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
  19 static inline bool oddparity8(const uint8_t x) {
  20     return OddByteParity[x];
  21 }
  22
  23
  24 static inline bool evenparity8(const uint8_t x) {
  25     return !OddByteParity[x];
  26 }
  27
  28
  29 static inline bool evenparity32(uint32_t x) {
  30 #if !defined __GNUC__
  31     x ^= x >> 16;
  32     x ^= x >> 8;
  33     return evenparity8(x);
  34 #else
  35     return __builtin_parity(x);
  36 #endif
  37 }
  38
  39
  40 static inline bool oddparity32(uint32_t x) {
  41 #if !defined __GNUC__
  42     x ^= x >> 16;
  43     x ^= x >> 8;
  44     return oddparity8(x);
  45 #else
  46     return !__builtin_parity(x);
  47 #endif
  48 }
  49
  50 #endif /* __PARITY_H */