refactor

varn/varn.go

@@ -0,0 +1,38 @@
+// Package varn implements variable-length encoding for unsigned integers and
+// byte slices. It is used in the OpenTimestamps protocol to encode
+// instructions and attestations. The encoding is similar to the one used in
+// Protocol Buffers, but with a different format for the variable-length
+// integers. The encoding is designed to be compact and efficient, while still
+// being easy to decode. The package provides functions to read and write
+// variable-length integers and byte slices, as well as a Buffer type for
+// reading and writing data in a more convenient way. The package is not
+// thread-safe and should not be used concurrently. It is intended for use in
+// the OpenTimestamps protocol and is not a general-purpose encoding library.
+package varn
+
+// AppendVarUint appends a variable-length unsigned integer to the buffer
+func AppendVarUint(buf []byte, value uint64) []byte {
+	if value == 0 {
+		buf = append(buf, 0)
+	} else {
+		for value != 0 {
+			b := byte(value & 0b01111111)
+			if value > 0b01111111 {
+				b |= 0b10000000
+			}
+			buf = append(buf, b)
+			if value <= 0b01111111 {
+				break
+			}
+			value >>= 7
+		}
+	}
+
+	return buf
+}
+
+func AppendVarBytes(buf []byte, value []byte) []byte {
+	buf = AppendVarUint(buf, uint64(len(value)))
+	buf = append(buf, value...)
+	return buf
+}