diff options
Diffstat (limited to 'src/3rdparty/libwebp/src/utils/bit_reader.c')
-rw-r--r-- | src/3rdparty/libwebp/src/utils/bit_reader.c | 42 |
1 files changed, 29 insertions, 13 deletions
diff --git a/src/3rdparty/libwebp/src/utils/bit_reader.c b/src/3rdparty/libwebp/src/utils/bit_reader.c index 64503e6..45198e1 100644 --- a/src/3rdparty/libwebp/src/utils/bit_reader.c +++ b/src/3rdparty/libwebp/src/utils/bit_reader.c @@ -20,17 +20,26 @@ //------------------------------------------------------------------------------ // VP8BitReader +void VP8BitReaderSetBuffer(VP8BitReader* const br, + const uint8_t* const start, + size_t size) { + br->buf_ = start; + br->buf_end_ = start + size; + br->buf_max_ = + (size >= sizeof(lbit_t)) ? start + size - sizeof(lbit_t) + 1 + : start; +} + void VP8InitBitReader(VP8BitReader* const br, - const uint8_t* const start, const uint8_t* const end) { + const uint8_t* const start, size_t size) { assert(br != NULL); assert(start != NULL); - assert(start <= end); + assert(size < (1u << 31)); // limit ensured by format and upstream checks br->range_ = 255 - 1; - br->buf_ = start; - br->buf_end_ = end; br->value_ = 0; br->bits_ = -8; // to load the very first 8bits br->eof_ = 0; + VP8BitReaderSetBuffer(br, start, size); VP8LoadNewBytes(br); } @@ -38,6 +47,7 @@ void VP8RemapBitReader(VP8BitReader* const br, ptrdiff_t offset) { if (br->buf_ != NULL) { br->buf_ += offset; br->buf_end_ += offset; + br->buf_max_ += offset; } } @@ -54,7 +64,7 @@ const uint8_t kVP8Log2Range[128] = { }; // range = ((range - 1) << kVP8Log2Range[range]) + 1 -const range_t kVP8NewRange[128] = { +const uint8_t kVP8NewRange[128] = { 127, 127, 191, 127, 159, 191, 223, 127, 143, 159, 175, 191, 207, 223, 239, 127, 135, 143, 151, 159, 167, 175, 183, 191, @@ -83,6 +93,8 @@ void VP8LoadFinalBytes(VP8BitReader* const br) { br->value_ <<= 8; br->bits_ += 8; br->eof_ = 1; + } else { + br->bits_ = 0; // This is to avoid undefined behaviour with shifts. } } @@ -136,7 +148,6 @@ void VP8LInitBitReader(VP8LBitReader* const br, const uint8_t* const start, br->val_ = 0; br->bit_pos_ = 0; br->eos_ = 0; - br->error_ = 0; if (length > sizeof(br->val_)) { length = sizeof(br->val_); @@ -157,8 +168,12 @@ void VP8LBitReaderSetBuffer(VP8LBitReader* const br, br->buf_ = buf; br->len_ = len; // pos_ > len_ should be considered a param error. - br->error_ = (br->pos_ > br->len_); - br->eos_ = br->error_ || VP8LIsEndOfStream(br); + br->eos_ = (br->pos_ > br->len_) || VP8LIsEndOfStream(br); +} + +static void VP8LSetEndOfStream(VP8LBitReader* const br) { + br->eos_ = 1; + br->bit_pos_ = 0; // To avoid undefined behaviour with shifts. } // If not at EOS, reload up to VP8L_LBITS byte-by-byte @@ -169,7 +184,9 @@ static void ShiftBytes(VP8LBitReader* const br) { ++br->pos_; br->bit_pos_ -= 8; } - br->eos_ = VP8LIsEndOfStream(br); + if (VP8LIsEndOfStream(br)) { + VP8LSetEndOfStream(br); + } } void VP8LDoFillBitWindow(VP8LBitReader* const br) { @@ -182,7 +199,7 @@ void VP8LDoFillBitWindow(VP8LBitReader* const br) { 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_) << + br->val_ |= (vp8l_val_t)WebPMemToUint32(br->buf_ + br->pos_) << (VP8L_LBITS - VP8L_WBITS); br->pos_ += VP8L_LOG8_WBITS; return; @@ -195,14 +212,13 @@ 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 <= VP8L_MAX_NUM_BIT_READ) { - const uint32_t val = - (uint32_t)(br->val_ >> br->bit_pos_) & kBitMask[n_bits]; + const uint32_t val = VP8LPrefetchBits(br) & kBitMask[n_bits]; const int new_bits = br->bit_pos_ + n_bits; br->bit_pos_ = new_bits; ShiftBytes(br); return val; } else { - br->error_ = 1; + VP8LSetEndOfStream(br); return 0; } } |