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compress/flate: remove unused huffmanEncoder.generateChains.

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R=rsc, gri
CC=golang-dev
https://golang.org/cl/5577061
This commit is contained in:
Ivan Krasin 2012-01-27 09:52:58 -08:00 committed by Robert Griesemer
parent b79ba6a609
commit 903752f484
1 changed files with 0 additions and 55 deletions
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55
src/pkg/compress/flate/huffman_code.go
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@ -121,61 +121,6 @@ func (h *huffmanEncoder) bitLength(freq []int32) int64 {
return total return total
} }
// Generate elements in the chain using an iterative algorithm.
func (h *huffmanEncoder) generateChains(top *levelInfo, list []literalNode) {
n := len(list)
list = list[0 : n+1]
list[n] = maxNode()
l := top
for {
if l.nextPairFreq == math.MaxInt32 && l.nextCharFreq == math.MaxInt32 {
// We've run out of both leafs and pairs.
// End all calculations for this level.
// To m sure we never come back to this level or any lower level,
// set nextPairFreq impossibly large.
l.lastChain = nil
l.needed = 0
l = l.up
l.nextPairFreq = math.MaxInt32
continue
}
prevFreq := l.lastChain.freq
if l.nextCharFreq < l.nextPairFreq {
// The next item on this row is a leaf node.
n := l.lastChain.leafCount + 1
l.lastChain = &chain{l.nextCharFreq, n, l.lastChain.up}
l.nextCharFreq = list[n].freq
} else {
// The next item on this row is a pair from the previous row.
// nextPairFreq isn't valid until we generate two
// more values in the level below
l.lastChain = &chain{l.nextPairFreq, l.lastChain.leafCount, l.down.lastChain}
l.down.needed = 2
}
if l.needed--; l.needed == 0 {
// We've done everything we need to do for this level.
// Continue calculating one level up. Fill in nextPairFreq
// of that level with the sum of the two nodes we've just calculated on
// this level.
up := l.up
if up == nil {
// All done!
return
}
up.nextPairFreq = prevFreq + l.lastChain.freq
l = up
} else {
// If we stole from below, move down temporarily to replenish it.
for l.down.needed > 0 {
l = l.down
}
}
}
}
// Return the number of literals assigned to each bit size in the Huffman encoding // Return the number of literals assigned to each bit size in the Huffman encoding
// //
// This method is only called when list.length >= 3 // This method is only called when list.length >= 3