1// Copyright 2012 Google Inc. All Rights Reserved. 2// 3// Use of this source code is governed by a BSD-style license 4// that can be found in the COPYING file in the root of the source 5// tree. An additional intellectual property rights grant can be found 6// in the file PATENTS. All contributing project authors may 7// be found in the AUTHORS file in the root of the source tree. 8// ----------------------------------------------------------------------------- 9// 10// Color Cache for WebP Lossless 11// 12// Authors: Jyrki Alakuijala (jyrki@google.com) 13// Urvang Joshi (urvang@google.com) 14 15#ifndef WEBP_UTILS_COLOR_CACHE_UTILS_H_ 16#define WEBP_UTILS_COLOR_CACHE_UTILS_H_ 17 18#include <assert.h> 19 20#include "src/webp/types.h" 21 22#ifdef __cplusplus 23extern "C" { 24#endif 25 26// Main color cache struct. 27typedef struct { 28 uint32_t *colors_; // color entries 29 int hash_shift_; // Hash shift: 32 - hash_bits_. 30 int hash_bits_; 31} VP8LColorCache; 32 33static const uint64_t kHashMul = 0x1e35a7bdull; 34 35static WEBP_INLINE int VP8LHashPix(uint32_t argb, int shift) { 36 return (int)(((argb * kHashMul) & 0xffffffffu) >> shift); 37} 38 39static WEBP_INLINE uint32_t VP8LColorCacheLookup( 40 const VP8LColorCache* const cc, uint32_t key) { 41 assert((key >> cc->hash_bits_) == 0u); 42 return cc->colors_[key]; 43} 44 45static WEBP_INLINE void VP8LColorCacheSet(const VP8LColorCache* const cc, 46 uint32_t key, uint32_t argb) { 47 assert((key >> cc->hash_bits_) == 0u); 48 cc->colors_[key] = argb; 49} 50 51static WEBP_INLINE void VP8LColorCacheInsert(const VP8LColorCache* const cc, 52 uint32_t argb) { 53 const int key = VP8LHashPix(argb, cc->hash_shift_); 54 cc->colors_[key] = argb; 55} 56 57static WEBP_INLINE int VP8LColorCacheGetIndex(const VP8LColorCache* const cc, 58 uint32_t argb) { 59 return VP8LHashPix(argb, cc->hash_shift_); 60} 61 62// Return the key if cc contains argb, and -1 otherwise. 63static WEBP_INLINE int VP8LColorCacheContains(const VP8LColorCache* const cc, 64 uint32_t argb) { 65 const int key = VP8LHashPix(argb, cc->hash_shift_); 66 return (cc->colors_[key] == argb) ? key : -1; 67} 68 69//------------------------------------------------------------------------------ 70 71// Initializes the color cache with 'hash_bits' bits for the keys. 72// Returns false in case of memory error. 73int VP8LColorCacheInit(VP8LColorCache* const color_cache, int hash_bits); 74 75void VP8LColorCacheCopy(const VP8LColorCache* const src, 76 VP8LColorCache* const dst); 77 78// Delete the memory associated to color cache. 79void VP8LColorCacheClear(VP8LColorCache* const color_cache); 80 81//------------------------------------------------------------------------------ 82 83#ifdef __cplusplus 84} 85#endif 86 87#endif // WEBP_UTILS_COLOR_CACHE_UTILS_H_ 88