131 lines
3.7 KiB
C++
131 lines
3.7 KiB
C++
/*
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Chassis polysynth framework
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Copyright 2024 Gordon JC Pearce <gordonjcp@gjcp.net>
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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// contains the actual sound generation code
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#include "voice.hpp"
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#include <math.h>
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#include <cstdio>
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static inline float poly3blep0(float t) {
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float t2 = t * t;
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return 2 * (t * t2 - 0.5f * t2 * t2);
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}
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static inline float poly3blep1(float t) {
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return -poly3blep0(1 - t);
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}
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void Voice::run(Synth &s, float *buffer, uint32_t samples) {
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float y, out, t;
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// 325, because it needs PW to be from 0 to 0.5
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// but really the control range is limited from 0 to 100
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// there's a resistor on the panel board to sprag the range
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float pw = s.ff4f / 32768.0f;
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float fb, res = s.patchRam.vcfReso / 28.0f; // guess
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// float cut = s.patchRam.vcfFreq / 400.0f; // guess
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float cut = 248.0f * (powf(2, (vcfenv - 0x1880) / 1143.0f));
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// now radians
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cut = 0.25 * 6.2832 * cut / 48000.0f;
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// now correct
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cut = cut / (1 + cut);
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float sqr = (s.patchRam.switch1 & 0x08) ? 0.63 : 0; //? 0.175 : 0;
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float saw = (s.patchRam.switch1 & 0x10) ? 0.8 : 0; //? 0.220 : 0;
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float sub = (s.patchRam.sub / 127.0f); // * 0.275;
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float gain = 0.5 * powf(2, (s.patchRam.vca / 64.0f) - 1);
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//printf("patchram.switches= %3d %3d\n", s.patchRam.switch1, s.patchRam.switch2);
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float vcaEnv = (s.patchRam.switch2 & 0x04) ? (float)ff11:(env / 16384.0f);
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for (uint32_t i = 0; i < samples; i++) {
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y = delay;
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delay = 0;
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phase += omega;
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// if(pw > 1) pw = 1;
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// if(pw < 0) pw = 0;
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while (true) {
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if (pulseStage == 0) {
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if (phase < pw) break;
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t = (phase - pw) / (lastpw - pw + omega);
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y -= poly3blep0(t) * sqr;
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delay -= poly3blep1(t) * sqr;
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pulseStage = 1;
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}
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if (pulseStage == 1) {
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if (phase < 1) break;
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t = (phase - 1) / omega;
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y += poly3blep0(t) * (saw + sqr);
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delay += poly3blep1(t) * (saw + sqr);
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y -= poly3blep0(t) * (sub * subosc);
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delay -= poly3blep1(t) * (sub * subosc);
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pulseStage = 0;
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phase -= 1;
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subosc = -subosc;
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}
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}
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delay += saw * (1 - (2 * phase));
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delay += sqr * (pulseStage ? -1.f : 1.f);
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delay += sub * subosc;
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// out = (2 * y) - 1;
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out = y;
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// widthDelay = pw;
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out *= 0.707;
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for (uint8_t ovs = 0; ovs < 4; ovs++) {
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fb = b4;
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// hard clip
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if (fb > 1) fb = 1;
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if (fb < -1) fb = -1;
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fb = out - (fb * res);
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b1 = ((fb - b1) * cut) + b1;
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b2 = ((b1 - b2) * cut) + b2;
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b3 = ((b2 - b3) * cut) + b3;
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b4 = ((b3 - b4) * cut) + b4;
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}
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vr58c106 += ((vcaEnv - vr58c106) * 0.005);
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lastpw = pw;
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out = b4 * (0.25);
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buffer[i] += (gain * out * vr58c106);
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}
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}
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