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cc65/samples/overlaydemo.c
Greg King 5d9f4dc89d Made the overlay demo programs compile for CBM targets again.
<conio.h> includes target-specific headers; so, we didn't bother to include <cbm.h> where it is needed.  But, '#include <conio.h>' was removed from some files; so now, we must include <cbm.h> explicitly.
2016-06-19 17:41:18 -04:00

138 lines
3.1 KiB
C

/*
** Minimalistic overlay demo program.
**
** Shows how to load overlay files from disk.
**
** 2009-10-02, Oliver Schmidt (ol.sc@web.de)
**
*/
#include <stdio.h>
#include <cc65.h>
#ifndef __CBM__
#include <fcntl.h>
#include <unistd.h>
#else
#include <cbm.h>
#include <device.h>
#endif
extern void _OVERLAY1_LOAD__[], _OVERLAY1_SIZE__[];
extern void _OVERLAY2_LOAD__[], _OVERLAY2_SIZE__[];
extern void _OVERLAY3_LOAD__[], _OVERLAY3_SIZE__[];
/* Functions resident in an overlay can call back functions resident in the
** main program at any time without any precautions. The function log() is
** an example for such a function resident in the main program.
*/
void log (char *msg)
{
printf ("Log: %s\n", msg);
}
/* In a real-world overlay program one would probably not use a #pragma but
** rather place all the code of certain source files into the overlay by
** compiling them with --code-name OVERLAY1.
*/
#pragma code-name (push, "OVERLAY1");
void foo (void)
{
/* Functions resident in an overlay can access all program variables and
** constants at any time without any precautions because those are never
** placed in overlays. The string constant below is an example for such
** a constant resident in the main program.
*/
log ("Calling main from overlay 1");
}
#pragma code-name (pop);
#pragma code-name (push, "OVERLAY2");
void bar (void)
{
log ("Calling main from overlay 2");
}
#pragma code-name (pop);
#pragma code-name (push, "OVERLAY3");
void foobar (void)
{
log ("Calling main from overlay 3");
}
#pragma code-name(pop);
unsigned char loadfile (char *name, void *addr, void *size)
{
#ifndef __CBM__
int file = open (name, O_RDONLY);
if (file == -1) {
log ("Opening overlay file failed");
return 0;
}
read (file, addr, (unsigned) size);
close (file);
#else
/* Avoid compiler warnings about unused parameters. */
(void) addr; (void) size;
if (cbm_load (name, getcurrentdevice (), NULL) == 0) {
log ("Loading overlay file failed");
return 0;
}
#endif
return 1;
}
void main (void)
{
log ("Calling overlay 1 from main");
/* The symbols _OVERLAY1_LOAD__ and _OVERLAY1_SIZE__ were generated by the
** linker. They contain the overlay area address and size specific to a
** certain program.
*/
if (loadfile ("ovrldemo.1", _OVERLAY1_LOAD__, _OVERLAY1_SIZE__)) {
/* The linker makes sure that the call to foo() ends up at the right mem
** addr. However it's up to user to make sure that the - right - overlay
** is actually loaded before making the the call.
*/
foo ();
}
log ("Calling overlay 2 from main");
/* Replacing one overlay with another one can only happen from the main
** program. This implies that an overlay can never load another overlay.
*/
if (loadfile ("ovrldemo.2", _OVERLAY2_LOAD__, _OVERLAY2_SIZE__)) {
bar ();
}
log ("Calling overlay 3 from main");
if (loadfile ("ovrldemo.3", _OVERLAY3_LOAD__, _OVERLAY3_SIZE__)) {
foobar ();
}
if (doesclrscrafterexit ()) {
getchar ();
}
}