; ASM implementation of a classic 'for' loop command
;
; sum = 0
; for (i = 0; i <= 10; i++)
;     sum += i;
;

; include directives
global asm_main
%include "../lib/asm_io.inc"

segment .data
    ; DX directives (read only, static data)

segment .bss
    ; RESX directives (writable data)

segment .text
asm_main:                   ; entry point (called from driver.c)
    ; instructions

    enter 0,0               ; Initialize register EBP
    pusha                   ; Push register contents to the stack
    ;

    mov   eax, 0            ; eax is the sum
    mov   ebx, 0            ; ebx is i
    mov   ecx, 10           ; ecx is the loop condition

loop_start:
    cmp   ebx, ecx          ; compare i to ECX
    jg    loop_end          ; loop condition

    ; loop body
    add   eax, ebx          ; sum += i
    inc   ebx               ; ebx++ 

    call  print_int         ; print for feedback
    call  print_nl

    jmp   loop_start        ; continue loop

loop_end:

    ;
    popa                    ; Restore register data from the stack
    mov   eax, 0            ; flush EAX of data
    leave                   ; restore the stack
    ret                     ; Return from main back into C library wrapper