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AmigActive 10
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AACD 10.iso
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vidhrdw
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champbas.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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144 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
static int gfxbank;
/***************************************************************************
Convert the color PROMs into a more useable format.
Pac Man has a 16 bytes palette PROM and a 128 bytes color lookup table PROM.
Pengo has a 32 bytes palette PROM and a 256 bytes color lookup table PROM
(actually that's 512 bytes, but the high address bit is grounded).
The palette PROM is 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 champbas_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++;
}
/* color_prom now points to the beginning of the lookup table */
/* TODO: there are 32 colors in the palette, but we are suing only 16 */
/* the only difference between the two banks is color #14, grey instead of green */
/* character lookup table */
/* sprites use the same color lookup table as characters */
for (i = 0;i < TOTAL_COLORS(0);i++)
COLOR(0,i) = (*(color_prom++) & 0x0f);
}
WRITE_HANDLER( champbas_gfxbank_w )
{
if (gfxbank != (data & 1))
{
gfxbank = 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 champbas_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 - 1;offs >= 0;offs--)
{
if (dirtybuffer[offs])
{
int sx,sy;
dirtybuffer[offs] = 0;
sx = 8 * (offs % 32);
sy = 8 * (offs / 32);
drawgfx(tmpbitmap,Machine->gfx[0 + gfxbank],
videoram[offs],
(colorram[offs] & 0x1f) + 32,
0,0,
sx,sy,
&Machine->drv->visible_area,TRANSPARENCY_NONE,0);
}
}
/* copy the character mapped graphics */
copybitmap(bitmap,tmpbitmap,0,0,0,0,&Machine->drv->visible_area,TRANSPARENCY_NONE,0);
/* Draw the sprites. Note that it is important to draw them exactly in this */
/* order, to have the correct priorities. */
for (offs = spriteram_size - 2;offs >= 0;offs -= 2)
{
drawgfx(bitmap,Machine->gfx[2 + gfxbank],
spriteram[offs] >> 2,
spriteram[offs + 1],
spriteram[offs] & 1,spriteram[offs] & 2,
((256+16 - spriteram_2[offs + 1]) & 0xff) - 16,spriteram_2[offs] - 16,
&Machine->drv->visible_area,TRANSPARENCY_COLOR,0);
}
}