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#include "opnassg.h"
/*
static const float voltable[32] = {
0.0f, 0.0f, 0x1.ae89f9p-8f, 0x1.000000p-7f,
0x1.306fe0p-7f, 0x1.6a09e6p-7f, 0x1.ae89f9p-7f, 0x1.000000p-6f,
0x1.306fe0p-6f, 0x1.6a09e6p-6f, 0x1.ae89f9p-6f, 0x1.000000p-5f,
0x1.306fe0p-5f, 0x1.6a09e6p-5f, 0x1.ae89f9p-5f, 0x1.000000p-4f,
0x1.306fe0p-4f, 0x1.6a09e6p-4f, 0x1.ae89f9p-4f, 0x1.000000p-3f,
0x1.306fe0p-3f, 0x1.6a09e6p-3f, 0x1.ae89f9p-3f, 0x1.000000p-2f,
0x1.306fe0p-2f, 0x1.6a09e6p-2f, 0x1.ae89f9p-2f, 0x1.000000p-1f,
0x1.306fe0p-1f, 0x1.6a09e6p-1f, 0x1.ae89f9p-1f, 0x1.000000p-0f
};
*/
// if (i < 2) voltable[i] = 0;
// else voltable[i] = round((0x7fff / 3.0) * pow(2.0, (i - 31)/4.0));
static const int16_t voltable[32] = {
0, 0, 72, 85,
101, 121, 144, 171,
203, 241, 287, 341,
406, 483, 574, 683,
812, 965, 1148, 1365,
1624, 1931, 2296, 2731,
3247, 3862, 4592, 5461,
6494, 7723, 9185, 10922
};
#define SINCTABLEBIT 7
#define SINCTABLELEN (1<<SINCTABLEBIT)
// GNU Octave
// Fc = 7987200
// Ff = Fc/144
// Fs = Fc/32
// Fe = 20000
// O = (((Ff/2)-Fe)*2)/(Fs/2)
// B = 128 * O / 2
// FILTER=sinc(linspace(-127.5,127.5,256)*2/9/2).*rotdim(kaiser(256,B))
// FILTERI=round(FILTER(1:128).*32768)
static const int16_t sinctable[SINCTABLELEN] = {
1, 0, -1, -2, -3, -5, -6, -6,
-6, -5, -2, 2, 7, 11, 16, 19,
20, 18, 13, 5, -5, -17, -29, -38,
-44, -45, -40, -29, -11, 12, 36, 60,
79, 90, 91, 80, 56, 21, -22, -68,
-112, -146, -166, -166, -144, -100, -37, 39,
119, 193, 251, 282, 280, 241, 166, 61,
-64, -195, -315, -406, -455, -450, -385, -264,
-96, 101, 306, 491, 632, 705, 694, 593,
405, 147, -154, -464, -744, -954, -1062, -1043,
-889, -607, -220, 230, 692, 1108, 1421, 1580,
1552, 1322, 902, 328, -343, -1032, -1655, -2125,
-2369, -2333, -1994, -1365, -498, 523, 1585, 2557,
3306, 3714, 3690, 3185, 2206, 815, -868, -2673,
-4391, -5798, -6670, -6809, -6067, -4359, -1681, 1886,
6178, 10957, 15928, 20765, 25133, 28724, 31275, 32600,
};
void opna_ssg_reset(struct opna_ssg *ssg) {
for (int i = 0; i < 3; i++) {
ssg->ch[i].tone_counter = 0;
ssg->ch[i].out = false;
}
for (int i = 0; i < 0x10; i++) {
ssg->regs[i] = 0;
}
ssg->noise_counter = 0;
ssg->lfsr = 0;
ssg->env_counter = 0;
ssg->env_level = 0;
ssg->env_att = false;
ssg->env_alt = false;
ssg->env_hld = false;
ssg->env_holding = false;
ssg->mask = 0;
}
void opna_ssg_resampler_reset(struct opna_ssg_resampler *resampler) {
for (int i = 0; i < SINCTABLELEN; i++) {
resampler->buf[i] = 0;
}
resampler->index = 0;
}
void opna_ssg_writereg(struct opna_ssg *ssg, unsigned reg, unsigned val) {
if (reg > 0xfu) return;
val &= 0xff;
ssg->regs[reg] = val;
if (reg == 0xd) {
ssg->env_att = ssg->regs[0xd] & 0x4;
if (ssg->regs[0xd] & 0x8) {
ssg->env_alt = ssg->regs[0xd] & 0x2;
ssg->env_hld = ssg->regs[0xd] & 0x1;
} else {
ssg->env_alt = ssg->env_att;
ssg->env_hld = true;
}
ssg->env_holding = false;
ssg->env_level = 0;
ssg->env_counter = 0;
}
}
unsigned opna_ssg_readreg(const struct opna_ssg *ssg, unsigned reg) {
if (reg > 0xfu) return 0xff;
return ssg->regs[reg];
}
static int opna_ssg_tone_period(const struct opna_ssg *ssg, int chan) {
return ssg->regs[0+chan*2] | ((ssg->regs[1+chan*2] & 0xf) << 8);
}
static bool opna_ssg_chan_env(const struct opna_ssg *ssg, int chan) {
return ssg->regs[0x8+chan] & 0x10;
}
static int opna_ssg_tone_volume(const struct opna_ssg *ssg, int chan) {
return ssg->regs[0x8+chan] & 0xf;
}
static bool opna_ssg_tone_out(const struct opna_ssg *ssg, int chan) {
unsigned reg = ssg->regs[0x7] >> chan;
return (ssg->ch[chan].out || (reg & 0x1)) && ((ssg->lfsr & 1) || (reg & 0x8));
}
static bool opna_ssg_tone_silent(const struct opna_ssg *ssg, int chan) {
unsigned reg = ssg->regs[0x7] >> chan;
return (reg & 0x1) && (reg & 0x8);
}
static int opna_ssg_noise_period(const struct opna_ssg *ssg) {
return ssg->regs[0x6] & 0x1f;
}
static int opna_ssg_env_period(const struct opna_ssg *ssg) {
return (ssg->regs[0xc] << 8) | ssg->regs[0xb];
}
static int opna_ssg_env_level(const struct opna_ssg *ssg) {
return ssg->env_att ? ssg->env_level : 31-ssg->env_level;
}
int opna_ssg_channel_level(const struct opna_ssg *ssg, int ch) {
return opna_ssg_chan_env(ssg, ch)
? opna_ssg_env_level(ssg)
: (opna_ssg_tone_volume(ssg, ch) << 1) + 1;
}
void opna_ssg_generate_raw(struct opna_ssg *ssg, int16_t *buf, int samples) {
for (int i = 0; i < samples; i++) {
if (((++ssg->noise_counter) >> 1) >= opna_ssg_noise_period(ssg)) {
ssg->noise_counter = 0;
ssg->lfsr |= (!((ssg->lfsr & 1) ^ ((ssg->lfsr >> 3) & 1))) << 17;
ssg->lfsr >>= 1;
}
if (!ssg->env_holding) {
if (++ssg->env_counter >= opna_ssg_env_period(ssg)) {
ssg->env_counter = 0;
ssg->env_level++;
if (ssg->env_level == 0x20) {
ssg->env_level = 0;
if (ssg->env_alt) {
ssg->env_att = !ssg->env_att;
}
if (ssg->env_hld) {
ssg->env_level = 0x1f;
ssg->env_holding = true;
}
}
}
}
int16_t out = 0;
for (int ch = 0; ch < 3; ch++) {
if (++ssg->ch[ch].tone_counter >= opna_ssg_tone_period(ssg, ch)) {
ssg->ch[ch].tone_counter = 0;
ssg->ch[ch].out = !ssg->ch[ch].out;
}
if (ssg->mask & (1<<ch)) continue;
#if 1
// may output DC offset
// YMF288 seems to disable output when 0 <= Tp < 8
if (opna_ssg_tone_out(ssg, ch)) {
int level = opna_ssg_chan_env(ssg, ch)
? opna_ssg_env_level(ssg)
: (opna_ssg_tone_volume(ssg, ch) << 1) + 1;
out += voltable[level];
}
#else
if (!opna_ssg_tone_silent(ssg, ch)) {
int level = opna_ssg_channel_level(ssg, ch);
out += (opna_ssg_tone_out(ssg, ch) ? voltable[level] : -voltable[level]) / 2;
}
#endif
}
buf[i] = out / 2;
}
}
#define BUFINDEX(n) ((((resampler->index)>>1)+n)&(SINCTABLELEN-1))
void opna_ssg_mix_55466(
struct opna_ssg *ssg, struct opna_ssg_resampler *resampler,
int16_t *buf, int samples) {
for (int i = 0; i < samples; i++) {
{
int ssg_samples = ((resampler->index + 9)>>1) - ((resampler->index)>>1);
int16_t ssgbuf[5];
opna_ssg_generate_raw(ssg, ssgbuf, ssg_samples);
for (int j = 0; j < ssg_samples; j++) {
resampler->buf[BUFINDEX(j)] = ssgbuf[j];
}
resampler->index += 9;
}
int32_t sample = 0;
for (int j = 0; j < SINCTABLELEN; j++) {
unsigned sincindex = j*2;
if (!(resampler->index&1)) sincindex++;
bool sincsign = sincindex & (1<<(SINCTABLEBIT));
unsigned sincmask = ((1<<(SINCTABLEBIT))-1);
sincindex = (sincindex & sincmask) ^ (sincsign ? sincmask : 0);
sample += (resampler->buf[BUFINDEX(j)] * sinctable[sincindex])>>2;
}
sample >>= 16;
sample *= 13000;
sample >>= 14;
int32_t lo = buf[i*2+0];
int32_t ro = buf[i*2+1];
lo += sample;
ro += sample;
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;
}
}
#undef BUFINDEX
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