added some info from @peterfillmore fork

[proxmark3-svn] / common / parity.h

//-----------------------------------------------------------------------------
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Parity functions
//-----------------------------------------------------------------------------

// all functions defined in header file by purpose. Allows compiler optimizations. 

#ifndef __PARITY_H
#define __PARITY_H

#include <stdint.h>
#include <stdbool.h>

extern const uint8_t OddByteParity[256];


static inline bool oddparity8(const uint8_t x) {
	return OddByteParity[x];
}


static inline bool evenparity8(const uint8_t x) {
	return !OddByteParity[x];
}


static inline bool evenparity32(uint32_t x) 
{
#if !defined __GNUC__
	x ^= x >> 16;
	x ^= x >> 8;
	return evenparity8(x);
#else
	return __builtin_parity(x);
#endif
}


static inline bool oddparity32(uint32_t x) 
{
#if !defined __GNUC__
	x ^= x >> 16;
	x ^= x >> 8;
	return oddparity8(x);
#else
	return !__builtin_parity(x);
#endif
}

#endif /* __PARITY_H */