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/dsp/dsp.h"
21 #include "src/webp/types.h"
22
23 #ifdef __cplusplus
24 extern "C" {
25 #endif
26
27 // Main color cache struct.
28 typedef struct {
29 uint32_t* colors_; // color entries
30 int hash_shift_; // Hash shift: 32 - hash_bits_.
31 int hash_bits_;
32 } VP8LColorCache;
33
34 static const uint32_t kHashMul = 0x1e35a7bdu;
35
36 static WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW WEBP_INLINE
VP8LHashPix(uint32_t argb,int shift)37 int VP8LHashPix(uint32_t argb, int shift) {
38 return (int)((argb * kHashMul) >> shift);
39 }
40
VP8LColorCacheLookup(const VP8LColorCache * const cc,uint32_t key)41 static WEBP_INLINE uint32_t VP8LColorCacheLookup(
42 const VP8LColorCache* const cc, uint32_t key) {
43 assert((key >> cc->hash_bits_) == 0u);
44 return cc->colors_[key];
45 }
46
VP8LColorCacheSet(const VP8LColorCache * const cc,uint32_t key,uint32_t argb)47 static WEBP_INLINE void VP8LColorCacheSet(const VP8LColorCache* const cc,
48 uint32_t key, uint32_t argb) {
49 assert((key >> cc->hash_bits_) == 0u);
50 cc->colors_[key] = argb;
51 }
52
VP8LColorCacheInsert(const VP8LColorCache * const cc,uint32_t argb)53 static WEBP_INLINE void VP8LColorCacheInsert(const VP8LColorCache* const cc,
54 uint32_t argb) {
55 const int key = VP8LHashPix(argb, cc->hash_shift_);
56 cc->colors_[key] = argb;
57 }
58
VP8LColorCacheGetIndex(const VP8LColorCache * const cc,uint32_t argb)59 static WEBP_INLINE int VP8LColorCacheGetIndex(const VP8LColorCache* const cc,
60 uint32_t argb) {
61 return VP8LHashPix(argb, cc->hash_shift_);
62 }
63
64 // Return the key if cc contains argb, and -1 otherwise.
VP8LColorCacheContains(const VP8LColorCache * const cc,uint32_t argb)65 static WEBP_INLINE int VP8LColorCacheContains(const VP8LColorCache* const cc,
66 uint32_t argb) {
67 const int key = VP8LHashPix(argb, cc->hash_shift_);
68 return (cc->colors_[key] == argb) ? key : -1;
69 }
70
71 //------------------------------------------------------------------------------
72
73 // Initializes the color cache with 'hash_bits' bits for the keys.
74 // Returns false in case of memory error.
75 int VP8LColorCacheInit(VP8LColorCache* const color_cache, int hash_bits);
76
77 void VP8LColorCacheCopy(const VP8LColorCache* const src,
78 VP8LColorCache* const dst);
79
80 // Delete the memory associated to color cache.
81 void VP8LColorCacheClear(VP8LColorCache* const color_cache);
82
83 //------------------------------------------------------------------------------
84
85 #ifdef __cplusplus
86 }
87 #endif
88
89 #endif // WEBP_UTILS_COLOR_CACHE_UTILS_H_
90