1 /***************************************************************************
2
3 vidhrdw.c
4
5 Functions to emulate the video hardware of the machine.
6
7 ***************************************************************************/
8
9 #include "driver.h"
10 #include "vidhrdw/generic.h"
11 #include "cpu/m6809/m6809.h"
12
13
14 static int flipscreen;
15 static int nmi_enable;
16
17
18 /***************************************************************************
19
20 Convert the color PROMs into a more useable format.
21
22 Yie Ar Kung-Fu has one 32x8 palette PROM, connected to the RGB output this
23 way:
24
25 bit 7 -- 220 ohm resistor -- BLUE
26 -- 470 ohm resistor -- BLUE
27 -- 220 ohm resistor -- GREEN
28 -- 470 ohm resistor -- GREEN
29 -- 1 kohm resistor -- GREEN
30 -- 220 ohm resistor -- RED
31 -- 470 ohm resistor -- RED
32 bit 0 -- 1 kohm resistor -- RED
33
34 ***************************************************************************/
yiear_vh_convert_color_prom(unsigned char * palette,unsigned short * colortable,const unsigned char * color_prom)35 void yiear_vh_convert_color_prom(unsigned char *palette, unsigned short *colortable,const unsigned char *color_prom)
36 {
37 int i;
38
39
40 for (i = 0;i < Machine->drv->total_colors;i++)
41 {
42 int bit0,bit1,bit2;
43
44 /* red component */
45 bit0 = (*color_prom >> 0) & 0x01;
46 bit1 = (*color_prom >> 1) & 0x01;
47 bit2 = (*color_prom >> 2) & 0x01;
48 *(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
49
50 /* green component */
51 bit0 = (*color_prom >> 3) & 0x01;
52 bit1 = (*color_prom >> 4) & 0x01;
53 bit2 = (*color_prom >> 5) & 0x01;
54 *(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
55
56 /* blue component */
57 bit0 = 0;
58 bit1 = (*color_prom >> 6) & 0x01;
59 bit2 = (*color_prom >> 7) & 0x01;
60 *(palette++) = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
61
62 color_prom++;
63 }
64 }
65
66
WRITE_HANDLER(yiear_control_w)67 WRITE_HANDLER( yiear_control_w )
68 {
69 /* bit 0 flips screen */
70 if (flipscreen != (data & 1))
71 {
72 flipscreen = data & 1;
73 memset(dirtybuffer,1,videoram_size);
74 }
75
76 /* bit 1 is NMI enable */
77 nmi_enable = data & 0x02;
78
79 /* bit 2 is IRQ enable */
80 interrupt_enable_w(0, data & 0x04);
81
82 /* bits 3 and 4 are coin counters */
83 coin_counter_w(0, (data >> 3) & 0x01);
84 coin_counter_w(1, (data >> 4) & 0x01);
85 }
86
87
yiear_nmi_interrupt(void)88 int yiear_nmi_interrupt(void)
89 {
90 /* can't use nmi_interrupt() because interrupt_enable_w() effects it */
91 return nmi_enable ? M6809_INT_NMI : ignore_interrupt();
92 }
93
94
95 /***************************************************************************
96
97 Draw the game screen in the given osd_bitmap.
98 Do NOT call osd_update_display() from this function, it will be called by
99 the main emulation engine.
100
101 ***************************************************************************/
yiear_vh_screenrefresh(struct osd_bitmap * bitmap,int full_refresh)102 void yiear_vh_screenrefresh(struct osd_bitmap *bitmap,int full_refresh)
103 {
104 int offs;
105
106
107 /* for every character in the Video RAM, check if it has been modified */
108 /* since last time and update it accordingly. */
109 for (offs = videoram_size - 2;offs >= 0;offs -= 2)
110 {
111 if (dirtybuffer[offs] || dirtybuffer[offs + 1])
112 {
113 int sx,sy,flipx,flipy;
114
115
116 dirtybuffer[offs] = dirtybuffer[offs + 1] = 0;
117
118 sx = (offs/2) % 32;
119 sy = (offs/2) / 32;
120 flipx = videoram[offs] & 0x80;
121 flipy = videoram[offs] & 0x40;
122 if (flipscreen)
123 {
124 sx = 31 - sx;
125 sy = 31 - sy;
126 flipx = !flipx;
127 flipy = !flipy;
128 }
129
130 drawgfx(tmpbitmap,Machine->gfx[0],
131 videoram[offs + 1] | ((videoram[offs] & 0x10) << 4),
132 0,
133 flipx,flipy,
134 8*sx,8*sy,
135 0,TRANSPARENCY_NONE,0);
136 }
137 }
138
139
140 /* copy the temporary bitmap to the screen */
141 copybitmap(bitmap,tmpbitmap,0,0,0,0,&Machine->visible_area,TRANSPARENCY_NONE,0);
142
143
144 /* draw sprites */
145 for (offs = spriteram_size - 2;offs >= 0;offs -= 2)
146 {
147 int sx,sy,flipx,flipy;
148
149
150 sy = 240 - spriteram[offs + 1];
151 sx = spriteram_2[offs];
152 flipx = ~spriteram[offs] & 0x40;
153 flipy = spriteram[offs] & 0x80;
154
155 if (flipscreen)
156 {
157 sy = 240 - sy;
158 flipy = !flipy;
159 }
160
161 if (offs < 0x26)
162 {
163 sy++; /* fix title screen & garbage at the bottom of the screen */
164 }
165
166 drawgfx(bitmap,Machine->gfx[1],
167 spriteram_2[offs + 1] + 256 * (spriteram[offs] & 1),
168 0,
169 flipx,flipy,
170 sx,sy,
171 &Machine->visible_area,TRANSPARENCY_PEN,0);
172 }
173 }
174