src/calf/synth.h

   1 /* Calf DSP Library
   2  * Framework for synthesizer-like plugins. This is based
   3  * on my earlier work on Drawbar electric organ emulator.
   4  *
   5  * Copyright (C) 2007 Krzysztof Foltman
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2 of the License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General
  18  * Public License along with this program; if not, write to the
  19  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20  * Boston, MA 02111-1307, USA.
  21  */
  22 #ifndef __CALF_SYNTH_H
  23 #define __CALF_SYNTH_H
  24
  25 #include <list>
  26 #include <stack>
  27 #include <bitset>
  28 #include "primitives.h"
  29 #include "audio_fx.h"
  30
  31 namespace dsp {
  32
  33 /**
  34  * A kind of set with fast non-ordered iteration, used for storing lists of pressed keys.
  35  */
  36 class keystack {
  37 private:
  38     int dcount;
  39     uint8_t active[128];
  40     uint8_t states[128];
  41 public:
  42     keystack() {
  43         memset(states, 0xFF, sizeof(states));
  44         dcount = 0;
  45     }
  46     void clear() {
  47         for (int i=0; i<dcount; i++)
  48             states[active[i]] = 0xFF;
  49         dcount = 0;
  50     }
  51     bool push(int key) {
  52         assert(key >= 0 && key <= 127);
  53         if (states[key] != 0xFF) {
  54             return true;
  55         }
  56         states[key] = dcount;
  57         active[dcount++] = key;
  58         return false;
  59     }
  60     bool pop(int key) {
  61         if (states[key] == 0xFF)
  62             return false;
  63         int pos = states[key];
  64         if (pos != dcount-1) {
  65             // reuse the popped item's stack position for stack top
  66             int last = active[dcount-1];
  67             active[pos] = last;
  68             // mark that position's new place on stack
  69             states[last] = pos;
  70         }
  71         states[key] = 0xFF;
  72         dcount--;
  73         return true;
  74     }
  75     inline bool has(int key) {
  76         return states[key] != 0xFF;
  77     }
  78     inline int count() {
  79         return dcount;
  80     }
  81     inline bool empty() {
  82         return (dcount == 0);
  83     }
  84     inline int nth(int n) {
  85         return active[n];
  86     }
  87 };
  88
  89 /**
  90  * Convert MIDI note number to normalized UINT phase (where 1<<32 is full cycle).
  91  * @param MIDI note number
  92  * @param cents detune in cents (1/100 of a semitone)
  93  * @param sr sample rate
  94  */
  95 inline unsigned int midi_note_to_phase(int note, double cents, int sr) {
  96     double incphase = 440*pow(2.0, (note-69)/12.0 + cents/1200.0)/sr;
  97     if (incphase >= 1.0) incphase = fmod(incphase, 1.0);
  98     incphase *= 65536.0*65536.0;
  99     return (unsigned int)incphase;
 100 }
 101
 102 // Base class for all voice objects
 103 class voice {
 104 public:
 105     int sample_rate;
 106     bool released, sostenuto, stolen;
 107
 108     voice() : sample_rate(-1), released(false), sostenuto(false), stolen(false) {}
 109
 110     /// reset voice to default state (used when a voice is to be reused)
 111     virtual void setup(int sr) { sample_rate = sr; }
 112     /// reset voice to default state (used when a voice is to be reused)
 113     virtual void reset()=0;
 114     /// a note was pressed
 115     virtual void note_on(int note, int vel)=0;
 116     /// a note was released
 117     virtual void note_off(int vel)=0;
 118     /// check if voice can be removed from active voice list
 119     virtual bool get_active()=0;
 120     /// render voice data to buffer
 121     virtual void render_to(float (*buf)[2], int nsamples)=0;
 122     /// very fast note off
 123     virtual void steal()=0;
 124     /// return the note used by this voice
 125     virtual int get_current_note()=0;
 126     virtual float get_priority() { return stolen ? 20000 : (released ? 1 : (sostenuto ? 200 : 100)); }
 127     /// empty virtual destructor
 128     virtual ~voice() {}
 129 };
 130
 131 /// An "optimized" voice class using fixed-size processing units
 132 /// and fixed number of channels. The drawback is that voice
 133 /// control is not sample-accurate, and no modulation input
 134 /// is possible, but it should be good enough for most cases
 135 /// (like Calf Organ).
 136 template<class Base>
 137 class block_voice: public Base {
 138 public:
 139     // derived from Base
 140     // enum { Channels = 2 };
 141     using Base::Channels;
 142     // enum { BlockSize = 16 };
 143     using Base::BlockSize;
 144     // float output_buffer[BlockSize][Channels];
 145     using Base::output_buffer;
 146     // void render_block();
 147     using Base::render_block;
 148     unsigned int read_ptr;
 149
 150     block_voice()
 151     {
 152         read_ptr = BlockSize;
 153     }
 154     virtual void reset()
 155     {
 156         Base::reset();
 157         read_ptr = BlockSize;
 158     }
 159     virtual void render_to(float (*buf)[2], int nsamples)
 160     {
 161         int p = 0;
 162         while(p < nsamples)
 163         {
 164             if (read_ptr == BlockSize)
 165             {
 166                 render_block();
 167                 read_ptr = 0;
 168             }
 169             int ncopy = std::min<int>(BlockSize - read_ptr, nsamples - p);
 170             for (int i = 0; i < ncopy; i++)
 171                 for (int c = 0; c < Channels; c++)
 172                     buf[p + i][c] += output_buffer[read_ptr + i][c];
 173             p += ncopy;
 174             read_ptr += ncopy;
 175         }
 176     }
 177 };
 178
 179 /// Base class for all kinds of polyphonic instruments, provides
 180 /// somewhat reasonable voice management, pedal support - and
 181 /// little else. It's implemented as a base class with virtual
 182 /// functions, so there's some performance loss, but it shouldn't
 183 /// be horrible.
 184 /// @todo it would make sense to support all notes off controller too
 185 struct basic_synth {
 186 protected:
 187     /// Current sample rate
 188     int sample_rate;
 189     /// Hold pedal state
 190     bool hold;
 191     /// Sostenuto pedal state
 192     bool sostenuto;
 193     /// Voices currently playing
 194     std::list<dsp::voice *> active_voices;
 195     /// Voices allocated, but not used
 196     std::stack<dsp::voice *> unused_voices;
 197     /// Gate values for all 128 MIDI notes
 198     std::bitset<128> gate;
 199     /// Maximum allocated number of channels
 200     unsigned int polyphony_limit;
 201
 202     void kill_note(int note, int vel, bool just_one);
 203 public:
 204     virtual void setup(int sr) {
 205         sample_rate = sr;
 206         hold = false;
 207         sostenuto = false;
 208         polyphony_limit = (unsigned)-1;
 209     }
 210     virtual void trim_voices();
 211     virtual dsp::voice *give_voice();
 212     virtual dsp::voice *alloc_voice()=0;
 213     virtual dsp::voice *steal_voice();
 214     virtual void render_to(float (*output)[2], int nsamples);
 215     virtual void note_on(int note, int vel);
 216     virtual void percussion_note_on(int note, int vel) {}
 217     virtual void control_change(int ctl, int val);
 218     virtual void note_off(int note, int vel);
 219     /// amt = -8192 to 8191
 220     virtual void pitch_bend(int amt) {}
 221     virtual void on_pedal_release();
 222     virtual bool check_percussion() { return active_voices.empty(); }
 223     virtual ~basic_synth();
 224 };
 225
 226 }
 227
 228 #endif