jrpacman.c

这个是延伸mame的在wince平台下的游戏模拟器的代码

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

  machine.c

  Functions to emulate general aspects of the machine (RAM, ROM, interrupts,
  I/O ports)

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

#include "driver.h"


static int speedcheat = 0;	/* a well known hack allows to make JrPac Man run at four times */
				/* his usual speed. When we start the emulation, we check if the */
				/* hack can be applied, and set this flag accordingly. */


void jrpacman_init_machine(void)
{
	unsigned char *RAM = Machine->memory_region[Machine->drv->cpu[0].memory_region];


	/* check if the loaded set of ROMs allows the Pac Man speed hack */
	if (RAM[0x180b] == 0xbe || RAM[0x180b] == 0x01)
		speedcheat = 1;
	else speedcheat = 0;
}



int jrpacman_interrupt(void)
{
	unsigned char *RAM = Machine->memory_region[Machine->drv->cpu[0].memory_region];


	/* speed up cheat */
	if (speedcheat)
	{
		if (readinputport(3) & 1)	/* check status of the fake dip switch */
		{
			/* activate the cheat */
			RAM[0x180b] = 0x01;
		}
		else
		{
			/* remove the cheat */
			RAM[0x180b] = 0xbe;
		}
	}

	return interrupt();
}