add old go tooling

macho-go/pkg/leb128/leb128.go

@@ -0,0 +1,40 @@
+package leb128
+
+import (
+	"bytes"
+)
+
+// Read unsigned leb128, no error
+func ReadULEB(buf *bytes.Buffer) (uint, uint) {
+	result := uint(0)
+	shift := uint(0)
+	bytes_read := uint(0)
+	for {
+		b, _ := buf.ReadByte()
+		bytes_read += 1
+		result |= uint(b&0b0111_1111) << shift
+		shift += 7
+		if (b & 0b1000_0000) == 0 {
+			return result, bytes_read
+		}
+	}
+}
+
+// Read signed leb128, no error
+func ReadSLEB(buf *bytes.Buffer) (int, uint) {
+	result := int(0)
+	shift := uint(0)
+	bytes_read := uint(0)
+	for {
+		b, _ := buf.ReadByte()
+		bytes_read += 1
+		result |= int(b&0b0111_1111) << shift
+		shift += 7
+		if (b & 0b1000_0000) == 0 {
+			if b&0x40 != 0 {
+				return result | (-1 << shift), bytes_read
+			}
+			return result, bytes_read
+		}
+	}
+}