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      1 /*	$NetBSD: hash.c,v 1.1 2023/07/30 09:20:14 riastradh Exp $	 */
      2 
      3 /*
      4  * Copyright 1996 John D. Polstra.
      5  * Copyright 1996 Matt Thomas <matt (at) 3am-software.com>
      6  * Copyright 2002 Charles M. Hannum <root (at) ihack.net>
      7  * All rights reserved.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *      This product includes software developed by John Polstra.
     20  * 4. The name of the author may not be used to endorse or promote products
     21  *    derived from this software without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     33  */
     34 
     35 /*
     36  * Dynamic linker for ELF.
     37  *
     38  * John Polstra <jdp (at) polstra.com>.
     39  */
     40 
     41 #include <sys/cdefs.h>
     42 #ifndef lint
     43 __RCSID("$NetBSD: hash.c,v 1.1 2023/07/30 09:20:14 riastradh Exp $");
     44 #endif /* not lint */
     45 
     46 #include <stdint.h>
     47 
     48 #include "hash.h"
     49 
     50 /*
     51  * SysV hash function for symbol table lookup.  It is a slightly optimized
     52  * version of the hash specified by the System V ABI.
     53  */
     54 Elf32_Word
     55 _rtld_sysv_hash(const char *name)
     56 {
     57 	const unsigned char *p = (const unsigned char *) name;
     58 	Elf32_Word h = 0;
     59 
     60 	while (__predict_true(*p != '\0')) {
     61 		h = (h << 4) + *p++;
     62 		h ^= (h >> 24) & 0xf0;
     63 	}
     64 	return (h & 0x0fffffff);
     65 }
     66 
     67 /*
     68  * Hash function for symbol table lookup.  Don't even think about changing
     69  * this.  It is specified by the GNU toolchain ABI.
     70  */
     71 Elf32_Word
     72 _rtld_gnu_hash(const char *name)
     73 {
     74 	const unsigned char *p = (const unsigned char *) name;
     75 	uint_fast32_t h = 5381;
     76 	unsigned char c;
     77 
     78 	for (c = *p; c != '\0'; c = *++p)
     79 		h = h * 33 + c;
     80 	return (h & 0xffffffff);
     81 }
     82