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