endian: add constant versions.

[ccan] / ccan / htable / htable.c

diff --git a/ccan/htable/htable.c b/ccan/htable/htable.c
index ba5f0de530a1a68d7acd5649cfeca6a67e64142b..b7e65d11966acc96be83dffbb25a273fec153145 100644 (file)
--- a/ccan/htable/htable.c
+++ b/ccan/htable/htable.c
@@ -1,7 +1,6 @@
 /* Licensed under LGPLv2+ - see LICENSE file for details */
 #include <ccan/htable/htable.h>
 #include <ccan/compiler/compiler.h>
-#include <stdint.h>
 #include <stdlib.h>
 #include <limits.h>
 #include <stdbool.h>
@@ -10,17 +9,6 @@
 /* We use 0x1 as deleted marker. */
 #define HTABLE_DELETED (0x1)
 
-struct htable {
-       size_t (*rehash)(const void *elem, void *priv);
-       void *priv;
-       unsigned int bits;
-       size_t elems, deleted, max, max_with_deleted;
-       /* These are the bits which are the same in all pointers. */
-       uintptr_t common_mask, common_bits;
-       uintptr_t perfect_bit;
-       uintptr_t *table;
-};
-
 /* We clear out the bits which are always the same, and put metadata there. */
 static inline uintptr_t get_extra_ptr_bits(const struct htable *ht,
                                           uintptr_t e)
@@ -54,33 +42,21 @@ static inline uintptr_t get_hash_ptr_bits(const struct htable *ht,
                & ht->common_mask & ~ht->perfect_bit;
 }
 
-struct htable *htable_new(size_t (*rehash)(const void *elem, void *priv),
-                         void *priv)
+void htable_init(struct htable *ht,
+                size_t (*rehash)(const void *elem, void *priv), void *priv)
 {
-       struct htable *ht = malloc(sizeof(struct htable));
-       if (ht) {
-               ht->bits = 0;
-               ht->rehash = rehash;
-               ht->priv = priv;
-               ht->elems = 0;
-               ht->deleted = 0;
-               ht->max = 0;
-               ht->max_with_deleted = 0;
-               /* This guarantees we enter update_common first add. */
-               ht->common_mask = -1;
-               ht->common_bits = 0;
-               ht->perfect_bit = 0;
-               /* Dummy table until first insert. */
-               ht->table = &ht->perfect_bit;
-       }
-       return ht;
+       struct htable empty = HTABLE_INITIALIZER(empty, NULL, NULL);
+       *ht = empty;
+       ht->rehash = rehash;
+       ht->priv = priv;
+       ht->table = &ht->perfect_bit;
 }
 
-void htable_free(const struct htable *ht)
+void htable_clear(struct htable *ht)
 {
        if (ht->table != &ht->perfect_bit)
                free((void *)ht->table);
-       free((void *)ht);
+       htable_init(ht, ht->rehash, ht->priv);
 }
 
 static size_t hash_bucket(const struct htable *ht, size_t h)
@@ -221,8 +197,17 @@ static COLD void update_common(struct htable *ht, const void *p)
        uintptr_t maskdiff, bitsdiff;
 
        if (ht->elems == 0) {
-               ht->common_mask = -1;
-               ht->common_bits = (uintptr_t)p;
+               /* Always reveal one bit of the pointer in the bucket,
+                * so it's not zero or HTABLE_DELETED (1), even if
+                * hash happens to be 0.  Assumes (void *)1 is not a
+                * valid pointer. */
+               for (i = sizeof(uintptr_t)*CHAR_BIT - 1; i > 0; i--) {
+                       if ((uintptr_t)p & ((uintptr_t)1 << i))
+                               break;
+               }
+
+               ht->common_mask = ~((uintptr_t)1 << i);
+               ht->common_bits = ((uintptr_t)p & ht->common_mask);
                ht->perfect_bit = 1;
                return;
        }