why does calling int 15h crashes my code?

Question

I spent hours on trying to solve this, but no matter what I try, for some reason int 15h crashes my entire code. I am currently using a loop for the delay in my code but it's not accurate enough.

I tried: Problems with BIOS delay function (INT 15h / AH = 86h) http://www.techhelpmanual.com/221-int_15h_86h__wait.html and many more, but none helped me... this is the section I would want to change to int 15h, but failed:

delay:
    mov ah, 00h
    int 1ah
    mov si, dx
    tick:
    mov ah, 00h
    int 1ah
    cmp si, dx
    jz tick 
    mov si, dx
    dec bx
    jnz tick
    ret

And here is the entire code, if it helps somehow:

    IDEAL
    MODEL small
    STACK 256h
    DATASEG
        BACKGROUND_COLOR DB 5Ah ; Guessed randomly for more than half an hour
        LINK_X DW 94h
        LINK_Y DW 65h
        start_x DB 0h
        start_y DB 0h
        ani_fr DB 0h
        x DW 0h
        y DW 0h
        cloop DB 0h
        ck DW 0h
        lu1 DB 5 dup(0h),6 dup(30h),8 dup(0h),8 dup(30h),5 dup(0h),2Bh,0h,8 dup(30h),0h,2Bh,0h,0h,0h,2Bh,10 dup(30h),2Bh,0h,0h,0h,2Bh,73h,8 dup(30h),73h,2Bh,0h,0h,0h,2Bh,2Bh,73h,73h,4 dup(30h),73h,73h,2Bh,2Bh,4 dup(0h),2Bh,3 dup(73h),30h,30h,3 dup(73h),2Bh,5 dup(0h),73h,30h,6 dup(73h),30h,73h,4 dup(0h),73h,73h,7 dup(30h),73h,73h,4 dup(0h),73h,73h,7 dup(30h),73h,73h,2Bh,4 dup(0h),73h,73h,6 dup(30h),73h,73h,2Bh,4 dup(0h),30h,30h,6 dup(73h),30h,2Bh,2Bh,4 dup(0h),10 dup(30h),5 dup(0h),3 dup(73h),5 dup(30h),73h,6 dup(0h),4 dup(73h),0h,0h,73h,73h,8 dup(0h),73h,73h,9 dup(0h)
        lu2 DB 5 dup(0h),6 dup(30h),8 dup(0h),8 dup(30h),5 dup(0h),2Bh,0h,8 dup(30h),0h,2Bh,0h,0h,0h,2Bh,10 dup(30h),2Bh,0h,0h,0h,2Bh,73h,8 dup(30h),73h,2Bh,0h,0h,0h,2Bh,2Bh,73h,73h,4 dup(30h),73h,73h,2Bh,2Bh,4 dup(0h),2Bh,3 dup(73h),30h,30h,3 dup(73h),2Bh,5 dup(0h),73h,30h,6 dup(73h),30h,73h,5 dup(0h),73h,73h,7 dup(30h),73h,73h,3 dup(0h),2Bh,73h,73h,7 dup(30h),73h,73h,3 dup(0h),2Bh,73h,73h,6 dup(30h),73h,73h,4 dup(0h),2Bh,2Bh,30h,6 dup(73h),30h,30h,5 dup(0h),10 dup(30h),6 dup(0h),73h,5 dup(30h),3 dup(73h),7 dup(0h),73h,73h,0h,0h,4 dup(73h),12 dup(0h),73h,73h,0h,0h,0h
        ld1 DB 5 dup(0h),6 dup(30h),8 dup(0h),8 dup(30h),5 dup(0h),2Bh,0h,30h,6 dup(73h),30h,0h,2Bh,3 dup(0h),2Bh,0h,8 dup(73h),0h,2Bh,3 dup(0h),2 dup(2Bh),73h,2Bh,30h,2 dup(2Bh),30h,2Bh,73h,2 dup(2Bh),3 dup(0h),2 dup(2Bh),73h,2Bh,73h,2 dup(2Bh),73h,2Bh,73h,2 dup(2Bh),4 dup(0h), 10 dup(2Bh),73h,4 dup(0h),2 dup(30h),2 dup(2Bh),2 dup(73h),2 dup(2Bh),2 dup(30h),73h,2 dup(0h),5 dup(73h),4 dup(2Bh),2 dup(30h),5 dup(73h),2Bh,4 dup(73h),5 dup(30h),2Bh,3 dup(73h),3 dup(2Bh),2 dup(73h),2Bh,2 dup(73h),2 dup(30h),3 dup(2Bh),3 dup(73h),2Bh,3 dup(73h),2Bh,30h,4 dup(73h),3 dup(2Bh),73h,73h,2Bh,3 dup(73h),2Bh,73h,73h,4 dup(30h),2Bh,0h,6 dup(73h),2Bh,5 dup(30h),4 dup(0h),5 dup(2Bh),73h,0h,0h,3 dup(73h),7 dup(0h),3 dup(73h),8 dup(0h)
        ld2 DB 5 dup(0h),6 dup(30h),8 dup(0h),8 dup(30h),3 dup(0h),0h,0h,2Bh,0h,30h,6 dup(73h),30h,0h,2Bh,0h,0h,0h,2Bh,0h,8 dup(73h),0h,2Bh,0h,0h,0h,2 dup(2Bh),73h,2Bh,30h,2 dup(2Bh),30h,2Bh,73h,2 dup(2Bh),0h,0h,0h,2 dup(2Bh),73h,2Bh,73h,2 dup(2Bh),73h,2Bh,73h,2 dup(2Bh),0h,3 dup(0h),10 dup(2Bh),73h,0h,4 dup(0h),30h,2Bh,2Bh,73h,73h,2Bh,2Bh,30h,73h,73h,0h,0h,0h,5 dup(73h),3 dup(2Bh),3 dup(30h),2Bh,0h,0h,73h,73h,2Bh,4 dup(73h),5 dup(30h),2Bh,0h,0h,73h,3 dup(2Bh),73h,73h,2Bh,73h,73h,30h,30h,73h,0h,0h,0h,73h,73h,2Bh,3 dup(73h),2Bh,30h,73h,73h,73h,30h,0h,0h,0h,2 dup(73h),2Bh,3 dup(73h),2Bh,73h,73h,3 dup(30h),0h,0h,0h,6 dup(73h),2Bh,3 dup(30h),73h,3 dup(0h),2 dup(0h),5 dup(2Bh),0h,0h,3 dup(73h),3 dup(0h),9 dup(0h),3 dup(73h),3 dup(0h)
        ll1 DB 6 dup(0h),4 dup(30h),8 dup(0h),4 dup(73h),5 dup(30h),5 dup(0h),6 dup(73h),30h,30h,2Bh,3 dup(30h),4 dup(0h),6 dup(73h),2Bh,2Bh,4 dup(30h),73h,0h,0h,2Bh,30h,2Bh,2Bh,73h,3 dup(2Bh),30h,30h,0h,30h,73h,3 dup(2Bh),73h,2Bh,2Bh,73h,2Bh,2Bh,73h,73h,30h,0h,0h,73h,0h,0h,6 dup(2Bh),3 dup(73h),0h,0h,0h,73h,0h,0h,4 dup(2Bh),4 dup(30h),4 dup(0h),73h,2Bh,3 dup(73h),7 dup(30h),73h,0h,0h,73h,2Bh,73h,73h,3 dup(30h),3 dup(2Bh),30h,3 dup(73h),0h,73h,0h,73h,73h,3 dup(30h),3 dup(2Bh),4 dup(73h),0h,73h,0h,0h,0h,73h,3 dup(30h),2Bh,2Bh,4 dup(73h),0h,73h,0h,0h,0h,4 dup(73h),30h,30h,73h,73h,30h,6 dup(0h),10 dup(30h),8 dup(0h),4 dup(73h),10 dup(0h),5 dup(73h),4 dup(0h)
        ll2 DB 21 dup(0h),4 dup(30h),8 dup(0h),4 dup(73h),5 dup(30h),5 dup(0h),6 dup(73h),30h,30h,2Bh,3 dup(30h),4 dup(0h),6 dup(73h),2Bh,2Bh,4 dup(30h),3 dup(0h),2Bh,30h,2Bh,2Bh,73h,3 dup(2Bh),30h,30h,0h,30h,0h,3 dup(2Bh),73h,2Bh,2Bh,73h,2Bh,2Bh,73h,73h,30h,3 dup(0h),73h,0h,6 dup(2Bh),3 dup(73h),4 dup(0h),73h,0h,4 dup(2Bh),4 dup(30h),5 dup(0h),73h,2Bh,73h,73h,3 dup(2Bh),30h,30h,73h,73h,30h,3 dup(0h),73h,2Bh,73h,30h,3 dup(2Bh),5 dup(73h),3 dup(0h),73h,0h,73h,30h,30h,2Bh,2Bh,5 dup(73h),30h,0h,0h,73h,0h,0h,73h,3 dup(30h),4 dup(73h),30h,30h,0h,0h,73h,0h,30h,4 dup(73h),5 dup(30h),73h,73h,0h,0h,73h,73h,8 dup(30h),3 dup(73h),0h,0h,0h,3 dup(73h),5 dup(0h),3 dup(73h),0h
        lr1 DB 21 dup(0h),4 dup(30h),9 dup(0h),5 dup(30h),4 dup(73h),4 dup(0h),3 dup(30h),2Bh,2 dup(30h),6 dup(73h),2 dup(0h),4 dup(30h),2 dup(2Bh),6 dup(73h),3 dup(0h),30h,0h,2 dup(30h),3 dup(2Bh),73h,2 dup(2Bh),30h,2Bh,5 dup(0h),30h,2 dup(73h),2 dup(2Bh),73h,2 dup(2Bh),73h,3 dup(2Bh),4 dup(0h),3 dup(73h),6 dup(2Bh),0h,73h,5 dup(0h),4 dup(30h),4 dup(2Bh),0h,73h,3 dup(0h),30h,2 dup(73h),2 dup(30h),3 dup(2Bh),2 dup(73h),2Bh,73h,3 dup(0h),5 dup(73h),3 dup(2Bh),30h,73h,2Bh,73h,2 dup(0h),30h,5 dup(73h),2 dup(2Bh),2 dup(30h),73h,0h,73h,2 dup(0h),2 dup(30h),4 dup(73h),3 dup(30h),73h,2 dup(0h),73h,0h,2 dup(73h),5 dup(30h),4 dup(73h),30h,0h,73h,0h,3 dup(73h),8 dup(30h),2 dup(73h),3 dup(0h),3 dup(73h),5 dup(0h),3 dup(73h),0h,0h
        lr2 DB 5 dup(0h),4 dup(30h),9 dup(0h),5 dup(30h),4 dup(73h),4 dup(0h),3 dup(30h),2Bh,2 dup(30h),6 dup(73h),2 dup(0h),4 dup(30h),2 dup(2Bh),6 dup(73h),3 dup(0h),30h,0h,2 dup(30h),3 dup(2Bh),73h,2 dup(2Bh),30h,2Bh,2 dup(0h),73h,2 dup(0h),30h,2 dup(73h),2 dup(2Bh),73h,2 dup(2Bh),73h,3 dup(2Bh),73h,3 dup(0h),3 dup(73h),6 dup(2Bh),2 dup(0h),73h,4 dup(0h),4 dup(30h),4 dup(2Bh),2 dup(0h),73h,2 dup(0h),73h,7 dup(30h),3 dup(73h),2Bh,73h,0h,3 dup(73h),30h,3 dup(2Bh),3 dup(30h),2 dup(73h),2Bh,73h,0h,4 dup(73h),3 dup(2Bh),3 dup(30h),2 dup(73h),0h,73h,0h,4 dup(73h),2 dup(2Bh),3 dup(30h),73h,3 dup(0h),73h,2 dup(0h),30h,2 dup(73h),2 dup(30h),4 dup(73h),3 dup(0h),73h,0h,10 dup(30h),8 dup(0h),4 dup(73h),11 dup(0h),5 dup(73h),6 dup(0h)
        lrs1 DB 5 dup(0h),4 dup(30h),8 dup(0h),4 dup(73h),5 dup(30h),5 dup(0h),6 dup(73h),2 dup(30h),2Bh,2 dup(30h),5 dup(0h),6 dup(73h),2 dup(2Bh),2 dup(30h),5 dup(0h),2Bh,30h,2 dup(2Bh),73h,3 dup(2Bh),3 dup(30h),2 dup(0h),3 dup(2Bh),73h,2 dup(2Bh),73h,2 dup(2Bh),2 dup(73h),3 dup(30h),3 dup(0h),6 dup(2Bh),3 dup(73h),2 dup(0h),30h,2 dup(0h),5 dup(2Bh),5 dup(30h),5 dup(0h),3 dup(2Bh),6 dup(73h),2 dup(30h),5 dup(0h),2 dup(2Bh),7 dup(73h),30h,6 dup(0h),30h,7 dup(73h),2 dup(30h),4 dup(0h),2 dup(73h),3 dup(30h),3 dup(73h),4 dup(30h),3 dup(0h),5 dup(73h),6 dup(30h),2 dup(73h),0h,2 dup(73h),9 dup(30h),7 dup(73h),7 dup(0h),3 dup(73h),16 dup(0h)
        ;lrs2 DB 
    CODESEG
link_move_prep:
    mov ax, [LINK_X]
    mov [x], ax
    mov ax, [LINK_Y]
    mov [y], ax
    call clear_tile
    ret
link_up:
    call link_move_prep
    sub [LINK_Y], 1h
    cmp [ani_fr], 4h
    jge call_lud1
    jle call_lud2
    call_lud1:
        mov si, offset lu1
        call draw_link
        ret
    call_lud2:
        mov si, offset lu2
        call draw_link
        ret
link_left:
    call link_move_prep
    sub [LINK_X], 1h
    cmp [ani_fr], 4h
    jge call_lld1
    jle call_lld2
    call_lld1:
        mov si, offset ll1
        call draw_link
        ret
    call_lld2:
        mov si, offset ll2
        call draw_link
        ret
link_right:
    call link_move_prep
    add [LINK_X], 1h
    cmp [ani_fr], 4h
    jge call_lrd1
    jle call_lrd2
    call_lrd1:
        mov si, offset lr1
        call draw_link
        ret
    call_lrd2:
        mov si, offset lr2
        call draw_link
        ret
link_down:
    call link_move_prep
    add [LINK_Y], 1h
    cmp [ani_fr], 4h
    jge call_ldd1
    jle call_ldd2
    call_ldd1:
        mov si, offset ld1
        call draw_link
        ret
    call_ldd2:
        mov si, offset ld2
        call draw_link
        ret
draw_pixel:
    mov ah, 0Ch         ; Changes to pixel writing
    mov cx, [x]   ; Sets X Coordinates for the pixel
    mov dx, [y]   ; Sets Y Coordinates for the pixel
    int 10h            ; Flushes the pixel
    ret
proc clear_tile
    mov [cloop], 00h
    clearmainloop:
        mov al, [BACKGROUND_COLOR]
        call draw_pixel
        add [x], 1h
        mov bx, [LINK_X]
        sub [x], bx
        cmp [x], 0Fh
        jge clearbreakline
        clearrepeat:
            add [x], bx
            add [cloop], 1h
            cmp [cloop], 0F0h
            jne clearmainloop
            ret
    clearbreakline:
        sub [x], 0Fh
        add [y], 1h
        jmp clearrepeat
endp
proc draw_link
    mov ax, [LINK_X]
    mov [x], ax
    mov ax, [LINK_Y]
    mov [y], ax
    mov [cloop], 0h
    lmainloop:
        mov al, [si]
        cmp al, 0h
        je ad
        mov ah, 0Ch
        mov bh, 0h
        mov cx, [x]
        mov dx, [y]
        int 10h
        ad:
            add [x], 1h
            mov ax, [LINK_X]
            sub [x], ax
            cmp [x], 0Fh
            jge lbreakline
        ldrepeat:
            add si, 1h
            add [x], ax
            add [cloop], 1h
            cmp [cloop], 0F0h
            jne lmainloop
            cmp [ani_fr], 6h
            je link_ani_res
            add [ani_fr], 1h
            ret
            link_ani_res:
                mov [ani_fr], 0h
                ret
    lbreakline:
        sub [x], 0Fh
        add [y], 1h
        jmp ldrepeat
endp
proc use_sword
    mov ax, 5h
    mov bx, 0h
    int 33h
    cmp ax, 1h
    je clkd
    ret
    clkd:
        mov [x],10h
        mov [y],10h
        call draw_pixel
        ret
        
endp
delay:
    mov al, 0h
    mov ah, 86h
    mov cx, 1h
    mov dx, 2h
    int 15h
    ret
start:
    mov ax, @data
    mov ds, ax
    
    mov ah, 00h ; Changes to display mode (who needs text?)
    mov al, 13h ; Changes screen resolution to 320x200 with 256 color options, for best display
    int 10h     ; Flushes the display mode

    mov ah, 06h    ; Changes to scroll up (so it can start drawing the background from the top)
    xor al, al     ; Clear entire screen because the terminal has already drew the screen black
    xor cx, cx     ; Moves to the upper left corner
    mov dx, 184Fh  ; Gets screen size
    mov bh, [BACKGROUND_COLOR]    ; Paints the screen the background color
    int 10h

call link_down
mainloop:
    mov ah, 1h
    int 16h             ; Get keystroke
    jz after_press
    mov ah, 0h
    int 16h
    cmp ax, 1177h       ; 1177h == scancode for W
    jne mlr1
    call link_up
    mlr1:
    cmp ax, 1E61h       ; 1E61h == scancode for A
    jne mlr2
    call link_left
    mlr2:
    cmp ax, 1F73h       ; 1F73h == scancode for S
    jne mlr3
    call link_down
    mlr3:
    cmp ax, 2064h       ; 2064h == scancode for D
    jne after_press
    call link_right
    after_press:
    mov bx, 1h ; delay time
    call delay
    jmp mainloop
END start

EDIT: found a way to make a proc that uses a milliseconds delay without int 15h:

proc delay
delay_loop:
    mov cx, 1h
    delRep: push cx
    mov cx, 086A0h
    delDec: dec cx
    jnz delDec
    pop cx
    dec cx
    jnz delRep
    sub bx, 1h
    cmp bx, 0h
    jnz delay_loop
ret
endp

enjoy if you're searching for one

Perhaps emu8086 has a rough go with that interrupt and code? Dosbox did at one time: [Dosbox is buggy with int 15h, ah=86h](https://stackoverflow.com/questions/43194265/dosbox-is-buggy-with-int-15h-ah-86h). But also be mindful of preserving registers as needed before you call it, as noted in some of the comments in that post. Also have a look at [Problems with BIOS delay function int 15h, ah=86h](https://stackoverflow.com/questions/34089884/problems-with-bios-delay-function-int-15h-ah-86h). — lurker, Jan 14 '22 at 13:56
You haven't said in your question what you mean by "crashes my entire code". I provided those links for information that you can read, not necessarily to indicate that you need to find another function. There could be helpful tips for proper usage. — lurker, Jan 14 '22 at 14:07
What exactly do you mean by "crash my entire code"? When you single-step by instructions in emu8086's debugger, where does execution end up? Does that `int 15h` not ever return to the next instruction in your code? If not, where is CS:IP? — Peter Cordes, Jan 14 '22 at 15:45
never mind, I found an alternative way to it! Thank you anyways — Tomergngn, Jan 14 '22 at 17:08

why does calling int 15h crashes my code?

0 Answers0