@Override
	protected T evaluatePtrSub(Program program, PcodeOp op, Map<Varnode, T> already) {
		Varnode baseVar = op.getInput(0);
		Varnode offsetVar = op.getInput(1);
		Varnode outVar = op.getOutput();
		T base = evaluateVarnode(program, baseVar, already);
		T offset = evaluateVarnode(program, offsetVar, already);
		return arithmetic.ptrSub(outVar.getSize(),
			baseVar.getSize(), base,
			offsetVar.getSize(), offset);
	}
Construct an evaluator

@param arithmetic the arithmetic for computing p-code op outputs
Ghidra/Debug/ProposedUtils/src/main/java/ghidra/pcode/eval/ArithmeticVarnodeEvaluator.java