Pre-decode byteCode

main.go

@@ -36,7 +36,7 @@ type Instruction struct {
 type State struct {
 	Error error
 
-	FunctionByteCode [][]byte
+	Functions        [][]*Instruction
 	FunctionIndex    int64
 	InstructionIndex int64
 
@@ -81,51 +81,73 @@ var OpHandlers = map[uint32]OpHandler{
 	0x00000402: (*State).JumpIfFalse,
 }
 
-func NewState(functionByteCode [][]byte) *State {
+func NewInstruction(byteCode []byte) (*Instruction, error) {
-	return &State{
+	instr := &Instruction{}
-		FunctionByteCode: functionByteCode,
+
+	reader := bytes.NewReader(byteCode)
+
+	err := struc.Unpack(reader, instr)
+	if err != nil {
+		return nil, errors.Wrap(err, "Error decoding instruction")
 	}
+
+	return instr, nil
+}
+
+func NewState(byteCodes [][]byte) (*State, error) {
+	state := &State{}
+
+	for i, byteCode := range byteCodes {
+		instrs := []*Instruction{}
+
+		for start := 0; start < len(byteCode); start += InstructionBytes {
+			chunk := byteCode[start : start+InstructionBytes]
+			instr, err := NewInstruction(chunk)
+			if err != nil {
+				return nil, errors.Wrapf(err, "At function index %d, byte offset %d", i, start)
+			}
+			instrs = append(instrs, instr)
+		}
+
+		state.Functions = append(state.Functions, instrs)
+	}
+
+	return state, nil
 }
 
 func (state *State) StackFrame() *StackFrame {
 	return state.Stack[len(state.Stack)-1]
 }
 
-func (state *State) Function() []byte {
+func (state *State) Function() []*Instruction {
-	return state.FunctionByteCode[state.FunctionIndex]
+	return state.Functions[state.FunctionIndex]
 }
 
 func (state *State) Execute() {
 	state.call(0)
 
-	for len(state.Stack) > 0 && state.Error == nil {
+	for len(state.Stack) > 0 {
-		start := state.InstructionIndex * InstructionBytes
+		state.ProcessInstruction()
-		chunk := state.Function()[start : start+InstructionBytes]
-		state.InstructionIndex += 1
-		state.ProcessInstruction(chunk)
 
-		if state.InstructionIndex >= int64(len(state.Function()) / InstructionBytes) {
+		if state.Error != nil {
+			break
+		}
+
+		if state.InstructionIndex >= int64(len(state.Function())) {
 			state.ret()
 		}
 	}
-
-	if state.Error != nil {
-		state.InstructionIndex -= 1
-	}
 }
 
-func (state *State) ProcessInstruction(byteCode []byte) {
+func (state *State) ProcessInstruction() {
-	reader := bytes.NewReader(byteCode)
+	fnc := state.Function()
 
-	instr := &Instruction{}
+	if state.InstructionIndex >= int64(len(fnc)) {
-
+		state.ret()
-	err := struc.Unpack(reader, instr)
-	if err != nil {
-		state.Error = errors.Wrap(err, "Error decoding instruction")
 		return
 	}
 
-	fmt.Printf("%+v\n", instr)
+	instr := fnc[state.InstructionIndex]
 
 	handler, found := OpHandlers[instr.OpCode]
 	if !found {
@@ -133,6 +155,8 @@ func (state *State) ProcessInstruction(byteCode []byte) {
 		return
 	}
 
+	state.InstructionIndex += 1
+
 	handler(state, instr)
 }
 
@@ -194,17 +218,15 @@ func (state *State) WriteSigned(op *Operand, value int64) {
 }
 
 func (state *State) NoOp(instr *Instruction) {
-	fmt.Printf("NoOp\n")
 }
 
 func (state *State) Call(instr *Instruction) {
-	fmt.Printf("Call\n")
 	in := state.ReadSigned(&instr.Operand1)
 	state.call(in)
 }
 
 func (state *State) call(functionOffset int64) {
-	if state.FunctionIndex + functionOffset >= int64(len(state.FunctionByteCode)) {
+	if state.FunctionIndex+functionOffset >= int64(len(state.Functions)) {
 		state.Error = fmt.Errorf("Invalid function call index: %d + %d = %d", state.FunctionIndex, functionOffset, state.FunctionIndex+functionOffset)
 		return
 	}
@@ -219,7 +241,6 @@ func (state *State) call(functionOffset int64) {
 }
 
 func (state *State) Return(instr *Instruction) {
-	fmt.Printf("Return\n")
 	state.ret()
 }
 
@@ -230,124 +251,106 @@ func (state *State) ret() {
 }
 
 func (state *State) Move(instr *Instruction) {
-	fmt.Printf("Move\n")
 	in := state.ReadUnsigned(&instr.Operand2)
 	state.WriteUnsigned(&instr.Operand1, in)
 }
 
 func (state *State) Add(instr *Instruction) {
-	fmt.Printf("Add\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.WriteUnsigned(&instr.Operand1, in1+in2)
 }
 
 func (state *State) Subtract(instr *Instruction) {
-	fmt.Printf("Subtract\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.WriteUnsigned(&instr.Operand1, in1-in2)
 }
 
 func (state *State) Multiply(instr *Instruction) {
-	fmt.Printf("Multiply\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.WriteUnsigned(&instr.Operand1, in1*in2)
 }
 
 func (state *State) DivideUnsigned(instr *Instruction) {
-	fmt.Printf("DivideUnsigned\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.WriteUnsigned(&instr.Operand1, in1/in2)
 }
 
 func (state *State) DivideSigned(instr *Instruction) {
-	fmt.Printf("DivideSigned\n")
 	in1 := state.ReadSigned(&instr.Operand1)
 	in2 := state.ReadSigned(&instr.Operand2)
 	state.WriteSigned(&instr.Operand1, in1/in2)
 }
 
 func (state *State) IsEqual(instr *Instruction) {
-	fmt.Printf("IsEqual\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.ComparisonResult = (in1 == in2)
 }
 
 func (state *State) IsLessThanUnsigned(instr *Instruction) {
-	fmt.Printf("IsLessThanUnsigned\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.ComparisonResult = (in1 < in2)
 }
 
 func (state *State) IsLessThanSigned(instr *Instruction) {
-	fmt.Printf("IsLessThanSigned\n")
 	in1 := state.ReadSigned(&instr.Operand1)
 	in2 := state.ReadSigned(&instr.Operand2)
 	state.ComparisonResult = (in1 < in2)
 }
 
 func (state *State) IsGreaterThanUnsigned(instr *Instruction) {
-	fmt.Printf("IsGreaterThanUnsigned\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.ComparisonResult = (in1 > in2)
 }
 
 func (state *State) IsGreaterThanSigned(instr *Instruction) {
-	fmt.Printf("IsGreaterThanSigned\n")
 	in1 := state.ReadSigned(&instr.Operand1)
 	in2 := state.ReadSigned(&instr.Operand2)
 	state.ComparisonResult = (in1 > in2)
 }
 
 func (state *State) IsLessThanOrEqualUnsigned(instr *Instruction) {
-	fmt.Printf("IsLessThanOrEqualUnsigned\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.ComparisonResult = (in1 <= in2)
 }
 
 func (state *State) IsLessThanOrEqualSigned(instr *Instruction) {
-	fmt.Printf("IsLessThanOrEqualSigned\n")
 	in1 := state.ReadSigned(&instr.Operand1)
 	in2 := state.ReadSigned(&instr.Operand2)
 	state.ComparisonResult = (in1 <= in2)
 }
 
 func (state *State) IsGreaterThanOrEqualUnsigned(instr *Instruction) {
-	fmt.Printf("IsGreaterThanOrEqualUnsigned\n")
 	in1 := state.ReadUnsigned(&instr.Operand1)
 	in2 := state.ReadUnsigned(&instr.Operand2)
 	state.ComparisonResult = (in1 >= in2)
 }
 
 func (state *State) IsGreaterThanOrEqualSigned(instr *Instruction) {
-	fmt.Printf("IsGreaterThanOrEqualSigned\n")
 	in1 := state.ReadSigned(&instr.Operand1)
 	in2 := state.ReadSigned(&instr.Operand2)
 	state.ComparisonResult = (in1 >= in2)
 }
 
 func (state *State) Jump(instr *Instruction) {
-	fmt.Printf("Jump\n")
 	in := state.ReadSigned(&instr.Operand1)
 	state.InstructionIndex += in - 1
 }
 
 func (state *State) JumpIfTrue(instr *Instruction) {
-	fmt.Printf("JumpIfTrue\n")
 	if state.ComparisonResult == true {
 		state.Jump(instr)
 	}
 }
 
 func (state *State) JumpIfFalse(instr *Instruction) {
-	fmt.Printf("JumpIfFalse\n")
 	if state.ComparisonResult == false {
 		state.Jump(instr)
 	}
@@ -379,18 +382,20 @@ func main() {
 		functionByteCode = append(functionByteCode, byteCode)
 	}
 
-	state := NewState(functionByteCode)
+	state, err := NewState(functionByteCode)
+	if err != nil {
+		panic(err)
+	}
+
 	state.Execute()
 
 	if state.Error != nil {
 		fmt.Printf("ERROR: %s\n", state.Error)
-		fmt.Printf("\tat function index 0x%016x, instruction index 0x%016x\n", state.FunctionIndex, state.InstructionIndex)
+		fmt.Printf("\tNext function index: 0x%016x\n", state.FunctionIndex)
+		fmt.Printf("\tNext instruction index: 0x%016x\n", state.InstructionIndex)
+		fmt.Printf("\n")
 	}
 
-	fmt.Printf("\n")
-	fmt.Printf("Comparison Result: %t\n", state.ComparisonResult)
-
-	fmt.Printf("\n")
 	fmt.Printf("Global memory:\n")
 	for i, v := range state.GlobalMemory {
 		fmt.Printf("\t0x%08x: 0x%016x %d %d\n", i, v, v, int64(v))