common/parity.h

   1 //-----------------------------------------------------------------------------
   2 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
   3 // at your option, any later version. See the LICENSE.txt file for the text of
   4 // the license.
   5 //-----------------------------------------------------------------------------
   6 // Parity functions
   7 //-----------------------------------------------------------------------------
   8
   9 // all functions defined in header file by purpose. Allows compiler optimizations.
  10
  11 #ifndef __PARITY_H
  12 #define __PARITY_H
  13
  14 #include "common.h"
  15
  16 extern const uint8_t OddByteParity[256];
  17
  18 static inline uint8_t oddparity8(const uint8_t x) {
  19     return OddByteParity[x];
  20 }
  21
  22 static inline uint8_t evenparity8(const uint8_t x) {
  23     return !OddByteParity[x];
  24 }
  25
  26 static inline uint8_t evenparity32(uint32_t x) {
  27 #if !defined __GNUC__
  28     x ^= x >> 16;
  29     x ^= x >> 8;
  30     return evenparity8(x);
  31 #else
  32     return (__builtin_parity(x) & 0xFF);
  33 #endif
  34 }
  35
  36 static inline uint8_t oddparity32(uint32_t x) {
  37 #if !defined __GNUC__
  38     x ^= x >> 16;
  39     x ^= x >> 8;
  40     return oddparity8(x);
  41 #else
  42     return !__builtin_parity(x);
  43 #endif
  44 }
  45
  46 #endif /* __PARITY_H */