usr/src/cmd/geniconvtbl/hash.h

   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 /*
  23  * Copyright (c) 1999 by Sun Microsystems, Inc.
  24  * All rights reserved.
  25  */
  26
  27 #ifndef _ICONV_TM_HASH_H
  28 #define _ICONV_TM_HASH_H
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32
  33 #ifdef  __cplusplus
  34 extern "C" {
  35 #endif
  36
  37
  38
  39 static itm_size_t       hash(const char *, itm_size_t, itm_size_t);
  40 static itm_num_t        hash_dense_encoding(const unsigned char *, itm_size_t,
  41                                     const unsigned char *,
  42                                     const unsigned char *);
  43
  44
  45 static itm_size_t
  46 hash(const char *ptr, itm_size_t size, itm_size_t hash_size)
  47 {
  48         itm_size_t      value;
  49
  50         value = *(ptr++);
  51         --size;
  52         for (; 0 < size; --size) {
  53                 value *= 27239;
  54                 value += *(ptr++);
  55         }
  56         return (value % hash_size);
  57 }
  58
  59 static itm_num_t
  60 hash_dense_encoding(
  61         const unsigned char     *byte_seq,
  62         itm_size_t              length,
  63         const unsigned char     *byte_seq_min,
  64         const unsigned char     *byte_seq_max)
  65 {
  66         long            i;
  67         itm_num_t       num;
  68
  69         num = (*byte_seq - *byte_seq_min);
  70         byte_seq_min++;
  71         byte_seq_max++;
  72         for (i = 1, byte_seq++; i < length;
  73             i++, byte_seq++, byte_seq_min++, byte_seq_max++) {
  74                 if ((*byte_seq < *byte_seq_min) ||
  75                     (*byte_seq_max < *byte_seq)) {
  76                         return (-1);
  77                 }
  78                 num *= (*byte_seq_max - *byte_seq_min + 1);
  79                 num += (*byte_seq - *byte_seq_min);
  80         }
  81         return (num);
  82 }
  83
  84 #ifdef  __cplusplus
  85 }
  86 #endif
  87
  88 #endif /* !_ICONV_TM_HASH_H */