radio/src/fifo.h

   1 /*
   2  * Copyright (C) OpenTX
   3  *
   4  * Based on code named
   5  *   th9x - http://code.google.com/p/th9x
   6  *   er9x - http://code.google.com/p/er9x
   7  *   gruvin9x - http://code.google.com/p/gruvin9x
   8  *
   9  * License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  */
  20
  21 #ifndef _FIFO_H_
  22 #define _FIFO_H_
  23
  24 template <class T, int N>
  25 class Fifo
  26 {
  27   static_assert((N > 1) & !(N & (N - 1)), "Fifo size must be a power of two!");
  28
  29   public:
  30     Fifo():
  31       widx(0),
  32       ridx(0)
  33     {
  34     }
  35
  36     void clear()
  37     {
  38       widx = ridx = 0;
  39     }
  40
  41     void push(T element)
  42     {
  43       uint32_t next = (widx+1) & (N-1);
  44       if (next != ridx) {
  45         fifo[widx] = element;
  46         widx = next;
  47       }
  48     }
  49
  50     bool pop(T & element)
  51     {
  52       if (isEmpty()) {
  53         return false;
  54       }
  55       else {
  56         element = fifo[ridx];
  57         ridx = (ridx+1) & (N-1);
  58         return true;
  59       }
  60     }
  61
  62     bool isEmpty() const
  63     {
  64       return (ridx == widx);
  65     }
  66
  67     bool isFull()
  68     {
  69       uint32_t next = (widx+1) & (N-1);
  70       return (next == ridx);
  71     }
  72
  73     void flush()
  74     {
  75       while (!isEmpty()) {};
  76     }
  77
  78     uint32_t size() const
  79     {
  80       return (N + widx - ridx) & (N-1);
  81     }
  82
  83     uint32_t hasSpace(uint32_t n) const
  84     {
  85       return (N > (size() + n));
  86     }
  87
  88     bool probe(T & element) const
  89     {
  90       if (isEmpty()) {
  91         return false;
  92       }
  93       else {
  94         element = fifo[ridx];
  95         return true;
  96       }
  97     }
  98
  99   protected:
 100     T fifo[N];
 101     volatile uint32_t widx;
 102     volatile uint32_t ridx;
 103 };
 104
 105 #endif // _FIFO_H_