/* An expandable hash tables datatype.
- Copyright (C) 1999 Free Software Foundation, Inc.
+ Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004
+ Free Software Foundation, Inc.
Contributed by Vladimir Makarov (vmakarov@cygnus.com).
This file is part of the libiberty library.
You should have received a copy of the GNU Library General Public
License along with libiberty; see the file COPYING.LIB. If
-not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
+Boston, MA 02110-1301, USA. */
/* This package implements basic hash table functionality. It is possible
to search for an entry, create an entry and destroy an entry.
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
+#ifdef HAVE_STRING_H
+#include <string.h>
+#endif
+#ifdef HAVE_MALLOC_H
+#include <malloc.h>
+#endif
+#ifdef HAVE_LIMITS_H
+#include <limits.h>
+#endif
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
#include <stdio.h>
#include "libiberty.h"
+#include "ansidecl.h"
#include "hashtab.h"
-/* The following variable is used for debugging. Its value is number
- of all calls of `find_hash_table_entry' for all hash tables. */
+#ifndef CHAR_BIT
+#define CHAR_BIT 8
+#endif
+
+static unsigned int higher_prime_index (unsigned long);
+static hashval_t htab_mod_1 (hashval_t, hashval_t, hashval_t, int);
+static hashval_t htab_mod (hashval_t, htab_t);
+static hashval_t htab_mod_m2 (hashval_t, htab_t);
+static hashval_t hash_pointer (const void *);
+static int eq_pointer (const void *, const void *);
+static int htab_expand (htab_t);
+static PTR *find_empty_slot_for_expand (htab_t, hashval_t);
+
+/* At some point, we could make these be NULL, and modify the
+ hash-table routines to handle NULL specially; that would avoid
+ function-call overhead for the common case of hashing pointers. */
+htab_hash htab_hash_pointer = hash_pointer;
+htab_eq htab_eq_pointer = eq_pointer;
+
+/* Table of primes and multiplicative inverses.
+
+ Note that these are not minimally reduced inverses. Unlike when generating
+ code to divide by a constant, we want to be able to use the same algorithm
+ all the time. All of these inverses (are implied to) have bit 32 set.
+
+ For the record, here's the function that computed the table; it's a
+ vastly simplified version of the function of the same name from gcc. */
+
+#if 0
+unsigned int
+ceil_log2 (unsigned int x)
+{
+ int i;
+ for (i = 31; i >= 0 ; --i)
+ if (x > (1u << i))
+ return i+1;
+ abort ();
+}
+
+unsigned int
+choose_multiplier (unsigned int d, unsigned int *mlp, unsigned char *shiftp)
+{
+ unsigned long long mhigh;
+ double nx;
+ int lgup, post_shift;
+ int pow, pow2;
+ int n = 32, precision = 32;
+
+ lgup = ceil_log2 (d);
+ pow = n + lgup;
+ pow2 = n + lgup - precision;
+
+ nx = ldexp (1.0, pow) + ldexp (1.0, pow2);
+ mhigh = nx / d;
+
+ *shiftp = lgup - 1;
+ *mlp = mhigh;
+ return mhigh >> 32;
+}
+#endif
+
+struct prime_ent
+{
+ hashval_t prime;
+ hashval_t inv;
+ hashval_t inv_m2; /* inverse of prime-2 */
+ hashval_t shift;
+};
+
+static struct prime_ent const prime_tab[] = {
+ { 7, 0x24924925, 0x9999999b, 2 },
+ { 13, 0x3b13b13c, 0x745d1747, 3 },
+ { 31, 0x08421085, 0x1a7b9612, 4 },
+ { 61, 0x0c9714fc, 0x15b1e5f8, 5 },
+ { 127, 0x02040811, 0x0624dd30, 6 },
+ { 251, 0x05197f7e, 0x073260a5, 7 },
+ { 509, 0x01824366, 0x02864fc8, 8 },
+ { 1021, 0x00c0906d, 0x014191f7, 9 },
+ { 2039, 0x0121456f, 0x0161e69e, 10 },
+ { 4093, 0x00300902, 0x00501908, 11 },
+ { 8191, 0x00080041, 0x00180241, 12 },
+ { 16381, 0x000c0091, 0x00140191, 13 },
+ { 32749, 0x002605a5, 0x002a06e6, 14 },
+ { 65521, 0x000f00e2, 0x00110122, 15 },
+ { 131071, 0x00008001, 0x00018003, 16 },
+ { 262139, 0x00014002, 0x0001c004, 17 },
+ { 524287, 0x00002001, 0x00006001, 18 },
+ { 1048573, 0x00003001, 0x00005001, 19 },
+ { 2097143, 0x00004801, 0x00005801, 20 },
+ { 4194301, 0x00000c01, 0x00001401, 21 },
+ { 8388593, 0x00001e01, 0x00002201, 22 },
+ { 16777213, 0x00000301, 0x00000501, 23 },
+ { 33554393, 0x00001381, 0x00001481, 24 },
+ { 67108859, 0x00000141, 0x000001c1, 25 },
+ { 134217689, 0x000004e1, 0x00000521, 26 },
+ { 268435399, 0x00000391, 0x000003b1, 27 },
+ { 536870909, 0x00000019, 0x00000029, 28 },
+ { 1073741789, 0x0000008d, 0x00000095, 29 },
+ { 2147483647, 0x00000003, 0x00000007, 30 },
+ /* Avoid "decimal constant so large it is unsigned" for 4294967291. */
+ { 0xfffffffb, 0x00000006, 0x00000008, 31 }
+};
+
+/* The following function returns an index into the above table of the
+ nearest prime number which is greater than N, and near a power of two. */
+
+static unsigned int
+higher_prime_index (unsigned long n)
+{
+ unsigned int low = 0;
+ unsigned int high = sizeof(prime_tab) / sizeof(prime_tab[0]);
+
+ while (low != high)
+ {
+ unsigned int mid = low + (high - low) / 2;
+ if (n > prime_tab[mid].prime)
+ low = mid + 1;
+ else
+ high = mid;
+ }
+
+ /* If we've run out of primes, abort. */
+ if (n > prime_tab[low].prime)
+ {
+ fprintf (stderr, "Cannot find prime bigger than %lu\n", n);
+ abort ();
+ }
+
+ return low;
+}
-static int all_searches = 0;
+/* Returns a hash code for P. */
+
+static hashval_t
+hash_pointer (const PTR p)
+{
+ return (hashval_t) ((long)p >> 3);
+}
-/* The following variable is used for debugging. Its value is number
- of collisions fixed for time of work with all hash tables. */
+/* Returns non-zero if P1 and P2 are equal. */
-static int all_collisions = 0;
+static int
+eq_pointer (const PTR p1, const PTR p2)
+{
+ return p1 == p2;
+}
-/* The following variable is used for debugging. Its value is number
- of all table expansions fixed for time of work with all hash
- tables. */
-static int all_expansions = 0;
+/* The parens around the function names in the next two definitions
+ are essential in order to prevent macro expansions of the name.
+ The bodies, however, are expanded as expected, so they are not
+ recursive definitions. */
-/* This macro defines reserved value for empty table entry. */
+/* Return the current size of given hash table. */
-#define EMPTY_ENTRY NULL
+#define htab_size(htab) ((htab)->size)
-/* This macro defines reserved value for table entry which contained
- a deleted element. */
+size_t
+(htab_size) (htab_t htab)
+{
+ return htab_size (htab);
+}
-#define DELETED_ENTRY ((void *) 1)
+/* Return the current number of elements in given hash table. */
-/* The following function returns the nearest prime number which is
- greater than given source number. */
+#define htab_elements(htab) ((htab)->n_elements - (htab)->n_deleted)
-static unsigned long
-higher_prime_number (number)
- unsigned long number;
+size_t
+(htab_elements) (htab_t htab)
{
- unsigned long i;
+ return htab_elements (htab);
+}
- for (number = (number / 2) * 2 + 3;; number += 2)
+/* Return X % Y. */
+
+static inline hashval_t
+htab_mod_1 (hashval_t x, hashval_t y, hashval_t inv, int shift)
+{
+ /* The multiplicative inverses computed above are for 32-bit types, and
+ requires that we be able to compute a highpart multiply. */
+#ifdef UNSIGNED_64BIT_TYPE
+ __extension__ typedef UNSIGNED_64BIT_TYPE ull;
+ if (sizeof (hashval_t) * CHAR_BIT <= 32)
{
- for (i = 3; i * i <= number; i += 2)
- if (number % i == 0)
- break;
- if (i * i > number)
- return number;
+ hashval_t t1, t2, t3, t4, q, r;
+
+ t1 = ((ull)x * inv) >> 32;
+ t2 = x - t1;
+ t3 = t2 >> 1;
+ t4 = t1 + t3;
+ q = t4 >> shift;
+ r = x - (q * y);
+
+ return r;
}
+#endif
+
+ /* Otherwise just use the native division routines. */
+ return x % y;
+}
+
+/* Compute the primary hash for HASH given HTAB's current size. */
+
+static inline hashval_t
+htab_mod (hashval_t hash, htab_t htab)
+{
+ const struct prime_ent *p = &prime_tab[htab->size_prime_index];
+ return htab_mod_1 (hash, p->prime, p->inv, p->shift);
+}
+
+/* Compute the secondary hash for HASH given HTAB's current size. */
+
+static inline hashval_t
+htab_mod_m2 (hashval_t hash, htab_t htab)
+{
+ const struct prime_ent *p = &prime_tab[htab->size_prime_index];
+ return 1 + htab_mod_1 (hash, p->prime - 2, p->inv_m2, p->shift);
}
/* This function creates table with length slightly longer than given
source length. Created hash table is initiated as empty (all the
- hash table entries are EMPTY_ENTRY). The function returns the
- created hash table. */
+ hash table entries are HTAB_EMPTY_ENTRY). The function returns the
+ created hash table, or NULL if memory allocation fails. */
+
+htab_t
+htab_create_alloc (size_t size, htab_hash hash_f, htab_eq eq_f,
+ htab_del del_f, htab_alloc alloc_f, htab_free free_f)
+{
+ htab_t result;
+ unsigned int size_prime_index;
+
+ size_prime_index = higher_prime_index (size);
+ size = prime_tab[size_prime_index].prime;
-hash_table_t
-create_hash_table (size, hash_function, eq_function)
- size_t size;
- unsigned (*hash_function) PARAMS ((hash_table_entry_t));
- int (*eq_function) PARAMS ((hash_table_entry_t, hash_table_entry_t));
+ result = (htab_t) (*alloc_f) (1, sizeof (struct htab));
+ if (result == NULL)
+ return NULL;
+ result->entries = (PTR *) (*alloc_f) (size, sizeof (PTR));
+ if (result->entries == NULL)
+ {
+ if (free_f != NULL)
+ (*free_f) (result);
+ return NULL;
+ }
+ result->size = size;
+ result->size_prime_index = size_prime_index;
+ result->hash_f = hash_f;
+ result->eq_f = eq_f;
+ result->del_f = del_f;
+ result->alloc_f = alloc_f;
+ result->free_f = free_f;
+ return result;
+}
+
+/* As above, but use the variants of alloc_f and free_f which accept
+ an extra argument. */
+
+htab_t
+htab_create_alloc_ex (size_t size, htab_hash hash_f, htab_eq eq_f,
+ htab_del del_f, void *alloc_arg,
+ htab_alloc_with_arg alloc_f,
+ htab_free_with_arg free_f)
{
- hash_table_t result;
+ htab_t result;
+ unsigned int size_prime_index;
+
+ size_prime_index = higher_prime_index (size);
+ size = prime_tab[size_prime_index].prime;
- size = higher_prime_number (size);
- result = (hash_table_t) xmalloc (sizeof (*result));
- result->entries
- = (hash_table_entry_t *) xmalloc (size * sizeof (hash_table_entry_t));
+ result = (htab_t) (*alloc_f) (alloc_arg, 1, sizeof (struct htab));
+ if (result == NULL)
+ return NULL;
+ result->entries = (PTR *) (*alloc_f) (alloc_arg, size, sizeof (PTR));
+ if (result->entries == NULL)
+ {
+ if (free_f != NULL)
+ (*free_f) (alloc_arg, result);
+ return NULL;
+ }
result->size = size;
- result->hash_function = hash_function;
- result->eq_function = eq_function;
- result->number_of_elements = 0;
- result->number_of_deleted_elements = 0;
- result->searches = 0;
- result->collisions = 0;
- memset (result->entries, 0, size * sizeof (hash_table_entry_t));
+ result->size_prime_index = size_prime_index;
+ result->hash_f = hash_f;
+ result->eq_f = eq_f;
+ result->del_f = del_f;
+ result->alloc_arg = alloc_arg;
+ result->alloc_with_arg_f = alloc_f;
+ result->free_with_arg_f = free_f;
return result;
}
+/* Update the function pointers and allocation parameter in the htab_t. */
+
+void
+htab_set_functions_ex (htab_t htab, htab_hash hash_f, htab_eq eq_f,
+ htab_del del_f, PTR alloc_arg,
+ htab_alloc_with_arg alloc_f, htab_free_with_arg free_f)
+{
+ htab->hash_f = hash_f;
+ htab->eq_f = eq_f;
+ htab->del_f = del_f;
+ htab->alloc_arg = alloc_arg;
+ htab->alloc_with_arg_f = alloc_f;
+ htab->free_with_arg_f = free_f;
+}
+
+/* These functions exist solely for backward compatibility. */
+
+#undef htab_create
+htab_t
+htab_create (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f)
+{
+ return htab_create_alloc (size, hash_f, eq_f, del_f, xcalloc, free);
+}
+
+htab_t
+htab_try_create (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f)
+{
+ return htab_create_alloc (size, hash_f, eq_f, del_f, calloc, free);
+}
+
/* This function frees all memory allocated for given hash table.
Naturally the hash table must already exist. */
void
-delete_hash_table (htab)
- hash_table_t htab;
+htab_delete (htab_t htab)
{
- free (htab->entries);
- free (htab);
+ size_t size = htab_size (htab);
+ PTR *entries = htab->entries;
+ int i;
+
+ if (htab->del_f)
+ for (i = size - 1; i >= 0; i--)
+ if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY)
+ (*htab->del_f) (entries[i]);
+
+ if (htab->free_f != NULL)
+ {
+ (*htab->free_f) (entries);
+ (*htab->free_f) (htab);
+ }
+ else if (htab->free_with_arg_f != NULL)
+ {
+ (*htab->free_with_arg_f) (htab->alloc_arg, entries);
+ (*htab->free_with_arg_f) (htab->alloc_arg, htab);
+ }
}
/* This function clears all entries in the given hash table. */
void
-empty_hash_table (htab)
- hash_table_t htab;
+htab_empty (htab_t htab)
+{
+ size_t size = htab_size (htab);
+ PTR *entries = htab->entries;
+ int i;
+
+ if (htab->del_f)
+ for (i = size - 1; i >= 0; i--)
+ if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY)
+ (*htab->del_f) (entries[i]);
+
+ memset (entries, 0, size * sizeof (PTR));
+}
+
+/* Similar to htab_find_slot, but without several unwanted side effects:
+ - Does not call htab->eq_f when it finds an existing entry.
+ - Does not change the count of elements/searches/collisions in the
+ hash table.
+ This function also assumes there are no deleted entries in the table.
+ HASH is the hash value for the element to be inserted. */
+
+static PTR *
+find_empty_slot_for_expand (htab_t htab, hashval_t hash)
{
- memset (htab->entries, 0, htab->size * sizeof (hash_table_entry_t));
+ hashval_t index = htab_mod (hash, htab);
+ size_t size = htab_size (htab);
+ PTR *slot = htab->entries + index;
+ hashval_t hash2;
+
+ if (*slot == HTAB_EMPTY_ENTRY)
+ return slot;
+ else if (*slot == HTAB_DELETED_ENTRY)
+ abort ();
+
+ hash2 = htab_mod_m2 (hash, htab);
+ for (;;)
+ {
+ index += hash2;
+ if (index >= size)
+ index -= size;
+
+ slot = htab->entries + index;
+ if (*slot == HTAB_EMPTY_ENTRY)
+ return slot;
+ else if (*slot == HTAB_DELETED_ENTRY)
+ abort ();
+ }
}
/* The following function changes size of memory allocated for the
entries and repeatedly inserts the table elements. The occupancy
of the table after the call will be about 50%. Naturally the hash
table must already exist. Remember also that the place of the
- table entries is changed. */
+ table entries is changed. If memory allocation failures are allowed,
+ this function will return zero, indicating that the table could not be
+ expanded. If all goes well, it will return a non-zero value. */
-static void
-expand_hash_table (htab)
- hash_table_t htab;
+static int
+htab_expand (htab_t htab)
{
- hash_table_t new_htab;
- hash_table_entry_t *entry_ptr;
- hash_table_entry_t *new_entry_ptr;
+ PTR *oentries;
+ PTR *olimit;
+ PTR *p;
+ PTR *nentries;
+ size_t nsize, osize, elts;
+ unsigned int oindex, nindex;
+
+ oentries = htab->entries;
+ oindex = htab->size_prime_index;
+ osize = htab->size;
+ olimit = oentries + osize;
+ elts = htab_elements (htab);
+
+ /* Resize only when table after removal of unused elements is either
+ too full or too empty. */
+ if (elts * 2 > osize || (elts * 8 < osize && osize > 32))
+ {
+ nindex = higher_prime_index (elts * 2);
+ nsize = prime_tab[nindex].prime;
+ }
+ else
+ {
+ nindex = oindex;
+ nsize = osize;
+ }
- new_htab = create_hash_table (htab->number_of_elements * 2,
- htab->hash_function, htab->eq_function);
- for (entry_ptr = htab->entries; entry_ptr < htab->entries + htab->size;
- entry_ptr++)
- if (*entry_ptr != EMPTY_ENTRY && *entry_ptr != DELETED_ENTRY)
- {
- new_entry_ptr = find_hash_table_entry (new_htab, *entry_ptr, 1);
- *new_entry_ptr = (*entry_ptr);
- }
- free (htab->entries);
- *htab = (*new_htab);
- free (new_htab);
-}
-
-/* This function searches for hash table entry which contains element
- equal to given value or empty entry in which given value can be
- placed (if the element with given value does not exist in the
- table). The function works in two regimes. The first regime is
- used only for search. The second is used for search and
- reservation empty entry for given value. The table is expanded if
- occupancy (taking into accout also deleted elements) is more than
- 75%. Naturally the hash table must already exist. If reservation
- flag is TRUE then the element with given value should be inserted
- into the table entry before another call of
- `find_hash_table_entry'. */
-
-hash_table_entry_t *
-find_hash_table_entry (htab, element, reserve)
- hash_table_t htab;
- hash_table_entry_t element;
- int reserve;
-{
- hash_table_entry_t *entry_ptr;
- hash_table_entry_t *first_deleted_entry_ptr;
- unsigned index, hash_value, secondary_hash_value;
-
- if (htab->size * 3 <= htab->number_of_elements * 4)
+ if (htab->alloc_with_arg_f != NULL)
+ nentries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize,
+ sizeof (PTR *));
+ else
+ nentries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *));
+ if (nentries == NULL)
+ return 0;
+ htab->entries = nentries;
+ htab->size = nsize;
+ htab->size_prime_index = nindex;
+ htab->n_elements -= htab->n_deleted;
+ htab->n_deleted = 0;
+
+ p = oentries;
+ do
{
- all_expansions++;
- expand_hash_table (htab);
+ PTR x = *p;
+
+ if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY)
+ {
+ PTR *q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x));
+
+ *q = x;
+ }
+
+ p++;
}
- hash_value = (*htab->hash_function) (element);
- secondary_hash_value = 1 + hash_value % (htab->size - 2);
- index = hash_value % htab->size;
+ while (p < olimit);
+
+ if (htab->free_f != NULL)
+ (*htab->free_f) (oentries);
+ else if (htab->free_with_arg_f != NULL)
+ (*htab->free_with_arg_f) (htab->alloc_arg, oentries);
+ return 1;
+}
+
+/* This function searches for a hash table entry equal to the given
+ element. It cannot be used to insert or delete an element. */
+
+PTR
+htab_find_with_hash (htab_t htab, const PTR element, hashval_t hash)
+{
+ hashval_t index, hash2;
+ size_t size;
+ PTR entry;
+
htab->searches++;
- all_searches++;
- first_deleted_entry_ptr = NULL;
- for (;;htab->collisions++, all_collisions++)
+ size = htab_size (htab);
+ index = htab_mod (hash, htab);
+
+ entry = htab->entries[index];
+ if (entry == HTAB_EMPTY_ENTRY
+ || (entry != HTAB_DELETED_ENTRY && (*htab->eq_f) (entry, element)))
+ return entry;
+
+ hash2 = htab_mod_m2 (hash, htab);
+ for (;;)
{
- entry_ptr = htab->entries + index;
- if (*entry_ptr == EMPTY_ENTRY)
- {
- if (reserve)
- {
- htab->number_of_elements++;
- if (first_deleted_entry_ptr != NULL)
- {
- entry_ptr = first_deleted_entry_ptr;
- *entry_ptr = EMPTY_ENTRY;
- }
- }
- break;
- }
- else if (*entry_ptr != DELETED_ENTRY)
- {
- if ((*htab->eq_function) (*entry_ptr, element))
- break;
- }
- else if (first_deleted_entry_ptr == NULL)
- first_deleted_entry_ptr = entry_ptr;
- index += secondary_hash_value;
- if (index >= htab->size)
- index -= htab->size;
+ htab->collisions++;
+ index += hash2;
+ if (index >= size)
+ index -= size;
+
+ entry = htab->entries[index];
+ if (entry == HTAB_EMPTY_ENTRY
+ || (entry != HTAB_DELETED_ENTRY && (*htab->eq_f) (entry, element)))
+ return entry;
}
- return entry_ptr;
}
-/* This function deletes element with given value from hash table.
- The hash table entry value will be `DELETED_ENTRY' after the
- function call. Naturally the hash table must already exist. Hash
- table entry for given value should be not empty (or deleted). */
+/* Like htab_find_slot_with_hash, but compute the hash value from the
+ element. */
+
+PTR
+htab_find (htab_t htab, const PTR element)
+{
+ return htab_find_with_hash (htab, element, (*htab->hash_f) (element));
+}
+
+/* This function searches for a hash table slot containing an entry
+ equal to the given element. To delete an entry, call this with
+ insert=NO_INSERT, then call htab_clear_slot on the slot returned
+ (possibly after doing some checks). To insert an entry, call this
+ with insert=INSERT, then write the value you want into the returned
+ slot. When inserting an entry, NULL may be returned if memory
+ allocation fails. */
+
+PTR *
+htab_find_slot_with_hash (htab_t htab, const PTR element,
+ hashval_t hash, enum insert_option insert)
+{
+ PTR *first_deleted_slot;
+ hashval_t index, hash2;
+ size_t size;
+ PTR entry;
+
+ size = htab_size (htab);
+ if (insert == INSERT && size * 3 <= htab->n_elements * 4)
+ {
+ if (htab_expand (htab) == 0)
+ return NULL;
+ size = htab_size (htab);
+ }
+
+ index = htab_mod (hash, htab);
+
+ htab->searches++;
+ first_deleted_slot = NULL;
+
+ entry = htab->entries[index];
+ if (entry == HTAB_EMPTY_ENTRY)
+ goto empty_entry;
+ else if (entry == HTAB_DELETED_ENTRY)
+ first_deleted_slot = &htab->entries[index];
+ else if ((*htab->eq_f) (entry, element))
+ return &htab->entries[index];
+
+ hash2 = htab_mod_m2 (hash, htab);
+ for (;;)
+ {
+ htab->collisions++;
+ index += hash2;
+ if (index >= size)
+ index -= size;
+
+ entry = htab->entries[index];
+ if (entry == HTAB_EMPTY_ENTRY)
+ goto empty_entry;
+ else if (entry == HTAB_DELETED_ENTRY)
+ {
+ if (!first_deleted_slot)
+ first_deleted_slot = &htab->entries[index];
+ }
+ else if ((*htab->eq_f) (entry, element))
+ return &htab->entries[index];
+ }
+
+ empty_entry:
+ if (insert == NO_INSERT)
+ return NULL;
+
+ if (first_deleted_slot)
+ {
+ htab->n_deleted--;
+ *first_deleted_slot = HTAB_EMPTY_ENTRY;
+ return first_deleted_slot;
+ }
+
+ htab->n_elements++;
+ return &htab->entries[index];
+}
+
+/* Like htab_find_slot_with_hash, but compute the hash value from the
+ element. */
+
+PTR *
+htab_find_slot (htab_t htab, const PTR element, enum insert_option insert)
+{
+ return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element),
+ insert);
+}
+
+/* This function deletes an element with the given value from hash
+ table (the hash is computed from the element). If there is no matching
+ element in the hash table, this function does nothing. */
void
-remove_element_from_hash_table_entry (htab, element)
- hash_table_t htab;
- hash_table_entry_t element;
+htab_remove_elt (htab_t htab, PTR element)
{
- hash_table_entry_t *entry_ptr;
+ htab_remove_elt_with_hash (htab, element, (*htab->hash_f) (element));
+}
+
+
+/* This function deletes an element with the given value from hash
+ table. If there is no matching element in the hash table, this
+ function does nothing. */
+
+void
+htab_remove_elt_with_hash (htab_t htab, PTR element, hashval_t hash)
+{
+ PTR *slot;
+
+ slot = htab_find_slot_with_hash (htab, element, hash, NO_INSERT);
+ if (*slot == HTAB_EMPTY_ENTRY)
+ return;
+
+ if (htab->del_f)
+ (*htab->del_f) (*slot);
- entry_ptr = find_hash_table_entry (htab, element, 0);
- *entry_ptr = DELETED_ENTRY;
- htab->number_of_deleted_elements++;
+ *slot = HTAB_DELETED_ENTRY;
+ htab->n_deleted++;
}
-/* This function clears a specified slot in a hash table.
- It is useful when you've already done the lookup and don't want to
- do it again. */
+/* This function clears a specified slot in a hash table. It is
+ useful when you've already done the lookup and don't want to do it
+ again. */
void
-clear_hash_table_slot (htab, slot)
- hash_table_t htab;
- hash_table_entry_t *slot;
+htab_clear_slot (htab_t htab, PTR *slot)
{
- if (slot < htab->entries || slot >= htab->entries + htab->size
- || *slot == EMPTY_ENTRY || *slot == DELETED_ENTRY)
+ if (slot < htab->entries || slot >= htab->entries + htab_size (htab)
+ || *slot == HTAB_EMPTY_ENTRY || *slot == HTAB_DELETED_ENTRY)
abort ();
- *slot = DELETED_ENTRY;
- htab->number_of_deleted_elements++;
+
+ if (htab->del_f)
+ (*htab->del_f) (*slot);
+
+ *slot = HTAB_DELETED_ENTRY;
+ htab->n_deleted++;
}
/* This function scans over the entire hash table calling
argument. */
void
-traverse_hash_table (htab, callback, info)
- hash_table_t htab;
- int (*callback) PARAMS ((hash_table_entry_t, void *));
- void *info;
+htab_traverse_noresize (htab_t htab, htab_trav callback, PTR info)
{
- hash_table_entry_t *entry_ptr;
- for (entry_ptr = htab->entries; entry_ptr < htab->entries + htab->size;
- entry_ptr++)
- if (*entry_ptr != EMPTY_ENTRY && *entry_ptr != DELETED_ENTRY)
- if (!callback (*entry_ptr, info))
- break;
+ PTR *slot;
+ PTR *limit;
+
+ slot = htab->entries;
+ limit = slot + htab_size (htab);
+
+ do
+ {
+ PTR x = *slot;
+
+ if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY)
+ if (!(*callback) (slot, info))
+ break;
+ }
+ while (++slot < limit);
}
-/* The following function returns current size of given hash table. */
+/* Like htab_traverse_noresize, but does resize the table when it is
+ too empty to improve effectivity of subsequent calls. */
-size_t
-hash_table_size (htab)
- hash_table_t htab;
+void
+htab_traverse (htab_t htab, htab_trav callback, PTR info)
{
- return htab->size;
+ if (htab_elements (htab) * 8 < htab_size (htab))
+ htab_expand (htab);
+
+ htab_traverse_noresize (htab, callback, info);
}
-/* The following function returns current number of elements in given
+/* Return the fraction of fixed collisions during all work with given
hash table. */
-size_t
-hash_table_elements_number (htab)
- hash_table_t htab;
+double
+htab_collisions (htab_t htab)
{
- return htab->number_of_elements - htab->number_of_deleted_elements;
-}
+ if (htab->searches == 0)
+ return 0.0;
-/* The following function returns number of percents of fixed
- collisions during all work with given hash table. */
+ return (double) htab->collisions / (double) htab->searches;
+}
-int
-hash_table_collisions (htab)
- hash_table_t htab;
+/* Hash P as a null-terminated string.
+
+ Copied from gcc/hashtable.c. Zack had the following to say with respect
+ to applicability, though note that unlike hashtable.c, this hash table
+ implementation re-hashes rather than chain buckets.
+
+ http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01021.html
+ From: Zack Weinberg <zackw@panix.com>
+ Date: Fri, 17 Aug 2001 02:15:56 -0400
+
+ I got it by extracting all the identifiers from all the source code
+ I had lying around in mid-1999, and testing many recurrences of
+ the form "H_n = H_{n-1} * K + c_n * L + M" where K, L, M were either
+ prime numbers or the appropriate identity. This was the best one.
+ I don't remember exactly what constituted "best", except I was
+ looking at bucket-length distributions mostly.
+
+ So it should be very good at hashing identifiers, but might not be
+ as good at arbitrary strings.
+
+ I'll add that it thoroughly trounces the hash functions recommended
+ for this use at http://burtleburtle.net/bob/hash/index.html, both
+ on speed and bucket distribution. I haven't tried it against the
+ function they just started using for Perl's hashes. */
+
+hashval_t
+htab_hash_string (const PTR p)
{
- int searches;
+ const unsigned char *str = (const unsigned char *) p;
+ hashval_t r = 0;
+ unsigned char c;
- searches = htab->searches;
- if (searches == 0)
- searches++;
- return htab->collisions * 100 / searches;
+ while ((c = *str++) != 0)
+ r = r * 67 + c - 113;
+
+ return r;
}
-/* The following function returns number of percents of fixed
- collisions during all work with all hash tables. */
+/* DERIVED FROM:
+--------------------------------------------------------------------
+lookup2.c, by Bob Jenkins, December 1996, Public Domain.
+hash(), hash2(), hash3, and mix() are externally useful functions.
+Routines to test the hash are included if SELF_TEST is defined.
+You can use this free for any purpose. It has no warranty.
+--------------------------------------------------------------------
+*/
+
+/*
+--------------------------------------------------------------------
+mix -- mix 3 32-bit values reversibly.
+For every delta with one or two bit set, and the deltas of all three
+ high bits or all three low bits, whether the original value of a,b,c
+ is almost all zero or is uniformly distributed,
+* If mix() is run forward or backward, at least 32 bits in a,b,c
+ have at least 1/4 probability of changing.
+* If mix() is run forward, every bit of c will change between 1/3 and
+ 2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.)
+mix() was built out of 36 single-cycle latency instructions in a
+ structure that could supported 2x parallelism, like so:
+ a -= b;
+ a -= c; x = (c>>13);
+ b -= c; a ^= x;
+ b -= a; x = (a<<8);
+ c -= a; b ^= x;
+ c -= b; x = (b>>13);
+ ...
+ Unfortunately, superscalar Pentiums and Sparcs can't take advantage
+ of that parallelism. They've also turned some of those single-cycle
+ latency instructions into multi-cycle latency instructions. Still,
+ this is the fastest good hash I could find. There were about 2^^68
+ to choose from. I only looked at a billion or so.
+--------------------------------------------------------------------
+*/
+/* same, but slower, works on systems that might have 8 byte hashval_t's */
+#define mix(a,b,c) \
+{ \
+ a -= b; a -= c; a ^= (c>>13); \
+ b -= c; b -= a; b ^= (a<< 8); \
+ c -= a; c -= b; c ^= ((b&0xffffffff)>>13); \
+ a -= b; a -= c; a ^= ((c&0xffffffff)>>12); \
+ b -= c; b -= a; b = (b ^ (a<<16)) & 0xffffffff; \
+ c -= a; c -= b; c = (c ^ (b>> 5)) & 0xffffffff; \
+ a -= b; a -= c; a = (a ^ (c>> 3)) & 0xffffffff; \
+ b -= c; b -= a; b = (b ^ (a<<10)) & 0xffffffff; \
+ c -= a; c -= b; c = (c ^ (b>>15)) & 0xffffffff; \
+}
-int
-all_hash_table_collisions ()
+/*
+--------------------------------------------------------------------
+hash() -- hash a variable-length key into a 32-bit value
+ k : the key (the unaligned variable-length array of bytes)
+ len : the length of the key, counting by bytes
+ level : can be any 4-byte value
+Returns a 32-bit value. Every bit of the key affects every bit of
+the return value. Every 1-bit and 2-bit delta achieves avalanche.
+About 36+6len instructions.
+
+The best hash table sizes are powers of 2. There is no need to do
+mod a prime (mod is sooo slow!). If you need less than 32 bits,
+use a bitmask. For example, if you need only 10 bits, do
+ h = (h & hashmask(10));
+In which case, the hash table should have hashsize(10) elements.
+
+If you are hashing n strings (ub1 **)k, do it like this:
+ for (i=0, h=0; i<n; ++i) h = hash( k[i], len[i], h);
+
+By Bob Jenkins, 1996. bob_jenkins@burtleburtle.net. You may use this
+code any way you wish, private, educational, or commercial. It's free.
+
+See http://burtleburtle.net/bob/hash/evahash.html
+Use for hash table lookup, or anything where one collision in 2^32 is
+acceptable. Do NOT use for cryptographic purposes.
+--------------------------------------------------------------------
+*/
+
+hashval_t
+iterative_hash (const PTR k_in /* the key */,
+ register size_t length /* the length of the key */,
+ register hashval_t initval /* the previous hash, or
+ an arbitrary value */)
{
- int searches;
+ register const unsigned char *k = (const unsigned char *)k_in;
+ register hashval_t a,b,c,len;
+
+ /* Set up the internal state */
+ len = length;
+ a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
+ c = initval; /* the previous hash value */
+
+ /*---------------------------------------- handle most of the key */
+#ifndef WORDS_BIGENDIAN
+ /* On a little-endian machine, if the data is 4-byte aligned we can hash
+ by word for better speed. This gives nondeterministic results on
+ big-endian machines. */
+ if (sizeof (hashval_t) == 4 && (((size_t)k)&3) == 0)
+ while (len >= 12) /* aligned */
+ {
+ a += *(hashval_t *)(k+0);
+ b += *(hashval_t *)(k+4);
+ c += *(hashval_t *)(k+8);
+ mix(a,b,c);
+ k += 12; len -= 12;
+ }
+ else /* unaligned */
+#endif
+ while (len >= 12)
+ {
+ a += (k[0] +((hashval_t)k[1]<<8) +((hashval_t)k[2]<<16) +((hashval_t)k[3]<<24));
+ b += (k[4] +((hashval_t)k[5]<<8) +((hashval_t)k[6]<<16) +((hashval_t)k[7]<<24));
+ c += (k[8] +((hashval_t)k[9]<<8) +((hashval_t)k[10]<<16)+((hashval_t)k[11]<<24));
+ mix(a,b,c);
+ k += 12; len -= 12;
+ }
- searches = all_searches;
- if (searches == 0)
- searches++;
- return all_collisions * 100 / searches;
+ /*------------------------------------- handle the last 11 bytes */
+ c += length;
+ switch(len) /* all the case statements fall through */
+ {
+ case 11: c+=((hashval_t)k[10]<<24);
+ case 10: c+=((hashval_t)k[9]<<16);
+ case 9 : c+=((hashval_t)k[8]<<8);
+ /* the first byte of c is reserved for the length */
+ case 8 : b+=((hashval_t)k[7]<<24);
+ case 7 : b+=((hashval_t)k[6]<<16);
+ case 6 : b+=((hashval_t)k[5]<<8);
+ case 5 : b+=k[4];
+ case 4 : a+=((hashval_t)k[3]<<24);
+ case 3 : a+=((hashval_t)k[2]<<16);
+ case 2 : a+=((hashval_t)k[1]<<8);
+ case 1 : a+=k[0];
+ /* case 0: nothing left to add */
+ }
+ mix(a,b,c);
+ /*-------------------------------------------- report the result */
+ return c;
}