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 (at) google.com) 13 // Urvang Joshi (urvang (at) 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 21 extern "C" { 22 #endif 23 24 // Main color cache struct. 25 typedef struct { 26 uint32_t *colors_; // color entries 27 int hash_shift_; // Hash shift: 32 - hash_bits. 28 } VP8LColorCache; 29 30 static const uint32_t kHashMul = 0x1e35a7bd; 31 32 static 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 38 static 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 44 static WEBP_INLINE int VP8LColorCacheGetIndex(const VP8LColorCache* const cc, 45 uint32_t argb) { 46 return (kHashMul * argb) >> cc->hash_shift_; 47 } 48 49 static 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. 59 int VP8LColorCacheInit(VP8LColorCache* const color_cache, int hash_bits); 60 61 // Delete the memory associated to color cache. 62 void VP8LColorCacheClear(VP8LColorCache* const color_cache); 63 64 //------------------------------------------------------------------------------ 65 66 #ifdef __cplusplus 67 } 68 #endif 69 70 #endif // WEBP_UTILS_COLOR_CACHE_H_ 71
