radio/src/bitfield.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  * This file is based on work published at http://www.coranac.com/documents/working-with-bits-and-bitfields
  10  *
  11  * License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License version 2 as
  15  * published by the Free Software Foundation.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  */
  22
  23 #ifndef BITFIELD_H
  24 #define BITFIELD_H
  25
  26 #include <inttypes.h>
  27
  28 // A set of bitfield handling macros
  29
  30 template <typename T>
  31 inline T bfBit(uint8_t n)
  32 {
  33   return T(1) << n;
  34 }
  35
  36 #define BFBIT_SET(y, mask)        ( y |=  (mask) )
  37 #define BFBIT_CLEAR(y, mask)      ( y &= ~(mask) )
  38 #define BFBIT_FLIP(y, mask)       ( y ^=  (mask) )
  39 #define BF_SINGLE_BIT_SET(y, i)    BFBIT_SET(y, bfBit(i))
  40
  41 //! Create a bitmask of length 'len'.
  42 template <typename T>
  43 inline T bfBitmask(uint8_t len)
  44 {
  45   return bfBit<T>(len) - 1;
  46 }
  47
  48 //! Create a bitfield mask of length 'len' starting at bit 'start'.
  49 template <typename T>
  50 inline T bfMask(uint8_t start, uint8_t len)
  51 {
  52   return bfBitmask<T>(len) << start;
  53 }
  54
  55 //! Prepare a bitmask for insertion or combining.
  56 template <typename T>
  57 inline T bfPrep(T x, uint8_t start, uint8_t len)
  58 {
  59   return (x & bfBitmask<T>(len)) << start;
  60 }
  61
  62 //! Extract a bitfield of length 'len' starting at bit 'start' from  'y'.
  63 template <typename T>
  64 inline T bfGet(T y, uint8_t start, uint8_t len)
  65 {
  66   return ((y)>>(start)) & bfBitmask<T>(len);
  67 }
  68
  69 //! Insert 'len' bits of 'x 'into 'y', starting at bit 'start' from  'y'.
  70 template <class T>
  71 inline T bfSet(T to, T from, uint8_t start, uint8_t len)
  72 {
  73   return (to & ~bfMask<T>(start, len)) | bfPrep<T>(from, start, len);
  74 }
  75
  76 template <class T>
  77 inline T bfBitGet(T y, T mask)
  78 {
  79   return (y & mask);
  80 }
  81
  82 template <class T>
  83 inline T bfSingleBitGet(T y, uint8_t i)
  84 {
  85   return bfBitGet(y, bfBit<T>(i));
  86 }
  87
  88 #endif //BITFIELD_H