147), MK(149), MK(151), MK(153), MK(155), MK(157), MK(159), |
|
MK(161), MK(163), MK(165), MK(167), MK(169), MK(171), MK(173), MK(175), |
|
MK(177), MK(179), MK(181), MK(183), MK(185), MK(187), MK(189), MK(191), |
|
MK(193), MK(195), MK(197), MK(199), MK(201), MK(203), MK(205), MK(207), |
|
MK(209), MK(211), MK(213), MK(215), MK(217), MK(219), MK(221), MK(223), |
|
MK(225), MK(227), MK(229), MK(231), MK(233), MK(235), MK(237), MK(239), |
|
MK(241), MK(243), MK(245), MK(247), MK(249), MK(251), MK(253), MK(127) |
|
}; |
|
|
|
#undef MK |
|
|
|
void VP8LoadFinalBytes(VP8BitReader* const br) { |
|
assert(br != NULL && br->buf_ != NULL); |
|
// Only read 8bits at a time |
|
if (br->buf_ < br->buf_end_) { |
|
#ifndef USE_RIGHT_JUSTIFY |
|
br->value_ |= (bit_t)(*br->buf_++) << ((BITS) - 8 - br->bits_); |
|
#else |
|
br->value_ = (bit_t)(*br->buf_++) | (br->value_ << 8); |
|
#endif |
|
br->bits_ += 8; |
|
} else if (!br->eof_) { |
|
#ifdef USE_RIGHT_JUSTIFY |
|
// These are not strictly needed, but it makes the behaviour |
|
// consistent for both USE_RIGHT_JUSTIFY and !USE_RIGHT_JUSTIFY. |
|
br->value_ <<= 8; |
|
br->bits_ += 8; |
|
#endif |
|
br->eof_ = 1; |
|
} |
|
} |
|
|
|
//------------------------------------------------------------------------------ |
|
// Higher-level calls |
|
|
|
uint32_t VP8GetValue(VP8BitReader* const br, int bits) { |
|
uint32_t v = 0; |
|
while (bits-- > 0) { |
|
v |= VP8GetBit(br, 0x80) << bits; |
|
} |
|
return v; |
|
} |
|
|
|
int32_t VP8GetSignedValue(VP8BitReader* const br, int bits) { |
|
const int value = VP8GetValue(br, bits); |
|
return VP8Get(br) ? -value : value; |
|
} |
|
|
|
//------------------------------------------------------------------------------ |
|
// VP8LBitReader |
|
|
|
#define MAX_NUM_BIT_READ 25 |
|
|
|
#define LBITS 64 // Number of bits prefetched. |
|
#define WBITS 32 // Minimum number of bytes needed after VP8LFillBitWindow. |
|
#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 VP8LInitBitReader(VP8LBitReader* 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_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (8 * i); |
|
++br->pos_; |
|
} |
|
} |
|
|
|
void VP8LBitReaderSetBuffer(VP8LBitReader* 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(VP8LBitReader* const br) { |
|
while (br->bit_pos_ >= 8 && br->pos_ < br->len_) { |
|
br->val_ >>= 8; |
|
br->val_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (LBITS - 8); |
|
++br->pos_; |
|
br->bit_pos_ -= 8; |
|
} |
|
} |
|
|
|
void VP8LFillBitWindow(VP8LBitReader* 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 vp8l_val_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 VP8LReadBits(VP8LBitReader* 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 (!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
|
|
|