38 lines
1.1 KiB
Go
38 lines
1.1 KiB
Go
// Copyright 2014 The zappy Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// 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 SNAPPY-GO-LICENSE file.
|
|
|
|
package zappy
|
|
|
|
import (
|
|
"encoding/binary"
|
|
)
|
|
|
|
// We limit how far copy back-references can go, the same as the snappy C++
|
|
// code.
|
|
const maxOffset = 1 << 20
|
|
|
|
// emitCopy writes a copy chunk and returns the number of bytes written.
|
|
func emitCopy(dst []byte, offset, length int) (n int) {
|
|
n = binary.PutVarint(dst, int64(-length))
|
|
n += binary.PutUvarint(dst[n:], uint64(offset))
|
|
return
|
|
}
|
|
|
|
// emitLiteral writes a literal chunk and returns the number of bytes written.
|
|
func emitLiteral(dst, lit []byte) (n int) {
|
|
n = binary.PutVarint(dst, int64(len(lit)-1))
|
|
n += copy(dst[n:], lit)
|
|
return
|
|
}
|
|
|
|
// MaxEncodedLen returns the maximum length of a zappy block, given its
|
|
// uncompressed length.
|
|
func MaxEncodedLen(srcLen int) int {
|
|
return 10 + srcLen + (srcLen+1)/2
|
|
}
|