diff --git a/bit/buf_reader.go b/bit/buf_reader.go
new file mode 100644
index 0000000..437441b
--- /dev/null
+++ b/bit/buf_reader.go
@@ -0,0 +1,60 @@
+package bit
+
+import (
+	"io"
+)
+
+type bufReader struct {
+	src  []byte // source of data
+	n    uint64 // bit buffer
+	bits uint   // number of valid bits in n
+	err  error  // stored error
+}
+
+func (r *bufReader) ReadBits(bits uint) (n uint64) {
+	for bits > r.bits {
+		if len(r.src) == 0 {
+			r.err = io.EOF
+			return 0
+		}
+		r.n |= uint64(r.src[0]) << r.bits
+		r.src = r.src[1:]
+		r.bits += 8
+	}
+	n = r.n & (1<<bits - 1)
+	r.n >>= bits
+	r.bits -= bits
+	return
+}
+
+func (r *bufReader) ReadByte() byte {
+	if r.bits == 0 {
+		if len(r.src) == 0 {
+			r.err = io.EOF
+			return 0
+		}
+		b := r.src[0]
+		r.src = r.src[1:]
+		return b
+	}
+	return byte(r.ReadBits(8))
+}
+
+func (r *bufReader) Read(buf []byte) int {
+	for i := 0; i < len(buf); i++ {
+		b := r.ReadByte()
+		if r.err != nil {
+			return 0
+		}
+		buf[i] = b
+	}
+	return len(buf)
+}
+
+func (r *bufReader) DiscardBytes(n int) {
+	for i := 0; i < n; i++ {
+		r.ReadByte()
+	}
+}
+
+func (r *bufReader) Err() error { return r.err }