CS 2734 Computer Organization II

• Here is that program in C:
  

        #include <stdio.h>
        void writebase(int, int);
        char *D[] =
          {"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"};
  
        void main()
        {  
           int N, B;
           printf("Enter N and B:");
           scanf("%d %d", &N, &B);
           writebase(N, B);
           printf("\n");
        }
  
        void writebase(int N, int B)
        {
           printf("Call Base with N and B = %d %d\n", N, B);
           if (N != 0) {
              writebase(N/B, B);
              printf("%s", D[N%B]);
           }
        }
  

  Along with sample output:

        Enter values for N and B:54790143
        16
        The values of N and B are: 54790143 16
        Call Base with N and B = 54790143 16
        Call Base with N and B = 3424383 16
        Call Base with N and B = 214023 16
        Call Base with N and B = 13376 16
        Call Base with N and B = 836 16
        Call Base with N and B = 52 16
        Call Base with N and B = 3 16
        Call Base with N and B = 0 16
        34407ff
  

• In implementing this programs in MIPS, you must again use $a0 and $a1 for the parameters to Base. Because these are recursive calls, you must save and store registers on the stack. In particular, after you have made a recursive call, if you have changed some $ai for the call, then you need to load it again from the stack if you want to use it again.

• You will need to use the div instruction, with quotient in the special register lo and remainder in hi. These registers must be accessed using the mfhi and the mflo instructions. (I want you to practice using the actual instructions, rather than corresponding pseudo-instructions.)

• You can simply select and copy the C code above for the program, and then compile and run it to see more sample output.

For checkoff:

• You must demonstrate your program in action using an input provided at the time of checkoff.
• Hand the laboratory TA a copy of your source code when you start the check off procedure.