Kenwood HP 9000 manual Source for file1.c and file2.c

Linker Tasks

Using Linker commands

foo_ptr = (void (*)()) dyn_load(base_prog, addr, obj_files, dest_file, entry_pt);

/*

STEP 3: Get the addresses of all desired routines using nlist(3C):

*/

nl[0].n_name = “bar”; nl[1].n_name = “counter”; nl[2].n_name = NULL;

if (nlist(dest_file, nl)) {

fprintf(stderr, “error obtaining namelist for %s\n”, dest_file);

exit(1);

}

/*

*Assign the addresses to meaningful variable names:

*/

bar_ptr = (void (*)()) nl[0].n_value; counter_ptr = (int *) nl[1].n_value;

/*

*Now you can call the routines and modify the variables:

*/

glorp(“main”); (*foo_ptr) ();

(*bar_ptr) (); (*counter_ptr) ++;

printf(“counter = %d\n”, *counter_ptr);

}
void	glorp(const char * from)
{

printf(“glorp called from %s\n”, from);

}

file1.o and file2.o . “Source for file1.c and file2.c” shows the source for file1.o and file2.o. Notice that foo and bar call glorp in dynprog.c. Also, both functions update the variable counter in file2.o; however, foo updates counter through the pointer (counter_ptr) defined in dynprog.c.

Source for file1.c and file2.c

/****************************************************************

*file1.c - Contains routines foo() and bar().

****************************************************************/

extern int	* counter_ptr;	/*	defined in		dynprog.c	*/
extern int	counter;	/*	defined	in	file2.c	*/
extern void glorp(const char * from); /*			defined	in	dynprog.c */

void foo()

{

Chapter 3 71