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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Functions for clustering similar histograms together.
#ifndef LIB_JXL_ENC_CLUSTER_H_
#define LIB_JXL_ENC_CLUSTER_H_
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <vector>
#include "lib/jxl/base/common.h"
#include "lib/jxl/base/status.h"
#include "lib/jxl/enc_ans_params.h"
namespace jxl {
struct Histogram {
Histogram() {
total_count_ = 0;
entropy_ = 0.0;
}
void Clear() {
data_.clear();
total_count_ = 0;
}
void Add(size_t symbol) {
if (data_.size() <= symbol) {
data_.resize(DivCeil(symbol + 1, kRounding) * kRounding);
}
++data_[symbol];
++total_count_;
}
void AddHistogram(const Histogram& other) {
if (other.data_.size() > data_.size()) {
data_.resize(other.data_.size());
}
for (size_t i = 0; i < other.data_.size(); ++i) {
data_[i] += other.data_[i];
}
total_count_ += other.total_count_;
}
size_t alphabet_size() const {
for (int i = data_.size() - 1; i >= 0; --i) {
if (data_[i] > 0) {
return i + 1;
}
}
return 1;
}
StatusOr<float> PopulationCost() const;
float ShannonEntropy() const;
std::vector<ANSHistBin> data_;
size_t total_count_;
mutable float entropy_; // WARNING: not kept up-to-date.
static constexpr size_t kRounding = 8;
};
Status ClusterHistograms(const HistogramParams& params,
const std::vector<Histogram>& in,
size_t max_histograms, std::vector<Histogram>* out,
std::vector<uint32_t>* histogram_symbols);
} // namespace jxl
#endif // LIB_JXL_ENC_CLUSTER_H_