220 lines
8.2 KiB
C
220 lines
8.2 KiB
C
// Copyright 2012 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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// Image transforms and color space conversion methods for lossless decoder.
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//
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// Authors: Vikas Arora (vikaas.arora@gmail.com)
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// Jyrki Alakuijala (jyrki@google.com)
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#ifndef WEBP_DSP_LOSSLESS_H_
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#define WEBP_DSP_LOSSLESS_H_
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#include "../webp/types.h"
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#include "../webp/decode.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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//------------------------------------------------------------------------------
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//
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typedef uint32_t (*VP8LPredClampedAddSubFunc)(uint32_t c0, uint32_t c1,
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uint32_t c2);
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typedef uint32_t (*VP8LPredSelectFunc)(uint32_t c0, uint32_t c1, uint32_t c2);
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typedef void (*VP8LSubtractGreenFromBlueAndRedFunc)(uint32_t* argb_data,
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int num_pixs);
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typedef void (*VP8LAddGreenToBlueAndRedFunc)(uint32_t* data_start,
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const uint32_t* data_end);
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extern VP8LPredClampedAddSubFunc VP8LClampedAddSubtractFull;
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extern VP8LPredClampedAddSubFunc VP8LClampedAddSubtractHalf;
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extern VP8LPredSelectFunc VP8LSelect;
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extern VP8LSubtractGreenFromBlueAndRedFunc VP8LSubtractGreenFromBlueAndRed;
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extern VP8LAddGreenToBlueAndRedFunc VP8LAddGreenToBlueAndRed;
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// Must be called before calling any of the above methods.
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void VP8LDspInit(void);
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//------------------------------------------------------------------------------
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// Image transforms.
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struct VP8LTransform; // Defined in dec/vp8li.h.
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// Performs inverse transform of data given transform information, start and end
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// rows. Transform will be applied to rows [row_start, row_end[.
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// The *in and *out pointers refer to source and destination data respectively
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// corresponding to the intermediate row (row_start).
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void VP8LInverseTransform(const struct VP8LTransform* const transform,
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int row_start, int row_end,
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const uint32_t* const in, uint32_t* const out);
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// Similar to the static method ColorIndexInverseTransform() that is part of
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// lossless.c, but used only for alpha decoding. It takes uint8_t (rather than
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// uint32_t) arguments for 'src' and 'dst'.
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void VP8LColorIndexInverseTransformAlpha(
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const struct VP8LTransform* const transform, int y_start, int y_end,
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const uint8_t* src, uint8_t* dst);
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void VP8LResidualImage(int width, int height, int bits,
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uint32_t* const argb, uint32_t* const argb_scratch,
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uint32_t* const image);
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void VP8LColorSpaceTransform(int width, int height, int bits, int step,
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uint32_t* const argb, uint32_t* image);
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//------------------------------------------------------------------------------
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// Color space conversion.
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// Converts from BGRA to other color spaces.
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void VP8LConvertFromBGRA(const uint32_t* const in_data, int num_pixels,
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WEBP_CSP_MODE out_colorspace, uint8_t* const rgba);
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//------------------------------------------------------------------------------
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// Misc methods.
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// Computes sampled size of 'size' when sampling using 'sampling bits'.
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static WEBP_INLINE uint32_t VP8LSubSampleSize(uint32_t size,
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uint32_t sampling_bits) {
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return (size + (1 << sampling_bits) - 1) >> sampling_bits;
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}
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// Faster logarithm for integers. Small values use a look-up table.
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#define LOG_LOOKUP_IDX_MAX 256
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extern const float kLog2Table[LOG_LOOKUP_IDX_MAX];
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extern const float kSLog2Table[LOG_LOOKUP_IDX_MAX];
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float VP8LFastLog2Slow(int v);
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float VP8LFastSLog2Slow(int v);
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static WEBP_INLINE float VP8LFastLog2(int v) {
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return (v < LOG_LOOKUP_IDX_MAX) ? kLog2Table[v] : VP8LFastLog2Slow(v);
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}
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// Fast calculation of v * log2(v) for integer input.
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static WEBP_INLINE float VP8LFastSLog2(int v) {
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return (v < LOG_LOOKUP_IDX_MAX) ? kSLog2Table[v] : VP8LFastSLog2Slow(v);
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}
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// -----------------------------------------------------------------------------
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// PrefixEncode()
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// use GNU builtins where available.
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#if defined(__GNUC__) && \
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((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
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static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
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return 31 ^ __builtin_clz(n);
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}
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#elif defined(_MSC_VER) && _MSC_VER > 1310 && \
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(defined(_M_X64) || defined(_M_IX86))
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#include <intrin.h>
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#pragma intrinsic(_BitScanReverse)
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static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
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unsigned long first_set_bit;
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_BitScanReverse(&first_set_bit, n);
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return first_set_bit;
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}
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#else
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// Returns (int)floor(log2(n)). n must be > 0.
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static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
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int log = 0;
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uint32_t value = n;
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int i;
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for (i = 4; i >= 0; --i) {
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const int shift = (1 << i);
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const uint32_t x = value >> shift;
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if (x != 0) {
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value = x;
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log += shift;
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}
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}
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return log;
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}
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#endif
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static WEBP_INLINE int VP8LBitsLog2Ceiling(uint32_t n) {
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const int log_floor = BitsLog2Floor(n);
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if (n == (n & ~(n - 1))) // zero or a power of two.
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return log_floor;
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else
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return log_floor + 1;
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}
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// Splitting of distance and length codes into prefixes and
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// extra bits. The prefixes are encoded with an entropy code
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// while the extra bits are stored just as normal bits.
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static WEBP_INLINE void VP8LPrefixEncodeBitsNoLUT(int distance, int* const code,
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int* const extra_bits) {
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const int highest_bit = BitsLog2Floor(--distance);
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const int second_highest_bit = (distance >> (highest_bit - 1)) & 1;
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*extra_bits = highest_bit - 1;
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*code = 2 * highest_bit + second_highest_bit;
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}
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static WEBP_INLINE void VP8LPrefixEncodeNoLUT(int distance, int* const code,
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int* const extra_bits,
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int* const extra_bits_value) {
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const int highest_bit = BitsLog2Floor(--distance);
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const int second_highest_bit = (distance >> (highest_bit - 1)) & 1;
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*extra_bits = highest_bit - 1;
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*extra_bits_value = distance & ((1 << *extra_bits) - 1);
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*code = 2 * highest_bit + second_highest_bit;
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}
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#define PREFIX_LOOKUP_IDX_MAX 512
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typedef struct {
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int8_t code_;
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int8_t extra_bits_;
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} VP8LPrefixCode;
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// These tables are derived using VP8LPrefixEncodeNoLUT.
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extern const VP8LPrefixCode kPrefixEncodeCode[PREFIX_LOOKUP_IDX_MAX];
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extern const uint8_t kPrefixEncodeExtraBitsValue[PREFIX_LOOKUP_IDX_MAX];
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static WEBP_INLINE void VP8LPrefixEncodeBits(int distance, int* const code,
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int* const extra_bits) {
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if (distance < PREFIX_LOOKUP_IDX_MAX) {
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const VP8LPrefixCode prefix_code = kPrefixEncodeCode[distance];
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*code = prefix_code.code_;
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*extra_bits = prefix_code.extra_bits_;
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} else {
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VP8LPrefixEncodeBitsNoLUT(distance, code, extra_bits);
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}
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}
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static WEBP_INLINE void VP8LPrefixEncode(int distance, int* const code,
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int* const extra_bits,
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int* const extra_bits_value) {
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if (distance < PREFIX_LOOKUP_IDX_MAX) {
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const VP8LPrefixCode prefix_code = kPrefixEncodeCode[distance];
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*code = prefix_code.code_;
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*extra_bits = prefix_code.extra_bits_;
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*extra_bits_value = kPrefixEncodeExtraBitsValue[distance];
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} else {
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VP8LPrefixEncodeNoLUT(distance, code, extra_bits, extra_bits_value);
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}
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}
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// In-place difference of each component with mod 256.
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static WEBP_INLINE uint32_t VP8LSubPixels(uint32_t a, uint32_t b) {
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const uint32_t alpha_and_green =
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0x00ff00ffu + (a & 0xff00ff00u) - (b & 0xff00ff00u);
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const uint32_t red_and_blue =
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0xff00ff00u + (a & 0x00ff00ffu) - (b & 0x00ff00ffu);
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return (alpha_and_green & 0xff00ff00u) | (red_and_blue & 0x00ff00ffu);
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}
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void VP8LBundleColorMap(const uint8_t* const row, int width,
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int xbits, uint32_t* const dst);
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//------------------------------------------------------------------------------
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif // WEBP_DSP_LOSSLESS_H_
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