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Use sort.Sort to sort Huffman trees.

This commit is contained in:
Andy Balholm 2020-05-07 17:51:21 -07:00
parent 7c7a5a10ef
commit 6b5963335e
2 changed files with 19 additions and 61 deletions
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11
brotli_bit_stream.go
View File

@ -1,6 +1,9 @@
package brotli
import "math"
import (
"math"
"sort"
)
const maxHuffmanTreeSize = (2*numCommandSymbols + 1)
@ -411,10 +414,6 @@ func buildAndStoreHuffmanTree(histogram []uint32, histogram_length uint, alphabe
}
}
func sortHuffmanTree1(v0 huffmanTree, v1 huffmanTree) bool {
return v0.total_count_ < v1.total_count_
}
func buildAndStoreHuffmanTreeFast(histogram []uint32, histogram_total uint, max_bits uint, depth []byte, bits []uint16, storage_ix *uint, storage []byte) {
var count uint = 0
var symbols = [4]uint{0}
@ -471,7 +470,7 @@ func buildAndStoreHuffmanTreeFast(histogram []uint32, histogram_total uint, max_
var j int = n + 1
var k int
sortHuffmanTreeItems(tree, uint(n), huffmanTreeComparator(sortHuffmanTree1))
sort.Sort(sortHuffmanTree(tree[:n]))
/* The nodes are:
[0, n): the sorted leaf nodes that we start with.

69
entropy_encode.go
View File

@ -1,6 +1,9 @@
package brotli
import "math"
import (
"math"
"sort"
)
/* Copyright 2010 Google Inc. All Rights Reserved.
@ -23,55 +26,6 @@ func initHuffmanTree(self *huffmanTree, count uint32, left int16, right int16) {
self.index_right_or_value_ = right
}
/* Input size optimized Shell sort. */
type huffmanTreeComparator func(huffmanTree, huffmanTree) bool
var sortHuffmanTreeItems_gaps = []uint{132, 57, 23, 10, 4, 1}
func sortHuffmanTreeItems(items []huffmanTree, n uint, comparator huffmanTreeComparator) {
if n < 13 {
/* Insertion sort. */
var i uint
for i = 1; i < n; i++ {
var tmp huffmanTree = items[i]
var k uint = i
var j uint = i - 1
for comparator(tmp, items[j]) {
items[k] = items[j]
k = j
if j == 0 {
break
}
j--
}
items[k] = tmp
}
return
} else {
var g int
if n < 57 {
g = 2
} else {
g = 0
}
for ; g < 6; g++ {
var gap uint = sortHuffmanTreeItems_gaps[g]
var i uint
for i = gap; i < n; i++ {
var j uint = i
var tmp huffmanTree = items[i]
for ; j >= gap && comparator(tmp, items[j-gap]); j -= gap {
items[j] = items[j-gap]
}
items[j] = tmp
}
}
}
}
/* Returns 1 if assignment of depths succeeded, otherwise 0. */
func setDepth(p0 int, pool []huffmanTree, depth []byte, max_depth int) bool {
var stack [16]int
@ -104,12 +58,17 @@ func setDepth(p0 int, pool []huffmanTree, depth []byte, max_depth int) bool {
}
/* Sort the root nodes, least popular first. */
func sortHuffmanTree(v0 huffmanTree, v1 huffmanTree) bool {
if v0.total_count_ != v1.total_count_ {
return v0.total_count_ < v1.total_count_
type sortHuffmanTree []huffmanTree
func (s sortHuffmanTree) Len() int { return len(s) }
func (s sortHuffmanTree) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s sortHuffmanTree) Less(i, j int) bool {
if s[i].total_count_ != s[j].total_count_ {
return s[i].total_count_ < s[j].total_count_
}
return v0.index_right_or_value_ > v1.index_right_or_value_
return s[i].index_right_or_value_ > s[j].index_right_or_value_
}
/* This function will create a Huffman tree.
@ -155,7 +114,7 @@ func createHuffmanTree(data []uint32, length uint, tree_limit int, tree []huffma
break
}
sortHuffmanTreeItems(tree, n, huffmanTreeComparator(sortHuffmanTree))
sort.Sort(sortHuffmanTree(tree[:n]))
/* The nodes are:
[0, n): the sorted leaf nodes that we start with.