--- /dev/null
+/*
+ * Routines to provide a memory-efficient hashtable.
+ *
+ * Copyright (C) 2007 Wayne Davison
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, visit the http://fsf.org website.
+ */
+
+#include "rsync.h"
+
+#define HASH_LOAD_LIMIT(size) ((size)*3/4)
+
+struct hashtable *hashtable_create(int size, int key64)
+{
+ struct hashtable *tbl;
+ int node_size = key64 ? sizeof (struct ht_int64_node )
+ : sizeof (struct ht_int32_node);
+
+ /* Pick a power of 2 that can hold the requested size. */
+ if (size & (size-1) || size < 16) {
+ int req = size;
+ size = 16;
+ while (size < req)
+ size *= 2;
+ }
+
+ if (!(tbl = new(struct hashtable))
+ || !(tbl->nodes = new_array0(char, size * node_size)))
+ out_of_memory("hashtable_create");
+ tbl->size = size;
+ tbl->entries = 0;
+ tbl->node_size = node_size;
+
+ return tbl;
+}
+
+void hashtable_destroy(struct hashtable *tbl)
+{
+ free(tbl->nodes);
+ free(tbl);
+}
+
+/* This returns the node for the indicated key, either newly created or
+ * already existing. Returns NULL if not allocating and not found. */
+void *hashtable_find(struct hashtable *tbl, int64 key, int allocate_if_missing)
+{
+ int key64 = (tbl->node_size > sizeof (struct ht_int32_node));
+ struct ht_int32_node *node;
+ uint32 ndx;
+
+ if (allocate_if_missing && tbl->entries > HASH_LOAD_LIMIT(tbl->size)) {
+ void *old_nodes = tbl->nodes;
+ int size = tbl->size * 2;
+ int i;
+
+ if (!(tbl->nodes = new_array0(char, size * tbl->node_size)))
+ out_of_memory("hashtable_node");
+ tbl->size = size;
+ tbl->entries = 0;
+
+ for (i = size / 2; i-- > 0; ) {
+ struct ht_int32_node *move_node = HT_NODE(tbl, old_nodes, i);
+ int64 move_key = HT_KEY(move_node, key64);
+ if (move_key == 0)
+ continue;
+ node = hashtable_find(tbl, move_key, 1);
+ node->data = move_node->data;
+ }
+
+ free(old_nodes);
+ }
+
+ if (!key64) {
+ /* Based on Jenkins One-at-a-time hash. */
+ uchar buf[4], *keyp = buf;
+ int i;
+
+ SIVAL(buf, 0, key);
+ for (ndx = 0, i = 0; i < 4; i++) {
+ ndx += keyp[i];
+ ndx += (ndx << 10);
+ ndx ^= (ndx >> 6);
+ }
+ ndx += (ndx << 3);
+ ndx ^= (ndx >> 11);
+ ndx += (ndx << 15);
+ } else {
+ /* Based on Jenkins hashword() from lookup3.c. */
+ uint32 a, b, c;
+
+ /* Set up the internal state */
+ a = b = c = 0xdeadbeef + (8 << 2);
+
+#define rot(x,k) (((x)<<(k)) ^ ((x)>>(32-(k))))
+ b += (uint32)(key >> 32);
+ a += (uint32)key;
+ c ^= b; c -= rot(b, 14);
+ a ^= c; a -= rot(c, 11);
+ b ^= a; b -= rot(a, 25);
+ c ^= b; c -= rot(b, 16);
+ a ^= c; a -= rot(c, 4);
+ b ^= a; b -= rot(a, 14);
+ c ^= b; c -= rot(b, 24);
+#undef rot
+ ndx = c;
+ }
+
+ /* If it already exists, return the node. If we're not
+ * allocating, return NULL if the key is not found. */
+ while (1) {
+ int64 nkey;
+
+ ndx &= tbl->size - 1;
+ node = HT_NODE(tbl, tbl->nodes, ndx);
+ nkey = HT_KEY(node, key64);
+
+ if (nkey == key)
+ return node;
+ if (nkey == 0) {
+ if (!allocate_if_missing)
+ return NULL;
+ break;
+ }
+ ndx++;
+ }
+
+ /* Take over this empty spot and then return the node. */
+ if (key64)
+ ((struct ht_int64_node*)node)->key = key;
+ else
+ node->key = key;
+ tbl->entries++;
+ return node;
+}