generic/general/hashpjw.c

/*
 *  Hash function
 *  by Tom Epperly
 *  10/24/89
 *  Version: $Revision: 1.1 $
 *  Version control file: $RCSfile: hashpjw.c,v $
 *  Date last modified: $Date: 1997/07/18 11:38:36 $
 *  Last modified by: $Author: mthomas $
 *
 *  This file is part of the Ascend Language Interpreter.
 */

#include <stdio.h>
#include "utilities/ascConfig.h"
#include "utilities/ascPanic.h"
#include "general/hashpjw.h"

#ifndef lint
static CONST char HashpjwID[] = "$Id: hashpjw.c,v 1.1 1997/07/18 11:38:36 mthomas Exp $";
#endif

unsigned long hashpjw(register CONST char *str,
                      register unsigned long int size)
{
  register CONST char *p;
  register unsigned long h=0,g;

  asc_assert((NULL != str) && (size > 0));

  for(p = str; *p != '\0'; p++) {
    h = (h << 4) + (*p);
    if (0 != (g = h&0xf0000000)) {
      h = h ^ (g >> 24);
      h = h ^ g;
    }
  }
  return h % size;
}

/*
 * This is a temporary integer hashing function.
 * It is relatively expensive, as we first do int to str
 * transformation. This needs to be fixed with a proper
 * integer hashing function.
 */
unsigned long hashpjw_int(int id,
                          register unsigned long int size)
{
  char tmp[64];

  (void)snprintf(tmp, 64, "%d", id);
  return hashpjw(tmp, size);
}


1	/*
2	* Hash function
3	* by Tom Epperly
4	* 10/24/89
5	* Version: $Revision: 1.1 $
6	* Version control file: $RCSfile: hashpjw.c,v $
7	* Date last modified: $Date: 1997/07/18 11:38:36 $
8	* Last modified by: $Author: mthomas $
9	*
10	* This file is part of the Ascend Language Interpreter.
11	*/
12
13	#include <stdio.h>
14	#include "utilities/ascConfig.h"
15	#include "utilities/ascPanic.h"
16	#include "general/hashpjw.h"
17
18	#ifndef lint
19	static CONST char HashpjwID[] = "$Id: hashpjw.c,v 1.1 1997/07/18 11:38:36 mthomas Exp $";
20	#endif
21
22	unsigned long hashpjw(register CONST char *str,
23	register unsigned long int size)
24	{
25	register CONST char *p;
26	register unsigned long h=0,g;
27
28	asc_assert((NULL != str) && (size > 0));
29
30	for(p = str; *p != '\0'; p++) {
31	h = (h << 4) + (*p);
32	if (0 != (g = h&0xf0000000)) {
33	h = h ^ (g >> 24);
34	h = h ^ g;
35	}
36	}
37	return h % size;
38	}
39
40	/*
41	* This is a temporary integer hashing function.
42	* It is relatively expensive, as we first do int to str
43	* transformation. This needs to be fixed with a proper
44	* integer hashing function.
45	*/
46	unsigned long hashpjw_int(int id,
47	register unsigned long int size)
48	{
49	char tmp[64];
50
51	(void)snprintf(tmp, 64, "%d", id);
52	return hashpjw(tmp, size);
53	}
54
55
56