travrusa.c

这个是延伸mame的在wince平台下的游戏模拟器的代码

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

  vidhrdw.c

  Traverse USA

L Taylor
J Clegg

  Functions to emulate the video hardware of the machine.

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

#include "driver.h"
#include "vidhrdw/generic.h"


unsigned char *travrusa_scroll_x_low;
unsigned char *travrusa_scroll_x_high;
unsigned char *travrusa_scroll_y_low;
unsigned char *travrusa_sprite_priority; /* JB 970912 */
static int flipscreen;


static struct rectangle spritevisiblearea =
{
	1*8, 31*8-1,
	0*8, 24*8-1
};
static struct rectangle spritevisibleareaflip =
{
	1*8, 31*8-1,
	8*8, 32*8-1
};



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

  Convert the color PROMs into a more useable format.

  Traverse USA has one 256x8 character palette PROM (some versions have two
  256x4), one 32x8 sprite palette PROM, and one 256x4 sprite color lookup
  table PROM.

  I don't know for sure how the palette PROMs are connected to the RGB
  output, but it's probably something like this; note that RED and BLUE
  are swapped wrt the usual configuration.

  bit 7 -- 220 ohm resistor  -- RED
        -- 470 ohm resistor  -- RED
        -- 220 ohm resistor  -- GREEN
        -- 470 ohm resistor  -- GREEN
        -- 1  kohm resistor  -- GREEN
        -- 220 ohm resistor  -- BLUE
        -- 470 ohm resistor  -- BLUE
  bit 0 -- 1  kohm resistor  -- BLUE

***************************************************************************/
void travrusa_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
	int i;
	#define TOTAL_COLORS(gfxn) (Machine->gfx[gfxn]->total_colors * Machine->gfx[gfxn]->color_granularity)
	#define COLOR(gfxn,offs) (colortable[Machine->drv->gfxdecodeinfo[gfxn].color_codes_start + offs])


	/* character palette */
	for (i = 0;i < 128;i++)
	{
		int bit0,bit1,bit2;


		/* red component */
		bit0 = 0;
		bit1 = (*color_prom >> 6) & 0x01;
		bit2 = (*color_prom >> 7) & 0x01;
		*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
		/* green component */
		bit0 = (*color_prom >> 3) & 0x01;
		bit1 = (*color_prom >> 4) & 0x01;
		bit2 = (*color_prom >> 5) & 0x01;
		*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
		/* blue component */
		bit0 = (*color_prom >> 0) & 0x01;
		bit1 = (*color_prom >> 1) & 0x01;
		bit2 = (*color_prom >> 2) & 0x01;
		*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;

		color_prom++;
	}

	/* skip bottom half - not used */
	color_prom += 128;

	/* sprite palette */
	for (i = 0;i < 32;i++)
	{
		int bit0,bit1,bit2;


		/* red component */
		bit0 = 0;
		bit1 = (*color_prom >> 6) & 0x01;
		bit2 = (*color_prom >> 7) & 0x01;
		*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
		/* green component */
		bit0 = (*color_prom >> 3) & 0x01;
		bit1 = (*color_prom >> 4) & 0x01;
		bit2 = (*color_prom >> 5) & 0x01;
		*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
		/* blue component */
		bit0 = (*color_prom >> 0) & 0x01;
		bit1 = (*color_prom >> 1) & 0x01;
		bit2 = (*color_prom >> 2) & 0x01;
		*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;

		color_prom++;
	}

	/* color_prom now points to the beginning of the lookup table */

	/* character lookup table */
	for (i = 0;i < TOTAL_COLORS(0);i++)
		COLOR(0,i) = i;

	/* sprite lookup table */
	for (i = 0;i < TOTAL_COLORS(1);i++)
		COLOR(1,i) = *(color_prom++) + 128;
}



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

  Start the video hardware emulation.

***************************************************************************/
int travrusa_vh_start(void)
{
	if ((dirtybuffer = malloc(videoram_size)) == 0)
		return 1;
	memset(dirtybuffer,1,videoram_size);

	if ((tmpbitmap = osd_create_bitmap(Machine->drv->screen_width*2,Machine->drv->screen_height)) == 0)
	{
		free(dirtybuffer);
		return 1;
	}

	return 0;
}



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

  Stop the video hardware emulation.

***************************************************************************/
void travrusa_vh_stop(void)
{
	free(dirtybuffer);
	osd_free_bitmap(tmpbitmap);
}



void travrusa_flipscreen_w(int offset,int data)
{
	/* screen flip is handled both by software and hardware */
	data ^= ~readinputport(4) & 1;

	if (flipscreen != (data & 1))
	{
		flipscreen = data & 1;
		memset(dirtybuffer,1,videoram_size);
	}
}



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

  Draw the game screen in the given osd_bitmap.
  Do NOT call osd_update_display() from this function, it will be called by
  the main emulation engine.

***************************************************************************/
void travrusa_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
	int offs;


	/* for every character in the Video RAM, check if it has been modified */
	/* since last time and update it accordingly. */
	for (offs = videoram_size-2;offs >= 0;offs-=2)
	{
		if (dirtybuffer[offs] || dirtybuffer[offs+1])
		{
			int sx,sy,flipx,flipy;


			dirtybuffer[offs] = dirtybuffer[offs+1] = 0;

			sx = (offs/2) % 64;
			sy = (offs/2) / 64;
			flipx = videoram[offs+1] & 0x20;
			flipy = videoram[offs+1] & 0x10;
			if (flipscreen)
			{
				sx = 63 - sx;
				sy = 31 - sy;
				flipx = !flipx;
				flipy = !flipy;
			}

			drawgfx(tmpbitmap,Machine->gfx[0],
					videoram[offs] + 4 * (videoram[offs+1] & 0xc0),
					videoram[offs+1] & 0x0f,
					flipx,flipy,
					8*sx,8*sy,
					0,TRANSPARENCY_NONE,0);
		}
	}


	/* copy the temporary bitmap to the screen */
	{
		int scroll[32];


		if (flipscreen)
		{
			for (offs = 0;offs < 24;offs++)
				scroll[31-offs] = 256 + (*travrusa_scroll_x_high * 0x100 + *travrusa_scroll_x_low);
			for (offs = 24;offs < 32;offs++)
				scroll[31-offs] = 256;
		}
		else
		{
			for (offs = 0;offs < 24;offs++)
				scroll[offs] = -(*travrusa_scroll_x_high * 0x100 + *travrusa_scroll_x_low);
			for (offs = 24;offs < 32;offs++)
				scroll[offs] = 0;
		}

		copyscrollbitmap(bitmap,tmpbitmap,32,scroll,0,0,&Machine->drv->visible_area,TRANSPARENCY_NONE,0);
	}


	/* copy the sprites */
	for (offs = spriteram_size - 4;offs >= 0;offs -= 4)
	{
		int sx,sy,flipx,flipy;


		sx = spriteram[offs + 3];
		sy = 240 - spriteram[offs];
		flipx = spriteram[offs + 1] & 0x40;
		flipy = spriteram[offs + 1] & 0x80;
		if (flipscreen)
		{
			sx = 240 - sx;
			sy = 240 - sy;
			flipx = !flipx;
			flipy = !flipy;
		}

		drawgfx(bitmap,Machine->gfx[1],
				spriteram[offs + 2],
				spriteram[offs + 1] & 0x0f,
				flipx,flipy,
				sx,sy,
				flipscreen ? &spritevisibleareaflip : &spritevisiblearea,TRANSPARENCY_PEN,0);
	}
}