libwebp-0.6.0-rc1

third_party/libwebp/enc/histogram.h

-// 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)
-//
-// Models the histograms of literal and distance codes.
-
-#ifndef WEBP_ENC_HISTOGRAM_H_
-#define WEBP_ENC_HISTOGRAM_H_
-
-#include <string.h>
-
-#include "./backward_references.h"
-#include "../webp/format_constants.h"
-#include "../webp/types.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-// Not a trivial literal symbol.
-#define VP8L_NON_TRIVIAL_SYM (0xffffffff)
-
-// A simple container for histograms of data.
-typedef struct {
-  // literal_ contains green literal, palette-code and
-  // copy-length-prefix histogram
-  uint32_t* literal_;         // Pointer to the allocated buffer for literal.
-  uint32_t red_[NUM_LITERAL_CODES];
-  uint32_t blue_[NUM_LITERAL_CODES];
-  uint32_t alpha_[NUM_LITERAL_CODES];
-  // Backward reference prefix-code histogram.
-  uint32_t distance_[NUM_DISTANCE_CODES];
-  int palette_code_bits_;
-  uint32_t trivial_symbol_;  // True, if histograms for Red, Blue & Alpha
-                             // literal symbols are single valued.
-  double bit_cost_;          // cached value of bit cost.
-  double literal_cost_;      // Cached values of dominant entropy costs:
-  double red_cost_;          // literal, red & blue.
-  double blue_cost_;
-} VP8LHistogram;
-
-// Collection of histograms with fixed capacity, allocated as one
-// big memory chunk. Can be destroyed by calling WebPSafeFree().
-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);
-
-// Return the size of the histogram for a given palette_code_bits.
-int VP8LGetHistogramSize(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);
-
-// Free the memory allocated for the histogram.
-void VP8LFreeHistogram(VP8LHistogram* const histo);
-
-// Free the memory allocated for the histogram set.
-void VP8LFreeHistogramSet(VP8LHistogramSet* 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);
-
-// Allocate and initialize histogram object with specified 'cache_bits'.
-// Returns NULL in case of memory error.
-// Special case of VP8LAllocateHistogramSet, with size equals 1.
-VP8LHistogram* VP8LAllocateHistogram(int cache_bits);
-
-// Accumulate a token 'v' into a histogram.
-void VP8LHistogramAddSinglePixOrCopy(VP8LHistogram* const histo,
-                                     const PixOrCopy* const v);
-
-static WEBP_INLINE int VP8LHistogramNumCodes(int palette_code_bits) {
-  return NUM_LITERAL_CODES + NUM_LENGTH_CODES +
-      ((palette_code_bits > 0) ? (1 << palette_code_bits) : 0);
-}
-
-// Builds the histogram image.
-int VP8LGetHistoImageSymbols(int xsize, int ysize,
-                             const VP8LBackwardRefs* const refs,
-                             int quality, int low_effort,
-                             int histogram_bits, int cache_bits,
-                             VP8LHistogramSet* const image_in,
-                             VP8LHistogramSet* const tmp_histos,
-                             uint16_t* const histogram_symbols);
-
-// Returns the entropy for the symbols in the input array.
-// Also sets trivial_symbol to the code value, if the array has only one code
-// value. Otherwise, set it to VP8L_NON_TRIVIAL_SYM.
-double VP8LBitsEntropy(const uint32_t* const array, int n,
-                       uint32_t* const trivial_symbol);
-
-// Estimate how many bits the combined entropy of literals and distance
-// approximately maps to.
-double VP8LHistogramEstimateBits(const VP8LHistogram* const p);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif  // WEBP_ENC_HISTOGRAM_H_