mirror of https://github.com/axmolengine/axmol.git
230 lines
7.0 KiB
C
230 lines
7.0 KiB
C
// Copyright 2010 Google Inc. All Rights Reserved.
|
|
//
|
|
// This code is licensed under the same terms as WebM:
|
|
// Software License Agreement: http://www.webmproject.org/license/software/
|
|
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
|
|
// -----------------------------------------------------------------------------
|
|
//
|
|
// Boolean decoder
|
|
//
|
|
// Author: Skal (pascal.massimino@gmail.com)
|
|
|
|
#include "./bit_reader.h"
|
|
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
|
extern "C" {
|
|
#endif
|
|
|
|
#define MK(X) (((bit_t)(X) << (BITS)) | (MASK))
|
|
|
|
//------------------------------------------------------------------------------
|
|
// 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->missing_ = 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 bit_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_) {
|
|
br->value_ |= (bit_t)(*br->buf_++) << ((BITS) - 8 + br->missing_);
|
|
br->missing_ -= 8;
|
|
} else {
|
|
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
|
|
|
|
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_ |= ((uint64_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;
|
|
}
|
|
|
|
static void ShiftBytes(VP8LBitReader* const br) {
|
|
while (br->bit_pos_ >= 8 && br->pos_ < br->len_) {
|
|
br->val_ >>= 8;
|
|
br->val_ |= ((uint64_t)br->buf_[br->pos_]) << 56;
|
|
++br->pos_;
|
|
br->bit_pos_ -= 8;
|
|
}
|
|
}
|
|
|
|
void VP8LFillBitWindow(VP8LBitReader* const br) {
|
|
if (br->bit_pos_ >= 32) {
|
|
#if defined(__x86_64__) || defined(_M_X64)
|
|
if (br->pos_ + 8 < br->len_) {
|
|
br->val_ >>= 32;
|
|
// 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_) << 32;
|
|
br->pos_ += 4;
|
|
br->bit_pos_ -= 32;
|
|
} else {
|
|
// Slow path.
|
|
ShiftBytes(br);
|
|
}
|
|
#else
|
|
// Always the slow path.
|
|
ShiftBytes(br);
|
|
#endif
|
|
}
|
|
if (br->pos_ == br->len_ && br->bit_pos_ == 64) {
|
|
br->eos_ = 1;
|
|
}
|
|
}
|
|
|
|
uint32_t VP8LReadOneBit(VP8LBitReader* const br) {
|
|
const uint32_t val = (br->val_ >> br->bit_pos_) & 1;
|
|
// Flag an error at end_of_stream.
|
|
if (!br->eos_) {
|
|
++br->bit_pos_;
|
|
if (br->bit_pos_ >= 32) {
|
|
ShiftBytes(br);
|
|
}
|
|
// After this last bit is read, check if eos needs to be flagged.
|
|
if (br->pos_ == br->len_ && br->bit_pos_ == 64) {
|
|
br->eos_ = 1;
|
|
}
|
|
} else {
|
|
br->error_ = 1;
|
|
}
|
|
return val;
|
|
}
|
|
|
|
uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) {
|
|
uint32_t val = 0;
|
|
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) {
|
|
// If this read is going to cross the read buffer, set the eos flag.
|
|
if (br->pos_ == br->len_) {
|
|
if ((br->bit_pos_ + n_bits) >= 64) {
|
|
br->eos_ = 1;
|
|
if ((br->bit_pos_ + n_bits) > 64) return val;
|
|
}
|
|
}
|
|
val = (br->val_ >> br->bit_pos_) & kBitMask[n_bits];
|
|
br->bit_pos_ += n_bits;
|
|
if (br->bit_pos_ >= 40) {
|
|
if (br->pos_ + 5 < br->len_) {
|
|
br->val_ >>= 40;
|
|
br->val_ |=
|
|
(((uint64_t)br->buf_[br->pos_ + 0]) << 24) |
|
|
(((uint64_t)br->buf_[br->pos_ + 1]) << 32) |
|
|
(((uint64_t)br->buf_[br->pos_ + 2]) << 40) |
|
|
(((uint64_t)br->buf_[br->pos_ + 3]) << 48) |
|
|
(((uint64_t)br->buf_[br->pos_ + 4]) << 56);
|
|
br->pos_ += 5;
|
|
br->bit_pos_ -= 40;
|
|
}
|
|
if (br->bit_pos_ >= 8) {
|
|
ShiftBytes(br);
|
|
}
|
|
}
|
|
} else {
|
|
br->error_ = 1;
|
|
}
|
|
return val;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
|
} // extern "C"
|
|
#endif
|