Initial commit

pkg/h264/golomb/golomb_writer.go

@@ -0,0 +1,56 @@
+package golomb
+
+import "math/bits"
+
+type Writer struct {
+	buf   []byte
+	b     byte // last byte
+	i     int  // last byte index
+	shift byte
+}
+
+func NewWriter() *Writer {
+	return &Writer{i: -1}
+}
+
+func (g *Writer) WriteBit(b byte) {
+	if g.shift == 0 {
+		g.buf = append(g.buf, 0)
+		g.b = 0
+		g.i++
+		g.shift = 7
+	} else {
+		g.shift--
+	}
+	g.b |= b << g.shift
+	g.buf[g.i] = g.b
+}
+
+func (g *Writer) WriteBits(b, n byte) {
+	for i := n - 1; i != 255; i-- {
+		g.WriteBit((b >> i) & 0b1)
+	}
+}
+
+func (g *Writer) WriteByte(b byte) {
+	g.buf = append(g.buf, b)
+	g.i++
+}
+
+func (g *Writer) WriteUEGolomb(b byte) {
+	b++
+	n := uint8(bits.Len8(b))*2 - 1
+	g.WriteBits(b, n)
+}
+
+func (g *Writer) WriteSEGolomb(b int8) {
+	if b > 0 {
+		g.WriteUEGolomb(byte(b)*2 - 1)
+	} else {
+		g.WriteUEGolomb(byte(-b) * 2)
+	}
+}
+
+func (g *Writer) Bytes() []byte {
+	return g.buf
+}