/*************************************************************************** video.c Functions to emulate the video hardware of the machine. ***************************************************************************/ #include "driver.h" static tilemap *bg_tilemap; /* This is strange; it's unlikely that the sprites actually have a hardware */ /* clipping region, but I haven't found another way to have them masked by */ /* the characters at the top and bottom of the screen. */ static rectangle spritevisiblearea = { 0*8, 32*8-1, 4*8, 29*8-1 }; /*************************************************************************** Convert the color PROMs into a more useable format. Ping Pong has a 32 bytes palette PROM and two 256 bytes color lookup table PROMs (one for sprites, one for characters). I don't know for sure how the palette PROM is connected to the RGB output, but it's probably the usual: bit 7 -- 220 ohm resistor -- BLUE -- 470 ohm resistor -- BLUE -- 220 ohm resistor -- GREEN -- 470 ohm resistor -- GREEN -- 1 kohm resistor -- GREEN -- 220 ohm resistor -- RED -- 470 ohm resistor -- RED bit 0 -- 1 kohm resistor -- RED ***************************************************************************/ PALETTE_INIT( pingpong ) { 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]) for (i = 0;i < machine->drv->total_colors;i++) { int bit0,bit1,bit2,r,g,b; /* red component */ bit0 = (*color_prom >> 0) & 0x01; bit1 = (*color_prom >> 1) & 0x01; bit2 = (*color_prom >> 2) & 0x01; r = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2; /* green component */ bit0 = (*color_prom >> 3) & 0x01; bit1 = (*color_prom >> 4) & 0x01; bit2 = (*color_prom >> 5) & 0x01; g = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2; /* blue component */ bit0 = 0; bit1 = (*color_prom >> 6) & 0x01; bit2 = (*color_prom >> 7) & 0x01; b = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2; palette_set_color(machine,i,MAKE_RGB(r,g,b)); color_prom++; } /* color_prom now points to the beginning of the char lookup table */ /* sprites */ for (i = 0;i < TOTAL_COLORS(1);i++) { int code; int bit0,bit1,bit2,bit3; /* the bits of the color code are in reverse order - 0123 instead of 3210 */ code = *(color_prom++) & 0x0f; bit0 = (code >> 0) & 1; bit1 = (code >> 1) & 1; bit2 = (code >> 2) & 1; bit3 = (code >> 3) & 1; code = (bit0 << 3) | (bit1 << 2) | (bit2 << 1) | (bit3 << 0); COLOR(1,i) = code; } /* characters */ for (i = 0;i < TOTAL_COLORS(0);i++) COLOR(0,i) = (*(color_prom++) & 0x0f) + 0x10; } WRITE8_HANDLER( pingpong_videoram_w ) { videoram[offset] = data; tilemap_mark_tile_dirty(bg_tilemap, offset); } WRITE8_HANDLER( pingpong_colorram_w ) { colorram[offset] = data; tilemap_mark_tile_dirty(bg_tilemap, offset); } static TILE_GET_INFO( get_bg_tile_info ) { int attr = colorram[tile_index]; int code = videoram[tile_index] + ((attr & 0x20) << 3); int color = attr & 0x1f; int flags = ((attr & 0x40) ? TILE_FLIPX : 0) | ((attr & 0x80) ? TILE_FLIPY : 0); SET_TILE_INFO(0, code, color, flags); } VIDEO_START( pingpong ) { bg_tilemap = tilemap_create(get_bg_tile_info, tilemap_scan_rows, TILEMAP_TYPE_PEN, 8, 8, 32, 32); } static void draw_sprites(running_machine *machine, mame_bitmap *bitmap, const rectangle *cliprect ) { int offs; for (offs = spriteram_size - 4;offs >= 0;offs -= 4) { int sx,sy,flipx,flipy,color,schar; sx = spriteram[offs + 3]; sy = 241 - spriteram[offs + 1]; flipx = spriteram[offs] & 0x40; flipy = spriteram[offs] & 0x80; color = spriteram[offs] & 0x1F; schar = spriteram[offs + 2] & 0x7F; drawgfx(bitmap,machine->gfx[1], schar, color, flipx,flipy, sx,sy, &spritevisiblearea,TRANSPARENCY_COLOR,0); } } VIDEO_UPDATE( pingpong ) { tilemap_draw(bitmap, cliprect, bg_tilemap, 0, 0); draw_sprites(machine, bitmap, cliprect); return 0; }