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vidhrdw
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travrusa.c
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C/C++ Source or Header
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2000-05-04
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7KB
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274 lines
/***************************************************************************
vidhrdw.c
Traverse USA
L Taylor
J Clegg
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
extern unsigned char *spriteram;
extern size_t spriteram_size;
unsigned char *travrusa_videoram;
static struct tilemap *bg_tilemap;
static int flipscreen;
/***************************************************************************
Convert the color PROMs into a more useable format.
Traverse USA has one 256x8 character palette PROM (some versions have two
256x4), one 32x8 sprite palette PROM, and one 256x4 sprite color lookup
table PROM.
I don't know for sure how the palette PROMs are connected to the RGB
output, but it's probably something like this; note that RED and BLUE
are swapped wrt the usual configuration.
bit 7 -- 220 ohm resistor -- RED
-- 470 ohm resistor -- RED
-- 220 ohm resistor -- GREEN
-- 470 ohm resistor -- GREEN
-- 1 kohm resistor -- GREEN
-- 220 ohm resistor -- BLUE
-- 470 ohm resistor -- BLUE
bit 0 -- 1 kohm resistor -- BLUE
***************************************************************************/
void travrusa_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
{
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])
/* character palette */
for (i = 0;i < 128;i++)
{
int bit0,bit1,bit2;
/* red component */
bit0 = 0;
bit1 = (*color_prom >> 6) & 0x01;
bit2 = (*color_prom >> 7) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* green component */
bit0 = (*color_prom >> 3) & 0x01;
bit1 = (*color_prom >> 4) & 0x01;
bit2 = (*color_prom >> 5) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* blue component */
bit0 = (*color_prom >> 0) & 0x01;
bit1 = (*color_prom >> 1) & 0x01;
bit2 = (*color_prom >> 2) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
color_prom++;
}
/* skip bottom half - not used */
color_prom += 128;
/* sprite palette */
for (i = 0;i < 32;i++)
{
int bit0,bit1,bit2;
/* red component */
bit0 = 0;
bit1 = (*color_prom >> 6) & 0x01;
bit2 = (*color_prom >> 7) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* green component */
bit0 = (*color_prom >> 3) & 0x01;
bit1 = (*color_prom >> 4) & 0x01;
bit2 = (*color_prom >> 5) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
/* blue component */
bit0 = (*color_prom >> 0) & 0x01;
bit1 = (*color_prom >> 1) & 0x01;
bit2 = (*color_prom >> 2) & 0x01;
*(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
color_prom++;
}
/* color_prom now points to the beginning of the lookup table */
/* character lookup table */
for (i = 0;i < TOTAL_COLORS(0);i++)
COLOR(0,i) = i;
/* sprite lookup table */
for (i = 0;i < TOTAL_COLORS(1);i++)
COLOR(1,i) = *(color_prom++) + 128;
}
/***************************************************************************
Callbacks for the TileMap code
***************************************************************************/
static void get_tile_info(int tile_index)
{
unsigned char attr = travrusa_videoram[2*tile_index+1];
SET_TILE_INFO(0,travrusa_videoram[2*tile_index] + ((attr & 0xc0) << 2),attr & 0x0f)
tile_info.flags = 0;
if (attr & 0x20) tile_info.flags |= TILE_FLIPX;
if (attr & 0x10) tile_info.flags |= TILE_FLIPY;
if ((attr & 0x0f) == 0x0f) tile_info.flags |= TILE_SPLIT(1); /* hack */
}
/***************************************************************************
Start the video hardware emulation.
***************************************************************************/
int travrusa_vh_start(void)
{
bg_tilemap = tilemap_create(get_tile_info,tilemap_scan_rows,TILEMAP_SPLIT,8,8,64,32);
if (!bg_tilemap)
return 1;
bg_tilemap->transmask[0] = 0xff; /* split type 0 is totally transparent in front half */
bg_tilemap->transmask[1] = 0x3f; /* split type 1 has pens 6 and 7 opaque - hack! */
tilemap_set_scroll_rows(bg_tilemap,32);
return 0;
}
/***************************************************************************
Memory handlers
***************************************************************************/
WRITE_HANDLER( travrusa_videoram_w )
{
if (travrusa_videoram[offset] != data)
{
travrusa_videoram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap,offset/2);
}
}
static int scrollx[2];
static void set_scroll(void)
{
int i;
for (i = 0;i < 24;i++)
tilemap_set_scrollx(bg_tilemap,i,scrollx[0] + 256 * scrollx[1]);
for (i = 24;i < 32;i++)
tilemap_set_scrollx(bg_tilemap,i,0);
}
WRITE_HANDLER( travrusa_scroll_x_low_w )
{
scrollx[0] = data;
set_scroll();
}
WRITE_HANDLER( travrusa_scroll_x_high_w )
{
scrollx[1] = data;
set_scroll();
}
WRITE_HANDLER( travrusa_flipscreen_w )
{
/* screen flip is handled both by software and hardware */
data ^= ~readinputport(4) & 1;
flipscreen = data & 1;
tilemap_set_flip(ALL_TILEMAPS,flipscreen ? (TILEMAP_FLIPY | TILEMAP_FLIPX) : 0);
coin_counter_w(0,data & 0x02);
coin_counter_w(1,data & 0x20);
}
/***************************************************************************
Display refresh
***************************************************************************/
static void draw_sprites(struct osd_bitmap *bitmap)
{
int offs;
static struct rectangle spritevisiblearea =
{
1*8, 31*8-1,
0*8, 24*8-1
};
static struct rectangle spritevisibleareaflip =
{
1*8, 31*8-1,
8*8, 32*8-1
};
for (offs = spriteram_size - 4;offs >= 0;offs -= 4)
{
int sx,sy,flipx,flipy;
sx = ((spriteram[offs + 3] + 8) & 0xff) - 8;
sy = 240 - spriteram[offs];
flipx = spriteram[offs + 1] & 0x40;
flipy = spriteram[offs + 1] & 0x80;
if (flipscreen)
{
sx = 240 - sx;
sy = 240 - sy;
flipx = !flipx;
flipy = !flipy;
}
drawgfx(bitmap,Machine->gfx[1],
spriteram[offs + 2],
spriteram[offs + 1] & 0x0f,
flipx,flipy,
sx,sy,
flipscreen ? &spritevisibleareaflip : &spritevisiblearea,TRANSPARENCY_PEN,0);
}
}
void travrusa_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
tilemap_update(ALL_TILEMAPS);
tilemap_render(ALL_TILEMAPS);
tilemap_draw(bitmap,bg_tilemap,TILEMAP_BACK);
draw_sprites(bitmap);
tilemap_draw(bitmap,bg_tilemap,TILEMAP_FRONT);
}