/***************************************************************************
video.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "emu.h"
#include "includes/pingpong.h"
/* 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 const 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;
/* allocate the colortable */
machine.colortable = colortable_alloc(machine, 0x20);
/* create a lookup table for the palette */
for (i = 0; i < 0x20; i++)
{
int bit0, bit1, bit2;
int r, g, b;
/* red component */
bit0 = (color_prom[i] >> 0) & 0x01;
bit1 = (color_prom[i] >> 1) & 0x01;
bit2 = (color_prom[i] >> 2) & 0x01;
r = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* green component */
bit0 = (color_prom[i] >> 3) & 0x01;
bit1 = (color_prom[i] >> 4) & 0x01;
bit2 = (color_prom[i] >> 5) & 0x01;
g = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* blue component */
bit0 = 0;
bit1 = (color_prom[i] >> 6) & 0x01;
bit2 = (color_prom[i] >> 7) & 0x01;
b = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
colortable_palette_set_color(machine.colortable, i, MAKE_RGB(r, g, b));
}
/* color_prom now points to the beginning of the lookup table */
color_prom += 0x20;
/* characters */
for (i = 0; i < 0x100; i++)
{
UINT8 ctabentry = (color_prom[i] & 0x0f) | 0x10;
colortable_entry_set_value(machine.colortable, i, ctabentry);
}
/* sprites */
for (i = 0x100; i < 0x200; i++)
{
UINT8 ctabentry = BITSWAP8(color_prom[i],7,6,5,4,0,1,2,3);
colortable_entry_set_value(machine.colortable, i, ctabentry);
}
}
WRITE8_HANDLER( pingpong_videoram_w )
{
pingpong_state *state = space->machine().driver_data<pingpong_state>();
state->m_videoram[offset] = data;
tilemap_mark_tile_dirty(state->m_bg_tilemap, offset);
}
WRITE8_HANDLER( pingpong_colorram_w )
{
pingpong_state *state = space->machine().driver_data<pingpong_state>();
state->m_colorram[offset] = data;
tilemap_mark_tile_dirty(state->m_bg_tilemap, offset);
}
static TILE_GET_INFO( get_bg_tile_info )
{
pingpong_state *state = machine.driver_data<pingpong_state>();
int attr = state->m_colorram[tile_index];
int code = state->m_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 )
{
pingpong_state *state = machine.driver_data<pingpong_state>();
state->m_bg_tilemap = tilemap_create(machine, get_bg_tile_info, tilemap_scan_rows, 8, 8, 32, 32);
}
static void draw_sprites(running_machine &machine, bitmap_t *bitmap, const rectangle *cliprect )
{
pingpong_state *state = machine.driver_data<pingpong_state>();
UINT8 *spriteram = state->m_spriteram;
int offs;
for (offs = state->m_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_transmask(bitmap,&spritevisiblearea,machine.gfx[1],
schar,
color,
flipx,flipy,
sx,sy,
colortable_get_transpen_mask(machine.colortable, machine.gfx[1], color, 0));
}
}
SCREEN_UPDATE( pingpong )
{
pingpong_state *state = screen->machine().driver_data<pingpong_state>();
tilemap_draw(bitmap, cliprect, state->m_bg_tilemap, 0, 0);
draw_sprites(screen->machine(), bitmap, cliprect);
return 0;
}