mirror of
https://github.com/RobTillaart/Arduino.git
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171 lines
3.7 KiB
C++
171 lines
3.7 KiB
C++
//
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// FILE: DistanceTable.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.2.1
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// PURPOSE: Arduino library to store a symmetrical distance table in less memory
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// URL: https://github.com/RobTillaart/DistanceTable
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// HISTORY
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// 0.1.00 initial version
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// 0.1.01 refactor
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// 0.1.2 fix overflow; add some error detection; revert float to float to memory
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// 0.1.3 2017-07-27 Fix issue #33
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// 0.1.4 2019-01-10 add size()
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// 0.1.5 2020-06-07 fix library.json, minor edits
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// 0.1.6 2020-12-20 arduino-ci + unit test
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// 0.2.0 2021-01-19 refactor
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// properly named functions,
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// add setAll(), minimum(), maximum() and count()
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// 0.2.1 2021-10-26 update build-CI, update readme.md
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// default value in constructor
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#include "DistanceTable.h"
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DistanceTable::DistanceTable(uint8_t dimension, float value)
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{
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// ATMEL 328 has ~2000 bytes RAM,
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// so roughly 30X30 = 900 floats(4Bytes) => 1740 bytes is max feasible
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_dimension = 0;
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_elements = 0;
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if (dimension < 2) return;
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_dimension = dimension;
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_elements = _dimension;
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_elements *= ((_dimension - 1) / 2);
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_distanceTable = (float *) malloc(_elements * sizeof(float));
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if (_distanceTable == NULL)
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{
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_dimension = 0;
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_elements = 0;
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}
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setAll(value);
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}
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DistanceTable::~DistanceTable()
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{
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if (_distanceTable != NULL)
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{
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free(_distanceTable);
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}
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}
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void DistanceTable::setAll(float value)
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{
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for (uint16_t index = 0; index < _elements; index++)
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{
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_distanceTable[index] = value;
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}
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};
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void DistanceTable::set(uint8_t x, uint8_t y, float value )
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{
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if ( x == y ) return;
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// comment next line to skip range check (squeeze performance)
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if ( (x >= _dimension) || (y >= _dimension)) return;
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if ( x < y )
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{
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uint8_t t = x; x = y; y = t; // swap
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}
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// prevent overflow by moving to 16 bit
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uint16_t index = x;
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index = (index * (index - 1)) / 2 + y;
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_distanceTable[index] = value;
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};
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float DistanceTable::get (uint8_t x, uint8_t y)
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{
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if ( x == y ) return 0.0; // TODO even true when x and y are out of range??
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// comment next line to skip range check (squeeze performance)
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if ( (x >= _dimension) || (y >= _dimension)) return -1; // NAN ?
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if ( x < y )
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{
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uint8_t t = x; x = y; y = t;
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}
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uint16_t index = x;
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index = (index * (index-1))/2 + y;
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return _distanceTable[index];
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};
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// triangular dump
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void DistanceTable::dump(Print * stream)
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{
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stream->println();
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uint16_t index = 0;
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for (uint8_t i = 0; i < _dimension - 1; i++)
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{
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for (uint8_t j = 0; j <= i; j++)
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{
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stream->print(_distanceTable[index++]);
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stream->print("\t");
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}
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stream->println();
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}
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stream->println();
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};
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float DistanceTable::minimum(uint8_t &x, uint8_t &y)
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{
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float mi = _distanceTable[0];
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for (uint8_t xx = 1; xx < _dimension; xx++)
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{
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uint16_t index = (xx * (xx - 1))/2;
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for (uint8_t yy = 0; yy < xx; yy++)
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{
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float value = _distanceTable[index + yy];
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if (value < mi)
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{
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mi = value;
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x = xx;
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y = yy;
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}
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}
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}
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return mi;
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}
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float DistanceTable::maximum(uint8_t &x, uint8_t &y)
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{
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float ma = _distanceTable[0];
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for (uint8_t xx = 1; xx < _dimension; xx++)
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{
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uint16_t index = (xx * (xx - 1))/2;
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for (uint8_t yy = 0; yy < xx; yy++)
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{
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float value = _distanceTable[index + yy];
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if (value > ma)
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{
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ma = value;
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x = xx;
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y = yy;
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}
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}
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}
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return ma;
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}
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uint16_t DistanceTable::count(float value, float epsilon)
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{
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uint16_t cnt = 0;
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for (uint16_t index = 0; index < _elements; index++)
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{
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if (abs (_distanceTable[index] - value) < epsilon) cnt++;
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}
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return cnt;
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}
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// --- END OF FILE ---
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