Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(26)

Unified Diff: third_party/libwebp/utils/bit_reader.c

Issue 653803003: libwebp: update to 0.4.2-rc2 (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Created 6 years, 2 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View side-by-side diff with in-line comments
Download patch
« no previous file with comments | « third_party/libwebp/utils/bit_reader.h ('k') | third_party/libwebp/utils/bit_writer.c » ('j') | no next file with comments »
Expand Comments ('e') | Collapse Comments ('c') | Show Comments Hide Comments ('s')
Index: third_party/libwebp/utils/bit_reader.c
diff --git a/third_party/libwebp/utils/bit_reader.c b/third_party/libwebp/utils/bit_reader.c
index 87b4f462152f0bb5c12f741f5b36454a534547d2..64503e6b92e5f4cea30a80ceb833538a907a2af0 100644
--- a/third_party/libwebp/utils/bit_reader.c
+++ b/third_party/libwebp/utils/bit_reader.c
@@ -105,9 +105,7 @@ int32_t VP8GetSignedValue(VP8BitReader* const br, int bits) {
//------------------------------------------------------------------------------
// VP8LBitReader
-#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.
+#define VP8L_LOG8_WBITS 4 // Number of bytes needed to store VP8L_WBITS bits.
#if !defined(WEBP_FORCE_ALIGNED) && \
(defined(__arm__) || defined(_M_ARM) || defined(__aarch64__) || \
@@ -151,16 +149,6 @@ void VP8LInitBitReader(VP8LBitReader* const br, const uint8_t* const start,
br->buf_ = start;
}
-// Special version that assumes br->pos_ <= br_len_.
-static int IsEndOfStreamSpecial(const VP8LBitReader* const br) {
- assert(br->pos_ <= br->len_);
- return br->pos_ == br->len_ && br->bit_pos_ >= LBITS;
-}
-
-static int IsEndOfStream(const VP8LBitReader* const br) {
- return (br->pos_ > br->len_) || IsEndOfStreamSpecial(br);
-}
-
void VP8LBitReaderSetBuffer(VP8LBitReader* const br,
const uint8_t* const buf, size_t len) {
assert(br != NULL);
@@ -168,38 +156,39 @@ void VP8LBitReaderSetBuffer(VP8LBitReader* const br,
assert(len < 0xfffffff8u); // can't happen with a RIFF chunk.
br->buf_ = buf;
br->len_ = len;
- br->eos_ = IsEndOfStream(br);
+ // pos_ > len_ should be considered a param error.
+ br->error_ = (br->pos_ > br->len_);
+ br->eos_ = br->error_ || VP8LIsEndOfStream(br);
}
-// If not at EOS, reload up to LBITS byte-by-byte
+// If not at EOS, reload up to VP8L_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->val_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (VP8L_LBITS - 8);
++br->pos_;
br->bit_pos_ -= 8;
}
+ br->eos_ = VP8LIsEndOfStream(br);
}
-void VP8LFillBitWindow(VP8LBitReader* const br) {
- if (br->bit_pos_ >= WBITS) {
- // TODO(jzern): given the fixed read size it may be possible to force
- // alignment in this block.
+void VP8LDoFillBitWindow(VP8LBitReader* const br) {
+ assert(br->bit_pos_ >= VP8L_WBITS);
+ // TODO(jzern): given the fixed read size it may be possible to force
+ // alignment in this block.
#if defined(VP8L_USE_UNALIGNED_LOAD)
- 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_ |= (vp8l_val_t)*(const uint32_t*)(br->buf_ + br->pos_) <<
- (LBITS - WBITS);
- br->pos_ += LOG8_WBITS;
- return;
- }
-#endif
- ShiftBytes(br); // Slow path.
- br->eos_ = IsEndOfStreamSpecial(br);
+ if (br->pos_ + sizeof(br->val_) < br->len_) {
+ br->val_ >>= VP8L_WBITS;
+ br->bit_pos_ -= VP8L_WBITS;
+ // The expression below needs a little-endian arch to work correctly.
+ // This gives a large speedup for decoding speed.
+ br->val_ |= (vp8l_val_t)*(const uint32_t*)(br->buf_ + br->pos_) <<
+ (VP8L_LBITS - VP8L_WBITS);
+ br->pos_ += VP8L_LOG8_WBITS;
+ return;
}
+#endif
+ ShiftBytes(br); // Slow path.
}
uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) {
@@ -210,8 +199,6 @@ uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) {
(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.
- br->eos_ = IsEndOfStreamSpecial(br);
ShiftBytes(br);
return val;
} else {
« no previous file with comments | « third_party/libwebp/utils/bit_reader.h ('k') | third_party/libwebp/utils/bit_writer.c » ('j') | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698