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Diffstat (limited to 'src/main/jni/libwebp/enc/backward_references.h')
-rw-r--r-- | src/main/jni/libwebp/enc/backward_references.h | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/src/main/jni/libwebp/enc/backward_references.h b/src/main/jni/libwebp/enc/backward_references.h new file mode 100644 index 000000000..c2c81c56e --- /dev/null +++ b/src/main/jni/libwebp/enc/backward_references.h @@ -0,0 +1,212 @@ +// Copyright 2012 Google Inc. All Rights Reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the COPYING file in the root of the source +// tree. An additional intellectual property rights grant can be found +// in the file PATENTS. All contributing project authors may +// be found in the AUTHORS file in the root of the source tree. +// ----------------------------------------------------------------------------- +// +// Author: Jyrki Alakuijala (jyrki@google.com) +// + +#ifndef WEBP_ENC_BACKWARD_REFERENCES_H_ +#define WEBP_ENC_BACKWARD_REFERENCES_H_ + +#include <assert.h> +#include <stdlib.h> +#include "../webp/types.h" +#include "../webp/format_constants.h" + +#ifdef __cplusplus +extern "C" { +#endif + +// The spec allows 11, we use 9 bits to reduce memory consumption in encoding. +// Having 9 instead of 11 only removes about 0.25 % of compression density. +#define MAX_COLOR_CACHE_BITS 9 + +// Max ever number of codes we'll use: +#define PIX_OR_COPY_CODES_MAX \ + (NUM_LITERAL_CODES + NUM_LENGTH_CODES + (1 << MAX_COLOR_CACHE_BITS)) + +// ----------------------------------------------------------------------------- +// PixOrCopy + +enum Mode { + kLiteral, + kCacheIdx, + kCopy, + kNone +}; + +typedef struct { + // mode as uint8_t to make the memory layout to be exactly 8 bytes. + uint8_t mode; + uint16_t len; + uint32_t argb_or_distance; +} PixOrCopy; + +static WEBP_INLINE PixOrCopy PixOrCopyCreateCopy(uint32_t distance, + uint16_t len) { + PixOrCopy retval; + retval.mode = kCopy; + retval.argb_or_distance = distance; + retval.len = len; + return retval; +} + +static WEBP_INLINE PixOrCopy PixOrCopyCreateCacheIdx(int idx) { + PixOrCopy retval; + assert(idx >= 0); + assert(idx < (1 << MAX_COLOR_CACHE_BITS)); + retval.mode = kCacheIdx; + retval.argb_or_distance = idx; + retval.len = 1; + return retval; +} + +static WEBP_INLINE PixOrCopy PixOrCopyCreateLiteral(uint32_t argb) { + PixOrCopy retval; + retval.mode = kLiteral; + retval.argb_or_distance = argb; + retval.len = 1; + return retval; +} + +static WEBP_INLINE int PixOrCopyIsLiteral(const PixOrCopy* const p) { + return (p->mode == kLiteral); +} + +static WEBP_INLINE int PixOrCopyIsCacheIdx(const PixOrCopy* const p) { + return (p->mode == kCacheIdx); +} + +static WEBP_INLINE int PixOrCopyIsCopy(const PixOrCopy* const p) { + return (p->mode == kCopy); +} + +static WEBP_INLINE uint32_t PixOrCopyLiteral(const PixOrCopy* const p, + int component) { + assert(p->mode == kLiteral); + return (p->argb_or_distance >> (component * 8)) & 0xff; +} + +static WEBP_INLINE uint32_t PixOrCopyLength(const PixOrCopy* const p) { + return p->len; +} + +static WEBP_INLINE uint32_t PixOrCopyArgb(const PixOrCopy* const p) { + assert(p->mode == kLiteral); + return p->argb_or_distance; +} + +static WEBP_INLINE uint32_t PixOrCopyCacheIdx(const PixOrCopy* const p) { + assert(p->mode == kCacheIdx); + assert(p->argb_or_distance < (1U << MAX_COLOR_CACHE_BITS)); + return p->argb_or_distance; +} + +static WEBP_INLINE uint32_t PixOrCopyDistance(const PixOrCopy* const p) { + assert(p->mode == kCopy); + return p->argb_or_distance; +} + +// ----------------------------------------------------------------------------- +// VP8LHashChain + +#define HASH_BITS 18 +#define HASH_SIZE (1 << HASH_BITS) + +typedef struct VP8LHashChain VP8LHashChain; +struct VP8LHashChain { + // Stores the most recently added position with the given hash value. + int32_t hash_to_first_index_[HASH_SIZE]; + // chain_[pos] stores the previous position with the same hash value + // for every pixel in the image. + int32_t* chain_; + // This is the maximum size of the hash_chain that can be constructed. + // Typically this is the pixel count (width x height) for a given image. + int size_; +}; + +// Must be called first, to set size. +int VP8LHashChainInit(VP8LHashChain* const p, int size); +void VP8LHashChainClear(VP8LHashChain* const p); // release memory + +// ----------------------------------------------------------------------------- +// VP8LBackwardRefs (block-based backward-references storage) + +// maximum number of reference blocks the image will be segmented into +#define MAX_REFS_BLOCK_PER_IMAGE 16 + +typedef struct PixOrCopyBlock PixOrCopyBlock; // forward declaration +typedef struct VP8LBackwardRefs VP8LBackwardRefs; + +// Container for blocks chain +struct VP8LBackwardRefs { + int block_size_; // common block-size + int error_; // set to true if some memory error occurred + PixOrCopyBlock* refs_; // list of currently used blocks + PixOrCopyBlock** tail_; // for list recycling + PixOrCopyBlock* free_blocks_; // free-list + PixOrCopyBlock* last_block_; // used for adding new refs (internal) +}; + +// Initialize the object. 'block_size' is the common block size to store +// references (typically, width * height / MAX_REFS_BLOCK_PER_IMAGE). +void VP8LBackwardRefsInit(VP8LBackwardRefs* const refs, int block_size); +// Release memory for backward references. +void VP8LBackwardRefsClear(VP8LBackwardRefs* const refs); +// Copies the 'src' backward refs to the 'dst'. Returns 0 in case of error. +int VP8LBackwardRefsCopy(const VP8LBackwardRefs* const src, + VP8LBackwardRefs* const dst); + +// Cursor for iterating on references content +typedef struct { + // public: + PixOrCopy* cur_pos; // current position + // private: + PixOrCopyBlock* cur_block_; // current block in the refs list + const PixOrCopy* last_pos_; // sentinel for switching to next block +} VP8LRefsCursor; + +// Returns a cursor positioned at the beginning of the references list. +VP8LRefsCursor VP8LRefsCursorInit(const VP8LBackwardRefs* const refs); +// Returns true if cursor is pointing at a valid position. +static WEBP_INLINE int VP8LRefsCursorOk(const VP8LRefsCursor* const c) { + return (c->cur_pos != NULL); +} +// Move to next block of references. Internal, not to be called directly. +void VP8LRefsCursorNextBlock(VP8LRefsCursor* const c); +// Move to next position, or NULL. Should not be called if !VP8LRefsCursorOk(). +static WEBP_INLINE void VP8LRefsCursorNext(VP8LRefsCursor* const c) { + assert(c != NULL); + assert(VP8LRefsCursorOk(c)); + if (++c->cur_pos == c->last_pos_) VP8LRefsCursorNextBlock(c); +} + +// ----------------------------------------------------------------------------- +// Main entry points + +// Evaluates best possible backward references for specified quality. +// Further optimize for 2D locality if use_2d_locality flag is set. +// The return value is the pointer to the best of the two backward refs viz, +// refs[0] or refs[1]. +VP8LBackwardRefs* VP8LGetBackwardReferences( + int width, int height, const uint32_t* const argb, int quality, + int cache_bits, int use_2d_locality, VP8LHashChain* const hash_chain, + VP8LBackwardRefs refs[2]); + +// Produce an estimate for a good color cache size for the image. +int VP8LCalculateEstimateForCacheSize(const uint32_t* const argb, + int xsize, int ysize, int quality, + VP8LHashChain* const hash_chain, + VP8LBackwardRefs* const ref, + int* const best_cache_bits); + +#ifdef __cplusplus +} +#endif + +#endif // WEBP_ENC_BACKWARD_REFERENCES_H_ |