bitbox_emu.c

#include "gnuboy.h"
#include "defs.h"
#include "regs.h"
#include "hw.h"
#include "cpu.h"
#include "sound.h"
#include "mem.h"
#include "lcd.h"
#include "rtc.h"
#include "rc.h"

#include "bitbox.h"

/*
static int framelen = 16743;
static int framecount;
*/

void emu_frame();
void emu_line(); // in lcd
void emu_init(int);
void gamepad_poll();

void menu_frame();
void menu_line();
void menu_setup();
extern int menu_done, menu_choice;
extern int bitbox_rom_load(int rom_id);

void game_init()
{
	menu_setup();
}

int emu_started=0;
void game_frame()
{
	if (emu_started) {
		emu_frame();
	} 
	else
	{
		menu_frame();
		if (menu_done) emu_init(menu_choice);
	}
}
void graph_frame(void) {}

void graph_line()
{
	if (emu_started) emu_line();
	else menu_line();
}

/*
 * emu_reset is called to initialize the state of the emulated
 * system. It should set cpu registers, hardware registers, etc. to
 * their appropriate values at powerup time.
 */

void emu_reset()
{
	hw_reset();
	lcd_reset();
	cpu_reset();
	mbc_reset();
	sound_reset();
}




/* emu_step()
	make CPU catch up with LCDC
*/
void emu_step()
{
	cpu_emulate(cpu.lcdc);
}


/*
	Time intervals throughout the code, unless otherwise noted, are
	specified in double-speed machine cycles (2MHz), each unit
	roughly corresponds to 0.477us.
	
	For CPU each cycle takes 2dsc (0.954us) in single-speed mode
	and 1dsc (0.477us) in double speed mode.
	
	Although hardware gbc LCDC would operate at completely different
	and fixed frequency, for emulation purposes timings for it are
	also specified in double-speed cycles.
	
	line = 228 dsc (109us)
	frame (154 lines) = 35112 dsc (16.7ms)
	of which
		visible lines x144 = 32832 dsc (15.66ms)
		vblank lines x10 = 2280 dsc (1.08ms)
*/

void emu_init(int game_id)
{
	vid_init();
	pcm_init();
	vid_preinit();

	// load ROM & load palette 
	bitbox_rom_load(game_id);

	emu_reset();

	vid_begin();
	lcd_begin();
	emu_started = 1; // at the end , start line blitting
}


//	void *timer = sys_timer();
//	int delay;
void emu_frame(void)
{
	/* FRAME BEGIN */
	
	/* FIXME: djudging by the time specified this was intended
	to emulate through vblank phase which is handled at the
	end of the loop. */
	cpu_emulate(2280);
	
	/* FIXME: R_LY >= 0; comparsion to zero can also be removed
	altogether, R_LY is always 0 at this point */
	while (R_LY > 0 && R_LY < 144)
	{
		/* Step through visible line scanning phase */
		emu_step();
	}
	
	/* VBLANK BEGIN */

	vid_end();
	rtc_tick();
	sound_mix();
	pcm_submit();

	/* pcm_submit() introduces delay, if it fails we use
	sys_sleep() instead */
	/* timebase is exclusively done with pcm submit. we shall sync with LCD ! 
	if (!pcm_submit())
	{
		delay = framelen - sys_elapsed(timer);
		sys_sleep(delay);
		sys_elapsed(timer);
	}*/
	// doevents(); // does not handle extra events
	gamepad_poll();
	vid_begin();
	
	if (!(R_LCDC & 0x80)) {
		/* LCDC operation stopped */
		/* FIXME: djudging by the time specified, this is
		intended to emulate through visible line scanning
		phase, even though we are already at vblank here */
		cpu_emulate(32832);
	}
	
	while (R_LY > 0) {
		/* Step through vblank phase */
		emu_step();
	}
	/* VBLANK END */
	/* FRAME END */


}