Pre-resolve handlers

main.go

@@ -20,6 +20,8 @@ const InstructionBytes = 32
 const GlobalMemoryEntries = 16
 const FunctionMemoryEntries = 16
 
+type OpHandler func(*State, *Instruction)
+
 type Operand struct {
 	Type     OperandType
 	Reserved [3]byte
@@ -31,6 +33,8 @@ type Instruction struct {
 	Reserved [4]byte
 	Operand1 Operand
 	Operand2 Operand
+
+	opHandler OpHandler `struc:"skip"`
 }
 
 type State struct {
@@ -51,8 +55,6 @@ type StackFrame struct {
 	FunctionMemory           [FunctionMemoryEntries]uint64
 }
 
-type OpHandler func(*State, *Instruction)
-
 var OpHandlers = map[uint32]OpHandler{
 	0x00000000: (*State).NoOp,
 	0x00000001: (*State).Call,
@@ -124,17 +126,24 @@ func (state *State) Function() []*Instruction {
 }
 
 func (state *State) Execute() {
+	state.prepare()
 	state.call(0)
 
-	for len(state.Stack) > 0 {
+	for len(state.Stack) > 0 && state.Error == nil{
 		state.ProcessInstruction()
+	}
+}
 
-		if state.Error != nil {
-			break
+func (state *State) prepare() {
+	for _, fnc := range state.Functions {
+		for _, instr := range fnc {
+			handler, found := OpHandlers[instr.OpCode]
+			if !found {
+				state.Error = fmt.Errorf("Invalid OpCode: 0x%08x", instr.OpCode)
+				return
 			}
 
-		if state.InstructionIndex >= int64(len(state.Function())) {
-			state.ret()
+			instr.opHandler = handler
 		}
 	}
 }
@@ -148,16 +157,8 @@ func (state *State) ProcessInstruction() {
 	}
 
 	instr := fnc[state.InstructionIndex]
-
-	handler, found := OpHandlers[instr.OpCode]
-	if !found {
-		state.Error = fmt.Errorf("Invalid OpCode: 0x%08x", instr.OpCode)
-		return
-	}
-
 	state.InstructionIndex += 1
-
-	handler(state, instr)
+	instr.opHandler(state, instr)
 }
 
 func (state *State) ReadUnsigned(op *Operand) uint64 {