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// 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 lzw
import (
"bytes"
"io"
"io/ioutil"
"runtime"
"strconv"
"strings"
"testing"
)
type lzwTest struct {
desc string
raw string
compressed string
err error
}
var lzwTests = []lzwTest{
{
"empty;LSB;8",
"",
"\x01\x01",
nil,
},
{
"empty;MSB;8",
"",
"\x80\x80",
nil,
},
{
"tobe;LSB;7",
"TOBEORNOTTOBEORTOBEORNOT",
"\x54\x4f\x42\x45\x4f\x52\x4e\x4f\x54\x82\x84\x86\x8b\x85\x87\x89\x81",
nil,
},
{
"tobe;LSB;8",
"TOBEORNOTTOBEORTOBEORNOT",
"\x54\x9e\x08\x29\xf2\x44\x8a\x93\x27\x54\x04\x12\x34\xb8\xb0\xe0\xc1\x84\x01\x01",
nil,
},
{
"tobe;MSB;7",
"TOBEORNOTTOBEORTOBEORNOT",
"\x54\x4f\x42\x45\x4f\x52\x4e\x4f\x54\x82\x84\x86\x8b\x85\x87\x89\x81",
nil,
},
{
"tobe;MSB;8",
"TOBEORNOTTOBEORTOBEORNOT",
"\x2a\x13\xc8\x44\x52\x79\x48\x9c\x4f\x2a\x40\xa0\x90\x68\x5c\x16\x0f\x09\x80\x80",
nil,
},
{
"tobe-truncated;LSB;8",
"TOBEORNOTTOBEORTOBEORNOT",
"\x54\x9e\x08\x29\xf2\x44\x8a\x93\x27\x54\x04",
io.ErrUnexpectedEOF,
},
// This example comes from http://en.wikipedia.org/wiki/Graphics_Interchange_Format.
{
"gif;LSB;8",
"\x28\xff\xff\xff\x28\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff",
"\x00\x51\xfc\x1b\x28\x70\xa0\xc1\x83\x01\x01",
nil,
},
// This example comes from http://compgroups.net/comp.lang.ruby/Decompressing-LZW-compression-from-PDF-file
{
"pdf;MSB;8",
"-----A---B",
"\x80\x0b\x60\x50\x22\x0c\x0c\x85\x01",
nil,
},
}
func TestReader(t *testing.T) {
var b bytes.Buffer
for _, tt := range lzwTests {
d := strings.Split(tt.desc, ";")
var order Order
switch d[1] {
case "LSB":
order = LSB
case "MSB":
order = MSB
default:
t.Errorf("%s: bad order %q", tt.desc, d[1])
}
litWidth, _ := strconv.Atoi(d[2])
rc := NewReader(strings.NewReader(tt.compressed), order, litWidth)
defer rc.Close()
b.Reset()
n, err := io.Copy(&b, rc)
if err != nil {
if err != tt.err {
t.Errorf("%s: io.Copy: %v want %v", tt.desc, err, tt.err)
}
continue
}
s := b.String()
if s != tt.raw {
t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.desc, n, s, len(tt.raw), tt.raw)
}
}
}
func benchmarkDecoder(b *testing.B, n int) {
b.StopTimer()
b.SetBytes(int64(n))
buf0, err := ioutil.ReadFile("../testdata/e.txt")
if err != nil {
b.Fatal(err)
}
if len(buf0) == 0 {
b.Fatalf("test file has no data")
}
compressed := new(bytes.Buffer)
w := NewWriter(compressed, LSB, 8)
for i := 0; i < n; i += len(buf0) {
if len(buf0) > n-i {
buf0 = buf0[:n-i]
}
w.Write(buf0)
}
w.Close()
buf1 := compressed.Bytes()
buf0, compressed, w = nil, nil, nil
runtime.GC()
b.StartTimer()
for i := 0; i < b.N; i++ {
io.Copy(ioutil.Discard, NewReader(bytes.NewReader(buf1), LSB, 8))
}
}
func BenchmarkDecoder1e4(b *testing.B) {
benchmarkDecoder(b, 1e4)
}
func BenchmarkDecoder1e5(b *testing.B) {
benchmarkDecoder(b, 1e5)
}
func BenchmarkDecoder1e6(b *testing.B) {
benchmarkDecoder(b, 1e6)
}
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