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AmigActive 10
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AACD 10.iso
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vidhrdw
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yiear.c
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C/C++ Source or Header
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2000-04-04
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4KB
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174 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
#include "cpu/m6809/m6809.h"
static int flipscreen;
static int nmi_enable;
/***************************************************************************
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;
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++;
}
}
WRITE_HANDLER( yiear_control_w )
{
/* bit 0 flips screen */
if (flipscreen != (data & 1))
{
flipscreen = data & 1;
memset(dirtybuffer,1,videoram_size);
}
/* bit 1 is NMI enable */
nmi_enable = data & 0x02;
/* bit 2 is IRQ enable */
interrupt_enable_w(0, data & 0x04);
/* bits 3 and 4 are coin counters */
coin_counter_w(0, (data >> 3) & 0x01);
coin_counter_w(1, (data >> 4) & 0x01);
}
int yiear_nmi_interrupt(void)
{
/* can't use nmi_interrupt() because interrupt_enable_w() effects it */
return nmi_enable ? M6809_INT_NMI : ignore_interrupt();
}
/***************************************************************************
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] | ((videoram[offs] & 0x10) << 4),
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 - 2;offs >= 0;offs -= 2)
{
int sx,sy,flipx,flipy;
sy = 240 - spriteram[offs + 1];
sx = spriteram_2[offs];
flipx = ~spriteram[offs] & 0x40;
flipy = spriteram[offs] & 0x80;
if (flipscreen)
{
sy = 240 - sy;
flipy = !flipy;
}
if (offs < 0x26)
{
sy++; /* fix title screen & garbage at the bottom of the screen */
}
drawgfx(bitmap,Machine->gfx[1],
spriteram_2[offs + 1] + 256 * (spriteram[offs] & 1),
0,
flipx,flipy,
sx,sy,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
}