IntMap.h

/*
 * IntMap.h
 *
 * Copyright 2012 Tim Barrass.
 *
 * This file is part of Mozzi.
 *
 * Mozzi is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
 *
 */

#ifndef INTMAP_H_
#define INTMAP_H_

/** A faster version of Arduino's map() function.
This uses ints instead of longs internally and does some of the maths at compile time.
*/
class IntMap {

public:
    /** Constructor.
    @param in_min the minimum of the input range.
    @param in_max the maximum of the input range.
    @param out_min the minimum of the output range.
    @param out_max the maximum of the output range.
    */
    IntMap(int in_min, int in_max, int out_min, int out_max)
            : _IN_MIN(in_min),_IN_MAX(in_max),_OUT_MIN(out_min),_OUT_MAX(out_max),
            _MULTIPLIER((256L * (out_max-out_min)) / (in_max-in_min))
    {
        ;
    }

    /** Process the next input value.
    @param n the next integer to process.
    @return the input integer mapped to the output range.
    */
    int operator()(int n) const {
        return (int) (((_MULTIPLIER*(n-_IN_MIN))>>8) + _OUT_MIN);
    }


private:
    const int _IN_MIN, _IN_MAX, _OUT_MIN, _OUT_MAX;
    const long _MULTIPLIER;
};

#endif /* INTMAP_H_ */