Carla/source/backend/native/zynaddsubfx/Effects/Phaser.cpp

/*

  Phaser.cpp  - Phasing and Approximate digital model of an analog JFET phaser.
  Analog modeling implemented by Ryan Billing aka Transmogrifox.
  ZynAddSubFX - a software synthesizer

  Phaser.cpp - Phaser effect
  Copyright (C) 2002-2005 Nasca Octavian Paul
  Copyright (C) 2009-2010 Ryan Billing
  Copyright (C) 2010-2010 Mark McCurry
  Author: Nasca Octavian Paul
          Ryan Billing
          Mark McCurry

  DSP analog modeling theory & practice largely influenced by various CCRMA publications, particularly works by Julius O. Smith.

  This program is free software; you can redistribute it and/or modify
  it under the terms of version 2 of the GNU General Public License
  as published by the Free Software Foundation.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License (version 2 or later) for more details.

  You should have received a copy of the GNU General Public License (version 2)
  along with this program; if not, write to the Free Software Foundation,
  Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA

*/

#include <cmath>
#include <algorithm>
#include "Phaser.h"

using namespace std;

#define PHASER_LFO_SHAPE 2
#define ONE_  0.99999f        // To prevent LFO ever reaching 1.0f for filter stability purposes
#define ZERO_ 0.00001f        // Same idea as above.

Phaser::Phaser(const int &insertion_, float *efxoutl_, float *efxoutr_)
    :Effect(insertion_, efxoutl_, efxoutr_, NULL, 0), old(NULL), xn1(NULL),
      yn1(NULL), diff(0.0f), oldgain(0.0f), fb(0.0f)
{
    analog_setup();
    setpreset(Ppreset);
    cleanup();
}

void Phaser::analog_setup()
{
    //model mismatch between JFET devices
    offset[0]  = -0.2509303f;
    offset[1]  = 0.9408924f;
    offset[2]  = 0.998f;
    offset[3]  = -0.3486182f;
    offset[4]  = -0.2762545f;
    offset[5]  = -0.5215785f;
    offset[6]  = 0.2509303f;
    offset[7]  = -0.9408924f;
    offset[8]  = -0.998f;
    offset[9]  = 0.3486182f;
    offset[10] = 0.2762545f;
    offset[11] = 0.5215785f;

    barber = 0;  //Deactivate barber pole phasing by default

    mis       = 1.0f;
    Rmin      = 625.0f; // 2N5457 typical on resistance at Vgs = 0
    Rmax      = 22000.0f; // Resistor parallel to FET
    Rmx       = Rmin / Rmax;
    Rconst    = 1.0f + Rmx; // Handle parallel resistor relationship
    C         = 0.00000005f; // 50 nF
    CFs       = 2.0f * synth->samplerate_f * C;
    invperiod = 1.0f / synth->buffersize_f;
}

Phaser::~Phaser()
{
    if(xn1.l)
        delete[] xn1.l;
    if(yn1.l)
        delete[] yn1.l;
    if(xn1.r)
        delete[] xn1.r;
    if(yn1.r)
        delete[] yn1.r;
}

/*
 * Effect output
 */
void Phaser::out(const Stereo<float *> &input)
{
    if(Panalog)
        AnalogPhase(input);
    else
        normalPhase(input);
}

void Phaser::AnalogPhase(const Stereo<float *> &input)
{
    Stereo<float> gain(0.0f), lfoVal(0.0f), mod(0.0f), g(0.0f), b(0.0f), hpf(
        0.0f);

    lfo.effectlfoout(&lfoVal.l, &lfoVal.r);
    mod.l = lfoVal.l * width + (depth - 0.5f);
    mod.r = lfoVal.r * width + (depth - 0.5f);

    mod.l = limit(mod.l, ZERO_, ONE_);
    mod.r = limit(mod.r, ZERO_, ONE_);

    if(Phyper) {
        //Triangle wave squared is approximately sin on bottom, tri on top
        //Result is exponential sweep more akin to filter in synth with
        //exponential generator circuitry.
        mod.l *= mod.l;
        mod.r *= mod.r;
    }

    //g.l,g.r is Vp - Vgs. Typical FET drain-source resistance follows constant/[1-sqrt(Vp - Vgs)]
    mod.l = sqrtf(1.0f - mod.l);
    mod.r = sqrtf(1.0f - mod.r);

    diff.r = (mod.r - oldgain.r) * invperiod;
    diff.l = (mod.l - oldgain.l) * invperiod;

    g = oldgain;
    oldgain = mod;

    for(int i = 0; i < synth->buffersize; ++i) {
        g.l += diff.l; // Linear interpolation between LFO samples
        g.r += diff.r;

        Stereo<float> xn(input.l[i] * pangainL, input.r[i] * pangainR);

        if(barber) {
            g.l = fmodf((g.l + 0.25f), ONE_);
            g.r = fmodf((g.r + 0.25f), ONE_);
        }

        xn.l = applyPhase(xn.l, g.l, fb.l, hpf.l, yn1.l, xn1.l);
        xn.r = applyPhase(xn.r, g.r, fb.r, hpf.r, yn1.r, xn1.r);


        fb.l = xn.l * feedback;
        fb.r = xn.r * feedback;
        efxoutl[i] = xn.l;
        efxoutr[i] = xn.r;
    }

    if(Poutsub) {
        invSignal(efxoutl, synth->buffersize);
        invSignal(efxoutr, synth->buffersize);
    }
}

float Phaser::applyPhase(float x, float g, float fb,
                         float &hpf, float *yn1, float *xn1)
{
    for(int j = 0; j < Pstages; ++j) { //Phasing routine
        mis = 1.0f + offsetpct * offset[j];

        //This is symmetrical.
        //FET is not, so this deviates slightly, however sym dist. is
        //better sounding than a real FET.
        float d = (1.0f + 2.0f * (0.25f + g) * hpf * hpf * distortion) * mis;
        Rconst = 1.0f + mis * Rmx;

        // This is 1/R. R is being modulated to control filter fc.
        float b    = (Rconst - g) / (d * Rmin);
        float gain = (CFs - b) / (CFs + b);
        yn1[j] = gain * (x + yn1[j]) - xn1[j];

        //high pass filter:
        //Distortion depends on the high-pass part of the AP stage.
        hpf = yn1[j] + (1.0f - gain) * xn1[j];

        xn1[j] = x;
        x      = yn1[j];
        if(j == 1)
            x += fb;  //Insert feedback after first phase stage
    }
    return x;
}
void Phaser::normalPhase(const Stereo<float *> &input)
{
    Stereo<float> gain(0.0f), lfoVal(0.0f);

    lfo.effectlfoout(&lfoVal.l, &lfoVal.r);
    gain.l =
        (expf(lfoVal.l
              * PHASER_LFO_SHAPE) - 1) / (expf(PHASER_LFO_SHAPE) - 1.0f);
    gain.r =
        (expf(lfoVal.r
              * PHASER_LFO_SHAPE) - 1) / (expf(PHASER_LFO_SHAPE) - 1.0f);

    gain.l = 1.0f - phase * (1.0f - depth) - (1.0f - phase) * gain.l * depth;
    gain.r = 1.0f - phase * (1.0f - depth) - (1.0f - phase) * gain.r * depth;

    gain.l = limit(gain.l, ZERO_, ONE_);
    gain.r = limit(gain.r, ZERO_, ONE_);

    for(int i = 0; i < synth->buffersize; ++i) {
        float x  = (float) i / synth->buffersize_f;
        float x1 = 1.0f - x;
        //TODO think about making panning an external feature
        Stereo<float> xn(input.l[i] * pangainL + fb.l,
                         input.r[i] * pangainR + fb.r);

        Stereo<float> g(gain.l * x + oldgain.l * x1,
                        gain.r * x + oldgain.r * x1);

        xn.l = applyPhase(xn.l, g.l, old.l);
        xn.r = applyPhase(xn.r, g.r, old.r);

        //Left/Right crossing
        crossover(xn.l, xn.r, lrcross);

        fb.l = xn.l * feedback;
        fb.r = xn.r * feedback;
        efxoutl[i] = xn.l;
        efxoutr[i] = xn.r;
    }

    oldgain = gain;

    if(Poutsub) {
        invSignal(efxoutl, synth->buffersize);
        invSignal(efxoutr, synth->buffersize);
    }
}

float Phaser::applyPhase(float x, float g, float *old)
{
    for(int j = 0; j < Pstages * 2; ++j) { //Phasing routine
        float tmp = old[j];
        old[j] = g * tmp + x;
        x      = tmp - g * old[j];
    }
    return x;
}

/*
 * Cleanup the effect
 */
void Phaser::cleanup()
{
    fb = oldgain = Stereo<float>(0.0f);
    for(int i = 0; i < Pstages * 2; ++i) {
        old.l[i] = 0.0f;
        old.r[i] = 0.0f;
    }
    for(int i = 0; i < Pstages; ++i) {
        xn1.l[i] = 0.0f;
        yn1.l[i] = 0.0f;
        xn1.r[i] = 0.0f;
        yn1.r[i] = 0.0f;
    }
}

/*
 * Parameter control
 */
void Phaser::setwidth(unsigned char Pwidth)
{
    this->Pwidth = Pwidth;
    width = ((float)Pwidth / 127.0f);
}

void Phaser::setfb(unsigned char Pfb)
{
    this->Pfb = Pfb;
    feedback  = (float) (Pfb - 64) / 64.2f;
}

void Phaser::setvolume(unsigned char Pvolume)
{
    this->Pvolume = Pvolume;
    outvolume     = Pvolume / 127.0f;
    if(insertion == 0)
        volume = 1.0f;
    else
        volume = outvolume;
}

void Phaser::setdistortion(unsigned char Pdistortion)
{
    this->Pdistortion = Pdistortion;
    distortion = (float)Pdistortion / 127.0f;
}

void Phaser::setoffset(unsigned char Poffset)
{
    this->Poffset = Poffset;
    offsetpct     = (float)Poffset / 127.0f;
}

void Phaser::setstages(unsigned char Pstages)
{
    if(xn1.l)
        delete[] xn1.l;
    if(yn1.l)
        delete[] yn1.l;
    if(xn1.r)
        delete[] xn1.r;
    if(yn1.r)
        delete[] yn1.r;


    this->Pstages = min(MAX_PHASER_STAGES, (int)Pstages);

    old = Stereo<float *>(new float[Pstages * 2],
                          new float[Pstages * 2]);

    xn1 = Stereo<float *>(new float[Pstages],
                          new float[Pstages]);

    yn1 = Stereo<float *>(new float[Pstages],
                          new float[Pstages]);

    cleanup();
}

void Phaser::setphase(unsigned char Pphase)
{
    this->Pphase = Pphase;
    phase = (Pphase / 127.0f);
}

void Phaser::setdepth(unsigned char Pdepth)
{
    this->Pdepth = Pdepth;
    depth = (float)(Pdepth) / 127.0f;
}


void Phaser::setpreset(unsigned char npreset)
{
    const int     PRESET_SIZE = 15;
    const int     NUM_PRESETS = 12;
    unsigned char presets[NUM_PRESETS][PRESET_SIZE] = {
        //Phaser
        //0   1    2    3  4   5     6   7   8    9 10   11 12  13 14
        {64, 64, 36,  0,   0, 64,  110, 64,  1,  0,   0, 20,
         0, 0,
         0 },
        {64, 64, 35,  0,   0, 88,  40,  64,  3,  0,   0, 20, 0,  0,
         0 },
        {64, 64, 31,  0,   0, 66,  68,  107, 2,  0,   0, 20, 0,  0,
         0 },
        {39, 64, 22,  0,   0, 66,  67,  10,  5,  0,   1, 20, 0,  0,
         0 },
        {64, 64, 20,  0,   1, 110, 67,  78,  10, 0,   0, 20, 0,  0,
         0 },
        {64, 64, 53,  100, 0, 58,  37,  78,  3,  0,   0, 20, 0,  0,
         0 },
        //APhaser
        //0   1    2   3   4   5     6   7   8    9 10   11 12  13 14
        {64, 64, 14,  0,   1, 64,  64,  40,  4,  10,  0, 110,1,  20,
         1 },
        {64, 64, 14,  5,   1, 64,  70,  40,  6,  10,  0, 110,1,  20,
         1 },
        {64, 64, 9,   0,   0, 64,  60,  40,  8,  10,  0, 40, 0,  20,
         1 },
        {64, 64, 14,  10,  0, 64,  45,  80,  7,  10,  1, 110,1,  20,
         1 },
        {25, 64, 127, 10,  0, 64,  25,  16,  8,  100, 0, 25, 0,  20,
         1 },
        {64, 64, 1,   10,  1, 64,  70,  40,  12, 10,  0, 110,1,  20,
         1 }
    };
    if(npreset >= NUM_PRESETS)
        npreset = NUM_PRESETS - 1;
    for(int n = 0; n < PRESET_SIZE; ++n)
        changepar(n, presets[npreset][n]);
    Ppreset = npreset;
}


void Phaser::changepar(int npar, unsigned char value)
{
    switch(npar) {
        case 0:
            setvolume(value);
            break;
        case 1:
            setpanning(value);
            break;
        case 2:
            lfo.Pfreq = value;
            lfo.updateparams();
            break;
        case 3:
            lfo.Prandomness = value;
            lfo.updateparams();
            break;
        case 4:
            lfo.PLFOtype = value;
            lfo.updateparams();
            barber = (2 == value);
            break;
        case 5:
            lfo.Pstereo = value;
            lfo.updateparams();
            break;
        case 6:
            setdepth(value);
            break;
        case 7:
            setfb(value);
            break;
        case 8:
            setstages(value);
            break;
        case 9:
            setlrcross(value);
            setoffset(value);
            break;
        case 10:
            Poutsub = min((int)value, 1);
            break;
        case 11:
            setphase(value);
            setwidth(value);
            break;
        case 12:
            Phyper = min((int)value, 1);
            break;
        case 13:
            setdistortion(value);
            break;
        case 14:
            Panalog = value;
            break;
    }
}

unsigned char Phaser::getpar(int npar) const
{
    switch(npar) {
        case 0:  return Pvolume;
        case 1:  return Ppanning;
        case 2:  return lfo.Pfreq;
        case 3:  return lfo.Prandomness;
        case 4:  return lfo.PLFOtype;
        case 5:  return lfo.Pstereo;
        case 6:  return Pdepth;
        case 7:  return Pfb;
        case 8:  return Pstages;
        case 9:  return Plrcross;
            return Poffset;      //same
        case 10: return Poutsub;
        case 11: return Pphase;
            return Pwidth;      //same
        case 12: return Phyper;
        case 13: return Pdistortion;
        case 14: return Panalog;
        default: return 0;
    }
}