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/*
* Purpose: A simple demonstration of
* Copyright (C) 4Front Technologies, 2007. All rights reserved.
*
* Description:
* This program is seriously broken. It's only purpose is to fail so that
* the !nlink SNDCTL_DSP_GETERROR} ioctl call can be tested. Otherwise this
* program is based on the {!nlink singen.c} program.
*
* However this program demonstrates how SNDCTL_DSP_GETERROR can be used in
* applications.
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <soundcard.h>
int fd_out;
static int
open_audio_device (char *name, int mode)
{
int tmp, fd;
int sample_rate;
if ((fd = open (name, mode, 0)) == -1)
{
perror (name);
exit (-1);
}
/*
* Setup the device. Note that it's important to set the
* sample format, number of channels and sample rate exactly in this order.
* Some devices depend on the order.
*/
/*
* Set the sample format
*/
tmp = AFMT_S16_NE; /* Native 16 bits */
if (ioctl (fd, SNDCTL_DSP_SETFMT, &tmp) == -1)
{
perror ("SNDCTL_DSP_SETFMT");
exit (-1);
}
if (tmp != AFMT_S16_NE)
{
fprintf (stderr,
"The device doesn't support the 16 bit sample format.\n");
exit (-1);
}
/*
* Set the number of channels
*/
tmp = 1;
if (ioctl (fd, SNDCTL_DSP_CHANNELS, &tmp) == -1)
{
perror ("SNDCTL_DSP_CHANNELS");
exit (-1);
}
if (tmp != 1)
{
fprintf (stderr, "The device doesn't support mono mode.\n");
exit (-1);
}
/*
* Set the sample rate
*/
sample_rate = 48000;
if (ioctl (fd, SNDCTL_DSP_SPEED, &sample_rate) == -1)
{
perror ("SNDCTL_DSP_SPEED");
exit (-1);
}
/*
* No need for error checking because we will automatically adjust the
* signal based on the actual sample rate. However most application must
* check the value of sample_rate and compare it to the requested rate.
*
* Small differences between the rates (10% or less) are normal and the
* applications should usually tolerate them. However larger differences may
* cause annoying pitch problems (Mickey Mouse).
*/
return fd;
}
int
main (int argc, char *argv[])
{
char *name_out = "/dev/dsp";
int tmp;
audio_errinfo ei;
audio_buf_info bi;
if (argc > 1)
name_out = argv[1];
fd_out = open_audio_device (name_out, O_WRONLY);
/*
* Cause an intentional error by using wrong parameter to SNDCTL_DSP_STEREO
* which expects 0 or 1. Don't do error checking in this case because
* we would like to see two errors reported.
*/
tmp = 2;
ioctl (fd_out, SNDCTL_DSP_STEREO, &tmp);
/*
* Cause an intentional failure by calling {!nlink SNDCTL_DSP_GETISPACE}
* which is not permitted on write-only devices.
*/
if (ioctl (fd_out, SNDCTL_DSP_GETISPACE, &bi) == -1)
{
perror ("SNDCTL_DSP_GETISPACE"); /* Report the "primary" error first */
/*
* Next show the explanation to the user.
*/
fprintf (stderr,
"Audio error: Cannot obtain recorded byte count from the device.\n");
fprintf (stderr, "\n");
/*
* Next call {!nlink SNDCTL_DSP_GETERROR} to see if there is
* any additional info available.
*/
if (ioctl (fd_out, SNDCTL_DSP_GETERROR, &ei) != -1)
{
if (ei.play_errorcount > 0 && ei.play_lasterror != 0)
fprintf (stderr, "%d OSS play event(s), last=%05d:%d\n",
ei.play_errorcount, ei.play_lasterror,
ei.play_errorparm);
if (ei.rec_errorcount > 0 && ei.rec_lasterror != 0)
fprintf (stderr, "%d OSS rec event(s), last=%05d:%d\n",
ei.rec_errorcount, ei.rec_lasterror, ei.rec_errorparm);
}
}
else
fprintf (stderr, "SNDCTL_DSP_GETISPACE didn't fail as expected.\n");
exit (0);
}
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