Implemented function calls

src/build/asm/Instructions.go

@@ -7,21 +7,28 @@ func (a *Assembler) MoveRegisterNumber(reg cpu.Register, number uint64) {
 	a.Instructions = append(a.Instructions, Instruction{
 		Mnemonic: MOVE,
 		Data: &RegisterNumber{
-			Register:  reg,
-			Number:    number,
-			IsPointer: false,
+			Register: reg,
+			Number:   number,
 		},
 	})
 }
 
-// MoveRegisterAddress moves an address into the given register.
-func (a *Assembler) MoveRegisterAddress(reg cpu.Register, address Address) {
+// Label adds a label at the current position.
+func (a *Assembler) Label(name string) {
 	a.Instructions = append(a.Instructions, Instruction{
-		Mnemonic: MOVE,
-		Data: &RegisterNumber{
-			Register:  reg,
-			Number:    uint64(address),
-			IsPointer: true,
+		Mnemonic: LABEL,
+		Data: &Label{
+			Name: name,
+		},
+	})
+}
+
+// Call calls a function whose position is identified by a label.
+func (a *Assembler) Call(name string) {
+	a.Instructions = append(a.Instructions, Instruction{
+		Mnemonic: CALL,
+		Data: &Label{
+			Name: name,
 		},
 	})
 }