; ASM implementation of an if-else statement
;
; if (condition) then  
;     then_block
; else
;     else_block


; 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, 4096         ; put test data in EAX
    mov   ecx, 96           ; put test data in ECX

    cmp   eax, ecx,         ; compare
    jg    else_block        ; jump to else on true condition
    ; then block
    sub   eax, ecx          ; manipulate data
    call  print_int         ; 4096 - 96 = 4000
    call  print_nl
    jmp   end_if            ; jump over the else block to end it

    ; else block
else_block:
    add    eax, ecx         ; manipulate data
    call   print_int        ; 4096 + 96 = 4192
    call   print_nl

end_if:
    mov    eax, 4097        ; Put data back in EAX to show end of if block
    call   print_nl
    call   print_int
    call   print_nl

    ;
    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