ee3cf211c6
Note that there are two Godot-specific changes made to libwebp for the javascript/HTML5 platform. They are documented in the README.md.
229 lines
6.9 KiB
C
229 lines
6.9 KiB
C
// Copyright 2010 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Boolean decoder non-inlined methods
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#ifdef HAVE_CONFIG_H
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#include "../webp/config.h"
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#endif
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#include "./bit_reader_inl.h"
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#include "../utils/utils.h"
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//------------------------------------------------------------------------------
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// VP8BitReader
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void VP8BitReaderSetBuffer(VP8BitReader* const br,
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const uint8_t* const start,
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size_t size) {
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br->buf_ = start;
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br->buf_end_ = start + size;
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br->buf_max_ =
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(size >= sizeof(lbit_t)) ? start + size - sizeof(lbit_t) + 1
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: start;
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}
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void VP8InitBitReader(VP8BitReader* const br,
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const uint8_t* const start, size_t size) {
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assert(br != NULL);
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assert(start != NULL);
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assert(size < (1u << 31)); // limit ensured by format and upstream checks
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br->range_ = 255 - 1;
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br->value_ = 0;
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br->bits_ = -8; // to load the very first 8bits
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br->eof_ = 0;
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VP8BitReaderSetBuffer(br, start, size);
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// -- GODOT -- begin
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#ifdef JAVASCRIPT_ENABLED // html5 required aligned reads
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while(((uintptr_t)br->buf_ & 1) != 0 && !br->eof_)
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VP8LoadFinalBytes(br);
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#else
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VP8LoadNewBytes(br);
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#endif
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// -- GODOT -- end
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}
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void VP8RemapBitReader(VP8BitReader* const br, ptrdiff_t offset) {
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if (br->buf_ != NULL) {
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br->buf_ += offset;
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br->buf_end_ += offset;
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br->buf_max_ += offset;
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}
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}
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const uint8_t kVP8Log2Range[128] = {
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7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
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3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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0
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};
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// range = ((range - 1) << kVP8Log2Range[range]) + 1
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const uint8_t kVP8NewRange[128] = {
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127, 127, 191, 127, 159, 191, 223, 127,
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143, 159, 175, 191, 207, 223, 239, 127,
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135, 143, 151, 159, 167, 175, 183, 191,
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199, 207, 215, 223, 231, 239, 247, 127,
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131, 135, 139, 143, 147, 151, 155, 159,
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163, 167, 171, 175, 179, 183, 187, 191,
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195, 199, 203, 207, 211, 215, 219, 223,
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227, 231, 235, 239, 243, 247, 251, 127,
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129, 131, 133, 135, 137, 139, 141, 143,
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145, 147, 149, 151, 153, 155, 157, 159,
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161, 163, 165, 167, 169, 171, 173, 175,
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177, 179, 181, 183, 185, 187, 189, 191,
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193, 195, 197, 199, 201, 203, 205, 207,
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209, 211, 213, 215, 217, 219, 221, 223,
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225, 227, 229, 231, 233, 235, 237, 239,
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241, 243, 245, 247, 249, 251, 253, 127
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};
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void VP8LoadFinalBytes(VP8BitReader* const br) {
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assert(br != NULL && br->buf_ != NULL);
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// Only read 8bits at a time
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if (br->buf_ < br->buf_end_) {
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br->bits_ += 8;
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br->value_ = (bit_t)(*br->buf_++) | (br->value_ << 8);
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} else if (!br->eof_) {
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br->value_ <<= 8;
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br->bits_ += 8;
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br->eof_ = 1;
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} else {
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br->bits_ = 0; // This is to avoid undefined behaviour with shifts.
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}
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}
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//------------------------------------------------------------------------------
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// Higher-level calls
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uint32_t VP8GetValue(VP8BitReader* const br, int bits) {
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uint32_t v = 0;
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while (bits-- > 0) {
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v |= VP8GetBit(br, 0x80) << bits;
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}
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return v;
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}
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int32_t VP8GetSignedValue(VP8BitReader* const br, int bits) {
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const int value = VP8GetValue(br, bits);
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return VP8Get(br) ? -value : value;
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}
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//------------------------------------------------------------------------------
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// VP8LBitReader
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#define VP8L_LOG8_WBITS 4 // Number of bytes needed to store VP8L_WBITS bits.
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#if defined(__arm__) || defined(_M_ARM) || defined(__aarch64__) || \
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defined(__i386__) || defined(_M_IX86) || \
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defined(__x86_64__) || defined(_M_X64)
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#define VP8L_USE_FAST_LOAD
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#endif
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static const uint32_t kBitMask[VP8L_MAX_NUM_BIT_READ + 1] = {
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0,
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0x000001, 0x000003, 0x000007, 0x00000f,
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0x00001f, 0x00003f, 0x00007f, 0x0000ff,
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0x0001ff, 0x0003ff, 0x0007ff, 0x000fff,
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0x001fff, 0x003fff, 0x007fff, 0x00ffff,
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0x01ffff, 0x03ffff, 0x07ffff, 0x0fffff,
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0x1fffff, 0x3fffff, 0x7fffff, 0xffffff
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};
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void VP8LInitBitReader(VP8LBitReader* const br, const uint8_t* const start,
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size_t length) {
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size_t i;
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vp8l_val_t value = 0;
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assert(br != NULL);
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assert(start != NULL);
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assert(length < 0xfffffff8u); // can't happen with a RIFF chunk.
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br->len_ = length;
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br->val_ = 0;
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br->bit_pos_ = 0;
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br->eos_ = 0;
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if (length > sizeof(br->val_)) {
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length = sizeof(br->val_);
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}
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for (i = 0; i < length; ++i) {
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value |= (vp8l_val_t)start[i] << (8 * i);
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}
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br->val_ = value;
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br->pos_ = length;
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br->buf_ = start;
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}
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void VP8LBitReaderSetBuffer(VP8LBitReader* const br,
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const uint8_t* const buf, size_t len) {
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assert(br != NULL);
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assert(buf != NULL);
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assert(len < 0xfffffff8u); // can't happen with a RIFF chunk.
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br->buf_ = buf;
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br->len_ = len;
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// pos_ > len_ should be considered a param error.
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br->eos_ = (br->pos_ > br->len_) || VP8LIsEndOfStream(br);
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}
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static void VP8LSetEndOfStream(VP8LBitReader* const br) {
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br->eos_ = 1;
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br->bit_pos_ = 0; // To avoid undefined behaviour with shifts.
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}
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// If not at EOS, reload up to VP8L_LBITS byte-by-byte
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static void ShiftBytes(VP8LBitReader* const br) {
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while (br->bit_pos_ >= 8 && br->pos_ < br->len_) {
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br->val_ >>= 8;
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br->val_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (VP8L_LBITS - 8);
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++br->pos_;
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br->bit_pos_ -= 8;
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}
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if (VP8LIsEndOfStream(br)) {
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VP8LSetEndOfStream(br);
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}
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}
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void VP8LDoFillBitWindow(VP8LBitReader* const br) {
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assert(br->bit_pos_ >= VP8L_WBITS);
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#if defined(VP8L_USE_FAST_LOAD)
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if (br->pos_ + sizeof(br->val_) < br->len_) {
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br->val_ >>= VP8L_WBITS;
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br->bit_pos_ -= VP8L_WBITS;
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br->val_ |= (vp8l_val_t)HToLE32(WebPMemToUint32(br->buf_ + br->pos_)) <<
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(VP8L_LBITS - VP8L_WBITS);
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br->pos_ += VP8L_LOG8_WBITS;
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return;
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}
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#endif
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ShiftBytes(br); // Slow path.
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}
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uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) {
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assert(n_bits >= 0);
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// Flag an error if end_of_stream or n_bits is more than allowed limit.
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if (!br->eos_ && n_bits <= VP8L_MAX_NUM_BIT_READ) {
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const uint32_t val = VP8LPrefetchBits(br) & kBitMask[n_bits];
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const int new_bits = br->bit_pos_ + n_bits;
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br->bit_pos_ = new_bits;
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ShiftBytes(br);
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return val;
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} else {
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VP8LSetEndOfStream(br);
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return 0;
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}
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}
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//------------------------------------------------------------------------------
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