mirror of
https://github.com/webmproject/libwebp.git
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69 lines
2.2 KiB
C
69 lines
2.2 KiB
C
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// Copyright 2012 Google Inc. All Rights Reserved.
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//
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// This code is licensed under the same terms as WebM:
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// Software License Agreement: http://www.webmproject.org/license/software/
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// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
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// -----------------------------------------------------------------------------
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//
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// Color Cache for WebP Lossless
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//
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// Authors: jyrki@google.com (Jyrki Alakuijala)
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// urvang@google.com (Urvang Joshi)
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#ifndef WEBP_UTILS_COLOR_CACHE_H_
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#define WEBP_UTILS_COLOR_CACHE_H_
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#include "../webp/types.h"
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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// Main color cache struct.
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typedef struct {
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uint32_t *colors_; // color entries
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int hash_shift_; // Hash shift: 32 - hash_bits.
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} VP8LColorCache;
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static const uint32_t kHashMul = 0x1e35a7bd;
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static WEBP_INLINE uint32_t VP8LColorCacheLookup(
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const VP8LColorCache* const cc, uint32_t key) {
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assert(key <= (~0U >> cc->hash_shift_));
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return cc->colors_[key];
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}
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static WEBP_INLINE void VP8LColorCacheInsert(const VP8LColorCache* const cc,
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uint32_t argb) {
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const uint32_t key = (kHashMul * argb) >> cc->hash_shift_;
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cc->colors_[key] = argb;
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}
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static WEBP_INLINE int VP8LColorCacheGetIndex(const VP8LColorCache* const cc,
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uint32_t argb) {
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return (kHashMul * argb) >> cc->hash_shift_;
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}
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static WEBP_INLINE int VP8LColorCacheContains(const VP8LColorCache* const cc,
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uint32_t argb) {
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const uint32_t key = (kHashMul * argb) >> cc->hash_shift_;
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return cc->colors_[key] == argb;
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}
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//------------------------------------------------------------------------------
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// Initializes the color cache with 'hash_bits' bits for the keys.
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// Returns false in case of memory error.
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int VP8LColorCacheInit(VP8LColorCache* const color_cache, int hash_bits);
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// Delete the color cache.
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void VP8LColorCacheDelete(VP8LColorCache* const color_cache);
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//------------------------------------------------------------------------------
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#if defined(__cplusplus) || defined(c_plusplus)
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}
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#endif
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#endif // WEBP_UTILS_COLOR_CACHE_H_
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