/*
* $Id: plat_linux_audio.c,v 1.3 1999/03/07 08:36:40 dirk Exp $
*
* This file is part of WorkMan, the civilized CD player library
* (c) 1991-1997 by Steven Grimm (original author)
* (c) by Dirk Försterling (current 'author' = maintainer)
* The maintainer can be contacted by his e-mail address:
* milliByte@DeathsDoor.com
*
* 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 library 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
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* Linux digital audio functions.
*/
#include "include/wm_config.h"
#if defined(linux) && defined(BUILD_CDDA) /* { */
static char plat_linux_audio_id[] = "$Id: plat_linux_audio.c,v 1.3 1999/03/07 08:36:40 dirk Exp $";
#include "include/wm_cdda.h"
/* types.h included by wm_cdda.h */
#include <stdio.h>
#include <malloc.h>
#include <sys/ioctl.h>
#include <sys/audioio.h>
#include <sys/stropts.h>
#include <sys/time.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#define WM_MSG_CLASS WM_MSG_CLASS_PLATFORM
/*
* Since there's a lag time between writing audio to the audio device and
* hearing it, we need to make sure the status indicators correlate to what's
* playing out the speaker. Luckily, Solaris gives us some audio
* synchronization facilities that make this pretty easy.
*
* We maintain a circular queue of status information. When we write some
* sound to the audio device, we put its status info into the queue. We write
* a marker into the audio stream; when the audio device driver encounters the
* marker, it increments a field in a status structure. When we see that
* field go up, we grab the next status structure from the queue and send it
* to the parent process.
*
* The minimum size of the queue depends on the latency of the audio stream.
*/
#define QSIZE 500
struct cdda_block queue[QSIZE];
int qtail;
int qstart;
/*
* We only send WMCDDA_PLAYED status messages upstream when the CD is supposed
* to be playing; this is used to keep track.
*/
extern int playing;
static int aufd, aucfd;
static int raw_audio = 1; /* Can /dev/audio take 44.1KHz stereo? */
/*
* For fast linear-to-ulaw mapping, we use a lookup table that's generated
* at startup.
*/
unsigned char *ulawmap, linear_to_ulaw();
char *getenv();
/*
* Dummy signal handler so writes to /dev/audio will interrupt.
*/
static void
dummy( void )
{
signal(SIGALRM, dummy);
}
/*
* Initialize the audio device.
*/
void
wmaudio_init( void )
{
audio_info_t info;
char *audiodev, *acdev;
int linval;
audiodev = getenv("AUDIODEV");
if (audiodev == NULL)
audiodev = "/dev/audio";
acdev = malloc(strlen(audiodev) + 4);
if (acdev == NULL)
{
perror("Can't allocate audio control filename");
exit(1);
}
strcpy(acdev, audiodev);
strcat(acdev, "ctl");
aucfd = open(acdev, O_WRONLY, 0);
if (aucfd < 0)
{
perror(acdev);
exit(1);
}
free(acdev);
aufd = open(audiodev, O_WRONLY, 0);
if (aufd < 0)
{
perror(audiodev);
exit(1);
}
signal(SIGALRM, dummy);
/*
* Try to set the device to CD-style audio; we can process it
* with the least CPU overhead.
*/
AUDIO_INITINFO(&info);
info.play.sample_rate = 44100;
info.play.channels = 2;
info.play.precision = 16;
info.play.encoding = AUDIO_ENCODING_LINEAR;
info.play.pause = 0;
info.record.pause = 0;
info.monitor_gain = 0;
if (ioctl(aufd, AUDIO_SETINFO, &info) < 0)
if (errno == EINVAL)
{
/*
* Oh well, so much for that idea.
*/
AUDIO_INITINFO(&info);
info.play.sample_rate = 8000;
info.play.channels = 1;
info.play.precision = 8;
info.play.encoding = AUDIO_ENCODING_ULAW;
info.play.pause = 0;
info.record.pause = 0;
info.monitor_gain = 0;
if (ioctl(aufd, AUDIO_SETINFO, &info) < 0)
{
perror("Can't set up audio device");
exit(1);
}
/*
* Initialize the linear-to-ulaw mapping table.
*/
if (ulawmap == NULL)
ulawmap = malloc(65536);
if (ulawmap == NULL)
{
perror("malloc");
exit(1);
}
for (linval = 0; linval < 65536; linval++)
ulawmap[linval] = linear_to_ulaw(linval-32768);
ulawmap += 32768;
raw_audio = 0;
}
else
{
perror(audiodev);
exit(1);
}
}
/*
* Get ready to play some sound.
*/
void
wmaudio_ready( void )
{
audio_info_t info;
/*
* Start at the correct queue position.
*/
if (ioctl(aucfd, AUDIO_GETINFO, &info) < 0) perror("AUDIO_GETINFO");
qtail = info.play.eof % QSIZE;
qstart = qtail;
queue[qtail].status = WMCDDA_OK;
}
/*
* Stop the audio immediately.
*/
void
wmaudio_stop( void )
{
if (ioctl(aufd, I_FLUSH, FLUSHRW) < 0)
perror("flush");
}
/*
* Close the audio device.
*/
void
wmaudio_close( void )
{
wmaudio_stop();
close(aufd);
close(aucfd);
}
/*
* Set the volume level.
*/
void
wmaudio_volume(int level)
{
audio_info_t info;
AUDIO_INITINFO(&info);
if (ioctl(aucfd, AUDIO_GETINFO, &info) < 0) perror("AUDIO_GETINFO");
info.play.gain = level;
if (ioctl(aucfd, AUDIO_SETINFO, &info) < 0) perror("AUDIO_SETINFO");
}
/*
* Set the balance level.
*/
void
wmaudio_balance(int level)
{
audio_info_t info;
AUDIO_INITINFO(&info);
if (ioctl(aucfd, AUDIO_GETINFO, &info) < 0) perror("AUDIO_GETINFO");
level *= AUDIO_RIGHT_BALANCE;
info.play.balance = level / 255;
if (ioctl(aucfd, AUDIO_SETINFO, &info) < 0) perror("AUDIO_SETINFO");
}
/*
* Mark the most recent audio block on the queue as the last one.
*/
void
wmaudio_mark_last( void )
{
queue[qtail].status = WMCDDA_DONE;
}
/*
* Figure out the most recent status information and send it upstream.
*/
int
wmaudio_send_status( void )
{
audio_info_t info;
int qhead;
/*
* Now send the most current status information to our parent.
*/
if (ioctl(aucfd, AUDIO_GETINFO, &info) < 0)
perror("AUDIO_GETINFO");
qhead = info.play.eof % QSIZE;
if (qhead != qstart && playing)
{
int balance;
if (queue[qhead].status != WMCDDA_DONE)
queue[qhead].status = WMCDDA_PLAYED;
queue[qhead].volume = info.play.gain;
queue[qhead].balance = (info.play.balance * 255) /
AUDIO_RIGHT_BALANCE;
send_status(queue + qhead);
qstart = -1;
}
return (queue[qhead].status == WMCDDA_DONE);
}
/*
* Play some audio and pass a status message upstream, if applicable.
* Returns 0 on success.
*/
int
wmaudio_play(unsigned char *rawbuf, long buflen, struct cdda_block *blk)
{
int i;
short *buf16;
int alarmcount = 0;
struct itimerval it;
alarm(1);
while (write(aufd, rawbuf, buflen) <= 0)
if (errno == EINTR)
{
if (! raw_audio && alarmcount++ < 5)
{
/*
* 8KHz /dev/audio blocks for several seconds
* waiting for its queue to drop below a low
* water mark.
*/
wmaudio_send_status();
timerclear(&it.it_interval);
timerclear(&it.it_value);
it.it_value.tv_usec = 500000;
setitimer(ITIMER_REAL, &it, NULL);
continue;
}
/* close(aufd);
close(aucfd);
wmaudio_init();
*/ wmaudio_stop( void );
alarm(2);
continue;
}
else
{
blk->status = WMCDDA_ERROR;
return (-1);
}
alarm(0);
/*
* Mark this spot in the audio stream.
*
* Marks don't always succeed (if the audio buffer is empty
* this call will block forever) so do it asynchronously.
*/
fcntl(aufd, F_SETFL, O_NONBLOCK);
if (write(aufd, rawbuf, 0) < 0)
{
if (errno != EAGAIN)
perror("audio mark");
}
else
qtail = (qtail + 1) % QSIZE;
fcntl(aufd, F_SETFL, 0);
queue[qtail] = *blk;
if (wmaudio_send_status() < 0)
return (-1);
else
return (0);
}
/*
* Get the current audio state.
*/
void
wmaudio_state(struct cdda_block *blk)
{
audio_info_t info;
int balance;
if (ioctl(aucfd, AUDIO_GETINFO, &info) < 0)
perror("AUDIO_GETINFO");
blk->volume = info.play.gain;
blk->balance = (info.play.balance * 255) / AUDIO_RIGHT_BALANCE;
}
/*
** This routine converts from linear to ulaw.
**
** Craig Reese: IDA/Supercomputing Research Center
** Joe Campbell: Department of Defense
** 29 September 1989
**
** References:
** 1) CCITT Recommendation G.711 (very difficult to follow)
** 2) "A New Digital Technique for Implementation of Any
** Continuous PCM Companding Law," Villeret, Michel,
** et al. 1973 IEEE Int. Conf. on Communications, Vol 1,
** 1973, pg. 11.12-11.17
** 3) MIL-STD-188-113,"Interoperability and Performance Standards
** for Analog-to_Digital Conversion Techniques,"
** 17 February 1987
**
** Input: Signed 16 bit linear sample
** Output: 8 bit ulaw sample
*/
#define ZEROTRAP /* turn on the trap as per the MIL-STD */
#define BIAS 0x84 /* define the add-in bias for 16 bit samples */
#define CLIP 32635
unsigned char
linear_to_ulaw( sample )
int sample;
{
static int exp_lut[256] = {0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7};
int sign, exponent, mantissa;
unsigned char ulawbyte;
/* Get the sample into sign-magnitude. */
sign = (sample >> 8) & 0x80; /* set aside the sign */
if ( sign != 0 ) sample = -sample; /* get magnitude */
if ( sample > CLIP ) sample = CLIP; /* clip the magnitude */
/* Convert from 16 bit linear to ulaw. */
sample = sample + BIAS;
exponent = exp_lut[( sample >> 7 ) & 0xFF];
mantissa = ( sample >> ( exponent + 3 ) ) & 0x0F;
ulawbyte = ~ ( sign | ( exponent << 4 ) | mantissa );
#ifdef ZEROTRAP
if ( ulawbyte == 0 ) ulawbyte = 0x02; /* optional CCITT trap */
#endif
return ulawbyte;
}
/*
* Downsample a block of CDDA data, if necessary, for playing out an old-style
* audio device.
*/
long
wmaudio_convert(unsigned char *rawbuf, long buflen, struct cdda_block *blk)
{
short *buf16 = (short *)rawbuf;
int i, j, samples;
int mono_value;
unsigned char *rbend = rawbuf + buflen;
/* Don't do anything if the audio device can take the raw values. */
if (raw_audio)
return (buflen);
for (i = 0; buf16 < (short *)(rbend); i++)
{
/* Downsampling to 8KHz is a little irregular. */
samples = (i & 1) ? ((i % 20) ? 10 : 12) : 12;
/* And unfortunately, we don't always end on a nice boundary. */
if (buf16 + samples > (short *)(rbend))
samples = ((short *)rbend) - buf16;
/*
* No need to average all the values; taking the first one
* is sufficient and less CPU-intensive. But we do need to
* do both channels.
*/
mono_value = (buf16[0] + buf16[1]) / 2;
buf16 += samples;
rawbuf[i] = ulawmap[mono_value];
}
return (i);
}
#endif /* ... && BUILD_CDDA */