//-------------------------------------------------------------------
//	waveinfo.cpp
//
//	This utility shows format-chunk information in a .wav file.
//
//		    compile using:  $ make waveinfo
//		    execute using:  $ waneinfo <filename>
//
//	References: 
//	"Multimedia Programming Interface and Data Specifications," 
//	IBM Corporation and Microsoft Corporation (1991); note also
//	Microsoft's "New Multimedia Data Types and Data Techniques" 
//	1994 and "Multiple Channel Audio Data and WAVE files" 2001. 
//
//	programmer: ALLAN CRUSE
//	written on: 17 AUG 2005
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for read(), lseek()
#include <string.h>	// for strncpy(), strtok(), strcat()

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

	// attach '.wav' suffix to the filename-argument
	char	filename[ 80 ] = {0};
	strncpy( filename, argv[1], 75 );
	strtok( filename, ". \n\t" );
	strcat( filename, ".wav" );

	// open the '.wav' file and obtain its size (in bytes)
	int	fd = open( filename, O_RDONLY );
	if ( fd < 0 ) { perror( filename ); exit(1); }
	int	filesize = lseek( fd, 0, SEEK_END );
	lseek( fd, 0, SEEK_SET );	
	printf( "\n\tFile is \'%s\' (%d bytes) \n", filename, filesize );
	
	// read and verify the RIFF chunk
	char 	chunk_name[4], chunk_type[4];
	int	chunk_size;
	read( fd, &chunk_name, 4 );
	read( fd, &chunk_size, 4 );
	read( fd, &chunk_type, 4 );
	if ( strncmp( chunk_name, "RIFF", 4 ) )
		{ fprintf( stderr, "not a RIFF file\n" ); exit(1); }
	if ( strncmp( chunk_type, "WAVE", 4 ) )
		{ fprintf( stderr, "not a WAVE file\n" ); exit(1); }

	// find the file's 'format' chunk
	int	morebytes = filesize - 12;
	while ( morebytes > 8 )
		{
		read( fd, &chunk_name, 4 );
		read( fd, &chunk_size, 4 );
		morebytes -= 8;
		if ( strncmp( chunk_name, "fmt ", 4 ) == 0 ) break;
		lseek( fd, chunk_size, SEEK_CUR );
		morebytes -= chunk_size;	
		}
	if ( morebytes < 16 ) 
		{ fprintf( stderr, "format not found\n" ); exit(1); }

	// read the format-chunk's parameters 
	short	formatTag, nChannels, blockAlignmnt, bitsPerSample;
	int	samplesPerSec, avBytesPerSec; 
	read( fd, &formatTag, 2 );
	read( fd, &nChannels, 2 );
	read( fd, &samplesPerSec, 4 );
	read( fd, &avBytesPerSec, 4 );
	read( fd, &blockAlignmnt, 2 );
	read( fd, &bitsPerSample, 2 );

	// display the standard format-chunk parameters
	printf( "\n\tformatTag=%d  ", formatTag );
	printf( "\n\tnChannels=%d  ", nChannels );
	printf( "\n\tsamplesPerSec=%d  ", samplesPerSec );
	printf( "\n\tavBytesPerSec=%d  ", avBytesPerSec );
	printf( "\n\tblockAlignmnt=%d  ", blockAlignmnt );
	printf( "\n\tbitsPerSample=%d  ", bitsPerSample );

	// display additional format-chunk information (if any)
	if ( chunk_size > 16 ) 
		printf( "\n\n\tAdditional format information: " );
	for (int i = 16; i < chunk_size; i++)
		{
		unsigned char 	inch = 0;
		if ( ( i % 16 ) == 0 ) printf( "\n\t" ); 
		read( fd, &inch, 1 );
		printf( "%02X ", inch );
		}
	printf( "\n\n" );
}