aboutsummaryrefslogtreecommitdiff
path: root/libopna/opnassg.c
diff options
context:
space:
mode:
Diffstat (limited to 'libopna/opnassg.c')
-rw-r--r--libopna/opnassg.c233
1 files changed, 233 insertions, 0 deletions
diff --git a/libopna/opnassg.c b/libopna/opnassg.c
new file mode 100644
index 0000000..d87dc91
--- /dev/null
+++ b/libopna/opnassg.c
@@ -0,0 +1,233 @@
+#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;
+}
+
+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;
+ }
+}
+
+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 (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];
+ }
+ */
+ 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];
+ }
+
+ }
+ buf[i] = out / 4;
+ }
+}
+
+#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
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 17:16:19 +0000