mkv in progress

format/mkv/mkvio/utils.go

@@ -0,0 +1,23 @@
+package mkvio
+
+func pack(n int, b []byte) uint64 {
+	var v uint64
+	var k uint64 = (uint64(n) - 1) * 8
+
+	for i := 0; i < n; i++ {
+		v |= uint64(b[i]) << k
+		k -= 8
+	}
+
+	return v
+}
+
+func unpack(n int, v uint64) []byte {
+	var b []byte
+
+	for i := uint(n); i > 0; i-- {
+		b = append(b, byte(v>>(8*i))&0xff)
+	}
+
+	return b
+}