using inline assembly in C++

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Oct 5th, 2001, 08:34 PM
abdul

using inline assembly in C++

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:

PHP Code:

#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; }
Oct 5th, 2001, 08:47 PM

You can't call interrupts directly from within Windows.

Int21H, for example.
Oct 5th, 2001, 08:49 PM
abdul

Quote:

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:)

Quote:

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?
Oct 5th, 2001, 08:50 PM
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++.
Oct 10th, 2001, 02:18 PM
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.
Oct 10th, 2001, 03:21 PM
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?
Oct 10th, 2001, 03:29 PM
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.