tomwalters@0: /*
tomwalters@0:     cosine.c    generate a cosine window
tomwalters@0:     --------
tomwalters@0: 
tomwalters@0:     1. Hann (or raised cosine) window
tomwalters@0: 
tomwalters@0: 	w[n] = 0.5 [ 1 - cos( TWOPI . n/(N-1) ) ]
tomwalters@0: 
tomwalters@0:     2. Hamming window
tomwalters@0: 
tomwalters@0: 	w[n] = 0.54 - 0.46 cos( TWOPI . n/(N-1) )
tomwalters@0: 
tomwalters@0:     Both windows are defined for 0 <= n <= N-1 and are zero otherwise.
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: #include "sigproc.h"
tomwalters@0: 
tomwalters@0: 
tomwalters@0: char applic[]     = "generate a cosine window." ;
tomwalters@0: 
tomwalters@0: static char *helpstr,  *debugstr, *sampstr,  *hammstr ;
tomwalters@0: static char *scalestr, *typestr,  *sizestr ;
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:     {   "size"      ,   "10ms"      ,  &sizestr     ,   "Size of window"                            , VAL     },
tomwalters@0:     {   "Hamming"   ,   "off"       ,  &hammstr     ,   "Hamming window (default raised cosine)"    , SETFLAG },
tomwalters@0:     {   "scale"     ,   "1000"      ,  &scalestr    ,   "Scale factor for output"                   , VAL     },
tomwalters@0:     {   "type"      ,   "short"     ,  &typestr     ,   "Output datatype (short/float)"             , VAL     },
tomwalters@0:    ( char * ) 0 } ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0: int     samplerate  ;
tomwalters@0: 
tomwalters@0: float  *window ;
tomwalters@0: int     n      ;
tomwalters@0: 
tomwalters@0: short  *buf    ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0: main (argc, argv)
tomwalters@0: int     argc;
tomwalters@0: char  **argv;
tomwalters@0: {
tomwalters@0:     float f ;
tomwalters@0: 
tomwalters@0:     getopts( option,argc,argv ) ;
tomwalters@0:     if ( !isoff( helpstr ) )
tomwalters@0: 	helpopts( helpstr, argv[0], applic, option ) ;
tomwalters@0: 
tomwalters@0:     samplerate = to_Hz( sampstr ) ;
tomwalters@0:     n          = to_p( sizestr, samplerate ) ;
tomwalters@0: 
tomwalters@0:     if ( ison( hammstr ) )
tomwalters@0: 	window = hamming( n ) ;
tomwalters@0: 
tomwalters@0:     else if ( isoff( hammstr ) )
tomwalters@0: 	window = raised_cosine( n ) ;
tomwalters@0: 
tomwalters@0:     else {
tomwalters@0: 	fprintf(stderr,"cosine: unknown window [%s]\n", hammstr) ;
tomwalters@0: 	exit( 1 ) ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     if ( iststr( typestr, "float" ) ) {
tomwalters@0: 	scalar( window, n, atof( scalestr ) ) ;
tomwalters@0: 	fwrite( window, sizeof(float), n, stdout ) ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     else if ( iststr( typestr, "short" ) ) {
tomwalters@0: 	buf = (short *)malloc( n * sizeof(short) ) ;
tomwalters@0: 	if ( ( f = ftos( window, buf, n, atof( scalestr ) ) ) < 1. )
tomwalters@0: 	    fprintf( stderr,"Warning: 16-bit overflow. Try scale factor < %f\n", f ) ;
tomwalters@0: 	fwrite( buf, sizeof(short), n, stdout ) ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     else
tomwalters@0: 	fprintf(stderr,"cosine: unknown datatype [%s]\n", typestr) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: scalar( y, n, scale )
tomwalters@0: float  *y ;
tomwalters@0: int     n ;
tomwalters@0: float   scale ;
tomwalters@0: {
tomwalters@0:     int  i ;
tomwalters@0: 
tomwalters@0:     if ( scale != 1. ) {
tomwalters@0: 	for ( i=0 ; i < n ; i++ )
tomwalters@0: 	    y[i] *= scale ;
tomwalters@0:     }
tomwalters@0: }