Move vm into subdir

vm/instruction.go

@@ -0,0 +1,52 @@
+package vm
+
+import "bytes"
+
+import "github.com/lunixbochs/struc"
+import "github.com/pkg/errors"
+
+type Instruction struct {
+	OpCode   OpCodeType
+	Reserved [4]byte
+	Operand1 Operand
+	Operand2 Operand
+
+	opHandler opHandler `struc:"skip"`
+}
+
+const instructionBytes = 32
+
+func NewInstructionFromByteCode(byteCode []byte) (*Instruction, error) {
+	instr := &Instruction{}
+
+	reader := bytes.NewReader(byteCode)
+
+	err := struc.Unpack(reader, instr)
+	if err != nil {
+		return nil, errors.Wrap(err, "Error decoding instruction")
+	}
+
+	return instr, nil
+}
+
+func NewInstructionsFromByteCode(byteCode []byte) ([]*Instruction, error) {
+	instrs := []*Instruction{}
+
+	for start := 0; start < len(byteCode); start += instructionBytes {
+		chunk := byteCode[start : start+instructionBytes]
+		instr, err := NewInstructionFromByteCode(chunk)
+		if err != nil {
+			return nil, errors.Wrapf(err, "At byte offset %d", start)
+		}
+		instrs = append(instrs, instr)
+	}
+
+	if len(instrs) == 0 || instrs[len(instrs)-1].OpCode != OpReturn {
+		// Add implicit return at the end of each function
+		instrs = append(instrs, &Instruction{
+			OpCode: OpReturn,
+		})
+	}
+
+	return instrs, nil
+}