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#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;
leveldata_init(&drum->drums[d].leveldata);
}
drum->total_level = 0;
drum->mask = 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) {
unsigned levels[6] = {0};
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);
unsigned outlevel = co > 0 ? co : -co;
if (outlevel > levels[d]) levels[d] = outlevel;
if (!(drum->mask & (1u << d))) {
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;
}
for (int d = 0; d < 6; d++) {
leveldata_update(&drum->drums[d].leveldata, levels[d]);
}
}
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;
}
}
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