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Diffstat (limited to 'drivers/webpold/enc/histogram.h')
-rw-r--r-- | drivers/webpold/enc/histogram.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/drivers/webpold/enc/histogram.h b/drivers/webpold/enc/histogram.h new file mode 100644 index 0000000000..5b5de25539 --- /dev/null +++ b/drivers/webpold/enc/histogram.h @@ -0,0 +1,115 @@ +// Copyright 2012 Google Inc. All Rights Reserved. +// +// This code is licensed under the same terms as WebM: +// Software License Agreement: http://www.webmproject.org/license/software/ +// Additional IP Rights Grant: http://www.webmproject.org/license/additional/ +// ----------------------------------------------------------------------------- +// +// Author: Jyrki Alakuijala (jyrki@google.com) +// +// Models the histograms of literal and distance codes. + +#ifndef WEBP_ENC_HISTOGRAM_H_ +#define WEBP_ENC_HISTOGRAM_H_ + +#include <assert.h> +#include <stddef.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> + +#include "./backward_references.h" +#include "../format_constants.h" +#include "../types.h" + +#if defined(__cplusplus) || defined(c_plusplus) +extern "C" { +#endif + +// A simple container for histograms of data. +typedef struct { + // literal_ contains green literal, palette-code and + // copy-length-prefix histogram + int literal_[PIX_OR_COPY_CODES_MAX]; + int red_[256]; + int blue_[256]; + int alpha_[256]; + // Backward reference prefix-code histogram. + int distance_[NUM_DISTANCE_CODES]; + int palette_code_bits_; + double bit_cost_; // cached value of VP8LHistogramEstimateBits(this) +} VP8LHistogram; + +// Collection of histograms with fixed capacity, allocated as one +// big memory chunk. Can be destroyed by simply calling 'free()'. +typedef struct { + int size; // number of slots currently in use + int max_size; // maximum capacity + VP8LHistogram** histograms; +} VP8LHistogramSet; + +// Create the histogram. +// +// The input data is the PixOrCopy data, which models the literals, stop +// codes and backward references (both distances and lengths). Also: if +// palette_code_bits is >= 0, initialize the histogram with this value. +void VP8LHistogramCreate(VP8LHistogram* const p, + const VP8LBackwardRefs* const refs, + int palette_code_bits); + +// Set the palette_code_bits and reset the stats. +void VP8LHistogramInit(VP8LHistogram* const p, int palette_code_bits); + +// Collect all the references into a histogram (without reset) +void VP8LHistogramStoreRefs(const VP8LBackwardRefs* const refs, + VP8LHistogram* const histo); + +// Allocate an array of pointer to histograms, allocated and initialized +// using 'cache_bits'. Return NULL in case of memory error. +VP8LHistogramSet* VP8LAllocateHistogramSet(int size, int cache_bits); + +// Accumulate a token 'v' into a histogram. +void VP8LHistogramAddSinglePixOrCopy(VP8LHistogram* const histo, + const PixOrCopy* const v); + +// Estimate how many bits the combined entropy of literals and distance +// approximately maps to. +double VP8LHistogramEstimateBits(const VP8LHistogram* const p); + +// This function estimates the cost in bits excluding the bits needed to +// represent the entropy code itself. +double VP8LHistogramEstimateBitsBulk(const VP8LHistogram* const p); + +static WEBP_INLINE void VP8LHistogramAdd(VP8LHistogram* const p, + const VP8LHistogram* const a) { + int i; + for (i = 0; i < PIX_OR_COPY_CODES_MAX; ++i) { + p->literal_[i] += a->literal_[i]; + } + for (i = 0; i < NUM_DISTANCE_CODES; ++i) { + p->distance_[i] += a->distance_[i]; + } + for (i = 0; i < 256; ++i) { + p->red_[i] += a->red_[i]; + p->blue_[i] += a->blue_[i]; + p->alpha_[i] += a->alpha_[i]; + } +} + +static WEBP_INLINE int VP8LHistogramNumCodes(const VP8LHistogram* const p) { + return 256 + NUM_LENGTH_CODES + + ((p->palette_code_bits_ > 0) ? (1 << p->palette_code_bits_) : 0); +} + +// Builds the histogram image. +int VP8LGetHistoImageSymbols(int xsize, int ysize, + const VP8LBackwardRefs* const refs, + int quality, int histogram_bits, int cache_bits, + VP8LHistogramSet* const image_in, + uint16_t* const histogram_symbols); + +#if defined(__cplusplus) || defined(c_plusplus) +} +#endif + +#endif // WEBP_ENC_HISTOGRAM_H_ |