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 |
37 | int VP8LHashPix(uint32_t argb, int shift) { |
38 | return (int)((argb * kHashMul) >> shift); |
39 | } |
40 | |
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 | |
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 | |
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 | |
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. |
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 | |