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vidhrdw
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gng.c
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C/C++ Source or Header
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2000-05-04
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5KB
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180 lines
/***************************************************************************
vidhrdw.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
extern unsigned char *spriteram;
extern size_t spriteram_size;
unsigned char *gng_fgvideoram,*gng_fgcolorram;
unsigned char *gng_bgvideoram,*gng_bgcolorram;
static struct tilemap *bg_tilemap,*fg_tilemap;
static int flipscreen;
/***************************************************************************
Callbacks for the TileMap code
***************************************************************************/
static void get_fg_tile_info(int tile_index)
{
unsigned char attr = gng_fgcolorram[tile_index];
SET_TILE_INFO(0,gng_fgvideoram[tile_index] + ((attr & 0xc0) << 2),attr & 0x0f)
tile_info.flags = TILE_FLIPYX((attr & 0x30) >> 4);
}
static void get_bg_tile_info(int tile_index)
{
unsigned char attr = gng_bgcolorram[tile_index];
SET_TILE_INFO(1,gng_bgvideoram[tile_index] + ((attr & 0xc0) << 2),attr & 0x07)
tile_info.flags = TILE_FLIPYX((attr & 0x30) >> 4) | TILE_SPLIT((attr & 0x08) >> 3);
}
/***************************************************************************
Start the video hardware emulation.
***************************************************************************/
int gng_vh_start(void)
{
fg_tilemap = tilemap_create(get_fg_tile_info,tilemap_scan_rows,TILEMAP_TRANSPARENT,8,8,32,32);
bg_tilemap = tilemap_create(get_bg_tile_info,tilemap_scan_cols,TILEMAP_SPLIT, 16,16,32,32);
if (!fg_tilemap || !bg_tilemap)
return 1;
fg_tilemap->transparent_pen = 3;
bg_tilemap->transmask[0] = 0xff; /* split type 0 is totally transparent in front half */
bg_tilemap->transmask[1] = 0x01; /* split type 1 has pen 1 transparent in front half */
return 0;
}
/***************************************************************************
Memory handlers
***************************************************************************/
WRITE_HANDLER( gng_fgvideoram_w )
{
if (gng_fgvideoram[offset] != data)
{
gng_fgvideoram[offset] = data;
tilemap_mark_tile_dirty(fg_tilemap,offset);
}
}
WRITE_HANDLER( gng_fgcolorram_w )
{
if (gng_fgcolorram[offset] != data)
{
gng_fgcolorram[offset] = data;
tilemap_mark_tile_dirty(fg_tilemap,offset);
}
}
WRITE_HANDLER( gng_bgvideoram_w )
{
if (gng_bgvideoram[offset] != data)
{
gng_bgvideoram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap,offset);
}
}
WRITE_HANDLER( gng_bgcolorram_w )
{
if (gng_bgcolorram[offset] != data)
{
gng_bgcolorram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap,offset);
}
}
WRITE_HANDLER( gng_bgscrollx_w )
{
static unsigned char scrollx[2];
scrollx[offset] = data;
tilemap_set_scrollx( bg_tilemap, 0, scrollx[0] + 256 * scrollx[1] );
}
WRITE_HANDLER( gng_bgscrolly_w )
{
static unsigned char scrolly[2];
scrolly[offset] = data;
tilemap_set_scrolly( bg_tilemap, 0, scrolly[0] + 256 * scrolly[1] );
}
WRITE_HANDLER( gng_flipscreen_w )
{
flipscreen = ~data & 1;
tilemap_set_flip(ALL_TILEMAPS,flipscreen ? (TILEMAP_FLIPY | TILEMAP_FLIPX) : 0);
}
/***************************************************************************
Display refresh
***************************************************************************/
static void draw_sprites(struct osd_bitmap *bitmap)
{
const struct GfxElement *gfx = Machine->gfx[2];
const struct rectangle *clip = &Machine->drv->visible_area;
int offs;
for (offs = spriteram_size - 4;offs >= 0;offs -= 4){
unsigned char attributes = spriteram[offs+1];
int sx = spriteram[offs + 3] - 0x100 * (attributes & 0x01);
int sy = spriteram[offs + 2];
int flipx = attributes & 0x04;
int flipy = attributes & 0x08;
if (flipscreen){
sx = 240 - sx;
sy = 240 - sy;
flipx = !flipx;
flipy = !flipy;
}
drawgfx(bitmap,gfx,
spriteram[offs] + ((attributes<<2) & 0x300),
(attributes >> 4) & 3,
flipx,flipy,
sx,sy,
clip,TRANSPARENCY_PEN,15);
}
}
void gng_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
{
tilemap_update(ALL_TILEMAPS);
if (palette_recalc())
tilemap_mark_all_pixels_dirty(ALL_TILEMAPS);
tilemap_render(ALL_TILEMAPS);
tilemap_draw(bitmap,bg_tilemap,TILEMAP_BACK);
draw_sprites(bitmap);
tilemap_draw(bitmap,bg_tilemap,TILEMAP_FRONT);
tilemap_draw(bitmap,fg_tilemap,0);
}