src/RadioFrequency.hpp

   1 /*
   2 Copyright_License {
   3
   4   XCSoar Glide Computer - http://www.xcsoar.org/
   5   Copyright (C) 2000-2013 The XCSoar Project
   6   A detailed list of copyright holders can be found in the file "AUTHORS".
   7
   8   This program is free software; you can redistribute it and/or
   9   modify it under the terms of the GNU General Public License
  10   as published by the Free Software Foundation; either version 2
  11   of the License, or (at your option) any later version.
  12
  13   This program is distributed in the hope that it will be useful,
  14   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16   GNU General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with this program; if not, write to the Free Software
  20   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 }
  22 */
  23
  24 #ifndef XCSOAR_RADIO_FREQUENCY_HPP
  25 #define XCSOAR_RADIO_FREQUENCY_HPP
  26
  27 #include "Compiler.h"
  28
  29 #include <assert.h>
  30 #include <stdint.h>
  31 #include <stddef.h>
  32 #include <tchar.h>
  33
  34 /**
  35  * This class tores a VHF radio frequency.
  36  */
  37 class RadioFrequency {
  38   static constexpr unsigned BASE_KHZ = 100000;
  39   static constexpr unsigned MAX_KHZ = BASE_KHZ + 50000;
  40
  41   /**
  42    * The radio frequency in kilohertz minus 100 MHz.
  43    */
  44   uint16_t value;
  45
  46   constexpr RadioFrequency(unsigned _value):value(_value) {}
  47
  48 public:
  49   /**
  50    * Uninitialized.
  51    */
  52   RadioFrequency() = default;
  53
  54   /**
  55    * Construct an empty instance.  Its IsDefined() method will return
  56    * false.
  57    */
  58   static constexpr RadioFrequency Null() {
  59     return { 0 };
  60   }
  61
  62   bool IsDefined() const {
  63     return value != 0;
  64   }
  65
  66   /**
  67    * Set this object to "undefined".
  68    */
  69   void Clear() {
  70     value = 0;
  71   }
  72
  73   unsigned GetKiloHertz() const {
  74     assert(IsDefined());
  75
  76     return BASE_KHZ + value;
  77   }
  78
  79   void SetKiloHertz(unsigned khz) {
  80     value = khz >= BASE_KHZ && khz < MAX_KHZ
  81       ? (khz - BASE_KHZ)
  82       : 0;
  83   }
  84
  85   TCHAR *Format(TCHAR *buffer, size_t max_size) const;
  86
  87   gcc_pure
  88   static RadioFrequency Parse(const TCHAR *p);
  89 };
  90
  91 #endif