Implemented register to register instructions

src/build/arch/x64/ModRM.go

@@ -0,0 +1,9 @@
+package x64
+
+// ModRM is used to generate a ModRM suffix.
+// - mod: 2 bits
+// - reg: 3 bits
+// - rm:  3 bits
+func ModRM(mod byte, reg byte, rm byte) byte {
+	return (mod << 6) | (reg << 3) | rm
+}

src/build/arch/x64/ModRM_test.go

@@ -0,0 +1,34 @@
+package x64_test
+
+import (
+	"testing"
+
+	"git.akyoto.dev/cli/q/src/build/arch/x64"
+	"git.akyoto.dev/go/assert"
+)
+
+func TestModRM(t *testing.T) {
+	testData := []struct{ mod, reg, rm, expected byte }{
+		{0b_00, 0b_111, 0b_000, 0b_00_111_000},
+		{0b_00, 0b_110, 0b_001, 0b_00_110_001},
+		{0b_00, 0b_101, 0b_010, 0b_00_101_010},
+		{0b_00, 0b_100, 0b_011, 0b_00_100_011},
+		{0b_00, 0b_011, 0b_100, 0b_00_011_100},
+		{0b_00, 0b_010, 0b_101, 0b_00_010_101},
+		{0b_00, 0b_001, 0b_110, 0b_00_001_110},
+		{0b_00, 0b_000, 0b_111, 0b_00_000_111},
+		{0b_11, 0b_111, 0b_000, 0b_11_111_000},
+		{0b_11, 0b_110, 0b_001, 0b_11_110_001},
+		{0b_11, 0b_101, 0b_010, 0b_11_101_010},
+		{0b_11, 0b_100, 0b_011, 0b_11_100_011},
+		{0b_11, 0b_011, 0b_100, 0b_11_011_100},
+		{0b_11, 0b_010, 0b_101, 0b_11_010_101},
+		{0b_11, 0b_001, 0b_110, 0b_11_001_110},
+		{0b_11, 0b_000, 0b_111, 0b_11_000_111},
+	}
+
+	for _, test := range testData {
+		modRM := x64.ModRM(test.mod, test.reg, test.rm)
+		assert.Equal(t, modRM, test.expected)
+	}
+}

src/build/arch/x64/Move.go

@@ -1,13 +1,43 @@
 package x64
 
+import "git.akyoto.dev/cli/q/src/build/cpu"
+
 // MoveRegNum32 moves a 32 bit integer into the given register.
-func MoveRegNum32(code []byte, register uint8, number uint32) []byte {
+func MoveRegNum32(code []byte, destination cpu.Register, number uint32) []byte {
+	if destination >= 8 {
+		code = append(code, REX(0, 0, 0, 1))
+		destination -= 8
+	}
+
 	return append(
 		code,
-		0xb8+register,
+		0xb8+byte(destination),
 		byte(number),
 		byte(number>>8),
 		byte(number>>16),
 		byte(number>>24),
 	)
 }
+
+// MoveRegReg64 moves a register value into another register.
+func MoveRegReg64(code []byte, destination cpu.Register, source cpu.Register) []byte {
+	r := byte(0) // Extension to the "reg" field in ModRM.
+	b := byte(0) // Extension to the "rm" field in ModRM or the SIB base (r8 up to r15 use this).
+
+	if source >= 8 {
+		r = 1
+		source -= 8
+	}
+
+	if destination >= 8 {
+		b = 1
+		destination -= 8
+	}
+
+	return append(
+		code,
+		REX(1, r, 0, b),
+		0x89,
+		ModRM(0b11, byte(source), byte(destination)),
+	)
+}

src/build/arch/x64/REX.go

@@ -0,0 +1,7 @@
+package x64
+
+// REX is used to generate a REX prefix.
+// w, r, x and b can only be set to either 0 or 1.
+func REX(w, r, x, b byte) byte {
+	return 0b_0100_0000 | (w << 3) | (r << 2) | (x << 1) | b
+}

src/build/arch/x64/REX_test.go

@@ -0,0 +1,34 @@
+package x64_test
+
+import (
+	"testing"
+
+	"git.akyoto.dev/cli/q/src/build/arch/x64"
+	"git.akyoto.dev/go/assert"
+)
+
+func TestREX(t *testing.T) {
+	testData := []struct{ w, r, x, b, expected byte }{
+		{0, 0, 0, 0, 0b_0100_0000},
+		{0, 0, 0, 1, 0b_0100_0001},
+		{0, 0, 1, 0, 0b_0100_0010},
+		{0, 0, 1, 1, 0b_0100_0011},
+		{0, 1, 0, 0, 0b_0100_0100},
+		{0, 1, 0, 1, 0b_0100_0101},
+		{0, 1, 1, 0, 0b_0100_0110},
+		{0, 1, 1, 1, 0b_0100_0111},
+		{1, 0, 0, 0, 0b_0100_1000},
+		{1, 0, 0, 1, 0b_0100_1001},
+		{1, 0, 1, 0, 0b_0100_1010},
+		{1, 0, 1, 1, 0b_0100_1011},
+		{1, 1, 0, 0, 0b_0100_1100},
+		{1, 1, 0, 1, 0b_0100_1101},
+		{1, 1, 1, 0, 0b_0100_1110},
+		{1, 1, 1, 1, 0b_0100_1111},
+	}
+
+	for _, test := range testData {
+		rex := x64.REX(test.w, test.r, test.x, test.b)
+		assert.Equal(t, rex, test.expected)
+	}
+}