small fixes in helps

[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>
#include "string.h"

extern const uint8_t OddByteParity[256];


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

static inline void oddparitybuf(const uint8_t *x, size_t len, uint8_t *parity) {
	memset(parity, 0x00, (len - 1) / 8 + 1);
	for (int i = 0; i < len; i++) 
		parity[i / 8] |= oddparity8(x[i]) << (7 - (i % 8));
}

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 */