xref: /titanic_44/usr/src/cmd/tic/tic_hash.c (revision b7f45089ccbe01bab3d7c7377b49d80d2ae18a69)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*	Copyright (c) 1988 AT&T	*/
23 /*	  All Rights Reserved  	*/
24 
25 
26 /*
27  * University Copyright- Copyright (c) 1982, 1986, 1988
28  * The Regents of the University of California
29  * All Rights Reserved
30  *
31  * University Acknowledgment- Portions of this document are derived from
32  * software developed by the University of California, Berkeley, and its
33  * contributors.
34  */
35 
36 #pragma ident	"%Z%%M%	%I%	%E% SMI"
37 
38 /*
39 *************************************************************************
40 *			COPYRIGHT NOTICE				*
41 *************************************************************************
42 *	This software is copyright(C) 1982 by Pavel Curtis		*
43 *									*
44 *	Permission is granted to reproduce and distribute		*
45 *	this file by any means so long as no fee is charged		*
46 *	above a nominal handling fee and so long as this		*
47 *	notice is always included in the copies.			*
48 *									*
49 *	Other rights are reserved except as explicitly granted		*
50 *	by written permission of the author.				*
51 *		Pavel Curtis						*
52 *		Computer Science Dept.					*
53 *		405 Upson Hall						*
54 *		Cornell University					*
55 *		Ithaca, NY 14853					*
56 *									*
57 *		Ph- (607) 256-4934					*
58 *									*
59 *		Pavel.Cornell@Udel-Relay(ARPAnet)			*
60 *		decvax!cornell!pavel(UUCPnet)				*
61 *********************************************************************** */
62 
63 /*
64  *	comp_hash.c --- Routines to deal with the hashtable of capability
65  *			names.
66  *
67  *  $Log:	RCS/comp_hash.v $
68  * Revision 2.1  82/10/25  14:45:34  pavel
69  * Added Copyright Notice
70  *
71  * Revision 2.0  82/10/24  15:16:34  pavel
72  * Beta-one Test Release
73  *
74  * Revision 1.3  82/08/23  22:29:33  pavel
75  * The REAL Alpha-one Release Version
76  *
77  * Revision 1.2  82/08/19  19:09:46  pavel
78  * Alpha Test Release One
79  *
80  * Revision 1.1  82/08/12  18:36:23  pavel
81  * Initial revision
82  *
83  *
84  */
85 
86 #include "curses_inc.h"
87 #include "compiler.h"
88 
89 
90 
91 /*
92  *	make_hash_table()
93  *
94  *	Takes the entries in cap_table[] and hashes them into cap_hash_table[]
95  *	by name.  There are Captabsize entries in cap_table[] and Hashtabsize
96  *	slots in cap_hash_table[].
97  *
98  */
99 
100 void
101 make_hash_table()
102 {
103 	int	i;
104 	int	hashvalue;
105 	int	collisions = 0;
106 
107 	make_nte();
108 	for (i = 0; i < Captabsize; i++) {
109 		hashvalue = hash_function(cap_table[i].nte_name);
110 		DEBUG(9, "%d\n", hashvalue);
111 
112 		if (cap_hash_table[hashvalue] != (struct name_table_entry *) 0)
113 			collisions++;
114 
115 		cap_table[i].nte_link = cap_hash_table[hashvalue];
116 		cap_hash_table[hashvalue] = &cap_table[i];
117 	}
118 
119 	DEBUG(3, "Hash table complete\n%d collisions ", collisions);
120 	DEBUG(3, "out of %d entries\n", Captabsize);
121 	return;
122 }
123 
124 /*
125  * Make the name_table_entry from the capnames.c set of tables.
126  */
127 make_nte()
128 {
129 	register int i, n;
130 	extern char *boolnames[], *numnames[], *strnames[];
131 
132 	n = 0;
133 
134 	for (i = 0; boolnames[i]; i++) {
135 		cap_table[n].nte_link = NULL;
136 		cap_table[n].nte_name = boolnames[i];
137 		cap_table[n].nte_type = BOOLEAN;
138 		cap_table[n].nte_index = i;
139 		n++;
140 	}
141 	BoolCount = i;
142 
143 	for (i = 0; numnames[i]; i++) {
144 		cap_table[n].nte_link = NULL;
145 		cap_table[n].nte_name = numnames[i];
146 		cap_table[n].nte_type = NUMBER;
147 		cap_table[n].nte_index = i;
148 		n++;
149 	}
150 	NumCount = i;
151 
152 	for (i 	= 0; strnames[i]; i++) {
153 		cap_table[n].nte_link = NULL;
154 		cap_table[n].nte_name = strnames[i];
155 		cap_table[n].nte_type = STRING;
156 		cap_table[n].nte_index = i;
157 		n++;
158 	}
159 	StrCount = i;
160 
161 	Captabsize = n;
162 }
163 
164 
165 /*
166  *	int hash_function(string)
167  *
168  *	Computes the hashing function on the given string.
169  *
170  *	The current hash function is the sum of each consectutive pair
171  *	of characters, taken as two-byte integers, mod Hashtabsize.
172  *
173  */
174 
175 static
176 int
177 hash_function(char *string)
178 {
179 	long	sum = 0;
180 
181 	while (*string) {
182 		sum += *string + (*(string + 1) << 8);
183 		string++;
184 	}
185 
186 	return (sum % Hashtabsize);
187 }
188 
189 
190 
191 /*
192  *	struct name_table_entry *
193  *	find_entry(string)
194  *
195  *	Finds the entry for the given string in the hash table if present.
196  *	Returns a pointer to the entry in the table or 0 if not found.
197  *
198  */
199 
200 struct name_table_entry *
201 find_entry(char *string)
202 {
203 	int	hashvalue;
204 	struct name_table_entry	*ptr;
205 
206 	hashvalue = hash_function(string);
207 
208 	ptr = cap_hash_table[hashvalue];
209 
210 	while (ptr != (struct name_table_entry *) 0 &&
211 	    strcmp(ptr->nte_name, string) != 0)
212 		ptr = ptr->nte_link;
213 
214 	return (ptr);
215 }
216