/***************************************************************************
video.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
static int gfxbank;
static tilemap *bg_tilemap;
/***************************************************************************
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
***************************************************************************/
PALETTE_INIT( champbas )
{
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,r,g,b;
/* red component */
bit0 = (*color_prom >> 0) & 0x01;
bit1 = (*color_prom >> 1) & 0x01;
bit2 = (*color_prom >> 2) & 0x01;
r = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* green component */
bit0 = (*color_prom >> 3) & 0x01;
bit1 = (*color_prom >> 4) & 0x01;
bit2 = (*color_prom >> 5) & 0x01;
g = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* blue component */
bit0 = 0;
bit1 = (*color_prom >> 6) & 0x01;
bit2 = (*color_prom >> 7) & 0x01;
b = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
palette_set_color(machine,i,MAKE_RGB(r,g,b));
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);
}
WRITE8_HANDLER( champbas_videoram_w )
{
videoram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap, offset);
}
WRITE8_HANDLER( champbas_colorram_w )
{
colorram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap, offset);
}
WRITE8_HANDLER( champbas_gfxbank_w )
{
if (gfxbank != (data & 0x01))
{
gfxbank = data & 0x01;
tilemap_mark_all_tiles_dirty(ALL_TILEMAPS);
}
}
WRITE8_HANDLER( champbas_flipscreen_w )
{
if (flip_screen != data)
{
flip_screen_set(data);
tilemap_mark_all_tiles_dirty(ALL_TILEMAPS);
}
}
static TILE_GET_INFO( get_bg_tile_info )
{
int code = videoram[tile_index];
int color = (colorram[tile_index] & 0x1f) + 32;
SET_TILE_INFO(gfxbank, code, color, 0);
}
VIDEO_START( champbas )
{
bg_tilemap = tilemap_create(get_bg_tile_info, tilemap_scan_rows,
TILEMAP_TYPE_PEN, 8, 8, 32, 32);
}
static void draw_sprites(running_machine *machine, mame_bitmap *bitmap, const rectangle *cliprect)
{
int offs;
for (offs = spriteram_size - 2; offs >= 0; offs -= 2)
{
int code = spriteram[offs] >> 2;
int color = spriteram[offs + 1];
int flipx = spriteram[offs] & 0x01;
int flipy = spriteram[offs] & 0x02;
int sx = ((256 + 16 - spriteram_2[offs + 1]) & 0xff) - 16;
int sy = spriteram_2[offs] - 16;
drawgfx(bitmap,
machine->gfx[2 + gfxbank],
code, color,
flipx, flipy,
sx, sy,
cliprect,
TRANSPARENCY_COLOR, 0);
}
}
VIDEO_UPDATE( champbas )
{
tilemap_draw(bitmap, cliprect, bg_tilemap, 0, 0);
draw_sprites(machine, bitmap, cliprect);
return 0;
}