MMDVMHost-Private/RSSIInterpolator.cpp

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/*
* Copyright (C) 2016 by Jonathan Naylor G4KLX
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "RSSIInterpolator.h"
#include "Log.h"
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
CRSSIInterpolator::CRSSIInterpolator() :
m_map()
{
}
CRSSIInterpolator::~CRSSIInterpolator()
{
m_map.clear();
}
bool CRSSIInterpolator::load(const std::string& filename)
{
FILE* fp = ::fopen(filename.c_str(), "rt");
if (fp == NULL) {
LogWarning("Cannot open the RSSI data file - %s", filename.c_str());
return false;
}
char buffer[100U];
while (::fgets(buffer, 100, fp) != NULL) {
if (buffer[0U] == '#')
continue;
char* p1 = ::strtok(buffer, " \t\r\n");
char* p2 = ::strtok(NULL, " \t\r\n");
if (p1 != NULL && p2 != NULL) {
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uint16_t raw = uint16_t(::atoi(p1));
int rssi = ::atoi(p2);
m_map.insert(std::pair<uint16_t, int>(raw, rssi));
}
}
::fclose(fp);
LogInfo("Loaded %u RSSI data mapping points from %s", m_map.size(), filename.c_str());
return true;
}
int CRSSIInterpolator::interpolate(uint16_t val) const
{
if (m_map.empty())
return 0;
std::map<uint16_t, int>::const_iterator it = m_map.lower_bound(val);
if (it == m_map.end())
return m_map.rbegin()->second;
if (it == m_map.begin())
return it->second;
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uint16_t x2 = it->first;
int y2 = it->second;
--it;
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uint16_t x1 = it->first;
int y1 = it->second;
float p = float(val - x1) / float(x2 - x1);
return int((1.0F - p) * float(y1) + p * float(y2));
}