Assembly - (NASM 32-bit) Printing a triangle of stars not working properly -

edit: problem solved. many mbratch.

my code outputs:

but should display this:

i think problem in innerloops can't fix it, works on first loop not on succeeding ones.

here's code:

innerloop1: ;;for(j=n-i;j>0;j--) mov bl, [i] sub byte [num], bl mov dl, [num] mov byte [j], dl cmp byte [j], 0 jle printstar  mov eax, 4     mov ebx, 1     mov ecx, space     mov edx, spacelen     int 80h dec dl     jmp innerloop1  printstar: mov eax, 4     mov ebx, 1     mov ecx, star     mov edx, starlen     int 80h  innerloop2: ;;for(k=0;k<(2*i)-1;k++) mov al, [i] mul byte [two] dec al cmp byte [k], al jge printme  mov eax, 4     mov ebx, 1     mov ecx, space     mov edx, spacelen     int 80h      inc byte [k]     jmp innerloop2  printme: mov eax, 4     mov ebx, 1     mov ecx, star     mov edx, starlen     int 80h      mov eax, 4     mov ebx, 1     mov ecx, newline     mov edx, newlinelen     int 80h      inc byte [i]     jmp outerloop      printspace: mov eax, 4     mov ebx, 1     mov ecx, space     mov edx, spacelen     int 80h 

there lots of inefficiencies in code , more , concisely written. however, i'll address areas causing functional problem.

there couple of problems innerloop1. modifying [num] every time through loop. instead, want prior loop initializer j. secondly, counting on value of dl being intact through execution of loop, mov edx, spacelen clobbers it, might call int 80h. can correct this:

    mov dl, [num]       ; initialize j=n-i     sub dl, byte [i] innerloop1: ;;for(j=n-i;j>0;j--)                         ; removed modification of 'num' here     mov byte [j], dl     cmp byte [j], 0     jle printstar      mov eax, 4     mov ebx, 1     mov ecx, space     push dx             ; save dx     mov edx, spacelen     int 80h     pop dx              ; restore dx     dec dl     jmp innerloop1 

in second inner loop (innerloop2) relying on pre-initialized value of k every time enter loop, no longer valid after first time loop encountered.. must initialize each time:

    mov byte [k], 0   ; initialize k=0 innerloop2: ;;for(k=0;k<(2*i)-1;k++)     mov al, [i]     mul byte [two]     dec al     cmp byte [k], al     jge printme 

this makes code work. additional comments:

• you need cautious counting on values of registers , watch may altered
• you should not rely on pre-initialized declarations initialize loop variables or other data can vary matter. it's practice explicitly initialize value in code if you're going change regularly
• think how optimize code (make more concise , clear) works.
• be more consistent in variable usage. asm program used num n defined value n, little confusing.
• be consistent in code indentation , spacing. make easier read.
• when doing constructs, such for loops, try maintain consistent approach doing them every time. reduce chance of errors. example, manage loop variables in same or similar ways.