/***************************************************************************
video.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
static int star_speed;
static int gfxbank;
static tilemap *fg_tilemap;
/***************************************************************************
Convert the color PROMs into a more useable format.
I'm using the same palette conversion as Lady Bug, but the Zero Hour
schematics show a different resistor network.
***************************************************************************/
PALETTE_INIT( redclash )
{
int i;
for (i = 0;i < 32;i++)
{
int bit1,bit2,r,g,b;
bit1 = (color_prom[i] >> 0) & 0x01;
bit2 = (color_prom[i] >> 5) & 0x01;
r = 0x47 * bit1 + 0x97 * bit2;
bit1 = (color_prom[i] >> 2) & 0x01;
bit2 = (color_prom[i] >> 6) & 0x01;
g = 0x47 * bit1 + 0x97 * bit2;
bit1 = (color_prom[i] >> 4) & 0x01;
bit2 = (color_prom[i] >> 7) & 0x01;
b = 0x47 * bit1 + 0x97 * bit2;
palette_set_color(machine,i,MAKE_RGB(r,g,b));
}
/* This is for the stars colors */
for (i = 32;i < 64;i++)
{
int bit1,bit2,r,g,b;
bit2 = (i >> 4) & 0x01;
bit1 = (i >> 3) & 0x01;
b = 0x47 * bit1 + 0x97 * bit2;
bit2 = (i >> 2) & 0x01;
bit1 = (i >> 1) & 0x01;
g = 0x47 * bit1 + 0x97 * bit2;
bit1 = i & 0x01;
r = 0x47 * bit1;
palette_set_color(machine,i,MAKE_RGB(r,g,b));
}
/* characters */
for (i = 0;i < 8;i++)
{
colortable[4 * i] = 0;
colortable[4 * i + 1] = i + 0x08;
colortable[4 * i + 2] = i + 0x10;
colortable[4 * i + 3] = i + 0x18;
}
/* sprites */
for (i = 0;i < 4 * 8;i++)
{
int bit0,bit1,bit2,bit3;
/* low 4 bits are for sprite n */
bit0 = (color_prom[i + 32] >> 3) & 0x01;
bit1 = (color_prom[i + 32] >> 2) & 0x01;
bit2 = (color_prom[i + 32] >> 1) & 0x01;
bit3 = (color_prom[i + 32] >> 0) & 0x01;
colortable[i + 4 * 8] = 1 * bit0 + 2 * bit1 + 4 * bit2 + 8 * bit3;
/* high 4 bits are for sprite n + 8 */
bit0 = (color_prom[i + 32] >> 7) & 0x01;
bit1 = (color_prom[i + 32] >> 6) & 0x01;
bit2 = (color_prom[i + 32] >> 5) & 0x01;
bit3 = (color_prom[i + 32] >> 4) & 0x01;
colortable[i + 4 * 16] = 1 * bit0 + 2 * bit1 + 4 * bit2 + 8 * bit3;
}
}
WRITE8_HANDLER( redclash_videoram_w )
{
videoram[offset] = data;
tilemap_mark_tile_dirty(fg_tilemap, offset);
}
WRITE8_HANDLER( redclash_gfxbank_w )
{
if (gfxbank != (data & 0x01))
{
gfxbank = data & 0x01;
tilemap_mark_all_tiles_dirty(ALL_TILEMAPS);
}
}
WRITE8_HANDLER( redclash_flipscreen_w )
{
flip_screen_set(data & 0x01);
}
void redclash_set_stars_enable( UINT8 on ); //temp
void redclash_set_stars_speed( UINT8 speed ); //temp
/*
star_speed:
0 = unused
1 = unused
2 = forward fast
3 = forward medium
4 = forward slow
5 = backwards slow
6 = backwards medium
7 = backwards fast
*/
WRITE8_HANDLER( redclash_star0_w )
{
star_speed = (star_speed & ~1) | ((data & 1) << 0);
redclash_set_stars_speed(star_speed);
}
WRITE8_HANDLER( redclash_star1_w )
{
star_speed = (star_speed & ~2) | ((data & 1) << 1);
redclash_set_stars_speed(star_speed);
}
WRITE8_HANDLER( redclash_star2_w )
{
star_speed = (star_speed & ~4) | ((data & 1) << 2);
redclash_set_stars_speed(star_speed);
}
WRITE8_HANDLER( redclash_star_reset_w )
{
redclash_set_stars_enable(1);
}
static TILE_GET_INFO( get_fg_tile_info )
{
int code = videoram[tile_index];
int color = (videoram[tile_index] & 0x70) >> 4; // ??
SET_TILE_INFO(0, code, color, 0);
}
VIDEO_START( redclash )
{
fg_tilemap = tilemap_create(get_fg_tile_info, tilemap_scan_rows,
TILEMAP_TYPE_PEN, 8, 8, 32, 32);
tilemap_set_transparent_pen(fg_tilemap, 0);
}
static void draw_sprites(running_machine *machine, mame_bitmap *bitmap, const rectangle *cliprect )
{
int i, offs;
for (offs = spriteram_size - 0x20;offs >= 0;offs -= 0x20)
{
i = 0;
while (i < 0x20 && spriteram[offs + i] != 0)
i += 4;
while (i > 0)
{
i -= 4;
if (spriteram[offs + i] & 0x80)
{
int color = spriteram[offs + i + 2] & 0x0f;
int sx = spriteram[offs + i + 3];
int sy = offs / 4 + (spriteram[offs + i] & 0x07);
switch ((spriteram[offs + i] & 0x18) >> 3)
{
case 3: /* 24x24 */
{
int code = ((spriteram[offs + i + 1] & 0xf0) >> 4) + ((gfxbank & 1) << 4);
drawgfx(bitmap,machine->gfx[3],
code,
color,
0,0,
sx,sy - 16,
cliprect,TRANSPARENCY_PEN,0);
/* wraparound */
drawgfx(bitmap,machine->gfx[3],
code,
color,
0,0,
sx - 256,sy - 16,
cliprect,TRANSPARENCY_PEN,0);
break;
}
case 2: /* 16x16 */
if (spriteram[offs + i] & 0x20) /* zero hour spaceships */
{
int code = ((spriteram[offs + i + 1] & 0xf8) >> 3) + ((gfxbank & 1) << 5);
int bank = (spriteram[offs + i + 1] & 0x02) >> 1;
drawgfx(bitmap,machine->gfx[4+bank],
code,
color,
0,0,
sx,sy - 16,
cliprect,TRANSPARENCY_PEN,0);
}
else
{
int code = ((spriteram[offs + i + 1] & 0xf0) >> 4) + ((gfxbank & 1) << 4);
drawgfx(bitmap,machine->gfx[2],
code,
color,
0,0,
sx,sy - 16,
cliprect,TRANSPARENCY_PEN,0);
}
break;
case 1: /* 8x8 */
drawgfx(bitmap,machine->gfx[1],
spriteram[offs + i + 1],// + 4 * (spriteram[offs + i + 2] & 0x10),
color,
0,0,
sx,sy - 16,
cliprect,TRANSPARENCY_PEN,0);
break;
case 0:
popmessage("unknown sprite size 0");
break;
}
}
}
}
}
static void draw_bullets(running_machine *machine, mame_bitmap *bitmap, const rectangle *cliprect )
{
int offs;
for (offs = 0; offs < 0x20; offs++)
{
// sx = videoram[offs];
int sx = 8 * offs + (videoram[offs] & 0x07); /* ?? */
int sy = 0xff - videoram[offs + 0x20];
if (flip_screen)
{
sx = 240 - sx;
}
if (sx >= cliprect->min_x && sx <= cliprect->max_x &&
sy >= cliprect->min_y && sy <= cliprect->max_y)
*BITMAP_ADDR16(bitmap, sy, sx) = machine->pens[0x0e];
}
}
/*
* These functions emulate the star generator board
* All this comes from the schematics for Zero Hour
*
* It has a 17-bit LFSR which has a period of 2^17-1 clocks
* (This is one pixel shy of "two screens" worth.)
* So, there are two starfields drawn on alternate frames
* These will scroll at a rate controlled by the speed register
*
* I'm basically doing the same thing by drawing each
* starfield on alternate frames, and then offseting them
*/
static UINT8 stars_enable = 0;
static UINT8 stars_speed = 0;
static UINT32 stars_state = 0;
static UINT16 stars_offset = 0;
/* This line can reset the LFSR to zero and disables the star generator */
void redclash_set_stars_enable( UINT8 on )
{
if ((stars_enable == 0) && (on == 1))
{
stars_offset = 0;
}
stars_enable = on;
}
/* This sets up which starfield to draw and the offset, */
/* To be called from VIDEO_EOF() */
void redclash_update_stars_state(void)
{
static UINT8 count = 0;
if (stars_enable == 0)
return;
count++;
count%=2;
if (count == 0)
{
stars_offset += ((stars_speed*2) - 0x09);
stars_offset %= 256*256;
stars_state = 0;
}
else
{
stars_state = 0x1fc71;
}
}
/* Set the speed register (3 bits) */
/*
* 0 left/down fastest (-9/2 pix per frame)
* 1 left/down faster (-7/2 pix per frame)
* 2 left/down fast (-5/2 pix per frame)
* 3 left/down medium (-3/2 pix per frame)
* 4 left/down slow (-1/2 pix per frame)
* 5 right/up slow (+1/2 pix per frame)
* 6 right/up medium (+3/2 pix per frame)
* 7 right/up fast (+5/2 pix per frame)
*/
void redclash_set_stars_speed( UINT8 speed )
{
stars_speed = speed;
}
/* Draw the stars */
/* Space Raider doesn't use the Va bit, and it is also set up to */
/* window the stars to a certain x range */
void redclash_draw_stars(running_machine *machine, mame_bitmap *bitmap, const rectangle *cliprect, UINT8 palette_offset, UINT8 sraider, UINT8 firstx, UINT8 lastx)
{
int i;
UINT8 tempbit, feedback, star_color, xloc, yloc;
UINT32 state;
UINT8 hcond,vcond;
if (stars_enable == 0)
return;
state = stars_state;
for(i=0;i<256*256;i++)
{
xloc = (stars_offset+i)%256;
yloc = ((stars_offset+i)/256)%256;
if ((state & 0x10000) == 0)
tempbit = 1;
else
tempbit = 0;
if ((state & 0x00020) != 0)
feedback = tempbit ^ 1;
else
feedback = tempbit ^ 0;
hcond = ((xloc+8) & 0x10) >> 4;
// sraider doesn't have Va hooked up
if (sraider)
vcond = 1;
else
vcond = yloc & 0x01;
if (xloc >= cliprect->min_x && xloc <= cliprect->max_x &&
yloc >= cliprect->min_y && yloc <= cliprect->max_y)
{
if ((hcond ^ vcond) == 0)
{
/* enable condition */
if (((state & 0x000ff) == 0x000ff) && (feedback == 0))
{
/* used by space raider */
if ((xloc>=firstx) && (xloc<=lastx))
{
star_color = (state >> 9) & 0x1f;
*BITMAP_ADDR16(bitmap, yloc, xloc) = machine->pens[palette_offset+star_color];
}
}
}
}
/* update LFSR state */
state = ((state<<1) & 0x1fffe) | feedback;
}
}
VIDEO_EOF( redclash )
{
redclash_update_stars_state();
}
VIDEO_UPDATE( redclash )
{
fillbitmap(bitmap, get_black_pen(machine), cliprect);
redclash_draw_stars(machine, bitmap, cliprect, 32, 0, 0x00, 0xff);
draw_sprites(machine, bitmap, cliprect);
draw_bullets(machine, bitmap, cliprect);
tilemap_draw(bitmap, cliprect, fg_tilemap, 0, 0);
return 0;
}