diff options
Diffstat (limited to 'src/mame/video/gyruss.c')
-rw-r--r-- | src/mame/video/gyruss.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/src/mame/video/gyruss.c b/src/mame/video/gyruss.c new file mode 100644 index 00000000000..7018f8b86df --- /dev/null +++ b/src/mame/video/gyruss.c @@ -0,0 +1,218 @@ +/*************************************************************************** + + video.c + + Functions to emulate the video hardware of the machine. + +***************************************************************************/ + +#include "driver.h" + + +static UINT8 flipscreen; + +/* +sprites are multiplexed, so we have to buffer the spriteram +scanline by scanline. +*/ +static UINT8 *sprite_mux_buffer; +static UINT32 scanline; + + +/*************************************************************************** + + Convert the color PROMs into a more useable format. + + Gyruss has one 32x8 palette PROM and two 256x4 lookup table PROMs + (one for characters, one for sprites). + The palette PROM is connected to the RGB output this way: + + 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( gyruss ) +{ + 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 sprite lookup table */ + + /* sprites */ + for (i = 0;i < TOTAL_COLORS(1);i++) + COLOR(1,i) = *(color_prom++) & 0x0f; + + /* characters */ + for (i = 0;i < TOTAL_COLORS(0);i++) + COLOR(0,i) = (*(color_prom++) & 0x0f) + 0x10; +} + + + +VIDEO_START( gyruss ) +{ + sprite_mux_buffer = auto_malloc(256 * spriteram_size); + + state_save_register_global(flipscreen); + state_save_register_global(scanline); + state_save_register_global_pointer(sprite_mux_buffer,256*spriteram_size); +} + + + +WRITE8_HANDLER( gyruss_flipscreen_w ) +{ + flipscreen = data & 1; +} + + + +/* Return the current video scan line */ +READ8_HANDLER( gyruss_scanline_r ) +{ + return scanline; +} + + + +static void draw_sprites(running_machine *machine, mame_bitmap *bitmap) +{ + rectangle clip = machine->screen[0].visarea; + int offs; + int line; + + + for (line = 0;line < 256;line++) + { + UINT8 *sr; + + sr = sprite_mux_buffer + line * spriteram_size; + clip.min_y = clip.max_y = line; + + for (offs = spriteram_size - 4;offs >= 0;offs -= 4) + { + int sx,sy; + + sx = sr[offs]; + sy = 241 - sr[offs + 3]; + if (sy > line-16 && sy <= line) + { + drawgfx(bitmap,machine->gfx[1 + (sr[offs + 1] & 1)], + sr[offs + 1]/2 + 4*(sr[offs + 2] & 0x20), + sr[offs + 2] & 0x0f, + !(sr[offs + 2] & 0x40),sr[offs + 2] & 0x80, + sx,sy, + &clip,TRANSPARENCY_PEN,0); + } + } + } +} + + +VIDEO_UPDATE( gyruss ) +{ + int offs; + + + /* for every character in the Video RAM, check if it has been modified */ + /* since last time and update it accordingly. */ + for (offs = videoram_size - 1;offs >= 0;offs--) + { + int sx,sy,flipx,flipy; + + sx = offs % 32; + sy = offs / 32; + flipx = colorram[offs] & 0x40; + flipy = colorram[offs] & 0x80; + if (flipscreen) + { + sx = 31 - sx; + sy = 31 - sy; + flipx = !flipx; + flipy = !flipy; + } + + drawgfx(bitmap,machine->gfx[0], + videoram[offs] + 8 * (colorram[offs] & 0x20), + colorram[offs] & 0x0f, + flipx,flipy, + 8*sx,8*sy, + cliprect,TRANSPARENCY_NONE,0); + } + + + draw_sprites(machine, bitmap); + + + /* redraw the characters which have priority over sprites */ + for (offs = videoram_size - 1;offs >= 0;offs--) + { + int sx,sy,flipx,flipy; + + + sx = offs % 32; + sy = offs / 32; + flipx = colorram[offs] & 0x40; + flipy = colorram[offs] & 0x80; + if (flipscreen) + { + sx = 31 - sx; + sy = 31 - sy; + flipx = !flipx; + flipy = !flipy; + } + + if ((colorram[offs] & 0x10) != 0) + drawgfx(bitmap,machine->gfx[0], + videoram[offs] + 8 * (colorram[offs] & 0x20), + colorram[offs] & 0x0f, + flipx,flipy, + 8*sx,8*sy, + cliprect,TRANSPARENCY_NONE,0); + } + return 0; +} + + +INTERRUPT_GEN( gyruss_6809_interrupt ) +{ + scanline = 255 - cpu_getiloops(); + + memcpy(sprite_mux_buffer + scanline * spriteram_size,spriteram,spriteram_size); + + if (scanline == 255) + irq0_line_hold(); +} |