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
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 int hash_bits_;
29 } VP8LColorCache;
30
31 static const uint32_t kHashMul = 0x1e35a7bd;
32
VP8LColorCacheLookup(const VP8LColorCache * const cc,uint32_t key)33 static WEBP_INLINE uint32_t VP8LColorCacheLookup(
34 const VP8LColorCache* const cc, uint32_t key) {
35 assert((key >> cc->hash_bits_) == 0u);
36 return cc->colors_[key];
37 }
38
VP8LColorCacheSet(const VP8LColorCache * const cc,uint32_t key,uint32_t argb)39 static WEBP_INLINE void VP8LColorCacheSet(const VP8LColorCache* const cc,
40 uint32_t key, uint32_t argb) {
41 assert((key >> cc->hash_bits_) == 0u);
42 cc->colors_[key] = argb;
43 }
44
VP8LColorCacheInsert(const VP8LColorCache * const cc,uint32_t argb)45 static WEBP_INLINE void VP8LColorCacheInsert(const VP8LColorCache* const cc,
46 uint32_t argb) {
47 const uint32_t key = (kHashMul * argb) >> cc->hash_shift_;
48 cc->colors_[key] = argb;
49 }
50
VP8LColorCacheGetIndex(const VP8LColorCache * const cc,uint32_t argb)51 static WEBP_INLINE int VP8LColorCacheGetIndex(const VP8LColorCache* const cc,
52 uint32_t argb) {
53 return (kHashMul * argb) >> cc->hash_shift_;
54 }
55
VP8LColorCacheContains(const VP8LColorCache * const cc,uint32_t argb)56 static WEBP_INLINE int VP8LColorCacheContains(const VP8LColorCache* const cc,
57 uint32_t argb) {
58 const uint32_t key = (kHashMul * argb) >> cc->hash_shift_;
59 return (cc->colors_[key] == argb);
60 }
61
62 //------------------------------------------------------------------------------
63
64 // Initializes the color cache with 'hash_bits' bits for the keys.
65 // Returns false in case of memory error.
66 int VP8LColorCacheInit(VP8LColorCache* const color_cache, int hash_bits);
67
68 void VP8LColorCacheCopy(const VP8LColorCache* const src,
69 VP8LColorCache* const dst);
70
71 // Delete the memory associated to color cache.
72 void VP8LColorCacheClear(VP8LColorCache* const color_cache);
73
74 //------------------------------------------------------------------------------
75
76 #ifdef __cplusplus
77 }
78 #endif
79
80 #endif // WEBP_UTILS_COLOR_CACHE_H_
81