ss_gen.c

   1 /*
   2
   3     Ann Hell Ex Machina - Music Software
   4     Copyright (C) 2003/2005 Angel Ortega <angel@triptico.com>
   5
   6     ss_gen.c - Software syntesizer's sound generators
   7
   8     This program is free software; you can redistribute it and/or
   9     modify it under the terms of the GNU General Public License
  10     as published by the Free Software Foundation; either version 2
  11     of the License, or (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21
  22     http://www.triptico.com
  23
  24 */
  25
  26 #include "config.h"
  27
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <math.h>
  32
  33 #include "ss_core.h"
  34 #include "ss_gen.h"
  35
  36 /*******************
  37         Data
  38 ********************/
  39
  40 /* number of generators */
  41 int ss_gen_num=SS_GEN_NUM;
  42
  43 /* generator pool */
  44 static struct ss_gen * ss_gen_pool=NULL;
  45
  46 /* free generator queue */
  47 static struct ss_gen * ss_gen_free_queue=NULL;
  48
  49
  50 /*******************
  51         Code
  52 ********************/
  53
  54 static void ss_gen_enqueue(struct ss_gen ** q, struct ss_gen * g)
  55 /* Enqueues a generator in a generator queue */
  56 {
  57         g->prev=NULL;
  58         g->next=*q;
  59
  60         if(*q != NULL)
  61                 (*q)->prev=g;
  62
  63         *q=g;
  64 }
  65
  66
  67 static struct ss_gen * ss_gen_dequeue(struct ss_gen ** q, struct ss_gen * g)
  68 /* Dequeues a generator from a generator queue */
  69 {
  70         if(g->prev != NULL)
  71                 g->prev->next=g->next;
  72         else
  73                 *q=g->next;
  74
  75         if(g->next != NULL)
  76                 g->next->prev=g->prev;
  77
  78         return(g);
  79 }
  80
  81
  82 static struct ss_gen * ss_gen_pop(struct ss_gen ** q)
  83 /* gets the first enqueued generator from q */
  84 {
  85         struct ss_gen * g=NULL;
  86
  87         if(*q != NULL)
  88                 g=ss_gen_dequeue(q, *q);
  89
  90         return(g);
  91 }
  92
  93
  94 /**
  95  * ss_gen_alloc - Allocs and enqueues a generator
  96  * @q: queue where the generator will be enqueued
  97  *
  98  * Allocs and enqueues a generator into the @q queue.
  99  *
 100  * The new generator is returned, or NULL if the
 101  * generator pool is empty.
 102  */
 103 struct ss_gen * ss_gen_alloc(struct ss_gen ** q)
 104 {
 105         int n;
 106         struct ss_gen * g;
 107
 108         /* first time allocation */
 109         if(ss_gen_pool == NULL)
 110         {
 111                 ss_gen_pool=(struct ss_gen *) malloc(ss_gen_num *
 112                         sizeof(struct ss_gen));
 113
 114                 memset(ss_gen_pool, '\0',
 115                         ss_gen_num * sizeof(struct ss_gen));
 116
 117                 /* enqueue all into the free generator queue */
 118                 for(n=0;n < ss_gen_num;n++)
 119                         ss_gen_enqueue(&ss_gen_free_queue, &ss_gen_pool[n]);
 120         }
 121
 122         if((g=ss_gen_pop(&ss_gen_free_queue)) != NULL)
 123                 ss_gen_enqueue(q, g);
 124
 125         return(g);
 126 }
 127
 128
 129 /**
 130  * ss_gen_free - Dequeues a generator and frees it
 131  * @q: the queue holding the generator
 132  * @g: the generator
 133  *
 134  * Dequeues a generator and sends it back to the generator pool.
 135  */
 136 void ss_gen_free(struct ss_gen ** q, struct ss_gen * g)
 137 {
 138         ss_gen_enqueue(&ss_gen_free_queue, ss_gen_dequeue(q, g));
 139 }
 140
 141
 142 /**
 143  * ss_gen_sustain - Sets sustain for a generator
 144  * @g: the generator
 145  * @sustain: sustain time in msecs
 146  *
 147  * Sets sustain for a generator, where @sustain is expressed
 148  * in milliseconds.
 149  */
 150 void ss_gen_sustain(struct ss_gen * g, double sustain)
 151 {
 152         g->sustain=MS2F(sustain);
 153 }
 154
 155
 156 /**
 157  * ss_gen_vibrato - Sets vibrato for a generator
 158  * @g: the generator
 159  * @depth: vibrato depth in msecs
 160  * @freq: vibrato frequency
 161  *
 162  * Sets vibrato for a generator, with a @depth expressed in
 163  * milliseconds and a frequency @freq expressed in hzs.
 164  */
 165 void ss_gen_vibrato(struct ss_gen * g, double depth, double freq)
 166 {
 167         /* good freq: 6 Hz (0.001) */
 168         /* good depth: 1/6 semitone (20, 30 frames) */
 169
 170         g->vib_depth=MS2F(depth);
 171         g->vib_inc=( 6.28 * freq ) / (double)ss_frequency;
 172         g->vibrato=0.0;
 173 }
 174
 175
 176 /**
 177  * ss_gen_play - Activates a generator.
 178  * @g: generator
 179  * @freq: frequency of the sound to be generated
 180  * @vol: volume
 181  * @note_id: note id
 182  * @w: the wave
 183  *
 184  * Activates a generator, usually as a response for a 'note on'
 185  * message from an upper level. The wave @w holds all the sample
 186  * data (PCM data, base frequency, etc.), @freq is the desired
 187  * frequency, @vol the volume and @note_id a positive, unique
 188  * identifier for the note.
 189  */
 190 void ss_gen_play(struct ss_gen * g, double freq, float vol, int note_id,
 191         struct ss_wave * w)
 192 {
 193         /* store data */
 194         g->note_id=note_id;
 195         g->vol=vol;
 196         g->w=w;
 197
 198         /* start from the beginning */
 199         g->cursor=0;
 200
 201         /* calculate increment */
 202         g->inc=freq / w->base_freq;
 203         g->inc *= (double) w->s_rate / (double) ss_frequency;
 204
 205         /* default sustain, vibrato and portamento */
 206         ss_gen_sustain(g, 50.0);
 207         ss_gen_vibrato(g, 0.0, 0.0);
 208         g->portamento=0;
 209 }
 210
 211
 212 /**
 213  * ss_gen_release - Releases a generator.
 214  * @g: the generator
 215  *
 216  * Releases a generator, usually as a response for a 'note off'
 217  * message from an upper level. The generator enters SS_GEN_RELEASED
 218  * mode, which starts generating sustain data until it's over.
 219  */
 220 void ss_gen_release(struct ss_gen * g)
 221 {
 222         /* note needs not be tracked anymore */
 223         g->note_id=-1;
 224
 225         /* calculates the delta volume */
 226         g->dvol=g->vol / (float) g->sustain;
 227 }
 228
 229
 230 /**
 231  * ss_gen_frame - Generates a frame of samples.
 232  * @g: the generator
 233  * @frame: array where the output samples will be stored
 234  *
 235  * Generates a frame of samples from the @g generator, that will be stored
 236  * in the @frame array.
 237  *
 238  * Returns non-zero if the generator is stopped and should be freed.
 239  */
 240 int ss_gen_frame(struct ss_gen * g, int n_channels, float frame[])
 241 {
 242         int n;
 243         int to_free=0;
 244         double v;
 245         float l_frame[SS_MAX_CHANNELS];
 246         struct ss_wave * w;
 247
 248         v=g->cursor;
 249         w=g->w;
 250
 251         /* process vibrato */
 252         if(g->vib_inc)
 253         {
 254                 g->vibrato += g->vib_inc;
 255                 v += sin(g->vibrato) * g->vib_depth;
 256         }
 257
 258         /* add samples to frame */
 259         for(n=0;n < w->n_channels;n++)
 260                 l_frame[n] = ss_get_sample(w->wave[n], w->size, v) * g->vol;
 261
 262         /* spread the frame into n_channels */
 263         for(n=0;n < n_channels;n++)
 264                 frame[n] += l_frame[n % w->n_channels];
 265
 266         /* increment pointer */
 267         g->cursor += g->inc;
 268
 269         /* test loop boundaries */
 270         if(g->cursor > w->loop_end)
 271         {
 272                 /* loop mode? */
 273                 if(w->loop_start < 0)
 274                         to_free=1;
 275                 else
 276                         g->cursor=w->loop_start;
 277         }
 278
 279         /* process sustain */
 280         if(g->note_id == -1)
 281         {
 282                 g->vol -= g->dvol;
 283
 284                 if(--g->sustain <= 0)
 285                         to_free=1;
 286         }
 287
 288         /* process portamento */
 289         g->inc += g->portamento;
 290
 291         return(to_free);
 292 }