mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-23 20:26:39 +00:00
59 lines
1.1 KiB
Go
59 lines
1.1 KiB
Go
|
// Copyright 2011 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.
|
||
|
|
|
||
|
|
package tiff
|
||
|
|
|
||
|
|
import (
|
||
|
|
"bufio"
|
||
|
|
"io"
|
||
|
|
)
|
||
|
|
|
||
|
|
type byteReader interface {
|
||
|
|
io.Reader
|
||
|
|
io.ByteReader
|
||
|
|
}
|
||
|
|
|
||
|
|
// unpackBits decodes the PackBits-compressed data in src and returns the
|
||
|
|
// uncompressed data.
|
||
|
|
//
|
||
|
|
// The PackBits compression format is described in section 9 (p. 42)
|
||
|
|
// of the TIFF spec.
|
||
|
|
func unpackBits(r io.Reader) ([]byte, error) {
|
||
|
|
buf := make([]byte, 128)
|
||
|
|
dst := make([]byte, 0, 1024)
|
||
|
|
br, ok := r.(byteReader)
|
||
|
|
if !ok {
|
||
|
|
br = bufio.NewReader(r)
|
||
|
|
}
|
||
|
|
|
||
|
|
for {
|
||
|
|
b, err := br.ReadByte()
|
||
|
|
if err != nil {
|
||
|
|
if err == io.EOF {
|
||
|
|
return dst, nil
|
||
|
|
}
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
code := int(int8(b))
|
||
|
|
switch {
|
||
|
|
case code >= 0:
|
||
|
|
n, err := io.ReadFull(br, buf[:code+1])
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
dst = append(dst, buf[:n]...)
|
||
|
|
case code == -128:
|
||
|
|
// No-op.
|
||
|
|
default:
|
||
|
|
if b, err = br.ReadByte(); err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
for j := 0; j < 1-code; j++ {
|
||
|
|
buf[j] = b
|
||
|
|
}
|
||
|
|
dst = append(dst, buf[:1-code]...)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|