File: obuffer_linux.cc

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/*
 *  @(#) obuffer_linux.cc 1.3, last edit: 02 Mar 1995 18:38:05
 *  @(#) Copyright (C) 1993, 1994 Tobias Bading (bading@cs.tu-berlin.de)
 *  @(#) Berlin University of Technology
 *
 *  LinuxObuffer class written by
 *  Louis P. Kruger (lpkruger@phoenix.princeton.edu)
 *
 *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *  Changes from version 1.1 to 1.2:
 *    - new LinuxObuffer class, which works with 16 bit soundcards
 *      like Gravis Ultrasound, SoundBlaster 16 or Pro Audio Spectrum 16,
 *      if attached to /dev/dsp
 */


// statics of class LinuxObuffer:
int LinuxObuffer::audio_fd = -1;


int LinuxObuffer::open_audio_device (void)
{
  int fd;

  if ((fd = open ("/dev/audio", O_WRONLY | O_NDELAY, 0)) < 0)
    if (errno == EBUSY)
    {
      extern boil verbose_mode, wait_if_busy;

      if (wait_if_busy)
      {
	if (verbose_mode)
	  cerr << "Dsp device is busy, waiting...\n";
	if ((fd = open ("/dev/audio", O_WRONLY, 0)) < 0)
	{
	  perror ("Can't open /dev/audio for writing");
	  exit (1);
	}
	if (verbose_mode)
	  cerr << "Starting playback...\n";
      }
      else
      {
	cerr << "Sorry, the dsp device is busy!\n";
	exit (1);
      }
    }
    else
    {
      perror ("Can't open /dev/audio for writing");
      exit (1);
    }

  // turn NDELAY mode on, because write() must never block maplay:
  int flags;
  if ((flags = fcntl (fd, F_GETFL, 0)) < 0)
  {
    perror ("fcntl F_GETFL on /dev/audio failed");
    exit (1);
  }
  flags |= O_NDELAY;
  if (fcntl (fd, F_SETFL, flags) < 0)
  {
    perror ("fcntl F_SETFL on /dev/audio failed");
    exit (1);
  }

  return fd;
}


LinuxObuffer::LinuxObuffer (uint32 number_of_channels, Header *header)
{
#ifdef DEBUG
  if (!number_of_channels || number_of_channels > MAXCHANNELS)
  {
    cerr << "LinuxObuffer: 0 < number of channels < " << MAXCHANNELS << "!\n";
    exit (1);
  }
#endif
  channels = number_of_channels;
  for (int i = 0; i < number_of_channels; ++i)
    bufferp[i] = buffer + i;

  if (audio_fd < 0)
  {
    cerr << "Internal error, LinuxObuffer::audio_fd has to be initialized\n"
	    "by LinuxObuffer::class_suitable()!\n";
    exit (1);
  }

  // configure the device:
  int play_precision = 8;
  int play_stereo = channels - 1;
  int play_encoding = AFMT_MU_LAW;

  // 486DX2's are too slow eh? fix the rate at 8 kHz
  int play_sample_rate = 8000;

  if(
      ioctl(audio_fd, SNDCTL_DSP_SAMPLESIZE, &play_precision) == -1 ||
      ioctl(audio_fd, SNDCTL_DSP_STEREO, &play_stereo) == -1 ||
      ioctl(audio_fd, SNDCTL_DSP_SPEED, &play_sample_rate) == -1 ||
      ioctl(audio_fd, SNDCTL_DSP_SETFMT, &play_encoding) == -1
    )
  {
    perror ("configuration of /dev/audio failed");
    exit (1);
  }
}


LinuxObuffer::~LinuxObuffer (void)
{
  close (audio_fd);
}


void LinuxObuffer::append (uint32 channel, int16 value)
{
#ifdef DEBUG
  if (channel >= channels)
  {
    cerr << "illegal channelnumber in LinuxObuffer::append()!\n";
    exit (1);
  }
  if (bufferp[channel] - buffer >= OBUFFERSIZE)
  {
    cerr << "buffer overflow!\n";
    exit (1);
  }
#endif

  *bufferp[channel] = linear2ulaw[value >> 3];
  bufferp[channel] += channels;
}


void LinuxObuffer::write_buffer (int)
{
  int length = (int)((char *)bufferp[0] - (char *)buffer);
  if (write (audio_fd, buffer, length) != length)
  {
    perror ("write to /dev/audio failed");
    exit (1);
  }
  for (int i = 0; i < channels; ++i)
    bufferp[i] = buffer + i;
}


boil LinuxObuffer::class_suitable (uint32 number_of_channels)
{
  // open the dsp audio device:
  audio_fd = open_audio_device ();
  return True;
}