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AmigActive 10
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AACD 10.iso
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vidhrdw
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ambush.c
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C/C++ Source or Header
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2000-03-03
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4KB
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183 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
unsigned char *ambush_scrollram;
unsigned char *ambush_colorbank;
/***************************************************************************
Convert the color PROMs into a more useable format.
I'm not sure about the resistor value, I'm using the Galaxian ones.
***************************************************************************/
void ambush_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
int i;
/* first, the char acter/sprite palette */
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++;
}
}
/***************************************************************************
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.
***************************************************************************/
static void draw_chars(struct osd_bitmap *bitmap, int priority)
{
int offs, transparency;
transparency = (priority == 0) ? TRANSPARENCY_NONE : TRANSPARENCY_PEN;
for (offs = 0; offs < videoram_size; offs++)
{
int code,sx,sy,col;
UINT8 scroll;
sy = (offs / 32);
sx = (offs % 32);
col = colorram[((sy & 0x1c) << 3) + sx];
if ((col & 0x10) != priority) continue;
scroll = ~ambush_scrollram[sx];
code = videoram[offs] | ((col & 0x60) << 3);
if (*flip_screen)
{
sx = 31 - sx;
sy = 31 - sy;
scroll = ~scroll - 1;
}
drawgfx(bitmap,Machine->gfx[0],
code,
(col & 0x0f) | ((*ambush_colorbank & 0x03) << 4),
*flip_screen,*flip_screen,
8*sx, (8*sy + scroll) & 0xff,
&Machine->drv->visible_area,transparency,0);
}
}
void ambush_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
int offs;
fillbitmap(bitmap,Machine->pens[0],&Machine->drv->visible_area);
/* Draw the background priority characters */
draw_chars(bitmap, 0x00);
/* Draw the sprites. */
for (offs = spriteram_size - 4;offs >= 0;offs -= 4)
{
int code,col,sx,sy,flipx,flipy,gfx;
sy = spriteram[offs + 0];
sx = spriteram[offs + 3];
if ( (sy == 0) ||
(sy == 0xff) ||
((sx < 0x40) && ( spriteram[offs + 2] & 0x10)) ||
((sx >= 0xc0) && (!(spriteram[offs + 2] & 0x10)))) continue; /* prevent wraparound */
code = (spriteram[offs + 1] & 0x3f) | ((spriteram[offs + 2] & 0x60) << 1);
if (spriteram[offs + 2] & 0x80)
{
/* 16x16 sprites */
gfx = 1;
if (!*flip_screen)
{
sy = 240 - sy;
}
else
{
sx = 240 - sx;
}
}
else
{
/* 8x8 sprites */
gfx = 0;
code <<= 2;
if (!*flip_screen)
{
sy = 248 - sy;
}
else
{
sx = 248 - sx;
}
}
col = spriteram[offs + 2] & 0x0f;
flipx = spriteram[offs + 1] & 0x40;
flipy = spriteram[offs + 1] & 0x80;
if (*flip_screen)
{
flipx = !flipx;
flipy = !flipy;
}
drawgfx(bitmap,Machine->gfx[gfx],
code, col | ((*ambush_colorbank & 0x03) << 4),
flipx, flipy,
sx,sy,
&Machine->drv->visible_area,TRANSPARENCY_PEN,0);
}
/* Draw the foreground priority characters */
draw_chars(bitmap, 0x10);
}