No ouput displayed for unsigned multplication Y86

Question

.pos 0x200
.align 4
InputArray: 
 .long 5
 .long 10
Done: .long 0x0

.pos 0x400
.align 4
OutputArray:

.pos 0x0
 irmovl InputArray,%eax
 irmovl OutputArray, %esi

Loop:  
 mrmovl (%eax), %ecx # get first element from InputArray
 mrmovl (%eax), %edi # a copy of first element used for multiplication
 irmovl $4, %ebx # increment the pointer of InputArray
 addl %ebx, %eax
 mrmovl (%eax), %edx # get second element from InputArray
 irmovl $1, %ebx # add first element to its copy for the amount of second element
 subl %ebx, %edx
 jg mult
 rmmovl %ecx,(%esi) # output value to OutputArray

mult:
 addl %edi, %ecx
 subl %ebx, %edx
 jg mult

Exit: halt

This is a really simple program that does unsigned mutiplication of a pair of integers (5 times 10) I wrote for Y86.

When I run the code, the result looks like this:

Stopped in 38 steps at PC = 0x42.  Status 'HLT', CC Z=1 S=0 O=0
Changes to registers:
%eax:   0x00000000      0x00000204
%ecx:   0x00000000      0x00000032
%ebx:   0x00000000      0x00000001
%esi:   0x00000000      0x00000400
%edi:   0x00000000      0x00000005

Changes to memory:

The register ecx for the result of calculation is 32 in hex so I definitely know that the mult loop has performed as intended, but nothing is being output into OutputArray which I don't understand why.

Answer 1

I am not sure if I understand what you mean by "No code is supposed to be after a jump statement in a label and the correct alternative was to locate the subsequent code in another label and use another jump statement to invoke that label", but the problem with your code is that you forgot a ret statement in your Mult loop.

Also, your code terminated ungracefully once you were done with the Loop part of the code (you ran through the Mult loop code again before encountering the halt.)

The following code works (but note that it is not ideal -- among other things, it does not account for negative values and overflow):

.pos 0x200
.align 4
InputArray: 
 .long 5
 .long 10
Done: .long 0x0

.pos 0x400
.align 4
OutputArray:

.pos 0x0
 irmovl InputArray,%eax
 irmovl OutputArray, %esi

Loop:  
 mrmovl (%eax), %ecx # get first element from InputArray
 mrmovl (%eax), %edi # a copy of first element used for multiplication
 irmovl $4, %ebx # increment the pointer of InputArray
 addl %ebx, %eax
 mrmovl (%eax), %edx # get second element from InputArray
 irmovl $1, %ebx # add first element to its copy for the amount of second element
 subl %ebx, %edx
 jg mult
 rmmovl %ecx,(%esi) # output value to OutputArray
 jmp Exit

mult:
 addl %edi, %ecx
 subl %ebx, %edx
 jg mult
 ret

Exit: halt