hashtbl.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1996-2009 The NASM Authors - All Rights Reserved
   4  *   See the file AUTHORS included with the NASM distribution for
   5  *   the specific copyright holders.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following
   9  *   conditions are met:
  10  *
  11  *   * Redistributions of source code must retain the above copyright
  12  *     notice, this list of conditions and the following disclaimer.
  13  *   * Redistributions in binary form must reproduce the above
  14  *     copyright notice, this list of conditions and the following
  15  *     disclaimer in the documentation and/or other materials provided
  16  *     with the distribution.
  17  *
  18  *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  19  *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  20  *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  21  *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  22  *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  23  *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  25  *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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  29  *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  30  *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * ----------------------------------------------------------------------- */
  33
  34 /*
  35  * hashtbl.c
  36  *
  37  * Efficient dictionary hash table class.
  38  */
  39
  40 #include "compiler.h"
  41
  42 #include <string.h>
  43 #include "nasm.h"
  44 #include "hashtbl.h"
  45
  46 #define HASH_MAX_LOAD   2 /* Higher = more memory-efficient, slower */
  47
  48 #define hash_calc(key)          crc64(CRC64_INIT, (key))
  49 #define hash_calci(key)         crc64i(CRC64_INIT, (key))
  50 #define hash_max_load(size)     ((size) * (HASH_MAX_LOAD - 1) / HASH_MAX_LOAD)
  51 #define hash_expand(size)       ((size) << 1)
  52 #define hash_mask(size)         ((size) - 1)
  53 #define hash_pos(hash, mask)    ((hash) & (mask))
  54 #define hash_inc(hash, mask)    ((((hash) >> 32) & (mask)) | 1) /* always odd */
  55 #define hash_pos_next(pos, inc, mask) (((pos) + (inc)) & (mask))
  56
  57 static struct hash_tbl_node *alloc_table(size_t newsize)
  58 {
  59     size_t bytes = newsize * sizeof(struct hash_tbl_node);
  60     return nasm_zalloc(bytes);
  61 }
  62
  63 void hash_init(struct hash_table *head, size_t size)
  64 {
  65     nasm_assert(is_power2(size));
  66     head->table    = alloc_table(size);
  67     head->load     = 0;
  68     head->size     = size;
  69     head->max_load = hash_max_load(size);
  70 }
  71
  72 /*
  73  * Find an entry in a hash table.
  74  *
  75  * On failure, if "insert" is non-NULL, store data in that structure
  76  * which can be used to insert that node using hash_add().
  77  *
  78  * WARNING: this data is only valid until the very next call of
  79  * hash_add(); it cannot be "saved" to a later date.
  80  *
  81  * On success, return a pointer to the "data" element of the hash
  82  * structure.
  83  */
  84 void **hash_find(struct hash_table *head, const char *key,
  85                  struct hash_insert *insert)
  86 {
  87     struct hash_tbl_node *np;
  88     struct hash_tbl_node *tbl = head->table;
  89     uint64_t hash = hash_calc(key);
  90     size_t mask = hash_mask(head->size);
  91     size_t pos = hash_pos(hash, mask);
  92     size_t inc = hash_inc(hash, mask);
  93
  94     while ((np = &tbl[pos])->key) {
  95         if (hash == np->hash && !strcmp(key, np->key))
  96             return &np->data;
  97         pos = hash_pos_next(pos, inc, mask);
  98     }
  99
 100     /* Not found.  Store info for insert if requested. */
 101     if (insert) {
 102         insert->head  = head;
 103         insert->hash  = hash;
 104         insert->where = np;
 105     }
 106     return NULL;
 107 }
 108
 109 /*
 110  * Same as hash_find, but for case-insensitive hashing.
 111  */
 112 void **hash_findi(struct hash_table *head, const char *key,
 113                   struct hash_insert *insert)
 114 {
 115     struct hash_tbl_node *np;
 116     struct hash_tbl_node *tbl = head->table;
 117     uint64_t hash = hash_calci(key);
 118     size_t mask = hash_mask(head->size);
 119     size_t pos = hash_pos(hash, mask);
 120     size_t inc = hash_inc(hash, mask);
 121
 122     while ((np = &tbl[pos])->key) {
 123         if (hash == np->hash && !nasm_stricmp(key, np->key))
 124             return &np->data;
 125         pos = hash_pos_next(pos, inc, mask);
 126     }
 127
 128     /* Not found.  Store info for insert if requested. */
 129     if (insert) {
 130         insert->head  = head;
 131         insert->hash  = hash;
 132         insert->where = np;
 133     }
 134     return NULL;
 135 }
 136
 137 /*
 138  * Insert node.  Return a pointer to the "data" element of the newly
 139  * created hash node.
 140  */
 141 void **hash_add(struct hash_insert *insert, const char *key, void *data)
 142 {
 143     struct hash_table *head  = insert->head;
 144     struct hash_tbl_node *np = insert->where;
 145
 146     /*
 147      * Insert node.  We can always do this, even if we need to
 148      * rebalance immediately after.
 149      */
 150     np->hash = insert->hash;
 151     np->key  = key;
 152     np->data = data;
 153
 154     if (++head->load > head->max_load) {
 155         /* Need to expand the table */
 156         size_t newsize                  = hash_expand(head->size);
 157         struct hash_tbl_node *newtbl    = alloc_table(newsize);
 158         size_t mask                     = hash_mask(newsize);
 159
 160         if (head->table) {
 161             struct hash_tbl_node *op, *xp;
 162             size_t i;
 163
 164             /* Rebalance all the entries */
 165             for (i = 0, op = head->table; i < head->size; i++, op++) {
 166                 if (op->key) {
 167                     size_t pos = hash_pos(op->hash, mask);
 168                     size_t inc = hash_inc(op->hash, mask);
 169
 170                     while ((xp = &newtbl[pos])->key)
 171                         pos = hash_pos_next(pos, inc, mask);
 172
 173                     *xp = *op;
 174                     if (op == np)
 175                         np = xp;
 176                 }
 177             }
 178             nasm_free(head->table);
 179         }
 180
 181         head->table    = newtbl;
 182         head->size     = newsize;
 183         head->max_load = hash_max_load(newsize);
 184     }
 185
 186     return &np->data;
 187 }
 188
 189 /*
 190  * Iterate over all members of a hash set.  For the first call,
 191  * iterator should be initialized to NULL.  Returns the data pointer,
 192  * or NULL on failure.
 193  */
 194 void *hash_iterate(const struct hash_table *head,
 195                    struct hash_tbl_node **iterator,
 196                    const char **key)
 197 {
 198     struct hash_tbl_node *np = *iterator;
 199     struct hash_tbl_node *ep = head->table + head->size;
 200
 201     if (!np) {
 202         np = head->table;
 203         if (!np)
 204             return NULL;        /* Uninitialized table */
 205     }
 206
 207     while (np < ep) {
 208         if (np->key) {
 209             *iterator = np + 1;
 210             if (key)
 211                 *key = np->key;
 212             return np->data;
 213         }
 214         np++;
 215     }
 216
 217     *iterator = NULL;
 218     if (key)
 219         *key = NULL;
 220     return NULL;
 221 }
 222
 223 /*
 224  * Free the hash itself.  Doesn't free the data elements; use
 225  * hash_iterate() to do that first, if needed.
 226  */
 227 void hash_free(struct hash_table *head)
 228 {
 229     void *p = head->table;
 230     head->table = NULL;
 231     nasm_free(p);
 232 }