diff options
Diffstat (limited to 'src/mame/video/lazercmd.c')
-rw-r--r-- | src/mame/video/lazercmd.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/src/mame/video/lazercmd.c b/src/mame/video/lazercmd.c new file mode 100644 index 00000000000..33a51ce08ec --- /dev/null +++ b/src/mame/video/lazercmd.c @@ -0,0 +1,85 @@ +/*************************************************************/ +/* */ +/* Lazer Command video handler */ +/* */ +/*************************************************************/ + +#include "driver.h" +#include "includes/lazercmd.h" + +int marker_x, marker_y; + + +/* scale a markers vertical position */ +/* the following table shows how the markers */ +/* vertical position worked in hardware */ +/* marker_y lines marker_y lines */ +/* 0 0 + 1 8 10 + 11 */ +/* 1 2 + 3 9 12 + 13 */ +/* 2 4 + 5 10 14 + 15 */ +/* 3 6 + 7 11 16 + 17 */ +/* 4 8 + 9 12 18 + 19 */ +static int vert_scale(int data) +{ + return ((data & 0x07)<<1) + ((data & 0xf8)>>3) * VERT_CHR; +} + +/* plot a bitmap marker */ +/* hardware has 2 marker sizes 2x2 and 4x2 selected by jumper */ +/* meadows lanes normaly use 2x2 pixels and lazer command uses either */ +static void plot_pattern(running_machine *machine, mame_bitmap *bitmap, int x, int y) +{ + int xbit, ybit, size; + + size = 2; + if (input_port_2_r(0) & 0x40) + { + size = 4; + } + + for (ybit = 0; ybit < 2; ybit++) + { + if (y+ybit < 0 || y+ybit >= VERT_RES * VERT_CHR) + return; + + for (xbit = 0; xbit < size; xbit++) + { + if (x+xbit < 0 || x+xbit >= HORZ_RES * HORZ_CHR) + continue; + + *BITMAP_ADDR16(bitmap, y+ybit, x+xbit) = machine->pens[2]; + } + } +} + + +VIDEO_UPDATE( lazercmd ) +{ + int i,x,y; + + int video_inverted = input_port_2_r(0) & 0x20; + + /* The first row of characters are invisible */ + for (i = 0; i < (VERT_RES - 1) * HORZ_RES; i++) + { + int sx,sy; + + sx = i % HORZ_RES; + sy = i / HORZ_RES; + + sx *= HORZ_CHR; + sy *= VERT_CHR; + + drawgfx(bitmap, machine->gfx[0], + videoram[i], video_inverted ? 1 : 0, + 0,0, + sx,sy, + &machine->screen[0].visarea,TRANSPARENCY_NONE,0); + } + + x = marker_x - 1; /* normal video lags marker by 1 pixel */ + y = vert_scale(marker_y) - VERT_CHR; /* first line used as scratch pad */ + plot_pattern(machine, bitmap,x,y); + + return 0; +} |