oss.c

/*

	Audio Overload SDK

	Copyright (c) 2007, R. Belmont and Richard Bannister.

	All rights reserved.

	Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

	* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
	* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
	* Neither the names of R. Belmont and Richard Bannister nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
	LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
	NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
	SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/soundcard.h>

#include "ao.h"
#include "m1sdr.h"

#define VALGRIND 	(0)

#define NUM_FRAGS_BROKEN    (8)
#define NUM_FRAGS_NORMAL    (4)
static INT32 num_frags;
#define OSS_FRAGMENT (0x000D | (num_frags<<16));  // 16k fragments (2 * 2^14).

// local variables
static INT32 is_broken_driver;
int nDSoundSegLen = 0;
int oss_nw = 0;

int audiofd;

static stereo_sample_t samples[44100];


// set # of samples per update

void m1sdr_SetSamplesPerTick(UINT32 spf)
{
	nDSoundSegLen = spf;
}

// m1sdr_Update - timer callback routine: runs sequencer and mixes sound

void m1sdr_Update(void)
{
	if (!hw_present) return;

	if (m1sdr_Callback)
	{
		m1sdr_Callback(nDSoundSegLen, samples);
	}
}
// checks the play position to see if we should trigger another update

m1sdr_ret_t m1sdr_TimeCheck(void)
{
	#if VALGRIND
	m1sdr_Update();
	#else
	audio_buf_info info;

	ioctl(audiofd, SNDCTL_DSP_GETOSPACE, &info);

	if (oss_nw)
	{
		int err;

		m1sdr_Update();

		// output the generated samples
		err = write(audiofd, samples, nDSoundSegLen * 4);
		if (err == -1)
		{
			perror("write\n");
		}
	}
	else
	{
		while (info.bytes >= (nDSoundSegLen * 4))
		{
			m1sdr_Update();

			// output the generated samples
			write(audiofd, samples, nDSoundSegLen * 4);

			ioctl(audiofd, SNDCTL_DSP_GETOSPACE, &info);
		}
	}

	#endif
	return M1SDR_WAIT;
}

void m1sdr_PrintDevices(void)
{
}

// m1sdr_Init - inits the output device and our global state

INT16 m1sdr_Init(char *device, int sample_rate)
{
	int format, stereo, rate, fsize;

	hw_present = 0;

	nDSoundSegLen = sample_rate / 60;

	memset(samples, 0, sizeof(samples));	// zero out samples

	audiofd = open("/dev/dsp", O_WRONLY, 0);
	if (audiofd == -1)
	{
		perror("/dev/dsp");

		audiofd = open("/dev/dsp1", O_WRONLY, 0);

		if (audiofd == -1)
		{
			perror("/dev/dsp1");
			return(0);
		}
	}

	// reset things
	ioctl(audiofd, SNDCTL_DSP_RESET, 0);

	is_broken_driver = 0;
	num_frags = NUM_FRAGS_NORMAL;

	// set the buffer size we want
	fsize = OSS_FRAGMENT;
	if (ioctl(audiofd, SNDCTL_DSP_SETFRAGMENT, &fsize) == - 1)
	{
		perror("SNDCTL_DSP_SETFRAGMENT");
		return(0);
	}

	// set 16-bit output
	format = AFMT_S16_NE;	// 16 bit signed "native"-endian
	if (ioctl(audiofd, SNDCTL_DSP_SETFMT, &format) == - 1)
	{
		perror("SNDCTL_DSP_SETFMT");
		return(0);
	}

	// now set stereo
	stereo = 1;
	if (ioctl(audiofd, SNDCTL_DSP_STEREO, &stereo) == - 1)
	{
		perror("SNDCTL_DSP_STEREO");
		return(0);
	}

	// and the sample rate
	rate = sample_rate;
	if (ioctl(audiofd, SNDCTL_DSP_SPEED, &rate) == - 1)
	{
		perror("SNDCTL_DSP_SPEED");
		return(0);
	}

	// and make sure that did what we wanted
	ioctl(audiofd, SNDCTL_DSP_GETBLKSIZE, &fsize);
	//printf("Fragment size: %d\n", fsize);

	hw_present = 1;

	return (1);
}

void m1sdr_Exit(void)
{
	if (!hw_present) return;

	close(audiofd);
}

// unused stubs for this driver, but the Win32 driver needs them
void m1sdr_PlayStart(void)
{
}

void m1sdr_PlayStop(void)
{
}

void m1sdr_FlushAudio(void)
{
	memset(samples, 0, nDSoundSegLen * 4);
	write(audiofd, samples, nDSoundSegLen * 4);
	write(audiofd, samples, nDSoundSegLen * 4);
}

void m1sdr_SetNoWait(int nw)
{
	oss_nw = nw;
}