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
23 extern "C" {
24 #endif
25
26 // Main color cache struct.
27 typedef struct {
28 uint32_t *colors_; // color entries
29 int hash_shift_; // Hash shift: 32 - hash_bits_.
30 int hash_bits_;
31 } VP8LColorCache;
32
33 static const uint64_t kHashMul = 0x1e35a7bdull;
34
VP8LHashPix(uint32_t argb,int shift)35 static WEBP_INLINE int VP8LHashPix(uint32_t argb, int shift) {
36 return (int)(((argb * kHashMul) & 0xffffffffu) >> shift);
37 }
38
VP8LColorCacheLookup(const VP8LColorCache * const cc,uint32_t key)39 static 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
VP8LColorCacheSet(const VP8LColorCache * const cc,uint32_t key,uint32_t argb)45 static 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
VP8LColorCacheInsert(const VP8LColorCache * const cc,uint32_t argb)51 static 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
VP8LColorCacheGetIndex(const VP8LColorCache * const cc,uint32_t argb)57 static 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.
VP8LColorCacheContains(const VP8LColorCache * const cc,uint32_t argb)63 static 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.
73 int VP8LColorCacheInit(VP8LColorCache* const color_cache, int hash_bits);
74
75 void VP8LColorCacheCopy(const VP8LColorCache* const src,
76 VP8LColorCache* const dst);
77
78 // Delete the memory associated to color cache.
79 void VP8LColorCacheClear(VP8LColorCache* const color_cache);
80
81 //------------------------------------------------------------------------------
82
83 #ifdef __cplusplus
84 }
85 #endif
86
87 #endif // WEBP_UTILS_COLOR_CACHE_UTILS_H_
88