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Diffstat (limited to 'third_party/libwebp/dec/bits.h')
-rw-r--r-- | third_party/libwebp/dec/bits.h | 107 |
1 files changed, 0 insertions, 107 deletions
diff --git a/third_party/libwebp/dec/bits.h b/third_party/libwebp/dec/bits.h deleted file mode 100644 index 82e4c3a..0000000 --- a/third_party/libwebp/dec/bits.h +++ /dev/null @@ -1,107 +0,0 @@ -// Copyright 2010 Google Inc. -// -// 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) - -#ifndef WEBP_DEC_BITS_H_ -#define WEBP_DEC_BITS_H_ - -#include <assert.h> -#include "webp/decode_vp8.h" - -#if defined(__cplusplus) || defined(c_plusplus) -extern "C" { -#endif - -//----------------------------------------------------------------------------- -// Bitreader and code-tree reader - -typedef struct { - const uint8_t* buf_; // next byte to be read - const uint8_t* buf_end_; // end of read buffer - int eof_; // true if input is exhausted - - // boolean decoder - uint32_t range_; // current range minus 1. In [127, 254] interval. - uint32_t value_; // current value - int missing_; // number of missing bits in value_ (8bit) -} VP8BitReader; - -// Initialize the bit reader and the boolean decoder. -void VP8InitBitReader(VP8BitReader* const br, - const uint8_t* const start, const uint8_t* const end); - -// return the next value made of 'num_bits' bits -uint32_t VP8GetValue(VP8BitReader* const br, int num_bits); -static inline uint32_t VP8Get(VP8BitReader* const br) { - return VP8GetValue(br, 1); -} - -// return the next value with sign-extension. -int32_t VP8GetSignedValue(VP8BitReader* const br, int num_bits); - -// Read a bit with proba 'prob'. Speed-critical function! -extern const uint8_t kVP8Log2Range[128]; -extern const uint8_t kVP8NewRange[128]; -static inline uint32_t VP8GetByte(VP8BitReader* const br) { - assert(br); - if (br->buf_ < br->buf_end_) { - assert(br->buf_); - return *br->buf_++; - } - br->eof_ = 1; - return 0xff; -} - -static inline uint32_t VP8BitUpdate(VP8BitReader* const br, uint32_t split) { - uint32_t bit; - // Make sure we have a least 8 bits in 'value_' - if (br->missing_ > 0) { - br->value_ |= VP8GetByte(br) << br->missing_; - br->missing_ -= 8; - } - bit = ((br->value_ >> 8) > split); - if (bit) { - br->range_ -= split + 1; - br->value_ -= (split + 1) << 8; - } else { - br->range_ = split; - } - return bit; -} - -static inline void VP8Shift(VP8BitReader* const br) { - // range_ is in [0..127] interval here. - const int shift = kVP8Log2Range[br->range_]; - br->range_ = kVP8NewRange[br->range_]; - br->value_ <<= shift; - br->missing_ += shift; -} - -static inline uint32_t VP8GetBit(VP8BitReader* const br, int prob) { - const uint32_t split = (br->range_ * prob) >> 8; - const uint32_t bit = VP8BitUpdate(br, split); - if (br->range_ < 0x7f) { - VP8Shift(br); - } - return bit; -} - -static inline int VP8GetSigned(VP8BitReader* const br, int v) { - const uint32_t split = br->range_ >> 1; - const uint32_t bit = VP8BitUpdate(br, split); - VP8Shift(br); - return bit ? -v : v; -} - -#if defined(__cplusplus) || defined(c_plusplus) -} // extern "C" -#endif - -#endif // WEBP_DEC_BITS_H_ |