Q35295: Getting the Address of a Function with FP_SEG and FP_OFF

Article: Q35295
Product(s): See article
Version(s): 3.00 4.00 5.00 5.10 | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_c
Last Modified: 12-OCT-1988

To get the address of a function, you may set a pointer to the
function by using FP_SEG and FP_OFF to get the segment and offset
for the function.

The following sample code demonstrates this process:

#include <dos.h>
#include <stdio.h>

int foo();
int (*foo_ptr)();
unsigned int seg_val;
unsigned int off_val;

void main(void);
void main(void)
{
    /* set the pointer to the function */
    foo_ptr = foo;

    /* use FP_SEG() and FP_OFF() to get segment and offset */
    seg_val = FP_SEG(foo_ptr);
    off_val = FP_OFF(foo_ptr);
    printf("Segment is %d; Offset is %d\n", seg_val, off_val);
}

int foo()
    {}

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