Calling functions written in assembly?

This is a discussion on Calling functions written in assembly? within the C Programming forums, part of the General Programming Boards category; Ok, I have a free compiler (Borland C++ 5.02) which requires a $125 assembler program (TASM) to do inline assembly. ...

  1. #1
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    Calling functions written in assembly?

    Ok, I have a free compiler (Borland C++ 5.02) which requires a $125 assembler program (TASM) to do inline assembly. I refuse to pay this; I'd write my own assembler first.

    I know there are some freeware assemblers (I own a few, come to think of it) -- can I use one of them assemble to an OBJ that I can link to, and call functions from within, a C/C++ program?

    And how do I have to declare the prototypes? extern C?

  2. #2
    Just one more wrong move. -KEN-'s Avatar
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    I downloaded a non-warez TASM for free...want me to email it to you?

  3. #3
    Just one more wrong move. -KEN-'s Avatar
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    oh wait, I don't have it anymore...sorry.

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    I use nasm and gcc so it possible to use a different assembler
    and still link the c code. tasm for dos is easy to
    pickup, tasm32 might be harder to find. You also need
    to assemble to your compiler's object format I think. Nasm
    supports a number of these ,-f elf is what I use on linux.

    This should work on linux

    Code:
    /* t.h */
    int f(int a, int b);
    
    /* main.c */
    #include <stdio.h>
    #include "t.h"
    
    int main(void)
    {
        printf("4 + 3 = %d\n", f(4, 3));
    
        return 0;
    }
    
    /* t.asm */
    section .text
    
    global f
    f:
    	push ebp
    	mov ebp, esp
    
    	mov eax, [ebp+8]     ; eax = a
    	mov ecx, [ebp+12]   ; ecx = b
    
    	add eax, ecx           ; return in eax
    .exit:
    	leave
    	ret

  5. #5
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    t.h should have the extern "c" stuft, that way you
    can link with c++ .

  6. #6
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    Thanks for the pointers. MASM is still free (it's bundled with some DLs from Microsoft) so I've gotten that, and (eventually) gotten it working.

    I just tried out the sample code of yours, and made it work under the compiler (I compiled the rest as C++ so I needed to declare the function as a "C" called function to disable name mangling) -- everything seems all well and good! Thanks!

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