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-rw-r--r--Godeps/_workspace/src/github.com/syndtr/gosnappy/snappy/encode.go258
1 files changed, 0 insertions, 258 deletions
diff --git a/Godeps/_workspace/src/github.com/syndtr/gosnappy/snappy/encode.go b/Godeps/_workspace/src/github.com/syndtr/gosnappy/snappy/encode.go
deleted file mode 100644
index dda372422..000000000
--- a/Godeps/_workspace/src/github.com/syndtr/gosnappy/snappy/encode.go
+++ /dev/null
@@ -1,258 +0,0 @@
-// Copyright 2011 The Snappy-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.
-
-package snappy
-
-import (
- "encoding/binary"
- "io"
-)
-
-// We limit how far copy back-references can go, the same as the C++ code.
-const maxOffset = 1 << 15
-
-// emitLiteral writes a literal chunk and returns the number of bytes written.
-func emitLiteral(dst, lit []byte) int {
- i, n := 0, uint(len(lit)-1)
- switch {
- case n < 60:
- dst[0] = uint8(n)<<2 | tagLiteral
- i = 1
- case n < 1<<8:
- dst[0] = 60<<2 | tagLiteral
- dst[1] = uint8(n)
- i = 2
- case n < 1<<16:
- dst[0] = 61<<2 | tagLiteral
- dst[1] = uint8(n)
- dst[2] = uint8(n >> 8)
- i = 3
- case n < 1<<24:
- dst[0] = 62<<2 | tagLiteral
- dst[1] = uint8(n)
- dst[2] = uint8(n >> 8)
- dst[3] = uint8(n >> 16)
- i = 4
- case int64(n) < 1<<32:
- dst[0] = 63<<2 | tagLiteral
- dst[1] = uint8(n)
- dst[2] = uint8(n >> 8)
- dst[3] = uint8(n >> 16)
- dst[4] = uint8(n >> 24)
- i = 5
- default:
- panic("snappy: source buffer is too long")
- }
- if copy(dst[i:], lit) != len(lit) {
- panic("snappy: destination buffer is too short")
- }
- return i + len(lit)
-}
-
-// emitCopy writes a copy chunk and returns the number of bytes written.
-func emitCopy(dst []byte, offset, length int) int {
- i := 0
- for length > 0 {
- x := length - 4
- if 0 <= x && x < 1<<3 && offset < 1<<11 {
- dst[i+0] = uint8(offset>>8)&0x07<<5 | uint8(x)<<2 | tagCopy1
- dst[i+1] = uint8(offset)
- i += 2
- break
- }
-
- x = length
- if x > 1<<6 {
- x = 1 << 6
- }
- dst[i+0] = uint8(x-1)<<2 | tagCopy2
- dst[i+1] = uint8(offset)
- dst[i+2] = uint8(offset >> 8)
- i += 3
- length -= x
- }
- return i
-}
-
-// Encode returns the encoded form of src. The returned slice may be a sub-
-// slice of dst if dst was large enough to hold the entire encoded block.
-// Otherwise, a newly allocated slice will be returned.
-// It is valid to pass a nil dst.
-func Encode(dst, src []byte) ([]byte, error) {
- if n := MaxEncodedLen(len(src)); len(dst) < n {
- dst = make([]byte, n)
- }
-
- // The block starts with the varint-encoded length of the decompressed bytes.
- d := binary.PutUvarint(dst, uint64(len(src)))
-
- // Return early if src is short.
- if len(src) <= 4 {
- if len(src) != 0 {
- d += emitLiteral(dst[d:], src)
- }
- return dst[:d], nil
- }
-
- // Initialize the hash table. Its size ranges from 1<<8 to 1<<14 inclusive.
- const maxTableSize = 1 << 14
- shift, tableSize := uint(32-8), 1<<8
- for tableSize < maxTableSize && tableSize < len(src) {
- shift--
- tableSize *= 2
- }
- var table [maxTableSize]int
-
- // Iterate over the source bytes.
- var (
- s int // The iterator position.
- t int // The last position with the same hash as s.
- lit int // The start position of any pending literal bytes.
- )
- for s+3 < len(src) {
- // Update the hash table.
- b0, b1, b2, b3 := src[s], src[s+1], src[s+2], src[s+3]
- h := uint32(b0) | uint32(b1)<<8 | uint32(b2)<<16 | uint32(b3)<<24
- p := &table[(h*0x1e35a7bd)>>shift]
- // We need to to store values in [-1, inf) in table. To save
- // some initialization time, (re)use the table's zero value
- // and shift the values against this zero: add 1 on writes,
- // subtract 1 on reads.
- t, *p = *p-1, s+1
- // If t is invalid or src[s:s+4] differs from src[t:t+4], accumulate a literal byte.
- if t < 0 || s-t >= maxOffset || b0 != src[t] || b1 != src[t+1] || b2 != src[t+2] || b3 != src[t+3] {
- s++
- continue
- }
- // Otherwise, we have a match. First, emit any pending literal bytes.
- if lit != s {
- d += emitLiteral(dst[d:], src[lit:s])
- }
- // Extend the match to be as long as possible.
- s0 := s
- s, t = s+4, t+4
- for s < len(src) && src[s] == src[t] {
- s++
- t++
- }
- // Emit the copied bytes.
- d += emitCopy(dst[d:], s-t, s-s0)
- lit = s
- }
-
- // Emit any final pending literal bytes and return.
- if lit != len(src) {
- d += emitLiteral(dst[d:], src[lit:])
- }
- return dst[:d], nil
-}
-
-// MaxEncodedLen returns the maximum length of a snappy block, given its
-// uncompressed length.
-func MaxEncodedLen(srcLen int) int {
- // Compressed data can be defined as:
- // compressed := item* literal*
- // item := literal* copy
- //
- // The trailing literal sequence has a space blowup of at most 62/60
- // since a literal of length 60 needs one tag byte + one extra byte
- // for length information.
- //
- // Item blowup is trickier to measure. Suppose the "copy" op copies
- // 4 bytes of data. Because of a special check in the encoding code,
- // we produce a 4-byte copy only if the offset is < 65536. Therefore
- // the copy op takes 3 bytes to encode, and this type of item leads
- // to at most the 62/60 blowup for representing literals.
- //
- // Suppose the "copy" op copies 5 bytes of data. If the offset is big
- // enough, it will take 5 bytes to encode the copy op. Therefore the
- // worst case here is a one-byte literal followed by a five-byte copy.
- // That is, 6 bytes of input turn into 7 bytes of "compressed" data.
- //
- // This last factor dominates the blowup, so the final estimate is:
- return 32 + srcLen + srcLen/6
-}
-
-// NewWriter returns a new Writer that compresses to w, using the framing
-// format described at
-// https://code.google.com/p/snappy/source/browse/trunk/framing_format.txt
-func NewWriter(w io.Writer) *Writer {
- return &Writer{
- w: w,
- enc: make([]byte, MaxEncodedLen(maxUncompressedChunkLen)),
- }
-}
-
-// Writer is an io.Writer than can write Snappy-compressed bytes.
-type Writer struct {
- w io.Writer
- err error
- enc []byte
- buf [checksumSize + chunkHeaderSize]byte
- wroteHeader bool
-}
-
-// Reset discards the writer's state and switches the Snappy writer to write to
-// w. This permits reusing a Writer rather than allocating a new one.
-func (w *Writer) Reset(writer io.Writer) {
- w.w = writer
- w.err = nil
- w.wroteHeader = false
-}
-
-// Write satisfies the io.Writer interface.
-func (w *Writer) Write(p []byte) (n int, errRet error) {
- if w.err != nil {
- return 0, w.err
- }
- if !w.wroteHeader {
- copy(w.enc, magicChunk)
- if _, err := w.w.Write(w.enc[:len(magicChunk)]); err != nil {
- w.err = err
- return n, err
- }
- w.wroteHeader = true
- }
- for len(p) > 0 {
- var uncompressed []byte
- if len(p) > maxUncompressedChunkLen {
- uncompressed, p = p[:maxUncompressedChunkLen], p[maxUncompressedChunkLen:]
- } else {
- uncompressed, p = p, nil
- }
- checksum := crc(uncompressed)
-
- // Compress the buffer, discarding the result if the improvement
- // isn't at least 12.5%.
- chunkType := uint8(chunkTypeCompressedData)
- chunkBody, err := Encode(w.enc, uncompressed)
- if err != nil {
- w.err = err
- return n, err
- }
- if len(chunkBody) >= len(uncompressed)-len(uncompressed)/8 {
- chunkType, chunkBody = chunkTypeUncompressedData, uncompressed
- }
-
- chunkLen := 4 + len(chunkBody)
- w.buf[0] = chunkType
- w.buf[1] = uint8(chunkLen >> 0)
- w.buf[2] = uint8(chunkLen >> 8)
- w.buf[3] = uint8(chunkLen >> 16)
- w.buf[4] = uint8(checksum >> 0)
- w.buf[5] = uint8(checksum >> 8)
- w.buf[6] = uint8(checksum >> 16)
- w.buf[7] = uint8(checksum >> 24)
- if _, err = w.w.Write(w.buf[:]); err != nil {
- w.err = err
- return n, err
- }
- if _, err = w.w.Write(chunkBody); err != nil {
- w.err = err
- return n, err
- }
- n += len(uncompressed)
- }
- return n, nil
-}