org.c

   1 /*
   2 org.c
   3 various software synths and samples
   4
   5 Copyright (C) 2009 Evan Rinehart
   6
   7 This software comes with no warranty.
   8 1. This software can be used for any purpose, good or evil.
   9 2. Modifications must retain this license, at least in spirit.
  10 */
  11
  12 #include <stdlib.h>
  13 #include <math.h>
  14
  15 #include <org.h>
  16
  17 /*
  18 heres a list of instrument ideas...
  19
  20 piano (not sure yet)
  21 brass (not sure yet)
  22 string (not sure yet)
  23 drum (probably samples)
  24 bass kick (classic analog algorithm)
  25 square triangle saw (polyblep ?)
  26 wind instruments (additive synth via uninterpolated table)
  27 sampler (perhaps a compressed array of samples)
  28 rendered ambient (PADsynth)
  29
  30 */
  31
  32 /* SINE TABLE */
  33 #define TABLE_SIZE (1<<8)
  34 #define RELEASE_STEPS (SAMPLE_RATE/333)
  35 #define RELEASE_RATE 0.999
  36 float sine_table[TABLE_SIZE];
  37
  38 float note2tablestep(float note){
  39         /* critical formula for tuning a table */
  40         /* table steps for 2pif/SAMPLE_RATE radians is...*/
  41         /* TABLE_SIZE/PI2 == entries per radian */
  42         /* step == 2pif/SAMPLE_RATE * (TABLE_SIZE/PI2) */
  43         /*      == f * TABLE_SIZE / SAMPLE_RATE */
  44         /*      == f_0 2^(note/12) TABLE_SIZE / SAMPLE_RATE */
  45         float f = 440 * pow(2, note/12.0);
  46         return f*TABLE_SIZE / SAMPLE_RATE;
  47 }
  48
  49 float sine_table_interp(float ptr){
  50         float i0 = floor(ptr);
  51         float i1 = i0+1;
  52         int I0 = i0;
  53         int I1 = i1;
  54         if(I0 < 0) I0 += TABLE_SIZE;
  55         if(I1 >= TABLE_SIZE) I1 -= TABLE_SIZE;
  56         float y0 = sine_table[I0];
  57         float y1 = sine_table[I1];
  58
  59         float ans = (ptr-i0)*((y1-y0)/(i1-i0)) + y0;
  60         return ans;
  61 }
  62
  63
  64 float normalize(float note){
  65         /* original
  66         -inf, -24 : 4
  67         -24, -12: 2
  68         -12, 24: 1
  69         24,36: 0.5
  70         36,48: 0.25
  71         48, +inf: 0.125*/
  72         const float min = -48;
  73         const float max = 48;
  74         const float left = 4;
  75         const float right = 0.125;
  76
  77         if(note < min) return left;
  78         if(note > max) return right;
  79
  80         float ans = (note - min)*((right-left) / (max-min)) + left;
  81         if(ans > 4) return 4;
  82         if(ans < 0.125) return 0.125;
  83         return ans;
  84 }
  85
  86
  87
  88 /* ORG_DEFAULT: default fallback instrument */
  89 struct defstate {
  90         int on[16];
  91         int note[16];
  92         float step[16];
  93         float ptr[16];
  94         float release[16];
  95         float bendstep[16];
  96         float bend;
  97 };
  98
  99 void default_gen(struct defstate* data, int z, float out[], int count){
 100         if(data->on[z] == 0) return;
 101         int i;
 102         for(i=0; i<count; i++){
 103                 float step = data->step[z] + data->bendstep[z];
 104                 if(data->on[z] == 2){
 105                         data->release[z] *= RELEASE_RATE;
 106                         if(data->release[z] < 0.01){
 107                                 data->on[z] = 0;
 108                                 break;
 109                         }
 110                 }
 111
 112         //      float factor = normalize(data->note[z] + data->bend) * data->release[z];
 113                 //float amp = sine_table[data->ptr[z]];
 114                 float amp = sine_table_interp(data->ptr[z]);
 115         //      out[i] += amp * factor;
 116                 out[i] += amp / 16.0 * data->release[z];
 117                 data->ptr[z] += step;
 118                 while(data->ptr[z] >= TABLE_SIZE){
 119                         data->ptr[z] -= TABLE_SIZE;
 120                 }
 121                 while(data->ptr[z] < 0){
 122                         data->ptr[z] += TABLE_SIZE;
 123                 }
 124         }
 125 }
 126
 127 void default_mix(void* ud, float out[], int count){
 128         struct defstate* data = ud;
 129         int i;
 130         for(i=0; i<16; i++){
 131                 default_gen(data, i, out, count);
 132         }
 133 }
 134
 135
 136 void default_bend_gen(struct defstate* data, int i, float bend){
 137         if(data->on[i] == 0) return;
 138         int note = data->note[i];
 139         data->bendstep[i] = note2tablestep(note + bend) - data->step[i];
 140 }
 141
 142 void default_turn_on(struct defstate* data, int note){
 143         float step = note2tablestep(note);
 144         int i;
 145         for(i=0; i<16; i++){
 146                 if(data->on[i]==0){
 147                         data->step[i] = step;
 148                         data->note[i] = note;
 149                         data->on[i] = 1;
 150                         data->ptr[i] = 0;
 151                         data->release[i] = 1.0;
 152                         default_bend_gen(data, i, data->bend);
 153                         return;
 154                 }
 155         }
 156 }
 157
 158 void default_turn_off(struct defstate* data, int note){
 159         int i;
 160         for(i=0; i<16; i++){
 161                 if(data->note[i] == note && data->on[i] == 1){
 162                         data->on[i] = 2;
 163                         return;
 164                 }
 165         }
 166 }
 167
 168 void default_bend(struct defstate* data, int amount){
 169         int max = 16383;
 170         int relative = amount - max/2;
 171         float bend = 1.0*relative/max * 4;
 172         int i;
 173         data->bend = bend;
 174         for(i=0; i<16; i++){
 175                 default_bend_gen(data, i, bend);
 176         }
 177 }
 178
 179 void default_control(void* ud, int type, int val1, int val2, int val){
 180         struct defstate* data = ud;
 181         switch(type){
 182                 case EV_NOTEON: default_turn_on(data, val1); break;
 183                 case EV_NOTEOFF: default_turn_off(data, val1); break;
 184                 case EV_PITCHBEND: default_bend(data, val); break;
 185         }
 186 }
 187
 188 void default_cleanup(void* data){ free(data); }
 189
 190 instrument make_default(){
 191         instrument ins;
 192         struct defstate* data = malloc(sizeof(struct defstate));
 193         int i;
 194         for(i=0; i<16; i++){
 195                 data->on[i] = 0;
 196                 data->note[i] = 0;
 197                 data->step[i] = 100;
 198                 data->ptr[i] = 0;
 199                 data->bendstep[i] = 0;
 200                 data->bend = 0;
 201         }
 202         ins.mix = default_mix;
 203         ins.control = default_control;
 204         ins.cleanup = default_cleanup;
 205         ins.data = data;
 206         return ins;
 207 }
 208
 209
 210
 211
 212 /* ORG_KARPLUS: karplus strong string synth */
 213
 214 #define KARF 1024
 215
 216 struct karplus {
 217         float buf[KARF];
 218         float ptr;
 219         float length;
 220         float note;
 221         float bend;
 222         float step;
 223         float offset;
 224 };
 225
 226 void karplus_mix(void* ud, float out[], int count){
 227         int i;
 228         struct karplus* data = ud;
 229         for(i=0; i<count; i++){
 230                 int L = data->length;
 231                 int z1 = floor(data->ptr);
 232                 int z0 = z1-1;
 233                 if(z1 >= L) z1 -= L;
 234                 if(z1 < 0) z1 += L;
 235                 if(z0 >= L) z0 -= L;
 236                 if(z0 < 0) z0 += L;
 237                 //out[i] = linterp(data->buf, data->ptr) * 6;
 238                 out[i] = data->buf[z0] * 10;
 239                 data->buf[z1] = (data->buf[z1] + data->buf[z0]) / 2.015;
 240                 data->ptr += 1;
 241                 if(data->ptr >= L){
 242                         data->ptr -= L;
 243                 }
 244         }
 245 }
 246
 247 void karplus_control(void* ud, int type, int val1, int val2, int val){
 248         struct karplus* data = ud;
 249         int i;
 250         float f, L;
 251         switch(type){
 252                 case EV_NOTEON:
 253                         data->note = val1;
 254                         f = 440*(pow(2, val1/12.0));
 255                         L = SAMPLE_RATE * 1.0 / f;
 256                         data->length = L*2;
 257                         for(i=0; i<100; i++){
 258                                 data->buf[i] += ((double)rand())/RAND_MAX - 0.5;
 259                         }
 260                         return;
 261                 case EV_NOTEOFF:
 262                         for(i=0; i<KARF; i++){
 263                                 data->buf[i] = 0;
 264                         }
 265                         return;
 266 //              case EV_PITCHBEND: default_bend(data, val); break;
 267         }
 268 }
 269
 270
 271 void karplus_cleanup(void* data){ free(data); }
 272
 273 instrument make_karplus(){
 274         instrument ins;
 275         struct karplus* data = malloc(sizeof(struct karplus));
 276         int i;
 277         data->length = 512;
 278         data->ptr = 0;
 279         for(i=0; i<KARF; i++){
 280                 data->buf[i] = 0;
 281         }
 282         ins.mix = karplus_mix;
 283         ins.control = karplus_control;
 284         ins.cleanup = karplus_cleanup;
 285         ins.data = data;
 286         return ins;
 287 }
 288
 289
 290
 291 /*** exported methods ***/
 292 instrument load_instrument(enum instrument_name name){
 293         switch(name){
 294                 case ORG_DEFAULT: return make_default();
 295                 case ORG_KARPLUS: return make_karplus();
 296 //              case ORG_COOL: return make_cool();
 297                 default: return make_default();
 298         }
 299 }
 300
 301
 302 void org_init(){
 303         int i;
 304         for(i=0; i<TABLE_SIZE; i++){
 305                 sine_table[i] = sin( (PI2*i) / TABLE_SIZE);
 306         }
 307 }
 308
 309
 310
 311