subroutine not working

zer0cool · **Joined:** Tue Nov 22, 2022 6:55 pm **Posts:** 2

i have a simple character write subroutine that looks like

Code:

writeChar:
    mov ah, 0x0A
    mov bh, 0x00
    mov cx, 1
    int 0x10
    ret

before i call the function i put the value for ascii A into al then i call it but it doesnt do anything, when i copy the code inplace of the call it work just fine, what could be causing this

Klakap · **Joined:** Sat Mar 10, 2018 10:16 am **Posts:** 296

what about posting all your code?

nullplan · **Joined:** Wed Aug 30, 2017 8:24 am **Posts:** 1605

I second Klakap's request for the full code, but in this case I presume you failed to set up a stack.

Octocontrabass · **Joined:** Mon Mar 25, 2013 7:01 pm **Posts:** 5146

My crystal ball says you moved the subroutine under a "bits 32" directive (or whatever is equivalent for your assembler).

iansjack · **Posted:** Tue Sep 19, 2023 8:49 am

There are so many things that you could have done wrong. Single-stepping your code in a debugger should make the cause obvious.

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subroutine not working

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