Question

This is my first project sorry for my lack of knowledge, this is the code I’m trying to replicate.

   int A[3] = {0, 1, 2}; 
    int x; 
    for ( int i = 0; i < 3; i++ ) 
    { 
         if ( A[i] > 1 )
         x = 1; 
         else 
         { 
                switch ( A[i] )  
                { case 0: 
                       x = 2; 
                  case 1: 
                       x = 3; 
                }  
         } 
         printf(“%d”, x); 
}

This is the code that I have in assembly.

   main:    li $s0, 0 
            sw $s0, ($s7) #int A[0] = {0};  
            li $s0, 1 
            sw $s0, 4($s7) #int A[1] = {1};  
            li $s0, 2 
            sw $s0, 8($s7) #int A[2] = {2}; 
            li $s1, 1  #initialize x = 1
            li $s0, 0 #initialize i = 0
            li $s2, 3 # constant 3
            li $s3, 1 # constant 1


    start:  blt $s0, $s2, for   
            j finish

    for:    add $t1,$s0,$s0 #reg $t1 = 2*i
            add $t1,$t1,$t1 #reg $t1 = 4*i
            add $t0,$t1,$s7  

    bgt $t0, $s3, exone  #a[i] is greater than 1 how to increment the array up?
    #switch statement
    lw  $t0, 0($t1)
    jr  $t0
    j  start

        L0: add $s0, $s0, 1
            li $s1, 2
            j  print

        L1: add $s0, $s0, 1
            li $s1, 3
            j  print


        exone:  add $s0, $s0, 1
            li $s1, 1
            j  print


        print:  li $v0, 1 # print integer 
             move $a0, $s1 # what to print is stored at $s1
             syscall
             j  start



         finish:  li $v0, 10 # exit system call 
               syscall 

I’m not sure where I’m going wrong it compiles but doesn’t give me the output I want or any output for that matter.

Based on some info I have updated my code.

    main:   add $s0,$zero, $zero
         li $s7, 200
         sw $s0, 0($s7) #int A[0] = {0};  
         addi $s0, $s0, 1
         sw $s0, 4($s7) #int A[1] = {1};  
         addi $s0, $s0, 1
         sw $s0, 8($s7) #int A[2] = {2}; 
         li $s1, 0  #initialize x = 0
         li $s0, 0 #initialize i = 0
         li $s2, 3 # constant 3
         li $s3, 1 # constant 1

    #check to enter the for loop
    for:    blt  $s0, $s2, enter   
                j finish
    #enter the for loop
    enter:    add $t1,$s0,$s0 #reg $t1 = 2*i
          add $t1,$t1,$t1 #reg $t1 = 4*i
          add $t0,$t1,$s7 #reg A[i]
          lw  $t2, 0($t0)   
          bgt $t2, $s3, exone  #a[i] is greater than 1 check
          #switch statement
          jr  $t2
          #just in case jump back to for loop
          j  for

          #address for the switch statements
      L0:     add $s0, $s0, 1
              li $s1, 2
          j  print

      L1:     add $s0, $s0, 1
          li $s1, 3
          j  print
         #address for the if else statement
      exone:  add $s0, $s0, 1
          li $s1, 1
          j  print


     print:  li $v0, 1 # print integer 
         move $a0, $s1 # what to print is stored at $s1
         syscall
         j  for



     finish:  li $v0, 10 # exit system call 
          syscall 

The output should be “231”.

Answer 1

      # [snip]
      add $t0,$t1,$s7 #reg A[i]
      lw  $t2, 0($t0)   
      bgt $t2, $s3, exone  #a[i] is greater than 1 check
      #switch statement
      jr  $t2

This is wrong jr means Jump Register and it jumps to the address contained in $t2 ( which at this point contains a[i], which here is 0, 1 or 2 — not great addresses to jump to).

You could do a lot of things to correct this (I’ll assume you meant to have break statements in your C code), but here’s some quick untested code that mimics the switch with a set of if-statements:

li $t3, 0
beq $t2, $t3, L0 # if (a[i] == 0) goto L0
li $t3, 1
beq $t2, $t3, L1 # if (a[i] == 1) goto L1
j print # else fall through