1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
#include "opnadrum.h"
static const uint16_t steps[49] = {
16, 17, 19, 21, 23, 25, 28,
31, 34, 37, 41, 45, 50, 55,
60, 66, 73, 80, 88, 97, 107,
118, 130, 143, 157, 173, 190, 209,
230, 253, 279, 307, 337, 371, 408,
449, 494, 544, 598, 658, 724, 796,
876, 963, 1060, 1166, 1282, 1411, 1552
};
static const int8_t step_inc[8] = {
-1, -1, -1, -1, 2, 5, 7, 9
};
void opna_drum_reset(struct opna_drum *drum) {
for (int d = 0; d < 6; d++) {
drum->drums[d].data = 0;
drum->drums[d].playing = false;
drum->drums[d].index = 0;
drum->drums[d].len = 0;
drum->drums[d].level = 0;
drum->drums[d].left = false;
drum->drums[d].right = false;
}
drum->total_level = 0;
}
void opna_drum_set_rom(struct opna_drum *drum, void *romptr) {
uint8_t *rom = (uint8_t *)romptr;
static const struct {
unsigned start;
unsigned end;
int div;
} part[6] = {
{OPNA_ROM_BD_START, OPNA_ROM_SD_START-1, 3},
{OPNA_ROM_SD_START, OPNA_ROM_TOP_START-1, 3},
{OPNA_ROM_TOP_START, OPNA_ROM_HH_START-1, 3},
{OPNA_ROM_HH_START, OPNA_ROM_TOM_START-1, 3},
{OPNA_ROM_TOM_START, OPNA_ROM_RIM_START-1, 6},
{OPNA_ROM_RIM_START, OPNA_ROM_SIZE-1, 6},
};
drum->drums[0].data = drum->rom_bd;
drum->drums[1].data = drum->rom_sd;
drum->drums[2].data = drum->rom_top;
drum->drums[3].data = drum->rom_hh;
drum->drums[4].data = drum->rom_tom;
drum->drums[5].data = drum->rom_rim;
for (int p = 0; p < 6; p++) {
drum->drums[p].playing = false;
drum->drums[p].index = 0;
unsigned addr = part[p].start << 1;
int step = 0;
unsigned acc = 0;
int outindex = 0;
for (;;) {
if ((addr>>1) == part[p].end) break;
unsigned data = rom[addr>>1];
if (!(addr&1)) data >>= 4;
data &= ((1<<4)-1);
int acc_diff = ((((data&7)<<1)|1) * steps[step]) >> 3;
if (data&8) acc_diff = -acc_diff;
acc += acc_diff;
step += step_inc[data&7];
if (step < 0) step = 0;
if (step > 48) step = 48;
addr++;
int out = acc & ((1u<<12)-1);
if (out >= (1<<11)) out -= (1<<12);
int16_t out16 = out << 4;
for (int i = 0; i < part[p].div; i++) {
drum->drums[p].data[outindex] = out16;
outindex++;
}
}
drum->drums[p].len = outindex;
}
}
void opna_drum_mix(struct opna_drum *drum, int16_t *buf, int samples) {
for (int i = 0; i < samples; i++) {
int32_t lo = buf[i*2+0];
int32_t ro = buf[i*2+1];
for (int d = 0; d < 6; d++) {
if (drum->drums[d].playing && drum->drums[d].data) {
int co = drum->drums[d].data[drum->drums[d].index];
co >>= 4;
unsigned level = (drum->drums[d].level^0x1f) + (drum->total_level^0x3f);
co *= 15 - (level&7);
co >>= 1+(level>>3);
if (drum->drums[d].left) lo += co;
if (drum->drums[d].right) ro += co;
drum->drums[d].index++;
if (drum->drums[d].index == drum->drums[d].len) {
drum->drums[d].index = 0;
drum->drums[d].playing = false;
}
}
}
if (lo < INT16_MIN) lo = INT16_MIN;
if (lo > INT16_MAX) lo = INT16_MAX;
if (ro < INT16_MIN) ro = INT16_MIN;
if (ro > INT16_MAX) ro = INT16_MAX;
buf[i*2+0] = lo;
buf[i*2+1] = ro;
}
}
void opna_drum_writereg(struct opna_drum *drum, unsigned reg, unsigned val) {
val &= 0xff;
switch (reg) {
case 0x10:
for (int d = 0; d < 6; d++) {
if (val & (1<<d)) {
drum->drums[d].playing = !(val & 0x80);
drum->drums[d].index = 0;
}
}
break;
case 0x11:
drum->total_level = val & 0x3f;
break;
case 0x18:
case 0x19:
case 0x1a:
case 0x1b:
case 0x1c:
case 0x1d:
{
int d = reg - 0x18;
drum->drums[d].left = val & 0x80;
drum->drums[d].right = val & 0x40;
drum->drums[d].level = val & 0x1f;
}
break;
default:
break;
}
}
|
