1 // Copyright 2012 Google Inc. All Rights Reserved. 2 // 3 // This code is licensed under the same terms as WebM: 4 // Software License Agreement: http://www.webmproject.org/license/software/ 5 // Additional IP Rights Grant: http://www.webmproject.org/license/additional/ 6 // ----------------------------------------------------------------------------- 7 // 8 // Color Cache for WebP Lossless 9 // 10 // Authors: Jyrki Alakuijala (jyrki@google.com) 11 // Urvang Joshi (urvang@google.com) 12 13 #ifndef WEBP_UTILS_COLOR_CACHE_H_ 14 #define WEBP_UTILS_COLOR_CACHE_H_ 15 16 #include "webp/types.h" 17 18 #if defined(__cplusplus) || defined(c_plusplus) 19 extern "C" { 20 #endif 21 22 // Main color cache struct. 23 typedef struct { 24 uint32_t *colors_; // color entries 25 int hash_shift_; // Hash shift: 32 - hash_bits. 26 } VP8LColorCache; 27 28 static const uint32_t kHashMul = 0x1e35a7bd; 29 VP8LColorCacheLookup(const VP8LColorCache * const cc,uint32_t key)30static WEBP_INLINE uint32_t VP8LColorCacheLookup( 31 const VP8LColorCache* const cc, uint32_t key) { 32 assert(key <= (~0U >> cc->hash_shift_)); 33 return cc->colors_[key]; 34 } 35 VP8LColorCacheInsert(const VP8LColorCache * const cc,uint32_t argb)36static WEBP_INLINE void VP8LColorCacheInsert(const VP8LColorCache* const cc, 37 uint32_t argb) { 38 const uint32_t key = (kHashMul * argb) >> cc->hash_shift_; 39 cc->colors_[key] = argb; 40 } 41 VP8LColorCacheGetIndex(const VP8LColorCache * const cc,uint32_t argb)42static WEBP_INLINE int VP8LColorCacheGetIndex(const VP8LColorCache* const cc, 43 uint32_t argb) { 44 return (kHashMul * argb) >> cc->hash_shift_; 45 } 46 VP8LColorCacheContains(const VP8LColorCache * const cc,uint32_t argb)47static WEBP_INLINE int VP8LColorCacheContains(const VP8LColorCache* const cc, 48 uint32_t argb) { 49 const uint32_t key = (kHashMul * argb) >> cc->hash_shift_; 50 return cc->colors_[key] == argb; 51 } 52 53 //------------------------------------------------------------------------------ 54 55 // Initializes the color cache with 'hash_bits' bits for the keys. 56 // Returns false in case of memory error. 57 int VP8LColorCacheInit(VP8LColorCache* const color_cache, int hash_bits); 58 59 // Delete the memory associated to color cache. 60 void VP8LColorCacheClear(VP8LColorCache* const color_cache); 61 62 //------------------------------------------------------------------------------ 63 64 #if defined(__cplusplus) || defined(c_plusplus) 65 } 66 #endif 67 68 #endif // WEBP_UTILS_COLOR_CACHE_H_ 69