tomwalters@0: /*
tomwalters@0:   ptrain.c    generate a pulse train of binary shorts.
tomwalters@0:   --------
tomwalters@0:     Generate samples of a pulse train at a given sample rate.
tomwalters@0:     Specify pulse amplitude and width (in s, ms, or p (sample points) ),
tomwalters@0:     and also the period of the waveform (in s, ms, or p (sample points) ).
tomwalters@0:     The pulse amplitude is the pulse height above the zero level, which is
tomwalters@0:     set by the offset option. The offset is "0" by default so that pulses
tomwalters@0:     of any given amplitude are non-negative by default.
tomwalters@0: 
tomwalters@0:     Output samples in binary shorts for the given waveform duration.
tomwalters@0: 
tomwalters@0:     Non-fixed period pulse trains:
tomwalters@0:     If a filename is given, then the period of the output pulse train is
tomwalters@0:     taken from the file. Binary shorts read from the file are subsequent
tomwalters@0:     periods in samples. Periods are output until the file is empty.
tomwalters@0: 
tomwalters@0: 
tomwalters@0: Examples:
tomwalters@0: 
tomwalters@0: 1. A pulse train with period 100 samples and pulse width 1 sample:
tomwalters@0: 
tomwalters@0: ptrain period=100p width=1p
tomwalters@0: 
tomwalters@0: 2. A pulse train with period 8ms at 20KHz and pulse width 4 samples
tomwalters@0: 
tomwalters@0: ptrain -p8ms -s20000 -w4
tomwalters@0: 
tomwalters@0: 3. A square wave (pulse width = half period) of period 4ms, sampled at 10kHz
tomwalters@0: 
tomwalters@0: ptrain period=4ms width=2ms samplerate=10kHz
tomwalters@0: 
tomwalters@0: 3. A square wave of period 4ms with zero mean value
tomwalters@0: 
tomwalters@0: ptrain period=4ms width=2ms offset=0
tomwalters@0: 
tomwalters@0: */
tomwalters@0: 
tomwalters@0: 
tomwalters@0: #include <stdio.h>
tomwalters@0: #include <math.h>
tomwalters@0: #include "options.h"
tomwalters@0: #include "units.h"
tomwalters@0: #include "strmatch.h"
tomwalters@0: 
tomwalters@0: char applic[]  = "generate a pulse train of binary shorts. " ;
tomwalters@0: char usage[]   = "ptrain [options]" ;
tomwalters@0: 
tomwalters@0: static char *helpstr, *debugstr, *sampstr, *pstr, *astr, *ostr, *wstr, *dstr, *phstr ;
tomwalters@0: 
tomwalters@0: static Options option[] = {
tomwalters@0:     {   "help"      ,   "off"       ,  &helpstr     ,   "help"                     , DEBUG   },
tomwalters@0:     {   "debug"     ,   "off"       ,  &debugstr    ,   "debugging switch"         , DEBUG   },
tomwalters@0:     {   "samplerate",   "20kHz"     ,  &sampstr     ,   "samplerate "              , VAL     },
tomwalters@0:     {   "duration"  ,   "500ms"     ,  &dstr        ,   "duration of waveform"     , VAL     },
tomwalters@0:     {   "period"    ,   "8ms"       ,  &pstr        ,   "period of pulse train"    , VAL     },
tomwalters@0:     {   "amplitude" ,   "1024"      ,  &astr        ,   "pulse amplitude"          , VAL     },
tomwalters@0:     {   "width"     ,   "4p"        ,  &wstr        ,   "pulse width"              , VAL     },
tomwalters@0:     {   "offset"    ,   "0"         ,  &ostr        ,   "dc offset"                , VAL     },
tomwalters@0:     {   "phase"     ,   "0"         ,  &phstr       ,   "phase offset"             , VAL     },
tomwalters@0:    ( char * ) 0 } ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0: main(argc, argv)
tomwalters@0: int   argc ;
tomwalters@0: char *argv[] ;
tomwalters@0: {
tomwalters@0:     FILE   *fp, *fopen() ;
tomwalters@0:     short  a, z = 0;   /* Zero */
tomwalters@0:     int    i, j, samplerate ;
tomwalters@0:     int    T, w, n, phase ;
tomwalters@0: 
tomwalters@0:     i = getopts( option,argc,argv ) ;
tomwalters@0:     if ( !isoff( helpstr ) )
tomwalters@0: 	helpopts3( helpstr, argv[0], applic, usage, option ) ;
tomwalters@0: 
tomwalters@0:     samplerate = to_Hz( sampstr ) ;
tomwalters@0:     T = (int)to_p( pstr, samplerate ) ; /* period */
tomwalters@0:     w = (int)to_p( wstr, samplerate ) ; /* width */
tomwalters@0:     n = to_p( dstr, samplerate ) ;      /* duration in points */
tomwalters@0: 
tomwalters@0:     z = atoi( ostr ) ;      /* zero level set to the dc offset (default 0) */
tomwalters@0:     a = atoi( astr ) + z ;  /* amplitude (pulse height above zero level)   */
tomwalters@0: 
tomwalters@0: 
tomwalters@0:     if ( ( phase = (int)to_p( pstr, samplerate ) ) > 0 ) {   /* initial phase offset */
tomwalters@0: 	for (j=0 ; j<phase ; j++ )
tomwalters@0: 	    fwrite(&z, sizeof(short), 1, stdout);
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     /* Using given arg T to generate fixed periods */
tomwalters@0: 
tomwalters@0:     if ( i == 0 ) {
tomwalters@0: 	for (i=0 ; i<n ;  ) {
tomwalters@0: 	    for (j=0 ; j<w && i<n ; j++, i++)
tomwalters@0: 		fwrite(&a, sizeof(short), 1, stdout);
tomwalters@0: 	    for ( ; j<T && i<n ; j++, i++)
tomwalters@0: 		fwrite(&z, sizeof(short), 1, stdout);
tomwalters@0: 	}
tomwalters@0:     }
tomwalters@0: 
tomwalters@0: 
tomwalters@0:     /* Reading periods T from file argv[argc-i] */
tomwalters@0: 
tomwalters@0:     else {
tomwalters@0: 	if ( ( fp = fopen( argv[argc-i], "r" ) ) == NULL ) {
tomwalters@0: 	    fprintf(stderr,"can't open %s\n", argv[argc-i] );
tomwalters@0: 	    exit(1);
tomwalters@0: 	}
tomwalters@0: 	while ( fread( &T, sizeof(short), 1, fp ) ) {
tomwalters@0: 	    for (j=0 ; j<w ; j++)
tomwalters@0: 		fwrite(&a, sizeof(short), 1, stdout);
tomwalters@0: 	    for ( ; j<T ; j++)
tomwalters@0: 		fwrite(&z, sizeof(short), 1, stdout);
tomwalters@0: 	}
tomwalters@0: 	fclose( fp ) ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0: }