alsa-lib/src/control/cards.c

/*
 *  Control Interface - main file
 *  Copyright (c) 1998 by Jaroslav Kysela <perex@jcu.cz>
 *
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library 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 Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include "asoundlib.h"

#define SND_FILE_CONTROL	"/dev/snd/control%i"

int snd_cards( void )
{
  int idx, count;
  unsigned int mask;
  
  mask = snd_cards_mask();
  for ( idx = 0, count = 0; idx < SND_CARDS; idx++ ) {
    if ( mask & (1 << idx) ) count++;
  }
  return count;
}

/*
 *  this routine uses very ugly method...
 *    need to do...
 */

unsigned int snd_cards_mask( void )
{
  int fd, idx;
  unsigned int mask;
  char filename[32];
  
  for ( idx = 0, mask = 0; idx < SND_CARDS; idx++ ) {
    sprintf( filename, SND_FILE_CONTROL, idx );
    if ( (fd = open( filename, O_RDWR )) < 0 ) continue;
    close( fd );
    mask |= 1 << idx;
  }
  return mask;
}

int snd_card_name( const char *string )
{
  int card, cards;
  void *handle;
  struct snd_ctl_hw_info info;

  cards = snd_cards();
  if ( cards <= 0 ) return -ENODEV;
  if ( !string ) return -EINVAL;
  if ( (isdigit( *string ) && *(string+1) == 0) ||
       (isdigit( *string ) && isdigit( *(string+1) ) && *(string+2) == 0) ) {
    sscanf( string, "%i", &card );
    card--;
    if ( card < 0 || card >= cards )
      return -EINVAL;
    return card;
  }
  for ( card = 0; card < cards; card++ ) {
    if ( snd_ctl_open( &handle, card ) < 0 )
      continue;
    if ( snd_ctl_hw_info( handle, &info ) < 0 ) {
      snd_ctl_close( handle );
      continue;
    }
    snd_ctl_close( handle );
    if ( !strcmp( info.id, string ) )
      return card;
  }
  return -ENODEV;
}