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2022: add PJW hash (lib)

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Bruno Raoult
2022-12-10 14:55:13 +01:00
parent 8aff410ff4
commit 68f200ff65
4 changed files with 97 additions and 0 deletions
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19
2022/include/bits.h
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@@ -44,11 +44,30 @@ typedef uint8_t u8;
/* convenience types
*/
typedef long long int llong;
typedef unsigned long long int ullong;
typedef unsigned long int ulong;
typedef unsigned int uint;
typedef unsigned short ushort;
typedef unsigned char uchar;
/* define common types sizes
*/
#define BITS_PER_CHAR 8
#ifndef BITS_PER_SHORT
#define BITS_PER_SHORT (BITS_PER_CHAR * sizeof (short))
#endif
#ifndef BITS_PER_INT
#define BITS_PER_INT (BITS_PER_CHAR * sizeof (int))
#endif
#ifndef BITS_PER_LONG
#define BITS_PER_LONG (BITS_PER_CHAR * sizeof (long))
#endif
#ifndef BITS_PER_LLONG
#define BITS_PER_LLONG (BITS_PER_CHAR * sizeof (long long))
#endif
/* count set bits: 10101000 -> 3
* ^ ^ ^
*/

42
2022/include/pjwhash-inline.h Normal file
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@@ -0,0 +1,42 @@
/* pjwhash-inline.h - PJW hash function, inline version.
*
* Copyright (C) 2021-2022 Bruno Raoult ("br")
* Licensed under the GNU General Public License v3.0 or later.
* Some rights reserved. See COPYING.
*
* You should have received a copy of the GNU General Public License along with this
* program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
*
* SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
*
*/
#ifndef _PJWHASH_INLINE_H
#define _PJWHASH_INLINE_H
#include "bits.h"
#define THREE_QUARTERS ((int) ((BITS_PER_INT * 3) / 4))
#define ONE_EIGHTH ((int) (BITS_PER_INT / 8))
#define HIGH_BITS ( ~((uint)(~0) >> ONE_EIGHTH ))
#ifndef _pjw_inline
#define _pjw_inline static inline
#endif
_pjw_inline unsigned int pjwhash(const char* str, uint length)
{
uint hash = 0, high;
for (uint i = 0; i < length; ++str, ++i) {
hash = (hash << ONE_EIGHTH) + *str;
high = hash & HIGH_BITS;
if (high != 0) {
hash ^= high >> THREE_QUARTERS;
hash &= ~high;
}
}
return hash;
}
#endif /* _PJWHASH_INLINE_H */

20
2022/include/pjwhash.h Normal file
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@@ -0,0 +1,20 @@
/* pjwhash.h - PJW hash function, extern version.
*
* Copyright (C) 2021-2022 Bruno Raoult ("br")
* Licensed under the GNU General Public License v3.0 or later.
* Some rights reserved. See COPYING.
*
* You should have received a copy of the GNU General Public License along with this
* program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
*
* SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
*/
#ifndef _PJWHASH_H
#define _PJWHASH_H
#include "bits.h"
extern unsigned int pjwhash(const char* str, uint length);
#endif /* _PJWHASH_H */

16
2022/libsrc/pjwhash.c Normal file
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@@ -0,0 +1,16 @@
/* pjwhash.c - PJW hash function.
*
* Copyright (C) 2021-2022 Bruno Raoult ("br")
* Licensed under the GNU General Public License v3.0 or later.
* Some rights reserved. See COPYING.
*
* You should have received a copy of the GNU General Public License along with this
* program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
*
* SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
*
*/
#define _pjw_inline extern
#include "pjwhash-inline.h"