ss_gen.c

   1 /*
   2
   3     Ann Hell Ex Machina - Music Software
   4     Copyright (C) 2003/2006 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 "ahxm.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 void ss_gen_init(void)
  67 /* inits the generator pool */
  68 {
  69         int n;
  70
  71         ss_gen_pool = (struct ss_gen *) realloc(ss_gen_pool, ss_gen_num *
  72                         sizeof(struct ss_gen));
  73
  74         memset(ss_gen_pool, '\0', ss_gen_num * sizeof(struct ss_gen));
  75
  76         /* enqueue all into the free generator queue */
  77         for(n = 0;n < ss_gen_num;n++)
  78                 ss_gen_enqueue(&ss_gen_free_queue, &ss_gen_pool[n]);
  79 }
  80
  81
  82 static struct ss_gen * ss_gen_dequeue(struct ss_gen ** q, struct ss_gen * g)
  83 /* Dequeues a generator from a generator queue */
  84 {
  85         if(g->prev != NULL)
  86                 g->prev->next = g->next;
  87         else
  88                 *q = g->next;
  89
  90         if(g->next != NULL)
  91                 g->next->prev = g->prev;
  92
  93         return(g);
  94 }
  95
  96
  97 static struct ss_gen * ss_gen_pop(struct ss_gen ** q)
  98 /* gets the first enqueued generator from q */
  99 {
 100         struct ss_gen * g = NULL;
 101
 102         if(*q != NULL)
 103                 g = ss_gen_dequeue(q, *q);
 104
 105         return(g);
 106 }
 107
 108
 109 /**
 110  * ss_gen_alloc - Allocs and enqueues a generator
 111  * @q: queue where the generator will be enqueued
 112  *
 113  * Allocs and enqueues a generator into the @q queue.
 114  *
 115  * The new generator is returned, or NULL if the
 116  * generator pool is empty.
 117  */
 118 struct ss_gen * ss_gen_alloc(struct ss_gen ** q)
 119 {
 120         struct ss_gen * g;
 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_portamento - Sets portamento for a generator
 178  * @g: the generator
 179  * @portamento: portamento value
 180  *
 181  * Sets portamento for a generator, where @portamento is an
 182  * increment to the internal cursor of the wave. This value must
 183  * be very small. Negative values will make the frequency slide
 184  * down and positive slide up.
 185  */
 186 void ss_gen_portamento(struct ss_gen * g, double portamento)
 187 {
 188         g->portamento = portamento;
 189 }
 190
 191
 192 /**
 193  * ss_gen_play - Activates a generator.
 194  * @g: generator
 195  * @freq: frequency of the sound to be generated
 196  * @vol: volume
 197  * @note_id: note id
 198  * @w: the wave
 199  *
 200  * Activates a generator, usually as a response for a 'note on'
 201  * message from an upper level. The wave @w holds all the sample
 202  * data (PCM data, base frequency, etc.), @freq is the desired
 203  * frequency, @vol the volume and @note_id a positive, unique
 204  * identifier for the note.
 205  */
 206 void ss_gen_play(struct ss_gen * g, double freq, sample_t vol, int note_id,
 207         struct ss_wave * w)
 208 {
 209         /* store data */
 210         g->note_id = note_id;
 211         g->vol = vol;
 212         g->w = w;
 213
 214         /* start from the beginning */
 215         g->cursor = 0;
 216
 217         /* calculate increment */
 218         g->inc = freq / w->base_freq;
 219         g->inc *= (double) w->s_rate / (double) ss_frequency;
 220
 221         /* default sustain, vibrato and portamento */
 222         ss_gen_sustain(g, 50.0);
 223         ss_gen_vibrato(g, 0.0, 0.0);
 224         ss_gen_portamento(g, 0.0);
 225 }
 226
 227
 228 /**
 229  * ss_gen_release - Releases a generator.
 230  * @g: the generator
 231  *
 232  * Releases a generator, usually as a response for a 'note off'
 233  * message from an upper level. The generator enters SS_GEN_RELEASED
 234  * mode, which starts generating sustain data until it's over.
 235  */
 236 void ss_gen_release(struct ss_gen * g)
 237 {
 238         /* note needs not be tracked anymore */
 239         g->note_id = -1;
 240
 241         /* calculates the delta volume */
 242         g->dvol = g->vol / (sample_t) g->sustain;
 243 }
 244
 245
 246 /**
 247  * ss_gen_frame - Generates a frame of samples.
 248  * @g: the generator
 249  * @n_channels: the desired number of channels
 250  * @frame: array where the output samples will be stored
 251  *
 252  * Generates a frame of samples from the @g generator, that will be stored
 253  * in the @frame array. If @n_channels is greater than the number
 254  * of channels the generator has, they are sequentially spread.
 255  *
 256  * Returns non-zero if the generator is stopped and should be freed.
 257  */
 258 int ss_gen_frame(struct ss_gen * g, int n_channels, sample_t frame[])
 259 {
 260         int n, m;
 261         int to_free = 0;
 262         double v;
 263         sample_t l_frame[SS_MAX_CHANNELS];
 264         struct ss_wave * w;
 265
 266         v = g->cursor;
 267         w = g->w;
 268
 269         /* process vibrato */
 270         if(g->vib_inc)
 271         {
 272                 g->vibrato += g->vib_inc;
 273                 v += sin(g->vibrato) * g->vib_depth;
 274         }
 275
 276         /* add samples to frame */
 277         for(n = 0;n < w->n_channels;n++)
 278                 l_frame[n] = ss_get_sample(w, n, v) * g->vol;
 279
 280         /* spread the frame into n_channels */
 281         for(n = w->first_channel, m = 0;n < n_channels;n++, m++)
 282         {
 283                 frame[n] += l_frame[m % w->n_channels];
 284
 285                 n += w->skip_channels;
 286         }
 287
 288         /* increment pointer */
 289         g->cursor += g->inc;
 290
 291         /* test loop boundaries */
 292         if(g->cursor > w->loop_end)
 293         {
 294                 /* loop mode? */
 295                 if(w->loop_start < 0)
 296                         to_free = 1;
 297                 else
 298                         g->cursor = w->loop_start;
 299         }
 300
 301         /* process sustain */
 302         if(g->note_id == -1)
 303         {
 304                 g->vol -= g->dvol;
 305
 306                 if(--g->sustain <= 0)
 307                         to_free = 1;
 308         }
 309
 310         /* process portamento */
 311         g->inc += g->portamento;
 312
 313         return(to_free);
 314 }