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Diffstat (limited to 'vendor/github.com/klauspost/compress/flate/gen.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/flate/gen.go | 265 |
1 files changed, 0 insertions, 265 deletions
diff --git a/vendor/github.com/klauspost/compress/flate/gen.go b/vendor/github.com/klauspost/compress/flate/gen.go deleted file mode 100644 index 154c89a488..0000000000 --- a/vendor/github.com/klauspost/compress/flate/gen.go +++ /dev/null @@ -1,265 +0,0 @@ -// Copyright 2012 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// +build ignore - -// This program generates fixedhuff.go -// Invoke as -// -// go run gen.go -output fixedhuff.go - -package main - -import ( - "bytes" - "flag" - "fmt" - "go/format" - "io/ioutil" - "log" -) - -var filename = flag.String("output", "fixedhuff.go", "output file name") - -const maxCodeLen = 16 - -// Note: the definition of the huffmanDecoder struct is copied from -// inflate.go, as it is private to the implementation. - -// chunk & 15 is number of bits -// chunk >> 4 is value, including table link - -const ( - huffmanChunkBits = 9 - huffmanNumChunks = 1 << huffmanChunkBits - huffmanCountMask = 15 - huffmanValueShift = 4 -) - -type huffmanDecoder struct { - min int // the minimum code length - chunks [huffmanNumChunks]uint32 // chunks as described above - links [][]uint32 // overflow links - linkMask uint32 // mask the width of the link table -} - -// Initialize Huffman decoding tables from array of code lengths. -// Following this function, h is guaranteed to be initialized into a complete -// tree (i.e., neither over-subscribed nor under-subscribed). The exception is a -// degenerate case where the tree has only a single symbol with length 1. Empty -// trees are permitted. -func (h *huffmanDecoder) init(bits []int) bool { - // Sanity enables additional runtime tests during Huffman - // table construction. It's intended to be used during - // development to supplement the currently ad-hoc unit tests. - const sanity = false - - if h.min != 0 { - *h = huffmanDecoder{} - } - - // Count number of codes of each length, - // compute min and max length. - var count [maxCodeLen]int - var min, max int - for _, n := range bits { - if n == 0 { - continue - } - if min == 0 || n < min { - min = n - } - if n > max { - max = n - } - count[n]++ - } - - // Empty tree. The decompressor.huffSym function will fail later if the tree - // is used. Technically, an empty tree is only valid for the HDIST tree and - // not the HCLEN and HLIT tree. However, a stream with an empty HCLEN tree - // is guaranteed to fail since it will attempt to use the tree to decode the - // codes for the HLIT and HDIST trees. Similarly, an empty HLIT tree is - // guaranteed to fail later since the compressed data section must be - // composed of at least one symbol (the end-of-block marker). - if max == 0 { - return true - } - - code := 0 - var nextcode [maxCodeLen]int - for i := min; i <= max; i++ { - code <<= 1 - nextcode[i] = code - code += count[i] - } - - // Check that the coding is complete (i.e., that we've - // assigned all 2-to-the-max possible bit sequences). - // Exception: To be compatible with zlib, we also need to - // accept degenerate single-code codings. See also - // TestDegenerateHuffmanCoding. - if code != 1<<uint(max) && !(code == 1 && max == 1) { - return false - } - - h.min = min - if max > huffmanChunkBits { - numLinks := 1 << (uint(max) - huffmanChunkBits) - h.linkMask = uint32(numLinks - 1) - - // create link tables - link := nextcode[huffmanChunkBits+1] >> 1 - h.links = make([][]uint32, huffmanNumChunks-link) - for j := uint(link); j < huffmanNumChunks; j++ { - reverse := int(reverseByte[j>>8]) | int(reverseByte[j&0xff])<<8 - reverse >>= uint(16 - huffmanChunkBits) - off := j - uint(link) - if sanity && h.chunks[reverse] != 0 { - panic("impossible: overwriting existing chunk") - } - h.chunks[reverse] = uint32(off<<huffmanValueShift | (huffmanChunkBits + 1)) - h.links[off] = make([]uint32, numLinks) - } - } - - for i, n := range bits { - if n == 0 { - continue - } - code := nextcode[n] - nextcode[n]++ - chunk := uint32(i<<huffmanValueShift | n) - reverse := int(reverseByte[code>>8]) | int(reverseByte[code&0xff])<<8 - reverse >>= uint(16 - n) - if n <= huffmanChunkBits { - for off := reverse; off < len(h.chunks); off += 1 << uint(n) { - // We should never need to overwrite - // an existing chunk. Also, 0 is - // never a valid chunk, because the - // lower 4 "count" bits should be - // between 1 and 15. - if sanity && h.chunks[off] != 0 { - panic("impossible: overwriting existing chunk") - } - h.chunks[off] = chunk - } - } else { - j := reverse & (huffmanNumChunks - 1) - if sanity && h.chunks[j]&huffmanCountMask != huffmanChunkBits+1 { - // Longer codes should have been - // associated with a link table above. - panic("impossible: not an indirect chunk") - } - value := h.chunks[j] >> huffmanValueShift - linktab := h.links[value] - reverse >>= huffmanChunkBits - for off := reverse; off < len(linktab); off += 1 << uint(n-huffmanChunkBits) { - if sanity && linktab[off] != 0 { - panic("impossible: overwriting existing chunk") - } - linktab[off] = chunk - } - } - } - - if sanity { - // Above we've sanity checked that we never overwrote - // an existing entry. Here we additionally check that - // we filled the tables completely. - for i, chunk := range h.chunks { - if chunk == 0 { - // As an exception, in the degenerate - // single-code case, we allow odd - // chunks to be missing. - if code == 1 && i%2 == 1 { - continue - } - panic("impossible: missing chunk") - } - } - for _, linktab := range h.links { - for _, chunk := range linktab { - if chunk == 0 { - panic("impossible: missing chunk") - } - } - } - } - - return true -} - -func main() { - flag.Parse() - - var h huffmanDecoder - var bits [288]int - initReverseByte() - for i := 0; i < 144; i++ { - bits[i] = 8 - } - for i := 144; i < 256; i++ { - bits[i] = 9 - } - for i := 256; i < 280; i++ { - bits[i] = 7 - } - for i := 280; i < 288; i++ { - bits[i] = 8 - } - h.init(bits[:]) - if h.links != nil { - log.Fatal("Unexpected links table in fixed Huffman decoder") - } - - var buf bytes.Buffer - - fmt.Fprintf(&buf, `// Copyright 2013 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file.`+"\n\n") - - fmt.Fprintln(&buf, "package flate") - fmt.Fprintln(&buf) - fmt.Fprintln(&buf, "// autogenerated by go run gen.go -output fixedhuff.go, DO NOT EDIT") - fmt.Fprintln(&buf) - fmt.Fprintln(&buf, "var fixedHuffmanDecoder = huffmanDecoder{") - fmt.Fprintf(&buf, "\t%d,\n", h.min) - fmt.Fprintln(&buf, "\t[huffmanNumChunks]uint32{") - for i := 0; i < huffmanNumChunks; i++ { - if i&7 == 0 { - fmt.Fprintf(&buf, "\t\t") - } else { - fmt.Fprintf(&buf, " ") - } - fmt.Fprintf(&buf, "0x%04x,", h.chunks[i]) - if i&7 == 7 { - fmt.Fprintln(&buf) - } - } - fmt.Fprintln(&buf, "\t},") - fmt.Fprintln(&buf, "\tnil, 0,") - fmt.Fprintln(&buf, "}") - - data, err := format.Source(buf.Bytes()) - if err != nil { - log.Fatal(err) - } - err = ioutil.WriteFile(*filename, data, 0644) - if err != nil { - log.Fatal(err) - } -} - -var reverseByte [256]byte - -func initReverseByte() { - for x := 0; x < 256; x++ { - var result byte - for i := uint(0); i < 8; i++ { - result |= byte(((x >> i) & 1) << (7 - i)) - } - reverseByte[x] = result - } -} |