isl_hash.c

   1 /*
   2  * Copyright 2008-2009 Katholieke Universiteit Leuven
   3  *
   4  * Use of this software is governed by the MIT 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 #include "isl_config.h"
  15
  16 uint32_t isl_hash_string(uint32_t hash, const char *s)
  17 {
  18         for (; *s; s++)
  19                 isl_hash_byte(hash, *s);
  20         return hash;
  21 }
  22
  23 uint32_t isl_hash_mem(uint32_t hash, const void *p, size_t len)
  24 {
  25         int i;
  26         const char *s = p;
  27         for (i = 0; i < len; ++i)
  28                 isl_hash_byte(hash, s[i]);
  29         return hash;
  30 }
  31
  32 static unsigned int round_up(unsigned int v)
  33 {
  34         int old_v = v;
  35
  36         while (v) {
  37                 old_v = v;
  38                 v ^= v & -v;
  39         }
  40         return old_v << 1;
  41 }
  42
  43 int isl_hash_table_init(struct isl_ctx *ctx, struct isl_hash_table *table,
  44                         int min_size)
  45 {
  46         size_t size;
  47
  48         if (!table)
  49                 return -1;
  50
  51         if (min_size < 2)
  52                 min_size = 2;
  53         table->bits = ffs(round_up(4 * (min_size + 1) / 3 - 1)) - 1;
  54         table->n = 0;
  55
  56         size = 1 << table->bits;
  57         table->entries = isl_calloc_array(ctx, struct isl_hash_table_entry,
  58                                           size);
  59         if (!table->entries)
  60                 return -1;
  61
  62         return 0;
  63 }
  64
  65 static int grow_table(struct isl_ctx *ctx, struct isl_hash_table *table,
  66                         int (*eq)(const void *entry, const void *val))
  67 {
  68         int n;
  69         size_t old_size, size;
  70         struct isl_hash_table_entry *entries;
  71         uint32_t h;
  72
  73         entries = table->entries;
  74         old_size = 1 << table->bits;
  75         size = 2 * old_size;
  76         table->entries = isl_calloc_array(ctx, struct isl_hash_table_entry,
  77                                           size);
  78         if (!table->entries) {
  79                 table->entries = entries;
  80                 return -1;
  81         }
  82
  83         n = table->n;
  84         table->n = 0;
  85         table->bits++;
  86
  87         for (h = 0; h < old_size; ++h) {
  88                 struct isl_hash_table_entry *entry;
  89
  90                 if (!entries[h].data)
  91                         continue;
  92
  93                 entry = isl_hash_table_find(ctx, table, entries[h].hash,
  94                                             eq, entries[h].data, 1);
  95                 if (!entry) {
  96                         table->bits--;
  97                         free(table->entries);
  98                         table->entries = entries;
  99                         table->n = n;
 100                         return -1;
 101                 }
 102
 103                 *entry = entries[h];
 104         }
 105
 106         free(entries);
 107
 108         return 0;
 109 }
 110
 111 struct isl_hash_table *isl_hash_table_alloc(struct isl_ctx *ctx, int min_size)
 112 {
 113         struct isl_hash_table *table = NULL;
 114
 115         table = isl_alloc_type(ctx, struct isl_hash_table);
 116         if (isl_hash_table_init(ctx, table, min_size))
 117                 goto error;
 118         return table;
 119 error:
 120         isl_hash_table_free(ctx, table);
 121         return NULL;
 122 }
 123
 124 void isl_hash_table_clear(struct isl_hash_table *table)
 125 {
 126         if (!table)
 127                 return;
 128         free(table->entries);
 129 }
 130
 131 void isl_hash_table_free(struct isl_ctx *ctx, struct isl_hash_table *table)
 132 {
 133         if (!table)
 134                 return;
 135         isl_hash_table_clear(table);
 136         free(table);
 137 }
 138
 139 struct isl_hash_table_entry *isl_hash_table_find(struct isl_ctx *ctx,
 140                                 struct isl_hash_table *table,
 141                                 uint32_t key_hash,
 142                                 int (*eq)(const void *entry, const void *val),
 143                                 const void *val, int reserve)
 144 {
 145         size_t size;
 146         uint32_t h, key_bits;
 147
 148         key_bits = isl_hash_bits(key_hash, table->bits);
 149         size = 1 << table->bits;
 150         for (h = key_bits; table->entries[h].data; h = (h+1) % size)
 151                 if (table->entries[h].hash == key_hash &&
 152                     eq(table->entries[h].data, val))
 153                         return &table->entries[h];
 154
 155         if (!reserve)
 156                 return NULL;
 157
 158         if (4 * table->n >= 3 * size) {
 159                 if (grow_table(ctx, table, eq) < 0)
 160                         return NULL;
 161                 return isl_hash_table_find(ctx, table, key_hash, eq, val, 1);
 162         }
 163
 164         table->n++;
 165         table->entries[h].hash = key_hash;
 166
 167         return &table->entries[h];
 168 }
 169
 170 int isl_hash_table_foreach(struct isl_ctx *ctx,
 171                                 struct isl_hash_table *table,
 172                                 int (*fn)(void **entry, void *user), void *user)
 173 {
 174         size_t size;
 175         uint32_t h;
 176
 177         size = 1 << table->bits;
 178         for (h = 0; h < size; ++ h)
 179                 if (table->entries[h].data &&
 180                     fn(&table->entries[h].data, user) < 0)
 181                         return -1;
 182
 183         return 0;
 184 }
 185
 186 void isl_hash_table_remove(struct isl_ctx *ctx,
 187                                 struct isl_hash_table *table,
 188                                 struct isl_hash_table_entry *entry)
 189 {
 190         int h, h2;
 191         size_t size;
 192
 193         if (!table || !entry)
 194                 return;
 195
 196         size = 1 << table->bits;
 197         h = entry - table->entries;
 198         isl_assert(ctx, h >= 0 && h < size, return);
 199
 200         for (h2 = h+1; table->entries[h2 % size].data; h2++) {
 201                 uint32_t bits = isl_hash_bits(table->entries[h2 % size].hash,
 202                                                 table->bits);
 203                 uint32_t offset = (size + bits - (h+1)) % size;
 204                 if (offset <= h2 - (h+1))
 205                         continue;
 206                 *entry = table->entries[h2 % size];
 207                 h = h2;
 208                 entry = &table->entries[h % size];
 209         }
 210
 211         entry->hash = 0;
 212         entry->data = NULL;
 213         table->n--;
 214 }