Implemented addition

src/build/arch/x64/Add.go

@@ -0,0 +1,18 @@
+package x64
+
+import "git.akyoto.dev/cli/q/src/build/cpu"
+
+// AddRegNum8 adds a byte to the given register.
+func AddRegNum8(code []byte, destination cpu.Register, number uint8) []byte {
+	if destination >= 8 {
+		code = append(code, REX(0, 0, 0, 1))
+		destination -= 8
+	}
+
+	return append(
+		code,
+		0x83,
+		ModRM(0b11, 0b000, byte(destination)),
+		byte(number),
+	)
+}