| 1 | /* $RCSfile: hash.c,v $$Revision: 4.1 $$Date: 92/08/07 18:29:20 $ |
| 2 | * |
| 3 | * Copyright (c) 1991, Larry Wall |
| 4 | * |
| 5 | * You may distribute under the terms of either the GNU General Public |
| 6 | * License or the Artistic License, as specified in the README file. |
| 7 | * |
| 8 | * $Log: hash.c,v $ |
| 9 | */ |
| 10 | |
| 11 | #include <stdio.h> |
| 12 | #include "EXTERN.h" |
| 13 | #include "a2p.h" |
| 14 | #include "util.h" |
| 15 | |
| 16 | STR * |
| 17 | hfetch(tb,key) |
| 18 | register HASH *tb; |
| 19 | char *key; |
| 20 | { |
| 21 | register char *s; |
| 22 | register int i; |
| 23 | register int hash; |
| 24 | register HENT *entry; |
| 25 | |
| 26 | if (!tb) |
| 27 | return Nullstr; |
| 28 | for (s=key, i=0, hash = 0; |
| 29 | /* while */ *s; |
| 30 | s++, i++, hash *= 5) { |
| 31 | hash += *s * coeff[i]; |
| 32 | } |
| 33 | entry = tb->tbl_array[hash & tb->tbl_max]; |
| 34 | for (; entry; entry = entry->hent_next) { |
| 35 | if (entry->hent_hash != hash) /* strings can't be equal */ |
| 36 | continue; |
| 37 | if (strNE(entry->hent_key,key)) /* is this it? */ |
| 38 | continue; |
| 39 | return entry->hent_val; |
| 40 | } |
| 41 | return Nullstr; |
| 42 | } |
| 43 | |
| 44 | bool |
| 45 | hstore(tb,key,val) |
| 46 | register HASH *tb; |
| 47 | char *key; |
| 48 | STR *val; |
| 49 | { |
| 50 | register char *s; |
| 51 | register int i; |
| 52 | register int hash; |
| 53 | register HENT *entry; |
| 54 | register HENT **oentry; |
| 55 | |
| 56 | if (!tb) |
| 57 | return FALSE; |
| 58 | for (s=key, i=0, hash = 0; |
| 59 | /* while */ *s; |
| 60 | s++, i++, hash *= 5) { |
| 61 | hash += *s * coeff[i]; |
| 62 | } |
| 63 | |
| 64 | oentry = &(tb->tbl_array[hash & tb->tbl_max]); |
| 65 | i = 1; |
| 66 | |
| 67 | for (entry = *oentry; entry; i=0, entry = entry->hent_next) { |
| 68 | if (entry->hent_hash != hash) /* strings can't be equal */ |
| 69 | continue; |
| 70 | if (strNE(entry->hent_key,key)) /* is this it? */ |
| 71 | continue; |
| 72 | /*NOSTRICT*/ |
| 73 | Safefree(entry->hent_val); |
| 74 | entry->hent_val = val; |
| 75 | return TRUE; |
| 76 | } |
| 77 | /*NOSTRICT*/ |
| 78 | entry = (HENT*) safemalloc(sizeof(HENT)); |
| 79 | |
| 80 | entry->hent_key = savestr(key); |
| 81 | entry->hent_val = val; |
| 82 | entry->hent_hash = hash; |
| 83 | entry->hent_next = *oentry; |
| 84 | *oentry = entry; |
| 85 | |
| 86 | if (i) { /* initial entry? */ |
| 87 | tb->tbl_fill++; |
| 88 | if ((tb->tbl_fill * 100 / (tb->tbl_max + 1)) > FILLPCT) |
| 89 | hsplit(tb); |
| 90 | } |
| 91 | |
| 92 | return FALSE; |
| 93 | } |
| 94 | |
| 95 | #ifdef NOTUSED |
| 96 | bool |
| 97 | hdelete(tb,key) |
| 98 | register HASH *tb; |
| 99 | char *key; |
| 100 | { |
| 101 | register char *s; |
| 102 | register int i; |
| 103 | register int hash; |
| 104 | register HENT *entry; |
| 105 | register HENT **oentry; |
| 106 | |
| 107 | if (!tb) |
| 108 | return FALSE; |
| 109 | for (s=key, i=0, hash = 0; |
| 110 | /* while */ *s; |
| 111 | s++, i++, hash *= 5) { |
| 112 | hash += *s * coeff[i]; |
| 113 | } |
| 114 | |
| 115 | oentry = &(tb->tbl_array[hash & tb->tbl_max]); |
| 116 | entry = *oentry; |
| 117 | i = 1; |
| 118 | for (; entry; i=0, oentry = &entry->hent_next, entry = entry->hent_next) { |
| 119 | if (entry->hent_hash != hash) /* strings can't be equal */ |
| 120 | continue; |
| 121 | if (strNE(entry->hent_key,key)) /* is this it? */ |
| 122 | continue; |
| 123 | safefree((char*)entry->hent_val); |
| 124 | safefree(entry->hent_key); |
| 125 | *oentry = entry->hent_next; |
| 126 | safefree((char*)entry); |
| 127 | if (i) |
| 128 | tb->tbl_fill--; |
| 129 | return TRUE; |
| 130 | } |
| 131 | return FALSE; |
| 132 | } |
| 133 | #endif |
| 134 | |
| 135 | void |
| 136 | hsplit(tb) |
| 137 | HASH *tb; |
| 138 | { |
| 139 | int oldsize = tb->tbl_max + 1; |
| 140 | register int newsize = oldsize * 2; |
| 141 | register int i; |
| 142 | register HENT **a; |
| 143 | register HENT **b; |
| 144 | register HENT *entry; |
| 145 | register HENT **oentry; |
| 146 | |
| 147 | a = (HENT**) saferealloc((char*)tb->tbl_array, newsize * sizeof(HENT*)); |
| 148 | bzero((char*)&a[oldsize], oldsize * sizeof(HENT*)); /* zero second half */ |
| 149 | tb->tbl_max = --newsize; |
| 150 | tb->tbl_array = a; |
| 151 | |
| 152 | for (i=0; i<oldsize; i++,a++) { |
| 153 | if (!*a) /* non-existent */ |
| 154 | continue; |
| 155 | b = a+oldsize; |
| 156 | for (oentry = a, entry = *a; entry; entry = *oentry) { |
| 157 | if ((entry->hent_hash & newsize) != i) { |
| 158 | *oentry = entry->hent_next; |
| 159 | entry->hent_next = *b; |
| 160 | if (!*b) |
| 161 | tb->tbl_fill++; |
| 162 | *b = entry; |
| 163 | continue; |
| 164 | } |
| 165 | else |
| 166 | oentry = &entry->hent_next; |
| 167 | } |
| 168 | if (!*a) /* everything moved */ |
| 169 | tb->tbl_fill--; |
| 170 | } |
| 171 | } |
| 172 | |
| 173 | HASH * |
| 174 | hnew() |
| 175 | { |
| 176 | register HASH *tb = (HASH*)safemalloc(sizeof(HASH)); |
| 177 | |
| 178 | tb->tbl_array = (HENT**) safemalloc(8 * sizeof(HENT*)); |
| 179 | tb->tbl_fill = 0; |
| 180 | tb->tbl_max = 7; |
| 181 | hiterinit(tb); /* so each() will start off right */ |
| 182 | bzero((char*)tb->tbl_array, 8 * sizeof(HENT*)); |
| 183 | return tb; |
| 184 | } |
| 185 | |
| 186 | #ifdef NOTUSED |
| 187 | hshow(tb) |
| 188 | register HASH *tb; |
| 189 | { |
| 190 | fprintf(stderr,"%5d %4d (%2d%%)\n", |
| 191 | tb->tbl_max+1, |
| 192 | tb->tbl_fill, |
| 193 | tb->tbl_fill * 100 / (tb->tbl_max+1)); |
| 194 | } |
| 195 | #endif |
| 196 | |
| 197 | int |
| 198 | hiterinit(tb) |
| 199 | register HASH *tb; |
| 200 | { |
| 201 | tb->tbl_riter = -1; |
| 202 | tb->tbl_eiter = Null(HENT*); |
| 203 | return tb->tbl_fill; |
| 204 | } |
| 205 | |
| 206 | HENT * |
| 207 | hiternext(tb) |
| 208 | register HASH *tb; |
| 209 | { |
| 210 | register HENT *entry; |
| 211 | |
| 212 | entry = tb->tbl_eiter; |
| 213 | do { |
| 214 | if (entry) |
| 215 | entry = entry->hent_next; |
| 216 | if (!entry) { |
| 217 | tb->tbl_riter++; |
| 218 | if (tb->tbl_riter > tb->tbl_max) { |
| 219 | tb->tbl_riter = -1; |
| 220 | break; |
| 221 | } |
| 222 | entry = tb->tbl_array[tb->tbl_riter]; |
| 223 | } |
| 224 | } while (!entry); |
| 225 | |
| 226 | tb->tbl_eiter = entry; |
| 227 | return entry; |
| 228 | } |
| 229 | |
| 230 | char * |
| 231 | hiterkey(entry) |
| 232 | register HENT *entry; |
| 233 | { |
| 234 | return entry->hent_key; |
| 235 | } |
| 236 | |
| 237 | STR * |
| 238 | hiterval(entry) |
| 239 | register HENT *entry; |
| 240 | { |
| 241 | return entry->hent_val; |
| 242 | } |