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//
// 1997/09/27 21:38:01
//
// --------------------------------------------------------------------------
// ``Open Sound System (OSS)'' / Linux specific audio interface.
// --------------------------------------------------------------------------
#include "audiodrv.h"
const char audioDriver::AUDIODEVICE[] = "/dev/dsp";
audioDriver::audioDriver()
{
// Reset everything.
errorString = "None";
frequency = 0;
channels = 0;
encoding = 0;
precision = 0;
audioHd = (-1);
}
bool audioDriver::IsThere()
{
// Check device availability and write permissions.
return (access(AUDIODEVICE,W_OK)==0);
}
bool audioDriver::Open(udword inFreq, int inPrecision, int inChannels,
int inFragments, int inFragBase)
{
if ((audioHd=open(AUDIODEVICE,O_WRONLY,0)) == (-1))
{
errorString = "AUDIO: Could not open audio device.";
return false;
}
// Transfer input parameters to this object.
// May later be replaced with driver defaults.
frequency = inFreq;
precision = inPrecision;
channels = inChannels;
fragments = inFragments;
fragSizeBase = inFragBase;
// Set sample precision and type of encoding.
int dsp_sampleSize;
if (precision == SIDEMU_16BIT)
dsp_sampleSize = 16;
else // if (precision == SIDEMU_8BIT)
dsp_sampleSize = 8;
if (ioctl(audioHd,SNDCTL_DSP_SAMPLESIZE,&dsp_sampleSize) == (-1))
{
errorString = "AUDIO: Could not set sample size.";
return false;
}
// Verify and accept the sample precision the driver accepted.
if (dsp_sampleSize == 16)
{
precision = SIDEMU_16BIT;
encoding = SIDEMU_SIGNED_PCM;
}
else if (dsp_sampleSize == 8)
{
precision = SIDEMU_8BIT;
encoding = SIDEMU_UNSIGNED_PCM;
}
else
{
errorString = "AUDIO: Could not set sample size.";
return false;
}
// Set mono/stereo.
int dsp_stereo;
if (channels == SIDEMU_STEREO)
dsp_stereo = 1;
else // if (channels == SIDEMU_MONO)
dsp_stereo = 0;
if (ioctl(audioHd,SNDCTL_DSP_STEREO,&dsp_stereo) == (-1))
{
errorString = "AUDIO: Could not set mono/stereo.";
return false;
}
// Verify and accept the number of channels the driver accepted.
if (dsp_stereo == 1)
channels = SIDEMU_STEREO;
else if (dsp_stereo == 0)
channels = SIDEMU_MONO;
else
{
errorString = "AUDIO: Could not set mono/stereo.";
return false;
}
// Set frequency.
int dsp_speed = frequency;
if (ioctl(audioHd,SNDCTL_DSP_SPEED,&dsp_speed) == (-1))
{
errorString = "AUDIO: Could not set frequency.";
return false;
}
// Accept the frequency the driver accepted.
frequency = dsp_speed;
// N fragments of size (2 ^ S) bytes
// NNNNSSSS
// e.g. frag = 0x0004000e;
// fragments should be out of [2,3,..,255]
// fragSizeBase should be out of [7,8,...,17]
// depending on the kernel audio driver buffer size
int frag = (fragments << 16) | fragSizeBase;
ioctl(audioHd,SNDCTL_DSP_SETFRAGMENT,&frag);
ioctl(audioHd,SNDCTL_DSP_GETBLKSIZE,&blockSize);
audio_buf_info myAudInfo;
if (ioctl(audioHd,SNDCTL_DSP_GETOSPACE,&myAudInfo) == (-1))
{
errorString = "AUDIO: Could not get audio_buf_info.";
return false;
}
fragments = myAudInfo.fragstotal;
//cout << "fragsize = " << (int)myAudInfo.fragsize << endl;
//cout << "bytes = " << (int)myAudInfo.bytes << endl;
return true;
}
// Close an opened audio device, free any allocated buffers and
// reset any variables that reflect the current state.
void audioDriver::Close()
{
if (audioHd != (-1))
{
close(audioHd);
audioHd = (-1);
}
}
void audioDriver::Play(ubyte* pBuffer, int bufferSize)
{
if (audioHd != (-1))
{
write(audioHd,pBuffer,bufferSize);
}
}
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