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 "annhell.h"
  34
  35 /*******************
  36         Data
  37 ********************/
  38
  39 /* maximum number of generators */
  40 int ss_gen_num=SS_MAX_GENERATORS;
  41
  42 /* generator pool */
  43 static struct ss_gen * ss_gen_pool=NULL;
  44
  45 /* free generator queue */
  46 static struct ss_gen * ss_gen_free_queue=NULL;
  47
  48
  49 /*******************
  50         Code
  51 ********************/
  52
  53 static void ss_gen_enqueue(struct ss_gen ** q, struct ss_gen * g)
  54 /* Enqueues a generator in a generator queue */
  55 {
  56         g->prev=NULL;
  57         g->next=*q;
  58
  59         if(*q != NULL)
  60                 (*q)->prev=g;
  61
  62         *q=g;
  63 }
  64
  65
  66 static struct ss_gen * ss_gen_dequeue(struct ss_gen ** q, struct ss_gen * g)
  67 /* Dequeues a generator from a generator queue */
  68 {
  69         if(g->prev != NULL)
  70                 g->prev->next=g->next;
  71         else
  72                 *q=g->next;
  73
  74         if(g->next != NULL)
  75                 g->next->prev=g->prev;
  76
  77         return(g);
  78 }
  79
  80
  81 static struct ss_gen * ss_gen_pop(struct ss_gen ** q)
  82 /* gets the first enqueued generator from q */
  83 {
  84         struct ss_gen * g=NULL;
  85
  86         if(*q != NULL)
  87                 g=ss_gen_dequeue(q, *q);
  88
  89         return(g);
  90 }
  91
  92
  93 /**
  94  * ss_gen_alloc - Allocs and enqueues a generator
  95  * @q: queue where the generator will be enqueued
  96  *
  97  * Allocs and enqueues a generator into the @q queue.
  98  *
  99  * The new generator is returned, or NULL if the
 100  * generator pool is empty.
 101  */
 102 struct ss_gen * ss_gen_alloc(struct ss_gen ** q)
 103 {
 104         int n;
 105         struct ss_gen * g;
 106
 107         /* first time allocation */
 108         if(ss_gen_pool == NULL)
 109         {
 110                 ss_gen_pool=(struct ss_gen *) malloc(ss_gen_num *
 111                         sizeof(struct ss_gen));
 112
 113                 memset(ss_gen_pool, '\0',
 114                         ss_gen_num * sizeof(struct ss_gen));
 115
 116                 /* enqueue all into the free generator queue */
 117                 for(n=0;n < ss_gen_num;n++)
 118                         ss_gen_enqueue(&ss_gen_free_queue, &ss_gen_pool[n]);
 119         }
 120
 121         if((g=ss_gen_pop(&ss_gen_free_queue)) != NULL)
 122                 ss_gen_enqueue(q, g);
 123
 124         return(g);
 125 }
 126
 127
 128 /**
 129  * ss_gen_free - Dequeues a generator and frees it
 130  * @q: the queue holding the generator
 131  * @g: the generator
 132  *
 133  * Dequeues a generator and sends it back to the generator pool.
 134  */
 135 void ss_gen_free(struct ss_gen ** q, struct ss_gen * g)
 136 {
 137         ss_gen_enqueue(&ss_gen_free_queue, ss_gen_dequeue(q, g));
 138 }
 139
 140
 141 /**
 142  * ss_gen_sustain - Sets sustain for a generator
 143  * @g: the generator
 144  * @sustain: sustain time in msecs
 145  *
 146  * Sets sustain for a generator, where @sustain is expressed
 147  * in milliseconds.
 148  */
 149 void ss_gen_sustain(struct ss_gen * g, double sustain)
 150 {
 151         g->sustain=MS2F(sustain);
 152 }
 153
 154
 155 /**
 156  * ss_gen_vibrato - Sets vibrato for a generator
 157  * @g: the generator
 158  * @depth: vibrato depth in msecs
 159  * @freq: vibrato frequency
 160  *
 161  * Sets vibrato for a generator, with a @depth expressed in
 162  * milliseconds and a frequency @freq expressed in hzs.
 163  */
 164 void ss_gen_vibrato(struct ss_gen * g, double depth, double freq)
 165 {
 166         /* good freq: 6 Hz (0.001) */
 167         /* good depth: 1/6 semitone (20, 30 frames) */
 168
 169         g->vib_depth=MS2F(depth);
 170         g->vib_inc=( 6.28 * freq ) / (double)ss_frequency;
 171         g->vibrato=0.0;
 172 }
 173
 174
 175 /**
 176  * ss_gen_play - Activates a generator.
 177  * @g: generator
 178  * @freq: frequency of the sound to be generated
 179  * @vol: volume
 180  * @note_id: note id
 181  * @w: the wave
 182  *
 183  * Activates a generator, usually as a response for a 'note on'
 184  * message from an upper level. The wave @w holds all the sample
 185  * data (PCM data, base frequency, etc.), @freq is the desired
 186  * frequency, @vol the volume and @note_id a positive, unique
 187  * identifier for the note.
 188  */
 189 void ss_gen_play(struct ss_gen * g, double freq, sample_t vol, int note_id,
 190         struct ss_wave * w)
 191 {
 192         /* store data */
 193         g->note_id=note_id;
 194         g->vol=vol;
 195         g->w=w;
 196
 197         /* start from the beginning */
 198         g->cursor=0;
 199
 200         /* calculate increment */
 201         g->inc=freq / w->base_freq;
 202         g->inc *= (double) w->s_rate / (double) ss_frequency;
 203
 204         /* default sustain, vibrato and portamento */
 205         ss_gen_sustain(g, 50.0);
 206         ss_gen_vibrato(g, 0.0, 0.0);
 207         g->portamento=0;
 208 }
 209
 210
 211 /**
 212  * ss_gen_release - Releases a generator.
 213  * @g: the generator
 214  *
 215  * Releases a generator, usually as a response for a 'note off'
 216  * message from an upper level. The generator enters SS_GEN_RELEASED
 217  * mode, which starts generating sustain data until it's over.
 218  */
 219 void ss_gen_release(struct ss_gen * g)
 220 {
 221         /* note needs not be tracked anymore */
 222         g->note_id=-1;
 223
 224         /* calculates the delta volume */
 225         g->dvol=g->vol / (sample_t) g->sustain;
 226 }
 227
 228
 229 /**
 230  * ss_gen_frame - Generates a frame of samples.
 231  * @g: the generator
 232  * @n_channels: the desired number of channels
 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. If @n_channels is greater than the number
 237  * of channels the generator has, they are sequentially spread.
 238  *
 239  * Returns non-zero if the generator is stopped and should be freed.
 240  */
 241 int ss_gen_frame(struct ss_gen * g, int n_channels, sample_t frame[])
 242 {
 243         int n;
 244         int to_free=0;
 245         double v;
 246         sample_t l_frame[SS_MAX_CHANNELS];
 247         struct ss_wave * w;
 248
 249         v=g->cursor;
 250         w=g->w;
 251
 252         /* process vibrato */
 253         if(g->vib_inc)
 254         {
 255                 g->vibrato += g->vib_inc;
 256                 v += sin(g->vibrato) * g->vib_depth;
 257         }
 258
 259         /* add samples to frame */
 260         for(n=0;n < w->n_channels;n++)
 261                 l_frame[n] = ss_gesample_t(w->wave[n], w->size, v) * g->vol;
 262
 263         /* spread the frame into n_channels */
 264         for(n=0;n < n_channels;n++)
 265                 frame[n] += l_frame[n % w->n_channels];
 266
 267         /* increment pointer */
 268         g->cursor += g->inc;
 269
 270         /* test loop boundaries */
 271         if(g->cursor > w->loop_end)
 272         {
 273                 /* loop mode? */
 274                 if(w->loop_start < 0)
 275                         to_free=1;
 276                 else
 277                         g->cursor=w->loop_start;
 278         }
 279
 280         /* process sustain */
 281         if(g->note_id == -1)
 282         {
 283                 g->vol -= g->dvol;
 284
 285                 if(--g->sustain <= 0)
 286                         to_free=1;
 287         }
 288
 289         /* process portamento */
 290         g->inc += g->portamento;
 291
 292         return(to_free);
 293 }