diff model/units.c @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/model/units.c	Fri May 20 15:19:45 2011 +0100
@@ -0,0 +1,185 @@
+/*
+    Copyright (c) Applied Psychology Unit, Medical Research Council. 1988, 1989
+    ===========================================================================
+
+    Permission to use, copy, modify, and distribute this software without fee 
+    is hereby granted for research purposes, provided that this copyright 
+    notice appears in all copies and in all supporting documentation, and that 
+    the software is not redistributed for any fee (except for a nominal shipping 
+    charge). Anyone wanting to incorporate all or part of this software in a
+    commercial product must obtain a license from the Medical Research Council.
+
+    The MRC makes no representations about the suitability of this 
+    software for any purpose.  It is provided "as is" without express or implied 
+    warranty.
+ 
+*/
+
+/*
+    units.c
+    =======
+
+
+    Unit conversion routines for APU model.
+
+
+
+    Copyright (c), 1989  The Medical Research Council, Applied Psychology Unit.
+
+
+    Author  : John Holdsworth
+    Written : 22th March, 1989.
+
+    Edited  : Mike Allerhand, 1990.
+
+*/
+
+#ifndef  lint
+static char *sccs_id = "@(#)units.c	1.3 John Holdsworth, Mike Allerhand (MRC-APU) 6/6/91" ;
+#endif
+
+
+
+/*********************** Unit conversion routines ***************************
+*  Values are stored as strings.
+*  Units are specified by the final char:
+*    p          sample points.
+*    s          seconds.
+*    b or B     decibels.
+*    Hz         Hertz.
+*  Unit multipliers are specified by the optional penultimate char:
+*    k  kilo  (scale by one thousand).
+*    d  deci  (scale by one tenth).
+*    c  centi (scale by one hundreth).
+*    m  milli (scale by one thousandth).
+*    u        (scale by one millionth).
+*
+*  Examples:    "10p"     time period of 10 sample points
+*               "10ms"    time period of 10 milliseconds
+*               "10kHz"   frequency of 10 kiloHertz
+*
+*  Conversion routines:
+* units( ch )          Multiplier for unit, (k,d,c,m,u).
+* Freq( str )          String to value (eg: 10, 10Hz, 10kHz).
+* Samples( str )       String to value (num samples) (eg: 10p, 10s, 10ms).
+* Scalar( str )        String to value (scalar number), also converts dB's.
+*
+*  Examples:   Freq("10000")    returns 10000
+*              Freq("10kHz")    returns 10000
+*              Samples("3p")    returns 3
+*              Samples("3ms")   return 30  (when the sample rate is 10kHz).
+*              Samples("3")     like "3ms" (milliseconds is default unit).
+*              Scalar("10.")    returns 10
+*              Scalar( "20dB" ) returns 10
+*
+* See also stitch.h for conversion routines:
+*   ToPoints(type,bytes)  Count in bytes to number of points of given type.
+*   ToBytes(type,points ) Number of points of given type to count in bytes.
+*
+* Cycles( str, cfreq )  This is like Samples( str ), except that it also
+*                       allows `c' (cycles) units. A given number of cycles
+*                       of a particular channel are converted to samples.
+*                       This requires the centre frequency of the channel,
+*                       cfreq = frequencies[chan].
+****************************************************************************/
+
+#include <math.h>
+
+#if defined(THINK_C) || defined(NeXT)
+#include <stdlib.h>
+#endif
+
+#include "units.h"
+#include "formulae.h"
+
+extern char *samplestr ;
+
+static double units( ch )
+char ch ;
+{
+    switch( ch ) {
+	case 'k' :
+	    return ( 1000.    ) ;
+	case 'd' :
+	    return ( 0.1      ) ;
+	case 'c' :
+	    return ( 0.01     ) ;
+	case 'm' :
+	    return ( 0.001    ) ;
+	case 'u' :
+	    return ( 0.000001 ) ;
+
+	default :
+	    return ( 1.       ) ;
+    }
+}
+
+double Freq( str )
+char *str ;
+{
+    char *eptr = str + strlen( str ) ;
+    double f ;
+
+    --eptr ;
+
+    if( *eptr == 'e' )
+	return ( FofErbScale( atof( str ) ) * units( *--eptr ) ) ;
+
+    if( *eptr == 'z' )
+	--eptr ;
+
+    if( *eptr == 'H' || *eptr == 'h' )
+	return ( atof( str ) * units( *--eptr ) ) ;
+
+    return ( atof( str ) * units( *eptr ) ) ;
+}
+
+double Samples( str, samplerate )
+char *str ;
+double samplerate ;
+{
+    char *eptr = str + strlen( str ) ;
+
+    switch( *--eptr ) {
+	case 's' : /* seconds */
+	    return ( atof( str ) * samplerate * units( *--eptr ) ) ;
+	case 'p' : /* points  */
+	    return ( atof( str )              * units( *--eptr ) ) ;
+
+	default: /* default to milliseconds for specification of sample parameters */
+	    return ( atof( str ) * samplerate * units( 'm' ) ) ;
+    }
+}
+
+double Scalar( str )
+char *str ;
+{
+    char *eptr = str + strlen( str ) ;
+
+    if( *--eptr == 'B' || *eptr == 'b' )
+	return ( pow( 10., atof( str ) * units( *--eptr ) / 2. ) ) ;
+    else
+	return ( atof( str ) * units( *eptr ) ) ;
+}
+
+double Cycles( str, cfreq, samplerate )
+char   *str ;
+double  cfreq, samplerate ;  /* centre frequency of a particular channel */
+{
+    char *eptr = str + strlen( str ) ;
+
+    /* Look at last char in the string */
+    switch( *--eptr ) {
+	case 's' : /* seconds */
+	    return ( atof( str ) * samplerate * units( *--eptr ) ) ;
+	case 'p' : /* points  */
+	    return ( atof( str )              * units( *--eptr ) ) ;
+	case 'c' : /* cycles  */
+	    return ( atof( str ) * samplerate / cfreq ) ;
+
+	default:   /* default to milliseconds, 'ms' */
+	    return ( atof( str ) * samplerate * units( 'm' ) ) ;
+
+    }
+}
+