Implemented subtraction

src/build/arch/x64/numberToRegister.go

@@ -0,0 +1,41 @@
+package x64
+
+import (
+	"math"
+
+	"git.akyoto.dev/cli/q/src/build/cpu"
+)
+
+// numberToRegister encodes an instruction with a register and a number parameter.
+func numberToRegister(opCode8 byte, opCode32 byte, reg byte, code []byte, destination cpu.Register, number int) []byte {
+	b := byte(0)
+
+	if destination >= 8 {
+		b = 1
+		destination -= 8
+	}
+
+	rex := REX(1, 0, 0, b)
+	modRM := ModRM(0b11, reg, byte(destination))
+
+	if number >= math.MinInt8 && number <= math.MaxInt8 {
+		return append(
+			code,
+			rex,
+			opCode8,
+			modRM,
+			byte(number),
+		)
+	}
+
+	return append(
+		code,
+		rex,
+		opCode32,
+		modRM,
+		byte(number),
+		byte(number>>8),
+		byte(number>>16),
+		byte(number>>24),
+	)
+}