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_H_ 16#define WEBP_UTILS_COLOR_CACHE_H_ 17 18#include "webp/types.h" 19 20#ifdef __cplusplus 21extern "C" { 22#endif 23 24// Main color cache struct. 25typedef struct { 26 uint32_t *colors_; // color entries 27 int hash_shift_; // Hash shift: 32 - hash_bits. 28} VP8LColorCache; 29 30static const uint32_t kHashMul = 0x1e35a7bd; 31 32static WEBP_INLINE uint32_t VP8LColorCacheLookup( 33 const VP8LColorCache* const cc, uint32_t key) { 34 assert(key <= (~0U >> cc->hash_shift_)); 35 return cc->colors_[key]; 36} 37 38static WEBP_INLINE void VP8LColorCacheInsert(const VP8LColorCache* const cc, 39 uint32_t argb) { 40 const uint32_t key = (kHashMul * argb) >> cc->hash_shift_; 41 cc->colors_[key] = argb; 42} 43 44static WEBP_INLINE int VP8LColorCacheGetIndex(const VP8LColorCache* const cc, 45 uint32_t argb) { 46 return (kHashMul * argb) >> cc->hash_shift_; 47} 48 49static WEBP_INLINE int VP8LColorCacheContains(const VP8LColorCache* const cc, 50 uint32_t argb) { 51 const uint32_t key = (kHashMul * argb) >> cc->hash_shift_; 52 return cc->colors_[key] == argb; 53} 54 55//------------------------------------------------------------------------------ 56 57// Initializes the color cache with 'hash_bits' bits for the keys. 58// Returns false in case of memory error. 59int VP8LColorCacheInit(VP8LColorCache* const color_cache, int hash_bits); 60 61// Delete the memory associated to color cache. 62void VP8LColorCacheClear(VP8LColorCache* const color_cache); 63 64//------------------------------------------------------------------------------ 65 66#ifdef __cplusplus 67} 68#endif 69 70#endif // WEBP_UTILS_COLOR_CACHE_H_ 71