- Add Add OpCode

- Add Opcode Function map

pkg/vm/vm_ops.go

@@ -0,0 +1,7 @@
+package vm
+
+import "github.com/CityOfZion/neo-go/pkg/vm/stack"
+
+var opFunc = map[stack.Instruction]func(ctx *stack.Context, istack *stack.Invocation) error{
+	stack.ADD: Add,
+}

pkg/vm/vm_ops_maths.go

@@ -0,0 +1,25 @@
+package vm
+
+import "github.com/CityOfZion/neo-go/pkg/vm/stack"
+
+// Add adds two stack Items together.
+// Returns an error if either items cannot be casted to an integer
+// or if integers cannot be added together
+func Add(ctx *stack.Context, istack *stack.Invocation) error {
+	operandA, err := ctx.Estack.PopInt()
+	if err != nil {
+		return err
+	}
+	operandB, err := ctx.Estack.PopInt()
+	if err != nil {
+		return err
+	}
+	res, err := operandA.Add(operandB)
+	if err != nil {
+		return err
+	}
+
+	ctx.Estack.Push(res)
+
+	return nil
+}