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-rw-r--r--src/mame/video/gyruss.c218
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
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+++ b/src/mame/video/gyruss.c
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+/***************************************************************************
+
+ 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();
+}