isl_hash.c

   1 /*
   2  * Copyright 2008-2009 Katholieke Universiteit Leuven
   3  *
   4  * Use of this software is governed by the GNU LGPLv2.1 license
   5  *
   6  * Written by Sven Verdoolaege, K.U.Leuven, Departement
   7  * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
   8  */
   9
  10 #include <stdlib.h>
  11 #include <strings.h>
  12 #include <isl/hash.h>
  13 #include <isl/ctx.h>
  14
  15 uint32_t isl_hash_string(uint32_t hash, const char *s)
  16 {
  17         for (; *s; s++)
  18                 isl_hash_byte(hash, *s);
  19         return hash;
  20 }
  21
  22 uint32_t isl_hash_mem(uint32_t hash, const void *p, size_t len)
  23 {
  24         int i;
  25         const char *s = p;
  26         for (i = 0; i < len; ++i)
  27                 isl_hash_byte(hash, s[i]);
  28         return hash;
  29 }
  30
  31 static unsigned int round_up(unsigned int v)
  32 {
  33         int old_v = v;
  34
  35         while (v) {
  36                 old_v = v;
  37                 v ^= v & -v;
  38         }
  39         return old_v << 1;
  40 }
  41
  42 int isl_hash_table_init(struct isl_ctx *ctx, struct isl_hash_table *table,
  43                         int min_size)
  44 {
  45         size_t size;
  46
  47         if (!table)
  48                 return -1;
  49
  50         if (min_size < 2)
  51                 min_size = 2;
  52         table->bits = ffs(round_up(4 * (min_size + 1) / 3 - 1)) - 1;
  53         table->n = 0;
  54
  55         size = 1 << table->bits;
  56         table->entries = isl_calloc_array(ctx, struct isl_hash_table_entry,
  57                                           size);
  58         if (!table->entries)
  59                 return -1;
  60
  61         return 0;
  62 }
  63
  64 static int grow_table(struct isl_ctx *ctx, struct isl_hash_table *table,
  65                         int (*eq)(const void *entry, const void *val))
  66 {
  67         size_t old_size, size;
  68         struct isl_hash_table_entry *entries;
  69         uint32_t h;
  70
  71         entries = table->entries;
  72         old_size = 1 << table->bits;
  73         size = 2 * old_size;
  74         table->entries = isl_calloc_array(ctx, struct isl_hash_table_entry,
  75                                           size);
  76         if (!table->entries) {
  77                 table->entries = entries;
  78                 return -1;
  79         }
  80
  81         table->bits++;
  82
  83         for (h = 0; h < old_size; ++h) {
  84                 struct isl_hash_table_entry *entry;
  85
  86                 if (!entries[h].data)
  87                         continue;
  88
  89                 entry = isl_hash_table_find(ctx, table, entries[h].hash,
  90                                             eq, entries[h].data, 1);
  91                 if (!entry) {
  92                         table->bits--;
  93                         free(table->entries);
  94                         table->entries = entries;
  95                         return -1;
  96                 }
  97
  98                 *entry = entries[h];
  99         }
 100
 101         free(entries);
 102
 103         return 0;
 104 }
 105
 106 struct isl_hash_table *isl_hash_table_alloc(struct isl_ctx *ctx, int min_size)
 107 {
 108         struct isl_hash_table *table = NULL;
 109
 110         table = isl_alloc_type(ctx, struct isl_hash_table);
 111         if (isl_hash_table_init(ctx, table, min_size))
 112                 goto error;
 113         return table;
 114 error:
 115         isl_hash_table_free(ctx, table);
 116         return NULL;
 117 }
 118
 119 void isl_hash_table_clear(struct isl_hash_table *table)
 120 {
 121         if (!table)
 122                 return;
 123         free(table->entries);
 124 }
 125
 126 void isl_hash_table_free(struct isl_ctx *ctx, struct isl_hash_table *table)
 127 {
 128         if (!table)
 129                 return;
 130         isl_hash_table_clear(table);
 131         free(table);
 132 }
 133
 134 struct isl_hash_table_entry *isl_hash_table_find(struct isl_ctx *ctx,
 135                                 struct isl_hash_table *table,
 136                                 uint32_t key_hash,
 137                                 int (*eq)(const void *entry, const void *val),
 138                                 const void *val, int reserve)
 139 {
 140         size_t size;
 141         uint32_t h, key_bits;
 142
 143         key_bits = isl_hash_bits(key_hash, table->bits);
 144         size = 1 << table->bits;
 145         for (h = key_bits; table->entries[h].data; h = (h+1) % size)
 146                 if (table->entries[h].hash == key_hash &&
 147                     eq(table->entries[h].data, val))
 148                         return &table->entries[h];
 149
 150         if (!reserve)
 151                 return NULL;
 152
 153         if (4 * table->n >= 3 * size) {
 154                 if (grow_table(ctx, table, eq) < 0)
 155                         return NULL;
 156                 return isl_hash_table_find(ctx, table, key_hash, eq, val, 1);
 157         }
 158
 159         table->n++;
 160         table->entries[h].hash = key_hash;
 161
 162         return &table->entries[h];
 163 }
 164
 165 int isl_hash_table_foreach(struct isl_ctx *ctx,
 166                                 struct isl_hash_table *table,
 167                                 int (*fn)(void **entry, void *user), void *user)
 168 {
 169         size_t size;
 170         uint32_t h;
 171
 172         size = 1 << table->bits;
 173         for (h = 0; h < size; ++ h)
 174                 if (table->entries[h].data &&
 175                     fn(&table->entries[h].data, user) < 0)
 176                         return -1;
 177
 178         return 0;
 179 }
 180
 181 void isl_hash_table_remove(struct isl_ctx *ctx,
 182                                 struct isl_hash_table *table,
 183                                 struct isl_hash_table_entry *entry)
 184 {
 185         int h, h2;
 186         size_t size;
 187
 188         if (!table || !entry)
 189                 return;
 190
 191         size = 1 << table->bits;
 192         h = entry - table->entries;
 193         isl_assert(ctx, h >= 0 && h < size, return);
 194
 195         for (h2 = h+1; table->entries[h2 % size].data; h2++) {
 196                 uint32_t bits = isl_hash_bits(table->entries[h2 % size].hash,
 197                                                 table->bits);
 198                 uint32_t offset = (size + bits - (h+1)) % size;
 199                 if (offset <= h2 - (h+1))
 200                         continue;
 201                 *entry = table->entries[h2 % size];
 202                 h = h2;
 203                 entry = &table->entries[h % size];
 204         }
 205
 206         entry->hash = 0;
 207         entry->data = NULL;
 208         table->n--;
 209 }