/* Peacock-8 VA polysynth Copyright 2025 Gordon JC Pearce Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include #include "module.hpp" #include "tables.hpp" // antialiasing using polybleps, as described in KVRAudio forum by Mystran static inline float poly3blep0(float t) { float t2 = t * t; return 2 * (t * t2 - 0.5f * t2 * t2); } static inline float poly3blep1(float t) { return -poly3blep0(1 - t); } Voice::Voice() { omega = 0.0; theta = 0.0; env = 0; } void Voice::on(uint8_t midiNote) { while (midiNote < 24) midiNote += 12; while (midiNote > 108) midiNote -= 12; note = midiNote - 24; envPhase = 1; } void Voice::off() { envPhase = 0; } // tanh(x)/x approximation, flatline at very high inputs // so might not be safe for very large feedback gains // [limit is 1/15 so very large means ~15 or +23dB] double tanhXdX(double x) { float s = 0.0333, d = 30.0; return 1.0f - s * (d + 1.0f) * x * x / (d + x * x); } void Voice::run(Module* m, float* buffer, uint32_t samples) { // carry out per-voice calculations for each block of samples float out, t, fb; // calculate cutoff frequency float cut = 261.0f * (powf(2, (vcfCut - 0x1880) / 1143.0f)); cut = M_PI * cut / sampleRate; cut = cut / (1 + cut); // correct tuning warp // if (cut > 0.7) cut = 0.7; double r = 5 * m->res; float amp = vcaEnv / 4096.0f; for (uint32_t i = 0; i < samples; i++) { out = delay; delay = 0; theta += omega; while (true) { if (pulseStage == 0) { if (theta < m->pwmBuf[i]) break; t = (theta - m->pwmBuf[i]) / (lastpw - m->pwmBuf[i] + omega); out -= poly3blep0(t) * m->square; delay -= poly3blep1(t) * m->square; pulseStage = 1; } if (pulseStage == 1) { if (theta < 1) break; // no need to blep yet t = (theta - 1) / omega; // scaled remainder of phase out += poly3blep0(t) * (m->saw + m->square); delay += poly3blep1(t) * (m->saw + m->square); out -= poly3blep0(t) * (m->subBuf[i] * subosc); delay -= poly3blep1(t) * (m->subBuf[i] * subosc); pulseStage = 0; subosc = -subosc; theta -= 1; } } // FIXME DC offset removal delay += m->saw * (1 - (2 * theta)); delay += m->square * ((pulseStage ? -1.f : 1.f) - m->pwmBuf[i] + 0.5); delay += m->subBuf[i] * subosc; out += m->noise * (0.8 - 1.6 * (rand() & 0xffff) / 65536.0); // out *= 0.1; // same time constant for both VCF and VCF RC circuits vcfRC = (cut - vcfRC) * m->vcaTC + vcfRC; #if 1 //// LICENSE TERMS: Copyright 2012 Teemu Voipio // // You can use this however you like for pretty much any purpose, // as long as you don't claim you wrote it. There is no warranty. // // Distribution of substantial portions of this code in source form // must include this copyright notice and list of conditions. // // input delay and state for member variables // cutoff as normalized frequency (eg 0.5 = Nyquist) // resonance from 0 to 1, self-oscillates at settings over 0.9 // void transistorLadder( // double cutoff, double resonance, // double * in, double * out, unsigned nsamples) //{ // tuning and feedback //------------------------------------------------------------------------------ sample loop // for(unsigned n = 0; n < nsamples; ++n) //{ out *= 0.025; // input with half delay, for non-linearities double ih = 0.5 * (out + zi); zi = out; // double ih = out; // evaluate the non-linear gains double t0 = tanhXdX((ih * (r + 1)) - r * s[3]); double t1 = tanhXdX(s[0]); double t2 = tanhXdX(s[1]); double t3 = tanhXdX(s[2]); double t4 = tanhXdX(s[3]); double f = vcfRC; // g# the denominators for solutions of individual stages double g0 = 1 / (1 + f * t1), g1 = 1 / (1 + f * t2); double g2 = 1 / (1 + f * t3), g3 = 1 / (1 + f * t4); // f# are just factored out of the feedback solution double f3 = f * t3 * g3, f2 = f * t2 * g2 * f3, f1 = f * t1 * g1 * f2, f0 = f * t0 * g0 * f1; // solve feedback double y3 = (g3 * s[3] + f3 * g2 * s[2] + f2 * g1 * s[1] + f1 * g0 * s[0] + f0 * out) / (1 + r * f0); // then solve the remaining outputs (with the non-linear gains here) double xx = t0 * ((out * (r + 1)) - r * y3); double y0 = t1 * g0 * (s[0] + f * xx); double y1 = t2 * g1 * (s[1] + f * y0); double y2 = t3 * g2 * (s[2] + f * y1); // update state s[0] += 2 * f * (xx - y0); s[1] += 2 * f * (y0 - y1); s[2] += 2 * f * (y1 - y2); s[3] += 2 * f * (y2 - t4 * y3); // out[n] = y3; // } // out *= 0.1; out = y3; #else out *= 0.5; for (uint8_t ovs = 0; ovs < 2; ovs++) { fb = y3; // hard clip fb = ((out * 0.5) - fb) * r; if (fb > 4) fb = 4; if (fb < -4) fb = -4; // fb = 1.5 * fb - 0.5 * fb * fb * fb; // y0 = ((out + fb - y0) * vcfRC) + y0; y1 = ((y0 - y1) * vcfRC) + y1; y2 = ((y1 - y2) * vcfRC) + y2; y3 = ((y2 - y3) * vcfRC) + y3; } #endif vcaRC = (amp - vcaRC) * m->vcaTC + vcaRC; buffer[i] += m->vcaBuf[i] * vcaRC * out; lastpw = m->pwmBuf[i]; } // buffer[0] += 1; }