#include <stdio.h>
#include "header.h"
/*
	Initialise subsystem XSYS.
	This function is called once.
	bla bla bla.

	Return -1 if not successfull
*/
int xsys_init (
	int memsize)		/* Amount of memory allocated to xsys */
{
	...
}

/*
	Terminate use of subsystem XSYS.

	This function frees all buffers and completes any pending operation.
	After it has been called, xsys_init may be call again.
*/
void xsys_end (void)
{
	....
}