using inline assembly in C++

[abdul]

I tried the following code to plot a pixel on the screen using asm but it shows me that shi*ty blue screen, and just terminates:

#include <iostream.h>

int main()
{
    __asm{
        mov ax,13h               ;mode = 13h                      
    int 10h                 ;call bios service

    mov ah,0Ch              ;function 0Ch
    mov al,4                ;color 4 - red
    mov cx,160              ;x position = 160
    mov dx,100              ;y position = 100
    int 10h                 ;call BIOS service

    xor ax,ax               ;function 00h - get a key
    int 16h                 ;call BIOS service
    mov ax,3                ;mode = 3
    int 10h                 ;call BIOS service

    mov ax,4C00h            ;exit to DOS
    int 21h
    }
    return 0;
} 

[jim mcnamara]

You can't call interrupts directly from within Windows.

Int21H, for example.

[abdul]

Originally posted by filburt1
That's what you get for using asm. Are you sure the assembly is cross-platform?

I don't no but I don't care about it unless it works correctly on mine for now

You can't call interrupts directly from within Windows.

Then why is there any need to use assembly if I can't call any interrupt?

[abdul]

And this code works well if I compile it as an assembly code, but it does not work when I use it as an inline assembly code in VC++.

[CornedBee]

Let me rephrase:

You can't call interrupts directly from within Windows PROGRAMS.

If you use inline assembly in vc++ you create a windows GUI or console application. If you compile as assembly code (with which compiler?) with NASM for example, you get a dos program and windows switches to a mode where this is allowed.

[abdul]

So its mean that NASM or any other asm compiler switch to DOS mode when they use interrupts.
21h is a DOS interrupt but 10h is a BIOS interrupt.
So I can't even call any interrupt other than DOS one?

[CornedBee]

No, not compiler switches. NASM is a assembler for DOS programs, where interrupts are always allowed. Windows allows interrupts only for DOS programs, I think Win95 (but not 98) allows the 21H interrupt. Maybe some others too, but I don't think so. This is the reason why I didn't find a way to set an interrupt handler using VC++: it's not possible.