initial commit

blockreader.go

@@ -0,0 +1,72 @@
+package main
+
+import "io"
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func readByte(r io.Reader) (byte, error) {
+	var buf [1]byte
+	n, err := r.Read(buf[:])
+	if n == 0 {
+		return 0, io.ErrUnexpectedEOF
+	}
+	return buf[0], err
+}
+
+func (v *blockReader) readNextBlock() error {
+	blockSize, err := readByte(v.r)
+	if err == io.EOF {
+		return io.ErrUnexpectedEOF
+	}
+	if err != nil {
+		return err
+	}
+	if blockSize == 0 {
+		return io.EOF
+	}
+	_, err = io.ReadFull(v.r, v.buf[:blockSize])
+	if err == io.EOF {
+		return io.ErrUnexpectedEOF
+	}
+	if err != nil {
+		return err
+	}
+	v.bufLen = int(blockSize)
+	v.bufNext = 0
+	return nil
+}
+
+func (v *blockReader) Read(p []byte) (n int, err error) {
+	if v.bufNext >= v.bufLen {
+		err = v.readNextBlock()
+		if err != nil {
+			return 0, err
+		}
+	}
+	n = min(len(p), v.bufLen-v.bufNext)
+	for i := 0; i < n; i++ {
+		p[i] = v.buf[i+v.bufNext]
+	}
+	v.bufNext += n
+	return
+}
+
+type blockReader struct {
+	buf     [255]byte
+	bufLen  int
+	bufNext int
+	r       io.Reader
+}
+
+func newBlockReader(r io.Reader) *blockReader {
+	return &blockReader{
+		r:       r,
+		bufLen:  0,
+		bufNext: 0,
+	}
+}