1 /*************************************************************************
2
3 Exidy 6502 hardware
4
5 *************************************************************************/
6
7 /* Sound channel usage
8 0 = CPU music, Shoot
9 1 = Crash
10 2 = Spectar sound
11 3 = Tone generator
12 */
13
14 #include "driver.h"
15 #include "exidy.h"
16
17 static int tone_channel;
18
19 unsigned char targ_spec_flag;
20 static unsigned char targ_sh_ctrl0=0;
21 static unsigned char targ_sh_ctrl1=0;
22 static unsigned char tone_active;
23
24 #define MAXFREQ_A_TARG 125000
25 #define MAXFREQ_A_SPECTAR 525000
26
27 static int sound_a_freq;
28 static unsigned char tone_pointer;
29 static unsigned char tone_offset;
30
31 static unsigned char tone_prom[32] =
32 {
33 0xE5,0xE5,0xED,0xED,0xE5,0xE5,0xED,0xED,0xE7,0xE7,0xEF,0xEF,0xE7,0xE7,0xEF,0xEF,
34 0xC1,0xE1,0xC9,0xE9,0xC5,0xE5,0xCD,0xED,0xC3,0xE3,0xCB,0xEB,0xC7,0xE7,0xCF,0xEF
35 };
36
37 /* waveforms for the audio hardware */
38 static unsigned char waveform1[32] =
39 {
40 /* sine-wave */
41 0x0F, 0x0F, 0x0F, 0x06, 0x06, 0x09, 0x09, 0x06, 0x06, 0x09, 0x06, 0x0D, 0x0F, 0x0F, 0x0D, 0x00,
42 0xE6, 0xDE, 0xE1, 0xE6, 0xEC, 0xE6, 0xE7, 0xE7, 0xE7, 0xEC, 0xEC, 0xEC, 0xE7, 0xE1, 0xE1, 0xE7,
43 };
44
45 /* some macros to make detecting bit changes easier */
46 #define RISING_EDGE(bit) ((data & bit) && !(targ_sh_ctrl0 & bit))
47 #define FALLING_EDGE(bit) (!(data & bit) && (targ_sh_ctrl0 & bit))
48
49
targ_tone_generator(int data)50 void targ_tone_generator(int data)
51 {
52 int maxfreq;
53
54
55 if (targ_spec_flag) maxfreq = MAXFREQ_A_TARG;
56 else maxfreq = MAXFREQ_A_SPECTAR;
57
58 sound_a_freq = data;
59 if (sound_a_freq == 0xFF || sound_a_freq == 0x00)
60 {
61 mixer_set_volume(tone_channel,0);
62 }
63 else
64 {
65 mixer_set_sample_frequency(tone_channel,maxfreq/(0xFF-sound_a_freq));
66 mixer_set_volume(tone_channel,tone_active*100);
67 }
68 }
69
targ_sh_start(const struct MachineSound * msound)70 int targ_sh_start(const struct MachineSound *msound)
71 {
72 tone_channel = mixer_allocate_channel(50);
73
74 tone_pointer=0;
75 tone_offset=0;
76 tone_active=0;
77 sound_a_freq = 0x00;
78 mixer_set_volume(tone_channel,0);
79 mixer_play_sample(tone_channel,(signed char*)waveform1,32,1000,1);
80 return 0;
81 }
82
targ_sh_stop(void)83 void targ_sh_stop(void)
84 {
85 mixer_stop_sample(tone_channel);
86 }
87
WRITE_HANDLER(targ_sh_w)88 WRITE_HANDLER( targ_sh_w )
89 {
90 int maxfreq;
91
92
93 if (targ_spec_flag) maxfreq = MAXFREQ_A_TARG;
94 else maxfreq = MAXFREQ_A_SPECTAR;
95
96 if (offset) {
97 if (targ_spec_flag) {
98 if (data & 0x02)
99 tone_offset=16;
100 else
101 tone_offset=0;
102
103 if ((data & 0x01) && !(targ_sh_ctrl1 & 0x01)) {
104 tone_pointer++;
105 if (tone_pointer > 15) tone_pointer = 0;
106 targ_tone_generator(tone_prom[tone_pointer+tone_offset]);
107 }
108 }
109 else {
110 targ_tone_generator(data);
111 }
112 targ_sh_ctrl1=data;
113 }
114 else
115 {
116 /* cpu music */
117 if ((data & 0x01) != (targ_sh_ctrl0 & 0x01)) {
118 DAC_data_w(0,(data & 0x01) * 0xFF);
119 }
120 /* Shoot */
121 if FALLING_EDGE(0x02) {
122 if (!sample_playing(0)) sample_start(0,1,0);
123 }
124 if RISING_EDGE(0x02) {
125 sample_stop(0);
126 }
127
128 /* Crash */
129 if RISING_EDGE(0x20) {
130 if (data & 0x40) {
131 sample_start(1,2,0); }
132 else {
133 sample_start(1,0,0); }
134 }
135
136 /* Sspec */
137 if (data & 0x10) {
138 sample_stop(2);
139 }
140 else {
141 if ((data & 0x08) != (targ_sh_ctrl0 & 0x08)) {
142 if (data & 0x08) {
143 sample_start(2,3,1); }
144 else {
145 sample_start(2,4,1); }
146 }
147 }
148
149 /* Game (tone generator enable) */
150 if FALLING_EDGE(0x80) {
151 tone_pointer=0;
152 tone_active=0;
153 if (sound_a_freq == 0xFF || sound_a_freq == 0x00)
154 {
155 mixer_set_volume(tone_channel,0);
156 }
157 else
158 {
159 mixer_set_sample_frequency(tone_channel,maxfreq/(0xFF-sound_a_freq));
160 mixer_set_volume(tone_channel,0);
161 }
162 }
163 if RISING_EDGE(0x80) {
164 tone_active=1;
165 }
166 targ_sh_ctrl0 = data;
167 }
168 }
169
170