00001 /* 00002 00003 Copyright (C) 2000, 2001 Silicon Graphics, Inc. All Rights Reserved. 00004 00005 This program is free software; you can redistribute it and/or modify it 00006 under the terms of version 2 of the GNU General Public License as 00007 published by the Free Software Foundation. 00008 00009 This program is distributed in the hope that it would be useful, but 00010 WITHOUT ANY WARRANTY; without even the implied warranty of 00011 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 00012 00013 Further, this software is distributed without any warranty that it is 00014 free of the rightful claim of any third person regarding infringement 00015 or the like. Any license provided herein, whether implied or 00016 otherwise, applies only to this software file. Patent licenses, if 00017 any, provided herein do not apply to combinations of this program with 00018 other software, or any other product whatsoever. 00019 00020 You should have received a copy of the GNU General Public License along 00021 with this program; if not, write the Free Software Foundation, Inc., 59 00022 Temple Place - Suite 330, Boston MA 02111-1307, USA. 00023 00024 Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pky, 00025 Mountain View, CA 94043, or: 00026 00027 http://www.sgi.com 00028 00029 For further information regarding this notice, see: 00030 00031 http://oss.sgi.com/projects/GenInfo/NoticeExplan 00032 00033 */ 00034 00035 00036 // -*-C++-*- 00037 // ==================================================================== 00038 // ==================================================================== 00039 // 00040 // Module: cxx_hash_util.cxx 00041 // $Revision: 1.2 $ 00042 // $Date: 02/11/07 23:41:35-00:00 $ 00043 // $Author: fchow@keyresearch.com $ 00044 // $Source: /scratch/mee/2.4-65/kpro64-pending/be/com/SCCS/s.cxx_hash_util.cxx $ 00045 // 00046 // Revision history: 00047 // 07-Dec-95 - Merged user-hash version from IPA 00048 // 00049 // Description: 00050 // 00051 // Non-template support for template hash map implementations in 00052 // cxx_hash.h/cxx_hash.cxx. 00053 // 00054 // ==================================================================== 00055 // ==================================================================== 00056 00057 #ifdef _KEEP_RCS_ID 00058 #define cxx_hash_util_CXX "cxx_hash_util.cxx" 00059 static char *rcs_id = cxx_hash_util_CXX" $Revision: 1.2 $"; 00060 #endif /* _KEEP_RCS_ID */ 00061 00062 #include "defs.h" 00063 #include "erglob.h" 00064 #include "cxx_hash.h" 00065 00066 // ==================================================================== 00067 // ==================================================================== 00068 // 00069 // String hash table support: 00070 // 00071 // Borrows from Bob Fraley's hash map STL implementation... 00072 // 00073 // ==================================================================== 00074 // ==================================================================== 00075 00076 // Utility table for hashing: 00077 static HASH Init_Hashing_Table(); 00078 static HASH Hashing_Table[256]; 00079 static HASH _dummy_var = Init_Hashing_Table(); 00080 00081 // Initialize a "random" table for hashing function: 00082 static HASH 00083 Init_Hashing_Table ( void ) 00084 { 00085 // randomize(); // 00086 unsigned i; 00087 for ( i = 0; i < 256; i++ ) { 00088 Hashing_Table[i] = i | (i << 8); // >>> i for orig algorithm <<< 00089 } 00090 for ( i = 0; i < 256; ++i ) { 00091 HASH r = (rand() >> 5) & 255; 00092 HASH xchg = Hashing_Table[i]; 00093 Hashing_Table[i] = Hashing_Table[r]; 00094 Hashing_Table[r] = xchg; 00095 } 00096 return 1; 00097 } 00098 00099 // Modified hash function: 00100 HASH 00101 String_Hash::operator() ( const char * k ) const 00102 { 00103 HASH res = 0; 00104 00105 while ( *k ) { 00106 res = Hashing_Table[(res & 255) ^ *k++] ^ (res << 3); 00107 } 00108 return res ; 00109 } 00110
1.5.6