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voice.c

/*
 *  Copyright (c) by Jaroslav Kysela <perex@suse.cz>
 *                   Creative Labs, Inc.
 *                   Lee Revell <rlrevell@joe-job.com>
 *  Routines for control of EMU10K1 chips - voice manager
 *
 *  Rewrote voice allocator for multichannel support - rlrevell 12/2004
 * 
 *  BUGS:
 *    --
 *
 *  TODO:
 *    --
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <sound/driver.h>
#include <linux/time.h>
#include <sound/core.h>
#include <sound/emu10k1.h>

/* Previously the voice allocator started at 0 every time.  The new voice 
 * allocator uses a round robin scheme.  The next free voice is tracked in 
 * the card record and each allocation begins where the last left off.  The 
 * hardware requires stereo interleaved voices be aligned to an even/odd 
 * boundary.  For multichannel voice allocation we ensure than the block of 
 * voices does not cross the 32 voice boundary.  This simplifies the 
 * multichannel support and ensures we can use a single write to the 
 * (set|clear)_loop_stop registers.  Otherwise (for example) the voices would 
 * get out of sync when pausing/resuming a stream.
 *                                        --rlrevell
 */

static int voice_alloc(struct snd_emu10k1 *emu, int type, int number,
                   struct snd_emu10k1_voice **rvoice)
{
      struct snd_emu10k1_voice *voice;
      int i, j, k, first_voice, last_voice, skip;

      *rvoice = NULL;
      first_voice = last_voice = 0;
      for (i = emu->next_free_voice, j = 0; j < NUM_G ; i += number, j += number) {
            // printk("i %d j %d next free %d!\n", i, j, emu->next_free_voice);
            i %= NUM_G;

            /* stereo voices must be even/odd */
            if ((number == 2) && (i % 2)) {
                  i++;
                  continue;
            }
                  
            skip = 0;
            for (k = 0; k < number; k++) {
                  voice = &emu->voices[(i+k) % NUM_G];
                  if (voice->use) {
                        skip = 1;
                        break;
                  }
            }
            if (!skip) {
                  // printk("allocated voice %d\n", i);
                  first_voice = i;
                  last_voice = (i + number) % NUM_G;
                  emu->next_free_voice = last_voice;
                  break;
            }
      }
      
      if (first_voice == last_voice)
            return -ENOMEM;
      
      for (i=0; i < number; i++) {
            voice = &emu->voices[(first_voice + i) % NUM_G];
            // printk("voice alloc - %i, %i of %i\n", voice->number, idx-first_voice+1, number);
            voice->use = 1;
            switch (type) {
            case EMU10K1_PCM:
                  voice->pcm = 1;
                  break;
            case EMU10K1_SYNTH:
                  voice->synth = 1;
                  break;
            case EMU10K1_MIDI:
                  voice->midi = 1;
                  break;
            case EMU10K1_EFX:
                  voice->efx = 1;
                  break;
            }
      }
      *rvoice = &emu->voices[first_voice];
      return 0;
}

int snd_emu10k1_voice_alloc(struct snd_emu10k1 *emu, int type, int number,
                      struct snd_emu10k1_voice **rvoice)
{
      unsigned long flags;
      int result;

      snd_assert(rvoice != NULL, return -EINVAL);
      snd_assert(number, return -EINVAL);

      spin_lock_irqsave(&emu->voice_lock, flags);
      for (;;) {
            result = voice_alloc(emu, type, number, rvoice);
            if (result == 0 || type == EMU10K1_SYNTH || type == EMU10K1_MIDI)
                  break;

            /* free a voice from synth */
            if (emu->get_synth_voice) {
                  result = emu->get_synth_voice(emu);
                  if (result >= 0) {
                        struct snd_emu10k1_voice *pvoice = &emu->voices[result];
                        pvoice->interrupt = NULL;
                        pvoice->use = pvoice->pcm = pvoice->synth = pvoice->midi = pvoice->efx = 0;
                        pvoice->epcm = NULL;
                  }
            }
            if (result < 0)
                  break;
      }
      spin_unlock_irqrestore(&emu->voice_lock, flags);

      return result;
}

EXPORT_SYMBOL(snd_emu10k1_voice_alloc);

int snd_emu10k1_voice_free(struct snd_emu10k1 *emu,
                     struct snd_emu10k1_voice *pvoice)
{
      unsigned long flags;

      snd_assert(pvoice != NULL, return -EINVAL);
      spin_lock_irqsave(&emu->voice_lock, flags);
      pvoice->interrupt = NULL;
      pvoice->use = pvoice->pcm = pvoice->synth = pvoice->midi = pvoice->efx = 0;
      pvoice->epcm = NULL;
      snd_emu10k1_voice_init(emu, pvoice->number);
      spin_unlock_irqrestore(&emu->voice_lock, flags);
      return 0;
}

EXPORT_SYMBOL(snd_emu10k1_voice_free);

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