mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-09-20 00:55:58 -04:00
113 lines
2.7 KiB
C++
113 lines
2.7 KiB
C++
#pragma once
|
|
//
|
|
// FILE: MultiMap.h
|
|
// AUTHOR: Rob Tillaart
|
|
// VERSION: 0.1.7
|
|
// DATE: 2011-01-26
|
|
// PURPOSE: Arduino library for fast non-linear mapping or interpolation of values
|
|
// URL: https://github.com/RobTillaart/MultiMap
|
|
// URL: http://playground.arduino.cc/Main/MultiMap
|
|
|
|
|
|
|
|
#define MULTIMAP_LIB_VERSION (F("0.1.7"))
|
|
|
|
|
|
#include "Arduino.h"
|
|
|
|
|
|
// note: the in array must have increasing values
|
|
template<typename T>
|
|
T multiMap(T value, T* _in, T* _out, uint8_t size)
|
|
{
|
|
// output is constrained to out array
|
|
if (value <= _in[0]) return _out[0];
|
|
if (value >= _in[size-1]) return _out[size-1];
|
|
|
|
// search right interval
|
|
uint8_t pos = 1; // _in[0] already tested
|
|
while(value > _in[pos]) pos++;
|
|
|
|
// this will handle all exact "points" in the _in array
|
|
if (value == _in[pos]) return _out[pos];
|
|
|
|
// interpolate in the right segment for the rest
|
|
return (value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1]) + _out[pos-1];
|
|
}
|
|
|
|
|
|
// performance optimized version if inputs do not change often
|
|
// e.g. 2 2 2 2 2 3 3 3 3 5 5 5 5 5 5 8 8 8 8 5 5 5 5 5
|
|
// implements a minimal cache of the lastValue.
|
|
//
|
|
// note: the in array must have increasing values
|
|
template<typename T>
|
|
T multiMapCache(T value, T* _in, T* _out, uint8_t size)
|
|
{
|
|
static T lastValue = -1;
|
|
static T cache = -1;
|
|
|
|
if (value == lastValue)
|
|
{
|
|
return cache;
|
|
}
|
|
lastValue = value;
|
|
|
|
// output is constrained to out array
|
|
if (value <= _in[0])
|
|
{
|
|
cache = _out[0];
|
|
}
|
|
else if (value >= _in[size-1])
|
|
{
|
|
cache = _out[size-1];
|
|
}
|
|
else
|
|
{
|
|
// search right interval; index 0 _in[0] already tested
|
|
uint8_t pos = 1;
|
|
while(value > _in[pos]) pos++;
|
|
|
|
// this will handle all exact "points" in the _in array
|
|
if (value == _in[pos])
|
|
{
|
|
cache = _out[pos];
|
|
}
|
|
else
|
|
{
|
|
// interpolate in the right segment for the rest
|
|
cache = (value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1]) + _out[pos-1];
|
|
}
|
|
}
|
|
return cache;
|
|
}
|
|
|
|
|
|
// binary search version, should be faster for size > 10
|
|
// (rule of thumb)
|
|
//
|
|
// note: the in array must have increasing values
|
|
template<typename T>
|
|
T multiMapBS(T value, T* _in, T* _out, uint16_t size)
|
|
{
|
|
// output is constrained to out array
|
|
if (value <= _in[0]) return _out[0];
|
|
if (value >= _in[size-1]) return _out[size-1];
|
|
|
|
// Binary Search
|
|
uint16_t lower = 0;
|
|
uint16_t upper = size - 1;
|
|
while (lower < upper - 1)
|
|
{
|
|
uint16_t mid = (lower + upper) / 2;
|
|
if (value >= _in[mid]) lower = mid;
|
|
else upper = mid;
|
|
}
|
|
|
|
return (value - _in[lower]) * (_out[upper] - _out[lower]) / (_in[upper] - _in[lower]) + _out[lower];
|
|
}
|
|
|
|
|
|
// -- END OF FILE --
|
|
|