/* Move the XL/XE OS to RAM.
   Based on the RAMROM code by Joe Miller, from the Mapping the
   Atari XL appendix (see the PORTB entry). Uses $6000 to $97FF as a
   buffer, so it won't step on the default GR.0 screen if BASIC is
   enabled.
*/

#include <stdio.h>
#include <string.h>
#include <atari.h>
#include <6502.h>

#define LO_ROM_SIZE 0x1000
#define HI_ROM_SIZE 0x2800

static char *lo_buf = (char *)0x6000;
static char *hi_buf = (char *)0x7000;
static char *lo_rom = (char *)0xc000;
static char *hi_rom = (char *)0xd800;

static char old_nmi;

static void enable_interrupts(void) {
	ANTIC.nmien = old_nmi;
	CLI();
}

static void disable_os_rom(void) {
	SEI();
	old_nmi = ANTIC.nmien;
	ANTIC.nmien = 0;
	PIA.portb &= 0xfe;
}

void os_to_ram(void) {
	memcpy(lo_buf, lo_rom, LO_ROM_SIZE);
	memcpy(hi_buf, hi_rom, HI_ROM_SIZE);
	disable_os_rom();
	memcpy(lo_rom, lo_buf, LO_ROM_SIZE);
	memcpy(hi_rom, hi_buf, HI_ROM_SIZE);
	enable_interrupts();
}

#if 0
void main(void) {
	if(is_xl()) {
		puts("XL/XE, copying OS to RAM.");
		os_to_ram();
		*((char *)0xe003) = 0x7e;
	} else {
		puts("400/800, can't do.");
	}
hang: goto hang;
}
#endif