yiear.c

这个是延伸mame的在wince平台下的游戏模拟器的代码

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

  vidhrdw.c

  Functions to emulate the video hardware of the machine.

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

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



static int flipscreen;



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

  Convert the color PROMs into a more useable format.

  Yie Ar Kung-Fu has one 32x8 palette PROM, connected to the RGB output this
  way:

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

***************************************************************************/
void yiear_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])


	for (i = 0;i < Machine->drv->total_colors;i++)
	{
		int bit0,bit1,bit2;

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

		color_prom++;
	}


	/* sprites lookup table */
	for (i = 0;i < TOTAL_COLORS(1);i++)
		COLOR(1,i) = i;

	/* characters lookup table */
	for (i = 0;i < TOTAL_COLORS(0);i++)
		COLOR(0,i) = i + 16;
}



void yiear_4f00_w(int offset,int data)
{
	/* bit 0 flips screen */
	if (flipscreen != (data & 1))
	{
		flipscreen = data & 1;
		memset(dirtybuffer,1,videoram_size);
	}

	/* bits 3 and 4 are for coin counters - we ignore them */
}



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

  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 yiear_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) % 32;
			sy = (offs/2) / 32;
			flipx = videoram[offs] & 0x80;
			flipy = videoram[offs] & 0x40;
			if (flipscreen)
			{
				sx = 31 - sx;
				sy = 31 - sy;
				flipx = !flipx;
				flipy = !flipy;
			}

			drawgfx(tmpbitmap,Machine->gfx[0],
				videoram[offs + 1] + 0x10 * (videoram[offs] & 0x10),
				0,
				flipx,flipy,
				8*sx,8*sy,
				0,TRANSPARENCY_NONE,0);
		}
	}


	/* copy the temporary bitmap to the screen */
	copybitmap(bitmap,tmpbitmap,0,0,0,0,&Machine->drv->visible_area,TRANSPARENCY_NONE,0);


	/* draw sprites */
	for (offs = spriteram_size - 16;offs >= 0;offs -= 16)
	{
		int sx,sy,flipx,flipy;


		sy = 240 - spriteram[offs + 6];

		if (sy < 240)
		{
			sx = spriteram[offs + 4];
			flipx = ~spriteram[offs + 15] & 0x40;
			flipy = spriteram[offs + 15] & 0x80;

			if (flipscreen)
			{
				sx = 240 - sx;
				sy = 240 - sy;
				flipx = !flipx;
				flipy = !flipy;
			}

			drawgfx(bitmap,Machine->gfx[1],
				spriteram[offs + 14] + 256 * (spriteram[offs + 15] & 1),
				0,
				flipx,flipy,
				sx,sy,
				&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
		}
	}
}