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- package brotli
- /* Copyright 2013 Google Inc. All Rights Reserved.
- Distributed under MIT license.
- See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
- */
- /* Functions for clustering similar histograms together. */
- type histogramPair struct {
- idx1 uint32
- idx2 uint32
- cost_combo float64
- cost_diff float64
- }
- func histogramPairIsLess(p1 *histogramPair, p2 *histogramPair) bool {
- if p1.cost_diff != p2.cost_diff {
- return p1.cost_diff > p2.cost_diff
- }
- return (p1.idx2 - p1.idx1) > (p2.idx2 - p2.idx1)
- }
- /* Returns entropy reduction of the context map when we combine two clusters. */
- func clusterCostDiff(size_a uint, size_b uint) float64 {
- var size_c uint = size_a + size_b
- return float64(size_a)*fastLog2(size_a) + float64(size_b)*fastLog2(size_b) - float64(size_c)*fastLog2(size_c)
- }
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