lbajardsilogic@0: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
lbajardsilogic@0: 
lbajardsilogic@0: /*
lbajardsilogic@0:     Sonic Visualiser
lbajardsilogic@0:     An audio file viewer and annotation editor.
lbajardsilogic@0:     Centre for Digital Music, Queen Mary, University of London.
lbajardsilogic@0:     This file copyright 2006 Chris Cannam.
lbajardsilogic@0:     
lbajardsilogic@0:     This program is free software; you can redistribute it and/or
lbajardsilogic@0:     modify it under the terms of the GNU General Public License as
lbajardsilogic@0:     published by the Free Software Foundation; either version 2 of the
lbajardsilogic@0:     License, or (at your option) any later version.  See the file
lbajardsilogic@0:     COPYING included with this distribution for more information.
lbajardsilogic@0: */
lbajardsilogic@0: 
lbajardsilogic@0: #include "LogRange.h"
lbajardsilogic@0: 
lbajardsilogic@0: #include <algorithm>
lbajardsilogic@0: #include <cmath>
lbajardsilogic@0: 
lbajardsilogic@0: void
lbajardsilogic@0: LogRange::mapRange(float &min, float &max, float logthresh)
lbajardsilogic@0: {
lbajardsilogic@0:     if (min > max) std::swap(min, max);
lbajardsilogic@0:     if (max == min) max = min + 1;
lbajardsilogic@0: 
lbajardsilogic@0:     if (min >= 0.f) {
lbajardsilogic@0: 
lbajardsilogic@0:         max = log10f(max); // we know max != 0
lbajardsilogic@0: 
lbajardsilogic@0:         if (min == 0.f) min = std::min(logthresh, max);
lbajardsilogic@0:         else min = log10f(min);
lbajardsilogic@0: 
lbajardsilogic@0:     } else if (max <= 0.f) {
lbajardsilogic@0:         
lbajardsilogic@0:         min = log10f(-min); // we know min != 0
lbajardsilogic@0:         
lbajardsilogic@0:         if (max == 0.f) max = std::min(logthresh, min);
lbajardsilogic@0:         else max = log10f(-max);
lbajardsilogic@0:         
lbajardsilogic@0:         std::swap(min, max);
lbajardsilogic@0:         
lbajardsilogic@0:     } else {
lbajardsilogic@0:         
lbajardsilogic@0:         // min < 0 and max > 0
lbajardsilogic@0:         
lbajardsilogic@0:         max = log10f(std::max(max, -min));
lbajardsilogic@0:         min = std::min(logthresh, max);
lbajardsilogic@0:     }
lbajardsilogic@0: 
lbajardsilogic@0:     if (min == max) min = max - 1;
lbajardsilogic@0: }        
lbajardsilogic@0: 
lbajardsilogic@0: float
lbajardsilogic@0: LogRange::map(float value, float thresh)
lbajardsilogic@0: {
lbajardsilogic@0:     if (value == 0.f) return thresh;
lbajardsilogic@0:     return log10f(fabsf(value));
lbajardsilogic@0: }
lbajardsilogic@0: