git.zerfleddert.de Git - proxmark3-svn/blob - 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 <stdint.h>
  15 #include <stdbool.h>
  16 #include "string.h"
  17
  18 extern const uint8_t OddByteParity[256];
  19
  20
  21 static inline bool oddparity8(const uint8_t x) {
  22         return OddByteParity[x];
  23 }
  24
  25 static inline void oddparitybuf(const uint8_t *x, size_t len, uint8_t *parity) {
  26         memset(parity, 0x00, (len - 1) / 8 + 1);
  27         for (int i = 0; i < len; i++)
  28                 parity[i / 8] |= oddparity8(x[i]) << (7 - (i % 8));
  29 }
  30
  31 static inline bool evenparity8(const uint8_t x) {
  32         return !OddByteParity[x];
  33 }
  34
  35
  36 static inline bool evenparity32(uint32_t x)
  37 {
  38 #if !defined __GNUC__
  39         x ^= x >> 16;
  40         x ^= x >> 8;
  41         return evenparity8(x);
  42 #else
  43         return __builtin_parity(x);
  44 #endif
  45 }
  46
  47
  48 static inline bool oddparity32(uint32_t x)
  49 {
  50 #if !defined __GNUC__
  51         x ^= x >> 16;
  52         x ^= x >> 8;
  53         return oddparity8(x);
  54 #else
  55         return !__builtin_parity(x);
  56 #endif
  57 }
  58
  59 #endif /* __PARITY_H */