capbowl.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"
#include "machine/ticket.h"

static int currentaddress = 0;
static int GRHighByte = 0;
static int GRMidByte  = 0;
static int GRLowByte = 0;

void capbowl_init_machine(void)
{
	/* Initialize the ticket dispenser to 100 milliseconds */
	/* (I'm not sure what the correct value really is) */
	ticket_dispenser_init(100, TICKET_MOTOR_ACTIVE_HIGH, TICKET_STATUS_ACTIVE_LOW);
}


void capbowl_rom_select_w(int offset,int data)
{
	int bankaddress = 0x10000 + ((data & 0x0c) << 13) + ((data & 0x01) << 14);
	unsigned char *RAM = Machine->memory_region[Machine->drv->cpu[0].memory_region];


	cpu_setbank(1,&RAM[bankaddress]);
}


/*
	Write to GR Address upper word (2 bits)
*/
void bowlrama_turbo_w(int offset, int data)
{
	switch( offset )
	{
		case 0x08:	  /* Write address high byte (only 2 bits used) */
			GRHighByte = data;
			break;

		case 0x17:    /* Write address mid byte (8 bits)   */
			GRMidByte = data;
			break;

		case 0x18:	  /* Write Address low byte (8 bits)   */
			GRLowByte = data;
			break;

		default:
			break;
	}

	currentaddress = ((GRHighByte << 16) | (GRMidByte << 8) | GRLowByte);
}


int bowlrama_turbo_r(int offset)
{
	int ret = 0;
	int data = Machine->memory_region[3][currentaddress];

	switch (offset)
	{
	case 0:	/* Read Mask */

		/*  Graphics data are 4bpp (2 pixels per byte).
			This function returns 0's for new pixel data.
			This allows data to be read as a mask, AND the mask with
			the screen data, then OR new data read by read data command.
		*/

		if(!(data & 0xf0))
		{
			ret = 0xf0;  /* High nibble is transparent */
		}

		if(!(data & 0x0f))
		{
			ret |= 0x0f;  /* Low nibble is transparent */
		}

		break;

	case 4: /* Read data and increment address */

		ret	= data;

		currentaddress = (currentaddress + 1) & 0x3ffff;

		GRHighByte = (currentaddress >> 16);
		GRMidByte  = (currentaddress >> 8) & 0xff;
		GRLowByte  = (currentaddress & 0xff);

		break;

	default:
		break;
	}

	return ret;
}