/***************************************************************************
video.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
static tilemap *bg_tilemap;
/* This is strange; it's unlikely that the sprites actually have a hardware */
/* clipping region, but I haven't found another way to have them masked by */
/* the characters at the top and bottom of the screen. */
static rectangle spritevisiblearea =
{
0*8, 32*8-1,
4*8, 29*8-1
};
/***************************************************************************
Convert the color PROMs into a more useable format.
Ping Pong has a 32 bytes palette PROM and two 256 bytes color lookup table
PROMs (one for sprites, one for characters).
I don't know for sure how the palette PROM is connected to the RGB output,
but it's probably the usual:
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( pingpong )
{
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 char lookup table */
/* sprites */
for (i = 0;i < TOTAL_COLORS(1);i++)
{
int code;
int bit0,bit1,bit2,bit3;
/* the bits of the color code are in reverse order - 0123 instead of 3210 */
code = *(color_prom++) & 0x0f;
bit0 = (code >> 0) & 1;
bit1 = (code >> 1) & 1;
bit2 = (code >> 2) & 1;
bit3 = (code >> 3) & 1;
code = (bit0 << 3) | (bit1 << 2) | (bit2 << 1) | (bit3 << 0);
COLOR(1,i) = code;
}
/* characters */
for (i = 0;i < TOTAL_COLORS(0);i++)
COLOR(0,i) = (*(color_prom++) & 0x0f) + 0x10;
}
WRITE8_HANDLER( pingpong_videoram_w )
{
videoram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap, offset);
}
WRITE8_HANDLER( pingpong_colorram_w )
{
colorram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap, offset);
}
static TILE_GET_INFO( get_bg_tile_info )
{
int attr = colorram[tile_index];
int code = videoram[tile_index] + ((attr & 0x20) << 3);
int color = attr & 0x1f;
int flags = ((attr & 0x40) ? TILE_FLIPX : 0) | ((attr & 0x80) ? TILE_FLIPY : 0);
SET_TILE_INFO(0, code, color, flags);
}
VIDEO_START( pingpong )
{
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 - 4;offs >= 0;offs -= 4)
{
int sx,sy,flipx,flipy,color,schar;
sx = spriteram[offs + 3];
sy = 241 - spriteram[offs + 1];
flipx = spriteram[offs] & 0x40;
flipy = spriteram[offs] & 0x80;
color = spriteram[offs] & 0x1F;
schar = spriteram[offs + 2] & 0x7F;
drawgfx(bitmap,machine->gfx[1],
schar,
color,
flipx,flipy,
sx,sy,
&spritevisiblearea,TRANSPARENCY_COLOR,0);
}
}
VIDEO_UPDATE( pingpong )
{
tilemap_draw(bitmap, cliprect, bg_tilemap, 0, 0);
draw_sprites(machine, bitmap, cliprect);
return 0;
}