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writer_test.go
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package nativewebp
import (
//------------------------------
//general
//------------------------------
"bytes"
"reflect"
//------------------------------
//imaging
//------------------------------
"image"
"image/color"
//------------------------------
//testing
//------------------------------
"testing"
)
func generateTestImageNRGBA(width int, height int, brightness float64, hasAlpha bool) image.Image {
dest := image.NewNRGBA(image.Rect(0, 0, width, height))
for y := 0; y < height; y++ {
for x := 0; x < width; x++ {
n := uint8(float64(x ^ y) * brightness)
var c color.Color
a := uint8(255)
if hasAlpha {
a = n
}
if y < height / 2 {
if x < width / 2 {
c = color.RGBA{n, 0, 0, a}
} else {
c = color.RGBA{0, n, 0, a}
}
} else {
if x < width / 2 {
c = color.RGBA{0, 0, n, a}
} else {
c = color.RGBA{n, n, 0, a}
}
}
dest.Set(x, y, c)
}
}
return dest
}
func TestWriteWebPHeader(t *testing.T) {
for id, tt := range []struct {
inputData []byte
expectedHeader []byte
}{
// Test case with an empty 'b' buffer
{
inputData: []byte{},
expectedHeader: []byte{
'R', 'I', 'F', 'F', // RIFF
0x0C, 0x00, 0x00, 0x00, // 12 in little-endian (12 + 0)
'W', 'E', 'B', 'P', // WEBP
'V', 'P', '8', 'L', // VP8L
0x00, 0x00, 0x00, 0x00, // 0 in little-endian (size of 'b' buffer)
},
},
// Test case with non-empty 'b' buffer
{
inputData: []byte{1, 2, 3, 4, 5},
expectedHeader: []byte{
'R', 'I', 'F', 'F', // RIFF
0x11, 0x00, 0x00, 0x00, // 12 in little-endian (12 + 5)
'W', 'E', 'B', 'P', // WEBP
'V', 'P', '8', 'L', // VP8L
0x05, 0x00, 0x00, 0x00, // 0 in little-endian (size of 'b' buffer)
},
},
}{
w := &bytes.Buffer{}
b := bytes.NewBuffer(tt.inputData)
writeWebPHeader(w, b)
if !bytes.Equal(w.Bytes(), tt.expectedHeader) {
t.Errorf("test %d: header mismatch expected: %v got: %v", id, tt.expectedHeader, w.Bytes())
continue
}
}
}
func TestWriteBitStreamHeader(t *testing.T) {
for id, tt := range []struct {
bounds image.Rectangle
hasAlpha bool
expectedBits []byte
}{
// Test case with no alpha channel
{
bounds: image.Rect(0, 0, 16, 16),
hasAlpha: false,
expectedBits: []byte{
0x2f, // Header prefix
0x0f, 0xc0, // Width - 1 (14 bits: 15) + first 6 bits of Height - 1
0x03, 0x00, // Remaining bits of Height - 1 (14 bits: 15) + no alpha + padding
},
},
// Test case with alpha channel
{
bounds: image.Rect(0, 0, 32, 32),
hasAlpha: true,
expectedBits: []byte{
0x2f, // Header prefix
0x1f, 0xc0, // Width - 1 (14 bits: 31) + first 6 bits of Height - 1
0x07, 0x10, // Remaining bits of Height - 1 (14 bits: 31) + alpha + padding
},
},
// Larger rectangle with no alpha
{
bounds: image.Rect(0, 0, 128, 64),
hasAlpha: false,
expectedBits: []byte{
0x2f, // Header prefix
0x7f, 0xc0, // Width - 1 (14 bits: 127) + first 6 bits of Height - 1
0x0f, 0x00, // Remaining bits of Height - 1 (14 bits: 63) + no alpha + padding
},
},
}{
buffer := &bytes.Buffer{}
writer := &bitWriter{
Buffer: buffer,
BitBuffer: 0,
BitBufferSize: 0,
}
writeBitStreamHeader(writer, tt.bounds, tt.hasAlpha)
if !bytes.Equal(buffer.Bytes(), tt.expectedBits) {
t.Errorf("test %d: buffer mismatch expected: %v got: %v\n", id, tt.expectedBits, buffer.Bytes())
continue
}
}
}
func TestWriteEncodeErrors(t *testing.T) {
for id, tt := range []struct {
img image.Image
expectedMsg string
}{
{
nil,
"image is nil",
},
{
image.NewNRGBA(image.Rectangle{}),
"invalid image size",
},
}{
b := &bytes.Buffer{}
err := Encode(b, tt.img, nil)
if err == nil {
t.Errorf("test %v: expected error %v got nil", id, tt.expectedMsg)
continue
}
if err != nil && err.Error() != tt.expectedMsg {
t.Errorf("test %v: expected error %v got %v", id, tt.expectedMsg, err)
continue
}
}
}
func TestEncode(t *testing.T) {
for id, tt := range []struct {
img image.Image
expectedBytes []byte
}{
{
generateTestImageNRGBA(8, 8, 64, true),
[]byte {
0x52, 0x49, 0x46, 0x46, 0xdc, 0x00, 0x00, 0x00,
0x57, 0x45, 0x42, 0x50, 0x56, 0x50, 0x38, 0x4c,
0xd0, 0x00, 0x00, 0x00, 0x2f, 0x07, 0xc0, 0x01,
0x10, 0x8d, 0x52, 0x46, 0xf4, 0x3f, 0x24, 0x0c,
0x08, 0x36, 0x12, 0x93, 0x03, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0xe1, 0x00, 0x00, 0xc0,
0x4c, 0x7f, 0x83, 0xda, 0x08, 0x90, 0x69, 0xd6,
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe0,
0x04, 0xc8, 0x34, 0xdf, 0x01, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x20, 0x01, 0x44, 0x62, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x23,
0x2c, 0x60, 0xf1, 0xc1, 0x84, 0xc6, 0x48, 0x0e,
0x6d, 0xbe, 0xb1, 0x9d, 0xe7, 0x6d, 0xee, 0xd6,
0xe3, 0xc8, 0x3c, 0x6f, 0xda, 0xe7, 0x6f, 0xef,
0x0f, 0x49, 0x80, 0x48, 0x10, 0x18, 0x5d, 0xfd,
0xd1, 0xf2, 0x32, 0x40, 0x74, 0x19, 0x11, 0xcb,
0xb0, 0xdc, 0x5e, 0x00,
},
},
}{
b := &bytes.Buffer{}
Encode(b, tt.img, nil)
result := b.Bytes()
if !bytes.Equal(result, tt.expectedBytes) {
t.Errorf("test %v: BitStream mismatch. Got %s, expected %s", id, result, tt.expectedBytes)
}
}
}
func TestWriteBitStreamDataErrors(t *testing.T) {
imgpal := image.NewNRGBA(image.Rect(0, 0, 257, 1))
for i := 0; i < 257; i++ {
imgpal.Set(i, 0, color.NRGBA{
R: uint8(i % 16 * 16),
G: uint8((i / 16) % 16 * 16),
B: uint8((i / 256) % 16 * 16),
A: 255,
})
}
for id, tt := range []struct {
img image.Image
transforms [4]bool
expectedMsg string
}{
{
image.NewRGBA(image.Rectangle{}),
[4]bool{ false, false, false, false, },
"unsupported image format",
},
{
imgpal,
[4]bool{ false, false, false, true, },
"palette exceeds 256 colors",
},
}{
b := &bytes.Buffer{}
s := &bitWriter{Buffer: b}
err := writeBitStreamData(s, tt.img, 0, tt.transforms)
if err == nil {
t.Errorf("test %v: expected error %v got nil", id, tt.expectedMsg)
continue
}
if err != nil && err.Error() != tt.expectedMsg {
t.Errorf("test %v: expected error %v got %v", id, tt.expectedMsg, err)
continue
}
}
}
func TestWriteBitStreamData(t *testing.T) {
img := generateTestImageNRGBA(8, 8, 64, true)
for id, tt := range []struct {
transforms [4]bool
colorCacheBits int
expectedBytes []byte
}{
{
[4]bool{
false, //transformPredict
false, //transformColor
true, //transformSubGreen
false, //transformColorIndexing
},
0,
[]byte{
0x85, 0x00, 0x22, 0x09, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x98, 0x01, 0x00, 0x80, 0x00,
0x22, 0x69, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0xb0, 0x00, 0x22, 0x69, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0xb0, 0x00, 0x82, 0x08,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe8,
0x02, 0x30, 0x2d, 0x1b, 0x54, 0x56, 0x55, 0x9b,
0xc0, 0xb6, 0x2a, 0x41, 0x75, 0xd5, 0x6a, 0x56,
0x55, 0x83, 0x4a, 0xdb, 0x32, 0xd7, 0x4a, 0x00,
0x58, 0x8e, 0x07, 0xc9, 0x54, 0x9a, 0x05, 0x3c,
0x97, 0x04, 0xe9, 0xd4, 0xca, 0xa6, 0xd2, 0x20,
0xc9, 0x73, 0xec, 0x9a, 0x04,
},
},
{
[4]bool{
false, //transformPredict
false, //transformColor
true, //transformSubGreen
false, //transformColorIndexing
},
8,
[]byte{
0x15, 0x21, 0x20, 0xd8, 0x36, 0x03, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0xca, 0x00, 0x00,
0x40, 0x00, 0x00, 0x07, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x1c, 0x66, 0x00, 0x00, 0x00,
0x00, 0x03, 0x00, 0x00, 0x80, 0x3b, 0x00, 0x00,
0x00, 0xc0, 0x01, 0x00, 0x00, 0x83, 0x3b, 0x00,
0x00, 0x00, 0xc0, 0x01, 0x02, 0x88, 0xa4, 0x01,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x02,
0x88, 0xe4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0xc0, 0x02, 0x88, 0x04, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x60, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x80, 0x01, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x5d, 0xc0, 0x2e,
0x3b, 0x76, 0xa3, 0xa4, 0x50, 0x0e, 0xee, 0x2a,
0xfe, 0x71, 0x8d, 0xf3, 0xa9, 0xbb, 0xc2, 0xb5,
0xc0, 0x9c, 0x99, 0x79, 0x44, 0x82, 0x38, 0x79,
0xbb, 0x99, 0xc3, 0x35, 0xc7, 0xa4, 0xdf, 0x4e,
0xd7,
},
},
{
[4]bool{
false, //transformPredict
true, //transformColor
false, //transformSubGreen
false, //transformColorIndexing
},
0,
[]byte{
0x93, 0x0a, 0x64, 0x07, 0xfa, 0x1f, 0x10, 0x40,
0x24, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x33, 0x00, 0x00, 0x10, 0x40, 0x24, 0x0d,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x26,
0x40, 0xa6, 0x69, 0x07, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x80, 0x0b, 0x20, 0x88, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x2e, 0x10,
0xa6, 0x65, 0x13, 0xc5, 0x52, 0xd9, 0x24, 0x6c,
0xab, 0x48, 0x94, 0x4b, 0xab, 0x59, 0x2a, 0x13,
0x45, 0xdb, 0x32, 0xd7, 0x22, 0x41, 0x70, 0x79,
0x7c, 0x22, 0x33, 0x2b, 0x9b, 0x4b, 0xf0, 0x79,
0x99, 0x44, 0x76, 0xd6, 0xca, 0xcd, 0xca, 0x26,
0x32, 0xf9, 0x3c, 0xee, 0x9a, 0x49,
},
},
{
[4]bool{
false, //transformPredict
true, //transformColor
false, //transformSubGreen
false, //transformColorIndexing
},
8,
[]byte{
0x53, 0xac, 0x40, 0x76, 0xa0, 0xff, 0x21, 0x42,
0x40, 0xb0, 0x6d, 0x06, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x94, 0x01, 0x00, 0x80, 0x00,
0x00, 0x00, 0x00, 0x00, 0x80, 0x03, 0x00, 0x00,
0x00, 0x00, 0x0c, 0x00, 0x00, 0x38, 0x0c, 0x06,
0x00, 0x00, 0x00, 0x1c, 0x00, 0x00, 0x00, 0x87,
0x03, 0x00, 0x00, 0x00, 0x07, 0x00, 0x00, 0x06,
0x87, 0x03, 0x04, 0x10, 0x49, 0x03, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x80, 0x05, 0x10, 0x89,
0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80,
0x05, 0x10, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0xba, 0x80, 0x2d, 0x1b, 0xdb,
0x28, 0x29, 0x94, 0x93, 0xb7, 0x8b, 0x7f, 0x5c,
0xf3, 0x7c, 0xea, 0xed, 0x74, 0x2d, 0x30, 0x67,
0x66, 0x1e, 0x29, 0x89, 0x74, 0x70, 0x57, 0x33,
0x87, 0x6b, 0x8c, 0x49, 0xdf, 0x15, 0xae,
},
},
{
[4]bool{
true, //transformPredict
false, //transformColor
false, //transformSubGreen
false, //transformColorIndexing
},
0,
[]byte{
0x91, 0x8c, 0xe8, 0x7f, 0x80, 0x00, 0x99, 0x66,
0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x71, 0x00, 0x00, 0x20, 0x80, 0x48, 0x1a, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x2c, 0x80,
0x48, 0x1a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x2c, 0x80, 0x48, 0x0c, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x18, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x70, 0x84, 0x05, 0x64,
0x00, 0x44, 0x00, 0x30, 0xb2, 0x8d, 0xcb, 0xe3,
0x18, 0xbf, 0x9a, 0x02, 0x86, 0x00, 0x18, 0xcb,
0x31, 0xc6, 0x63, 0xc1, 0x00, 0x48, 0x03, 0xc0,
0x68, 0x1e, 0x77, 0x2f, 0xb7, 0xcf, 0x84, 0x75,
0x60, 0xd1, 0x9c, 0xe9, 0x36, 0xc6, 0xcb,
},
},
{
[4]bool{
true, //transformPredict
false, //transformColor
false, //transformSubGreen
false, //transformColorIndexing
},
8,
[]byte{
0x51, 0xcc, 0x88, 0xfe, 0x87, 0x88, 0x01, 0xc1,
0x46, 0x62, 0x72, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0xa0, 0x1c, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x60, 0x00, 0xa0, 0xc0,
0x03, 0x80, 0xf7, 0xc0, 0x00, 0x06, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x1e, 0x00, 0x00, 0x06,
0x00, 0x0a, 0x0c, 0x00, 0x00, 0x18, 0xc0, 0x00,
0xc0, 0x00, 0x10, 0x40, 0x24, 0x0d, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x16, 0x40, 0x24,
0x0d, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x16, 0x40, 0x24, 0x06, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x38, 0xc2, 0x02, 0xc4, 0x00,
0x13, 0x82, 0x3d, 0xc9, 0x6c, 0x58, 0xb9, 0x58,
0x9c, 0xae, 0x53, 0xe1, 0xc2, 0xed, 0xe4, 0x3a,
0x92, 0xff, 0xc3, 0x6c, 0x44, 0x63, 0x2f, 0x34,
0x3e, 0xba, 0x2b, 0x6b, 0x37, 0x9f, 0x4b, 0xc7,
0x15, 0x4f, 0xf3, 0x3b, 0x92,
},
},
{
[4]bool{
true, //transformPredict
false, //transformColor
true, //transformSubGreen
false, //transformColorIndexing
},
0,
[]byte{
0x8d, 0x64, 0x44, 0xff, 0x03, 0x04, 0xc8, 0x34,
0x3b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x88, 0x03, 0x00, 0x00, 0x02, 0x64, 0x9a, 0x75,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x38,
0x01, 0x32, 0xcd, 0x3a, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x5c, 0x00, 0x91, 0x18, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x08,
0x0b, 0xc8, 0x01, 0x10, 0x15, 0x00, 0x47, 0x76,
0xe3, 0xd6, 0xfb, 0xaf, 0xc6, 0xaf, 0x4e, 0x0b,
0xec, 0x57, 0x01, 0x8c, 0xe5, 0x6a, 0x8c, 0xf7,
0x2f, 0x38, 0x00, 0x92, 0x00, 0x70, 0x34, 0x1f,
0x67, 0xcf, 0x4f, 0x9f, 0x09, 0x97, 0x81, 0xb9,
0xe4, 0x4c, 0xa7, 0x31, 0x9e,
},
},
{
[4]bool{
true, //transformPredict
false, //transformColor
true, //transformSubGreen
false, //transformColorIndexing
},
8,
[]byte{
0x8d, 0x62, 0x46, 0xf4, 0x3f, 0x44, 0x0c, 0x08,
0x36, 0x12, 0x93, 0x03, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0xe5, 0x00, 0x00, 0x00, 0x00,
0x18, 0x00, 0x00, 0x3c, 0x00, 0x00, 0x00, 0x28,
0x00, 0x60, 0xf0, 0x1e, 0x18, 0xc0, 0x03, 0x00,
0x0c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x50, 0x00, 0xc0, 0x00, 0xc0, 0x00, 0x06,
0x00, 0x30, 0x00, 0x01, 0x32, 0xcd, 0x3a, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x9c, 0x00,
0x99, 0xa6, 0x1d, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x2e, 0x80, 0x48, 0x0c, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x18, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x84, 0x05,
0x14, 0x0f, 0x62, 0x8a, 0xc2, 0x9e, 0xd4, 0xbc,
0xd1, 0x9a, 0xeb, 0x5f, 0x39, 0x5d, 0xa7, 0x86,
0xeb, 0x77, 0x3b, 0xd9, 0x7f, 0x32, 0x3e, 0x9c,
0x0d, 0x04, 0x7b, 0xc1, 0xf8, 0x91, 0x5d, 0xbe,
0xb8, 0xf9, 0x5a, 0x32, 0x2e, 0xf7, 0x34, 0xbf,
0x67, 0x72,
},
},
{ // paletted image
[4]bool{
true, //transformPredict
false, //transformColor
true, //transformSubGreen
true, //transformColorIndexing
},
8,
[]byte{
0x67, 0x88, 0x06, 0xc8, 0xb6, 0xd9, 0x01, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x01, 0x00,
0x00, 0x0e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x40, 0x00, 0x91, 0x34, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x58, 0x00, 0x91, 0x34,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf8,
0x40, 0x80, 0xf1, 0x9b, 0x41, 0xc9, 0x39, 0x5d,
0x1a, 0xc5, 0x8c, 0xe8, 0x7f, 0x88, 0x18, 0x10,
0x8c, 0x23, 0xc6, 0xb6, 0xd9, 0xdb, 0x0c, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x30, 0x7b, 0x9b, 0xcd, 0x28,
0x00, 0x00, 0x28, 0x00, 0x00, 0x00, 0x00, 0x00,
0x30, 0x80, 0x03, 0x00, 0x30, 0x18, 0xc0, 0x00,
0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0c, 0x60,
0x00, 0x00, 0x80, 0x02, 0x0c, 0x00, 0x00, 0x30,
0x00, 0x00, 0x30, 0x00, 0x00, 0x00, 0x02, 0x02,
0x40, 0x22, 0xad, 0x9c, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x29, 0xa5, 0x0a, 0x01, 0x01, 0x20, 0x91,
0x56, 0x4e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x94,
0x52, 0x15, 0x02, 0x88, 0x04, 0x20, 0x0f, 0x00,
0x00, 0x00, 0x5e, 0xdc, 0xc1, 0x8a, 0x58, 0x77,
0x5b, 0xb7, 0x01, 0x54, 0x33, 0x2a, 0x77, 0x97,
0xf7, 0x9a, 0x2a, 0xd9, 0x4a, 0x30, 0x13, 0x05,
0x92, 0x6e, 0xe9, 0xbf, 0x52, 0x26, 0xe4, 0xff,
0x3b, 0x77, 0xf0, 0x89, 0xb9, 0x8d, 0xd0, 0x37,
0x8a, 0xf4, 0x66, 0xc6, 0xaf, 0x07, 0x83, 0xea,
0x69, 0xfc, 0xec, 0xd2,
},
},
}{
b := &bytes.Buffer{}
s := &bitWriter{Buffer: b}
err := writeBitStreamData(s, img, tt.colorCacheBits, tt.transforms)
if err != nil {
t.Fatalf("test %v: writeBitStreamData returned error: %v", id, err)
}
result := b.Bytes()
if !bytes.Equal(result, tt.expectedBytes) {
t.Errorf("test %v: BitStream mismatch. Got %s, expected %s", id, result, tt.expectedBytes)
}
}
}
func TestWriteImageData(t *testing.T) {
for id, tt := range []struct {
inputPixels []color.NRGBA
width int
height int
isRecursive bool
colorCacheBits int
expectedBits []byte
}{
{
inputPixels: []color.NRGBA{
{R: 100, G: 50, B: 150, A: 255},
{R: 200, G: 100, B: 50, A: 255},
{R: 100, G: 50, B: 150, A: 255}, // Same as the first pixel
},
width: 3,
height: 1,
isRecursive: false,
colorCacheBits: 2,
expectedBits: []byte{
0x45, 0x00, 0x91, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x4f,
0x86, 0x7c, 0x19, 0xcb, 0xfe, 0x47,
},
},
{
inputPixels: []color.NRGBA{
{R: 100, G: 50, B: 150, A: 255},
{R: 200, G: 100, B: 50, A: 255},
{R: 100, G: 50, B: 150, A: 255}, // Same as the first pixel
},
width: 3,
height: 1,
isRecursive: false,
colorCacheBits: 0,
expectedBits: []byte{
0x2e, 0x43, 0x76, 0x32, 0xe4, 0xcb, 0x58, 0xf6,
0x3f, 0x38,
},
},
{
inputPixels: []color.NRGBA{
{R: 100, G: 50, B: 150, A: 255},
{R: 200, G: 100, B: 50, A: 255},
{R: 100, G: 50, B: 150, A: 255}, // Same as the first pixel
},
width: 3,
height: 1,
isRecursive: true,
colorCacheBits: 2,
expectedBits: []byte{
0x85, 0x00, 0x22, 0x01, 0x00, 0x00, 0x00, 0x00,
0x00, 0x60, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x9f,
0x0c, 0xf9, 0x32, 0x96, 0xfd, 0x8f, 0xd4,
},
},
{
inputPixels: []color.NRGBA{
{R: 100, G: 50, B: 150, A: 255},
{R: 200, G: 100, B: 50, A: 255},
{R: 100, G: 50, B: 150, A: 255}, // Same as the first pixel
},
width: 3,
height: 1,
isRecursive: true,
colorCacheBits: 0,
expectedBits: []byte{
0x5c, 0x86, 0xec, 0x64, 0xc8, 0x97, 0xb1, 0xec,
0x7f, 0x70,
},
},
} {
buffer := &bytes.Buffer{}
writer := &bitWriter{
Buffer: buffer,
BitBuffer: 0,
BitBufferSize: 0,
}
writeImageData(writer, tt.inputPixels, tt.width, tt.height, tt.isRecursive, tt.colorCacheBits)
if !bytes.Equal(buffer.Bytes(), tt.expectedBits) {
t.Errorf("test %d: buffer mismatch\nexpected: %v got: %v", id, tt.expectedBits, buffer.Bytes())
continue
}
}
}
func TestEncodeImageData(t *testing.T) {
for id, tt := range []struct {
inputPixels []color.NRGBA
width int
height int
colorCacheBits int
expectedEncoded []int
}{
{ //cached encoding
inputPixels: []color.NRGBA{
{R: 100, G: 50, B: 150, A: 255},
{R: 200, G: 100, B: 50, A: 255},
{R: 100, G: 50, B: 150, A: 255}, // Same as the first pixel
},
width: 3,
height: 1,
colorCacheBits: 2,
expectedEncoded: []int{
50, 100, 150, 255, // First pixel
100, 200, 50, 255, // Second pixel
256 + 24 + 3, // Cached first pixel (hash index 0)
},
},
{ //full RGBA encoding
inputPixels: []color.NRGBA{
{R: 100, G: 50, B: 150, A: 255},
{R: 200, G: 100, B: 50, A: 255},
{R: 100, G: 50, B: 150, A: 255}, // Same as the first pixel
},
width: 3,
height: 1,
colorCacheBits: 0,
expectedEncoded: []int{
50, 100, 150, 255,
100, 200, 50, 255,
50, 100, 150, 255,
},
},
} {
encoded := encodeImageData(tt.inputPixels, tt.width, tt.height, tt.colorCacheBits)
if !reflect.DeepEqual(encoded, tt.expectedEncoded) {
t.Errorf("test %d: encoded data mismatch\nexpected: %+v\n got: %+v", id, tt.expectedEncoded, encoded)
continue
}
}
}
func TestPrefixEncodeCode(t *testing.T) {
tests := []struct {
n int // input value
expectedCode int // expected prefix code
expectedRemainder int // expected remainder value
}{
// n <= 5: code should be max(0, n-1) and remainder 0.
{-1, 0, 0}, // even negative numbers fall in this branch
{0, 0, 0},
{1, 0, 0},
{2, 1, 0},
{3, 2, 0},
{4, 3, 0},
{5, 4, 0},
// n > 5: calculations using shifts.
// For n = 6: n-1 = 5, loop runs once (5 >> 1 = 2) → shift=1, rem=2,
// so returns (2 + 2*1, 6 - (2<<1) - 1) = (4, 1).
{6, 4, 1},
// For n = 7: n-1 = 6, loop: 6 >> 1 = 3 → shift=1, rem=3,
// so returns (3 + 2*1, 7 - (3<<1) - 1) = (5, 0).
{7, 5, 0},
// For n = 8: n-1 = 7, loop: 7 >> 1 = 3 → shift=1, rem=3,
// returns (3 + 2*1, 8 - (3<<1) - 1) = (5, 1).
{8, 5, 1},
// For n = 9: n-1 = 8, loop:
// 8 >> 1 = 4, shift becomes 1; then 4 >> 1 = 2, shift becomes 2;
// rem == 2 so returns (2 + 2*2, 9 - (2<<2) - 1) = (6, 0).
{9, 6, 0},
// For n = 10: returns (6, 1)
{10, 6, 1},
// For n = 11: returns (6, 2)
{11, 6, 2},
// For n = 12: returns (6, 3)
{12, 6, 3},
// For n = 13: n-1 = 12, loop: 12 >> 1 = 6 (shift=1),
// then 6 >> 1 = 3 (shift=2), rem becomes 3 so returns (3+2*2, 13 - (3<<2) -1) = (7, 0).
{13, 7, 0},
// For n = 14: returns (7, 1)
{14, 7, 1},
// For n = 15: returns (7, 2)
{15, 7, 2},
// For n = 16: returns (7, 3)
{16, 7, 3},
}
for idx, tt := range tests {
code, remainder := prefixEncodeCode(tt.n)
if code != tt.expectedCode {
t.Errorf("Test %d: expected code %d, got %d", idx, tt.expectedCode, code)
continue
}
if remainder != tt.expectedRemainder {
t.Errorf("Test %d: expected remainder %d, got %d", idx, tt.expectedRemainder, remainder)
continue
}
}
}
func TestPrefixEncodeBits(t *testing.T) {
tests := []struct {
prefix int
expected int
}{
// For prefix values less than 4, the function returns 0.
{-10, 0},
{-1, 0},
{0, 0},
{1, 0},
{2, 0},
{3, 0},
// For prefix values 4 and above, the function computes (prefix-2) >> 1.
// Example: For prefix = 4, (4-2) >> 1 = 2 >> 1 = 1.
{4, 1},
// For prefix = 5, (5-2) >> 1 = 3 >> 1 = 1.
{5, 1},
// For prefix = 6, (6-2) >> 1 = 4 >> 1 = 2.
{6, 2},
// For prefix = 7, (7-2) >> 1 = 5 >> 1 = 2.
{7, 2},
// For prefix = 8, (8-2) >> 1 = 6 >> 1 = 3.
{8, 3},
// For prefix = 9, (9-2) >> 1 = 7 >> 1 = 3.
{9, 3},
// For prefix = 10, (10-2) >> 1 = 8 >> 1 = 4.
{10, 4},
// Additional test cases
{11, 4}, // (11-2)=9, 9 >> 1 = 4 (integer division)
{12, 5}, // (12-2)=10, 10 >> 1 = 5
}
for idx, tt := range tests {
result := prefixEncodeBits(tt.prefix)
if result != tt.expected {
t.Errorf("Test %d: expected %d got %d", idx, tt.expected, result)
}
}
}
func TestHash(t *testing.T) {
tests := []struct {
c color.NRGBA
shifts int
expected uint32
}{
{
c: color.NRGBA{R: 0, G: 0, B: 0, A: 0},
shifts: 8,
expected: 0,
},
{
// Note: hash uses c.A as the most significant byte.
// This test uses A=0, R=0, G=0, B=1 so that:
// x = 0<<24 | 0<<16 | 0<<8 | 1 = 1,
// then hash = (1 * 0x1e35a7bd) >> (32-8) = 0x1e35a7bd >> 24.
// 0x1e35a7bd in hex is: 0x1e 0x35 0xa7 0xbd, so shifting right 24 bits yields 0x1e (30 in decimal).
c: color.NRGBA{R: 0, G: 0, B: 1, A: 0},
shifts: 8,
expected: 30,
},
{
// Here x = 2 and so hash = (2*0x1e35a7bd) >> 24.
// Since 0x1e35a7bd >> 24 is 30, doubling gives 60.
c: color.NRGBA{R: 0, G: 0, B: 2, A: 0},
shifts: 8,
expected: 60,
},
{
// For c = {255,255,255,255} we have:
// x = 0xFF<<24 | 0xFF<<16 | 0xFF<<8 | 0xFF = 0xFFFFFFFF.
// In 32-bit arithmetic, multiplying by 0x1e35a7bd gives:
// 0xFFFFFFFF * 0x1e35a7bd ≡ -0x1e35a7bd (mod 2^32)
// which equals 0x100000000 - 0x1e35a7bd = 0xE1CA5823 = 3788134467.
c: color.NRGBA{R: 255, G: 255, B: 255, A: 255},
shifts: 32,
expected: 3788134467,
},
{
// Here x = 1<<24 = 0x01000000.
// Multiplying by 0x1e35a7bd is equivalent to shifting the magic left 24 bits:
// (0x1e35a7bd << 24) mod 2^32.
// Only the lower 8 bits of the magic survive in the final result,
// so expected = (0x1e35a7bd & 0xFF) << 24 = 0xbd << 24 = 0xbd000000.
c: color.NRGBA{R: 0, G: 0, B: 0, A: 1},
shifts: 32,
expected: 0xbd000000,
},
{
// With c = {R:0, G:0, B:1, A:0}, x = 1.
// Then hash = (0x1e35a7bd) >> (32-16) = (0x1e35a7bd) >> 16.
// Shifting 0x1e35a7bd right 16 bits yields 0x1e35, which is 7733 in decimal.
c: color.NRGBA{R: 0, G: 0, B: 1, A: 0},
shifts: 16,
expected: 7733,
},
{
// case where shift is higher than maximum of 32 (should be set back to 32)
c: color.NRGBA{R: 255, G: 255, B: 255, A: 255},
shifts: 33,
expected: 3788134467,
},
}
for id, tt := range tests {
result := hash(tt.c, tt.shifts)
if result != tt.expected {
t.Errorf("test %v: expected hash as %v got %v", id, tt.expected, result)
}
}
}
func TestComputeHistograms(t *testing.T) {
for id, tt := range []struct {
pixels []int
colorCacheBits int
expectedSizes []int
expectedCounts []map[int]int
}{
{
pixels: []int{
0xff, 0x01, 0x00, 0xff,
0x00, 0xff, 0x00, 0xff,
0x01, 0x01, 0xff, 0xff,
},
colorCacheBits: 0,
expectedSizes: []int{256 + 24, 256, 256, 256, 40},
expectedCounts: []map[int]int{
{0: 1, 1: 1, 255: 1}, // histos[0]
{0: 0, 1: 2, 255: 1}, // histos[1]
{0: 2, 1: 0, 255: 1}, // histos[2]
{0: 0, 1: 0, 255: 3}, // histos[3]
{}, // histos[4] (unused in this case)
},
},
{
pixels: []int{
0xff, 0x01, 0x00, 0xff,
0x00, 0xff, 0x00, 0xff,
0x01, 0x01, 0xff, 0xff,
},