/***************************************************************************
Atari Drag Race video emulation
***************************************************************************/
#include "emu.h"
#include "includes/dragrace.h"
static TILE_GET_INFO( get_tile_info )
{
dragrace_state *state = machine.driver_data<dragrace_state>();
UINT8 code = state->m_playfield_ram[tile_index];
int num = 0;
int col = 0;
num = code & 0x1f;
if ((code & 0xc0) == 0x40)
num |= 0x20;
switch (code & 0xA0)
{
case 0x00:
col = 0;
break;
case 0x20:
col = 1;
break;
case 0x80:
col = (code & 0x40) ? 1 : 0;
break;
case 0xA0:
col = (code & 0x40) ? 3 : 2;
break;
}
SET_TILE_INFO(((code & 0xA0) == 0x80) ? 1 : 0, num, col, 0);
}
VIDEO_START( dragrace )
{
dragrace_state *state = machine.driver_data<dragrace_state>();
state->m_bg_tilemap = tilemap_create(machine, get_tile_info, tilemap_scan_rows, 16, 16, 16, 16);
}
SCREEN_UPDATE( dragrace )
{
dragrace_state *state = screen->machine().driver_data<dragrace_state>();
int y;
tilemap_mark_all_tiles_dirty(state->m_bg_tilemap);
for (y = 0; y < 256; y += 4)
{
rectangle rect = *cliprect;
int xl = state->m_position_ram[y + 0] & 15;
int xh = state->m_position_ram[y + 1] & 15;
int yl = state->m_position_ram[y + 2] & 15;
int yh = state->m_position_ram[y + 3] & 15;
tilemap_set_scrollx(state->m_bg_tilemap, 0, 16 * xh + xl - 8);
tilemap_set_scrolly(state->m_bg_tilemap, 0, 16 * yh + yl);
if (rect.min_y < y + 0) rect.min_y = y + 0;
if (rect.max_y > y + 3) rect.max_y = y + 3;
tilemap_draw(bitmap, &rect, state->m_bg_tilemap, 0, 0);
}
return 0;
}