Finding the Max and Min values of a 10 element array in MIPS

Question

I am still very much a newbie once it comes to MIPS programming so bear with me. I am trying to write a function that goes through a 10 element array and returns the max and minimum values of the array. So far I have:

.data

X .word 31, 17, 92, 46, 172, 208, 13, 93, 65, 112
N .word 10
minValue .asciiz "Minimum Value: "
maxValue .asciiz "\nMaximum Value: "
values .asciiz "\nValues divisible by 4: "


.text

main:

la $a0, X
la $a1, N


jal MaxMin


MaxMin:
lw $t0, 0($a0)


swap:
move $t0, $s0
move $s0, $s1
move $s0, $t0

The MaxMin function is supposed to return the maximum and minimum values of the X array for me to print out. My plan is to go through the array and if an element is greater than or less than another element, they get swapped using the swap function. The problem is I have no idea how to go about doing this because I do not really know the syntax that you are supposed to use when dealing with arrays. If anyone could help I would appreciate it.

EOF · Answer 1 · 2014-10-20T22:27:04.840

How about writing the algorithm in C first?

#include <stddef.h>

struct minmax
{
int max;
int min;
};

struct minmax maxmin(int const *in, size_t n)
{
  struct minmax ret = {*in,*in};
  for (size_t i = 1; i<n; i++)
  {
    in++;
    if (*in > ret.max)
      {
        ret.max = *in;
      }
    if (*in < ret.min)
      {
        ret.min = *in;
      }
  }
  return ret;
}

To iterate over an array in the equivalent MIPS-assembly, you can load the pointer in into a temporary register:

la $t0, in

then dereference the pointer by loading the value from memory:

lw $t1, ($t0)

and finally increment the pointer in the loop:

addiu $t0, $t0, 4

score 2 · Accepted Answer · answered Oct 21 '14 at 05:47

Here an idea of how to read and print elements of an array through a function. Would make comparisons and make the swap.

.data
space: .asciiz " "
X: .word 31, 17, 92, 46, 172, 208, 13, 93, 65, 112
N: .word 10

.text
main:   la $a0, X       #$a0=load address of array X
    lw $a1, N       #$a1=10  --number elements
    jal readArray  #call readArray
    li $v0, 10      #exit program   
    syscall 

readArray:
    li $t0, 0       #$t0=0
    li $t1, 0       #$t1=0
buc:    bge $t0, $a1, final #if  $t0 >= $a1 then goto final
    lw $a0, X($t1) #$a0 = X(i)
    li $v0, 1       #Print integer              
    syscall

    la $a0, space   #load a space:  " "
    li $v0, 4       #print string               
    syscall

    addi $t1, $t1, 4    #Every 4 bytes there is an integer in the array
    addi $t0, $t0, 1    #$t0=$t0+1
    b buc       #goto buc
final:  
    jr $ra      #return

Finding the Max and Min values of a 10 element array in MIPS

2 Answers2