CSCI 255 Homework 8

This assignment must be submitted, as a PIC assembly file, to the Moodle submission page for Homework 8 by 11:00 PM on Thursday, 1 November.

Problem 1 and only

In Lab 8 you wrote a small PIC program to work on the Syracuse problem for 16-bit integers. Your task for this homework assignment is to extend that solution to 32-bit integers.

Here’s a few things you will need to get started.

• You will need to increase the space allocated for x from 2 bytes to 4 bytes.
• In the lab you used one register, W5, for x. This time you will need to use a two registers for x. I suggest W4 and W5.
• In the, you used the following code to initialize x.

             .equ        initX,2012
             MOV         #initX,W0
             MOV         WREG,x
  

  Because the initial value of x is now 32-bits, you will need to do something different. I suggest the following:

             .equ        initX,7527
             MOV         #(initX&0xFFFF),W0
             MOV         WREG,x
             MOV         #(initX>>16),W0
             MOV         WREG,x+2
  

Once you’ve made those changes, the task isn’t that hard. Find the places in your lab program where your tested, added, and shifted x. Replace those few instructions with 32-bit versions as found in Chapter 5. It’s not that hard. There were about six instructions testing and modifying x in the 16-bit version. Each will be doubled in the 32-bit version.

However, don’t wait too long to get started.

Some test cases