/***************************************************************************
video.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "emu.h"
#include "includes/mrdo.h"
/***************************************************************************
Convert the color PROMs into a more useable format.
Mr. Do! has two 32 bytes palette PROM and a 32 bytes sprite color lookup
table PROM.
The palette PROMs are connected to the RGB output this way:
U2:
bit 7 -- unused
-- unused
-- 100 ohm resistor -diode- BLUE
-- 75 ohm resistor -diode- BLUE
-- 100 ohm resistor -diode- GREEN
-- 75 ohm resistor -diode- GREEN
-- 100 ohm resistor -diode- RED
bit 0 -- 75 ohm resistor -diode- RED
T2:
bit 7 -- unused
-- unused
-- 150 ohm resistor -diode- BLUE
-- 120 ohm resistor -diode- BLUE
-- 150 ohm resistor -diode- GREEN
-- 120 ohm resistor -diode- GREEN
-- 150 ohm resistor -diode- RED
bit 0 -- 120 ohm resistor -diode- RED
200 ohm pulldown on all three components
***************************************************************************/
PALETTE_INIT( mrdo )
{
int i;
const int R1 = 150;
const int R2 = 120;
const int R3 = 100;
const int R4 = 75;
const int pull = 220;
float pot[16];
int weight[16];
const float potadjust = 0.7f; /* diode voltage drop */
for (i = 0x0f; i >= 0; i--)
{
float par = 0;
if (i & 1) par += 1.0f/(float)R1;
if (i & 2) par += 1.0f/(float)R2;
if (i & 4) par += 1.0f/(float)R3;
if (i & 8) par += 1.0f/(float)R4;
if (par)
{
par = 1/par;
pot[i] = pull/(pull+par) - potadjust;
}
else pot[i] = 0;
weight[i] = 0xff * pot[i] / pot[0x0f];
if (weight[i] < 0) weight[i] = 0;
}
/* allocate the colortable */
machine.colortable = colortable_alloc(machine, 0x100);
for (i = 0; i < 0x100; i++)
{
int a1,a2;
int bits0, bits2;
int r, g, b;
a1 = ((i >> 3) & 0x1c) + (i & 0x03) + 0x20;
a2 = ((i >> 0) & 0x1c) + (i & 0x03);
/* red component */
bits0 = (color_prom[a1] >> 0) & 0x03;
bits2 = (color_prom[a2] >> 0) & 0x03;
r = weight[bits0 + (bits2 << 2)];
/* green component */
bits0 = (color_prom[a1] >> 2) & 0x03;
bits2 = (color_prom[a2] >> 2) & 0x03;
g = weight[bits0 + (bits2 << 2)];
/* blue component */
bits0 = (color_prom[a1] >> 4) & 0x03;
bits2 = (color_prom[a2] >> 4) & 0x03;
b = weight[bits0 + (bits2 << 2)];
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 += 0x40;
/* characters */
for (i = 0; i < 0x100; i++)
colortable_entry_set_value(machine.colortable, i, i);
/* sprites */
for (i = 0x100; i < 0x140; i++)
{
UINT8 ctabentry = color_prom[(i - 0x100) & 0x1f];
if ((i - 0x100) & 0x20)
ctabentry >>= 4; /* high 4 bits are for sprite color n + 8 */
else
ctabentry &= 0x0f; /* low 4 bits are for sprite color n */
colortable_entry_set_value(machine.colortable, i, ctabentry + ((ctabentry & 0x0c) << 3));
}
}
/***************************************************************************
Callbacks for the TileMap code
***************************************************************************/
static TILE_GET_INFO( get_bg_tile_info )
{
mrdo_state *state = machine.driver_data<mrdo_state>();
UINT8 attr = state->m_bgvideoram[tile_index];
SET_TILE_INFO(
1,
state->m_bgvideoram[tile_index + 0x400] + ((attr & 0x80) << 1),
attr & 0x3f,
(attr & 0x40) ? TILE_FORCE_LAYER0 : 0);
}
static TILE_GET_INFO( get_fg_tile_info )
{
mrdo_state *state = machine.driver_data<mrdo_state>();
UINT8 attr = state->m_fgvideoram[tile_index];
SET_TILE_INFO(
0,
state->m_fgvideoram[tile_index+0x400] + ((attr & 0x80) << 1),
attr & 0x3f,
(attr & 0x40) ? TILE_FORCE_LAYER0 : 0);
}
/***************************************************************************
Start the video hardware emulation.
***************************************************************************/
VIDEO_START( mrdo )
{
mrdo_state *state = machine.driver_data<mrdo_state>();
state->m_bg_tilemap = tilemap_create(machine, get_bg_tile_info,tilemap_scan_rows,8,8,32,32);
state->m_fg_tilemap = tilemap_create(machine, get_fg_tile_info,tilemap_scan_rows,8,8,32,32);
tilemap_set_transparent_pen(state->m_bg_tilemap,0);
tilemap_set_transparent_pen(state->m_fg_tilemap,0);
tilemap_set_scrolldx(state->m_bg_tilemap, 0, 56);
tilemap_set_scrolldx(state->m_fg_tilemap, 0, 56);
tilemap_set_scrolldy(state->m_bg_tilemap, 0, 6);
tilemap_set_scrolldy(state->m_fg_tilemap, 0, 6);
state->m_flipscreen = 0;
state->save_item(NAME(state->m_flipscreen));
}
/***************************************************************************
Memory handlers
***************************************************************************/
WRITE8_HANDLER( mrdo_bgvideoram_w )
{
mrdo_state *state = space->machine().driver_data<mrdo_state>();
state->m_bgvideoram[offset] = data;
tilemap_mark_tile_dirty(state->m_bg_tilemap, offset & 0x3ff);
}
WRITE8_HANDLER( mrdo_fgvideoram_w )
{
mrdo_state *state = space->machine().driver_data<mrdo_state>();
state->m_fgvideoram[offset] = data;
tilemap_mark_tile_dirty(state->m_fg_tilemap, offset & 0x3ff);
}
WRITE8_HANDLER( mrdo_scrollx_w )
{
mrdo_state *state = space->machine().driver_data<mrdo_state>();
tilemap_set_scrollx(state->m_bg_tilemap, 0, data);
}
WRITE8_HANDLER( mrdo_scrolly_w )
{
mrdo_state *state = space->machine().driver_data<mrdo_state>();
/* This is NOT affected by flipscreen (so stop it happening) */
if (state->m_flipscreen)
tilemap_set_scrolly(state->m_bg_tilemap, 0,((256 - data) & 0xff));
else
tilemap_set_scrolly(state->m_bg_tilemap, 0, data);
}
WRITE8_HANDLER( mrdo_flipscreen_w )
{
mrdo_state *state = space->machine().driver_data<mrdo_state>();
/* bits 1-3 control the playfield priority, but they are not used by */
/* Mr. Do! so we don't emulate them */
state->m_flipscreen = data & 0x01;
tilemap_set_flip_all(space->machine(), state->m_flipscreen ? (TILEMAP_FLIPY | TILEMAP_FLIPX) : 0);
}
/***************************************************************************
Display refresh
***************************************************************************/
static void draw_sprites( running_machine &machine, bitmap_t *bitmap,const rectangle *cliprect )
{
mrdo_state *state = machine.driver_data<mrdo_state>();
UINT8 *spriteram = state->m_spriteram;
int offs;
for (offs = state->m_spriteram_size - 4; offs >= 0; offs -= 4)
{
if (spriteram[offs + 1] != 0)
{
drawgfx_transpen(bitmap, cliprect, machine.gfx[2],
spriteram[offs], spriteram[offs + 2] & 0x0f,
spriteram[offs + 2] & 0x10, spriteram[offs + 2] & 0x20,
spriteram[offs + 3], 256 - spriteram[offs + 1], 0);
}
}
}
SCREEN_UPDATE( mrdo )
{
mrdo_state *state = screen->machine().driver_data<mrdo_state>();
bitmap_fill(bitmap, cliprect,0);
tilemap_draw(bitmap, cliprect, state->m_bg_tilemap, 0, 0);
tilemap_draw(bitmap, cliprect, state->m_fg_tilemap, 0, 0);
draw_sprites(screen->machine(), bitmap, cliprect);
return 0;
}