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/* this file is a part of amp software, (C) tomislav uzelac 1996,1997
Origional code by: Lutz Vieweg
Modified by:
* Andrew Richards - moved code from audio.c
*/
#include <sys/audio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/lock.h>
#include <unistd.h>
#include <stdio.h>
#include "audioIO.h"
/* declare these static to effectively isolate the audio device */
static int audio_fd;
/* audioOpen() */
/* should open the audio device, perform any special initialization */
/* Set the frequency, no of channels and volume. Volume is only set if */
/* it is not -1 */
void audioOpen() {
if ((audio_fd = open("/dev/audio",O_RDWR))==-1)
die(" unable to open the audio device\n");
DB(audio, msg("Audio device opened on %d\n",audio_fd); )
}
void
audioInit(int sampleSize,int frequency, int stereo)
{
int flags;
int failed = 0;
int volume=100;
if ((flags = fcntl (audio_fd, F_GETFL, 0)) < 0) {
die("unable to set non-blocking mode for /dev/audio\n");
}
flags |= O_NDELAY;
if (fcntl (audio_fd, F_SETFL, flags) < 0) {
die("unable to set non-blocking mode for /dev/audio\n");
}
if ( ioctl(audio_fd, AUDIO_SET_DATA_FORMAT, AUDIO_FORMAT_LINEAR16BIT) < 0 ||
ioctl(audio_fd, AUDIO_SET_CHANNELS, stereo ? 2 : 1) < 0 ||
ioctl(audio_fd, AUDIO_SET_OUTPUT, AUDIO_OUT_SPEAKER | AUDIO_OUT_HEADPHONE
| AUDIO_OUT_LINE) < 0 ||
ioctl(audio_fd, AUDIO_SET_SAMPLE_RATE, frequency) < 0) {
failed = -1;
}
if (volume != -1) {
struct audio_describe description;
struct audio_gains gains;
float fvolume = (float)volume / 100.0f;
if (ioctl(audio_fd, AUDIO_DESCRIBE, &description)) {
failed = -1;
}
if (ioctl (audio_fd, AUDIO_GET_GAINS, &gains)) {
failed = -1;
}
gains.transmit_gain = (int)((float)description.min_transmit_gain +
(float)(description.max_transmit_gain
- description.min_transmit_gain)
* fvolume);
/* gains.monitor_gain = description.min_monitor_gain; */ /* don't monitor ! */
if (ioctl (audio_fd, AUDIO_SET_GAINS, &gains)) {
failed = -1;
}
}
if (ioctl(audio_fd, AUDIO_SET_TXBUFSIZE, 4096 * 8)) {
failed = -1;
}
if (failed)
die(" unable to setup /dev/audio\n");
}
/* audioSetVolume - only code this if your system can change the volume while */
/* playing. sets the output volume 0-100 */
void
audioSetVolume(int volume)
{
struct audio_describe description;
struct audio_gains gains;
int failed = 0;
float fvolume = ((float)volume) / 100.0f;
if (ioctl(audio_fd, AUDIO_DESCRIBE, &description)) {
failed = -1;
}
if (ioctl (audio_fd, AUDIO_GET_GAINS, &gains)) {
failed = -1;
}
gains.transmit_gain = (int)((float)description.min_transmit_gain +
(float)(description.max_transmit_gain
- description.min_transmit_gain)
* fvolume);
if (ioctl (audio_fd, AUDIO_SET_GAINS, &gains)) {
failed = -1;
}
/* could evaluate "failed" here - but who cares? */
DB(audio, msg("volume set to %d%%\n",volume); )
}
/* audioFlush() */
/* should flush the audio device */
inline void
audioFlush()
{
DB(audio, msg("audio: flush %d\n",audio_fd) );
}
/* audioClose() */
/* should close the audio device and perform any special shutdown */
void
audioClose()
{
close(audio_fd);
DB(audio, msg("audio: closed %d\n",audio_fd) );
}
/* audioWrite */
/* writes count bytes from buffer to the audio device */
/* returns the number of bytes actually written */
int audioWrite(char *buffer, int count)
{
DB(audio, msg("audio: Writing %d bytes to audio descriptor %d\n",count,getAudioFd()) );
return(write(audio_fd,buffer,count));
}
/* Let buffer.c have the audio descriptor so it can select on it. This means */
/* that the program is dependent on an file descriptor to work. Should really */
/* move the select's etc (with inlines of course) in here so that this is the */
/* ONLY file which has hardware dependent audio stuff in it */
int
getAudioFd()
{
return(audio_fd);
}
/*
Try to set the priority of this process to a value which
allows us to play without buffering, thus saving memory
and avoiding cache-misses.
If we cannot get any priority high enough to allow for
undisturbed replay (because we don't have sufficient
privilege), return a zero, otherwise, return a one.
*/
int audioSetPriority(void) {
/* try to lock process in physical memory, just ignore if this fails */
plock(PROCSHLIBLOCK);
/* try to set a realtime-priority of 64 */
if (-1 != rtprio(0, 64)) {
DB(audio, msg("using real-time priority\n"); )
return 1;
}
/* try to set a nice-level of -20 */
if (-1 != nice(-20)) {
DB(audio, msg("using nice-level -20\n"); )
return 1;
}
DB(audio, msg("using buffered output\n"); )
return 0; /* need to use a buffer */
}
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