University of California at Berkeley

College of Engineering

Department of Electrical Engineering and Computer Science

EECS 61C, Summer 2004

Lab 2-2

Goals

These lab exercises are intended to familiarize you with recursive function calls in MIPS, and give you practice on more advanced instructions as well as testing your understanding of the MIPS conventions.

Exercise 1: Function Calls and Recursion in MIPS

Copy the file fib.s from ~cs61c/labs/lab2-2 into your home directory.

Part a) Multiplier

Implement the function called Multiply, in the same fib.s file, that takes two integers in $a0 and $a1 and puts the lower 32 bits of the result in register $v0. You do not need to detect overflow. DO NOT use the MIPS instruction mul, write your own function to multiply.

Part b) Fibonacci

Write a function called fib that takes an integer n as argument in register $a0 and computes the nth fibonacci value using recursion, puts the result in register $v0.

Exercise 2

Verify that C ignores integer overflow in two ways:

• (a) Add 1 to the largest possible positive signed integer, and print the result.
• (b) Using MIPSgcc, generate the assembly language equivalent of your program for (a) and examine the arithmetic instructions it uses.