- case POP: stack[--sp] = null;
- case POP2: stack[--sp] = null; stack[--sp] = null; /** fixme: pops a WORD, not an item */
- case DUP: stack[sp] = stack[sp-1]; sp++;
- case DUP2: stack[sp] = stack[sp-2]; stack[sp+1] = stack[sp-1]; sp+=2;
+ case POP: pop(); return null;
+ case POP2: pop(); pop(); return null;
+ case DUP: push(stack[sp-1]); return null;
+ case DUP2: push(stack[sp-2]); push(stack[sp-2]); return null;