Assembler working

assembler/assembler.go

@@ -0,0 +1,138 @@
+package assembler
+
+import "fmt"
+import "strconv"
+import "strings"
+
+import "github.com/firestuff/subcoding/vm"
+import "github.com/pkg/errors"
+
+var opCodeByName = map[string]vm.OpCodeType{
+	"add":  vm.OpAdd,
+	"call": vm.OpCall,
+	"ltu":  vm.OpLTU,
+	"jmpt": vm.OpJmpT,
+}
+
+var operandsByOpCode = map[vm.OpCodeType]int{
+	vm.OpAdd:  2,
+	vm.OpCall: 1,
+	vm.OpLTU:  2,
+	vm.OpJmpT: 1,
+}
+
+func Assemble(src []byte) ([][]*vm.Instruction, error) {
+	prog, err := parse(src)
+	if err != nil {
+		return nil, err
+	}
+
+	fncs := [][]*vm.Instruction{}
+
+	for f, fnc := range prog.Functions {
+		instrs, err := assembleFunction(fnc)
+		if err != nil {
+			return nil, errors.Wrapf(err, "At function index %d\n", f)
+		}
+
+		fncs = append(fncs, instrs)
+	}
+
+	return fncs, nil
+}
+
+func AssembleString(src string) ([][]*vm.Instruction, error) {
+	return Assemble([]byte(src))
+}
+
+func assembleFunction(fnc function) ([]*vm.Instruction, error) {
+	instrs := []*vm.Instruction{}
+
+	for i, in := range fnc {
+		instr, err := assembleInstruction(in)
+		if err != nil {
+			return nil, errors.Wrapf(err, "At instruction index %d\n", i)
+		}
+
+		instrs = append(instrs, instr)
+	}
+
+	return instrs, nil
+}
+
+func assembleInstruction(in instruction) (*vm.Instruction, error) {
+	if len(in) < 1 {
+		return nil, fmt.Errorf("Empty instruction")
+	}
+
+	instr := &vm.Instruction{}
+
+	opCode, found := opCodeByName[in[0]]
+	if !found {
+		return nil, fmt.Errorf("Invalid op name: %s\n", in[0])
+	}
+
+	instr.OpCode = opCode
+
+	operands := in[1:]
+	if len(operands) != operandsByOpCode[instr.OpCode] {
+		return nil, fmt.Errorf("Incorrect number of operands: expected %d, found %d\n", operandsByOpCode[instr.OpCode], len(operands))
+	}
+
+	if len(operands) >= 1 {
+		op1, err := assembleOperand(operands[0])
+		if err != nil {
+			return nil, errors.Wrapf(err, "In first operand")
+		}
+
+		instr.Operand1 = op1
+	}
+
+	if len(operands) >= 2 {
+		op2, err := assembleOperand(operands[0])
+		if err != nil {
+			return nil, errors.Wrapf(err, "In second operand")
+		}
+
+		instr.Operand2 = op2
+	}
+
+	return instr, nil
+}
+
+func assembleOperand(op string) (vm.Operand, error) {
+	ret := vm.Operand{}
+	numStr := ""
+
+	switch {
+	case strings.HasPrefix(op, "f"):
+		ret.Type = vm.FunctionMemoryIndex
+		numStr = strings.TrimPrefix(op, "f")
+
+	case strings.HasPrefix(op, "g"):
+		ret.Type = vm.GlobalMemoryIndex
+		numStr = strings.TrimPrefix(op, "g")
+
+	default:
+		ret.Type = vm.Literal
+		numStr = op
+	}
+
+	switch {
+	case strings.HasPrefix(numStr, "+") || strings.HasPrefix(numStr, "-"):
+		num, err := strconv.ParseInt(numStr, 10, 64)
+		if err != nil {
+			return ret, errors.Wrapf(err, "While parsing operand value %s", numStr)
+		}
+		ret.Value = uint64(num)
+
+	default:
+		num, err := strconv.ParseUint(numStr, 10, 64)
+		if err != nil {
+			return ret, errors.Wrapf(err, "While parsing operand value %s", numStr)
+		}
+		ret.Value = num
+	}
+
+	return ret, nil
+}