//-------------------------------------------------------------------
//	1second.cpp
//
//	This program captures input from a microphone and stores it 
//	as a Waveform Audio File (.wav) whose filename was provided 
//	by the user as a command-line argument.
//
//		  compile using:  $ make 1second
//		  execute using:  $ 1second <filename>	
//	
//	Online reference: "Audio Programming," 4Front Technologies,
//		<http://www.4front-tech.com/pguide/audio.html>
//
//	programmer: ALLAN CRUSE
//	written on: 25 SEP 2005
//-------------------------------------------------------------------

#include <stdio.h>	// for fprintf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for read(), write(), close() 
#include <string.h>	// for strncmp()
#include <sys/ioctl.h>	// for ioctl()
#include <sys/soundcard.h>	

#define SAMPLE_RATE	48000
#define NUM_SECONDS	1
#define	NUM_SAMPLES	( SAMPLE_RATE * NUM_SECONDS )

char 		devname[] = "/dev/dsp1";
unsigned char	pulsecode[ NUM_SAMPLES ];

int main( int argc, char **argv )
{
	// check for required command-line argument
	if ( argc == 1 )
		{
		fprintf( stderr, "usage: 1second <filename> \n" ); 
		exit(1); 
		}

	// setup the filename for waveform audio data
	char	wavname[ 100 ];
	strncpy( wavname, argv[ 1 ], 95 );
	strtok( wavname, ". \n\t" );
	strcat( wavname, ".wav" );

	// check for a preexistence of this file  
	int	old = open( wavname, O_RDONLY );
	if ( old != -1 ) 
		{ 
		printf( "file \'%s\' exists ", wavname ); 
		printf( "-- overwrite (y,n)? " );
		if ( getchar() == 'y' ) close( old );
		else	exit(1); 
		}

	// define the wave file's audio parameters	
	short	formatTag = 1;
	short	nChannels = 1;
	int	samplesPerSec = SAMPLE_RATE;
	int	avBytesPerSec = samplesPerSec;
	short	blockAlignmnt = 1;
	short	bitsPerSample = 8;

	// wait till the user is ready to begin recording
	printf( "\nPress <ENTER> to begin recording " );
	printf( "for %d seconds ... ", NUM_SECONDS );
	fflush( stdout );
	char	inch[80];
	read( 0, inch, sizeof( inch ) );

	// open the audio device-file and set its capture parameters 
	int	bits = ( bitsPerSample == 8 ) ? AFMT_U8 : AFMT_S16_BE;
	int	chns = ( nChannels == 1 ) ? 1 : 2;
	int	rate = samplesPerSec;
	int	dsp = open( devname, O_RDONLY );
	if ( dsp < 0 ) { perror( devname ); exit(1); }
	if ( ioctl( dsp, SNDCTL_DSP_RESET, NULL ) < 0 )
		{ perror( "ioctl" ); exit(1); }
	if (	  ( ioctl( dsp, SNDCTL_DSP_SETFMT,   &bits ) < 0 )
		||( ioctl( dsp, SNDCTL_DSP_CHANNELS, &chns ) < 0 )
		||( ioctl( dsp, SNDCTL_DSP_SPEED,    &rate ) < 0 )	)
		{ perror( "audio format not not supported\n" ); exit(1); }

	// main loop to capture the waveform audio data	
	printf( "\nOK, ready to begin recording now... \n" );
	unsigned char	*data = pulsecode;
	int	begun = 0;
	int	bytes_to_grab = NUM_SAMPLES / 16;
	int	bytes_to_save = NUM_SAMPLES;
	while ( bytes_to_save > 0 )
		{
		int	nbytes = read( dsp, data, bytes_to_grab );
		if ( !begun )
			{
			int	max = 0;
			for (int i = 0; i < nbytes; i++) 
				if ( data[i] > max ) max = data[i];
			if ( max > 0x99 ) begun = 1;
			else	continue;
			}
		bytes_to_save -= nbytes;
		data += nbytes;
		}
	close( dsp );

	// open the wave file for writing 
	int	wav = open( wavname, O_WRONLY | O_CREAT | O_TRUNC, 0666 );
	if ( wav < 0 ) { perror( wavname ); exit(1); }


	// write the RIFF chunk
	int	dataChunkSize = NUM_SAMPLES;
	int	fmt_ChunkSize = 16;
	int	riffChunkSize = 4 + (8 + fmt_ChunkSize) +(8 + dataChunkSize);
	write( wav, "RIFF", 4 );
	write( wav, &riffChunkSize, 4 );
	write( wav, "WAVE", 4 );

	// write the FORMAT chunk
	write( wav, "fmt ", 4 );
	write( wav, &fmt_ChunkSize, 4 );
	write( wav, &formatTag, 2 );
	write( wav, &nChannels, 2 );
	write( wav, &samplesPerSec, 4 );
	write( wav, &avBytesPerSec, 4 );
	write( wav, &blockAlignmnt, 2 );
	write( wav, &bitsPerSample, 2 );

	// write the DATA chunk
	write( wav, "data", 4 );
	write( wav, &dataChunkSize, 4 );
	data = pulsecode;
	bytes_to_save = dataChunkSize;
	while ( bytes_to_save > 0 )
		{
		int	nbytes = write( wav, data, bytes_to_save );
		bytes_to_save -= nbytes;
		data += nbytes;
		}	
	close( wav );
	printf( "done\n\n" );
}