diff -r e79a60b3a7cb -r 7c3ff86ee9d4 ucx/cx/hash_map.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ucx/cx/hash_map.h	Tue May 23 11:11:28 2023 +0200
@@ -0,0 +1,134 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+/**
+ * \file hash_map.h
+ * \brief Hash map implementation.
+ * \author Mike Becker
+ * \author Olaf Wintermann
+ * \version 3.0
+ * \copyright 2-Clause BSD License
+ */
+
+#ifndef UCX_HASH_MAP_H
+#define UCX_HASH_MAP_H
+
+#include "map.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Internal structure for an element of a hash map. */
+struct cx_hash_map_element_s;
+
+/**
+ * Internal structure for a hash map.
+ */
+struct cx_hash_map_s {
+    /**
+     * Base structure for maps.
+     */
+    struct cx_map_s base;
+    /**
+     * The buckets of this map, each containing a linked list of elements.
+     */
+    struct cx_hash_map_element_s **buckets;
+    /**
+     * The number of buckets.
+     */
+    size_t bucket_count;
+};
+
+
+/**
+ * Creates a new hash map with the specified number of buckets.
+ *
+ * If \p buckets is zero, an implementation defined default will be used.
+ *
+ * If \p item_size is CX_STORE_POINTERS, the created map will be created as if
+ * cxMapStorePointers() was called immediately after creation.
+ *
+ * @note Iterators provided by this hash map implementation provide the remove operation.
+ * The index value of an iterator is the incremented when the iterator advanced without removal.
+ * In other words, when the iterator is finished, \c index==size .
+ *
+ * @param allocator the allocator to use
+ * @param itemsize the size of one element
+ * @param buckets the initial number of buckets in this hash map
+ * @return a pointer to the new hash map
+ */
+__attribute__((__nonnull__, __warn_unused_result__))
+CxMap *cxHashMapCreate(
+        CxAllocator const *allocator,
+        size_t itemsize,
+        size_t buckets
+);
+
+/**
+ * Creates a new hash map with a default number of buckets.
+ *
+ * If \p item_size is CX_STORE_POINTERS, the created map will be created as if
+ * cxMapStorePointers() was called immediately after creation.
+ *
+ * @note Iterators provided by this hash map implementation provide the remove operation.
+ * The index value of an iterator is the incremented when the iterator advanced without removal.
+ * In other words, when the iterator is finished, \c index==size .
+ *
+ * @param itemsize the size of one element
+ * @return a pointer to the new hash map
+ */
+#define cxHashMapCreateSimple(itemsize) \
+    cxHashMapCreate(cxDefaultAllocator, itemsize, 0)
+
+/**
+ * Increases the number of buckets, if necessary.
+ *
+ * The load threshold is \c 0.75*buckets. If the element count exceeds the load
+ * threshold, the map will be rehashed. Otherwise, no action is performed and
+ * this function simply returns 0.
+ *
+ * The rehashing process ensures, that the number of buckets is at least
+ * 2.5 times the element count. So there is enough room for additional
+ * elements without the need of another soon rehashing.
+ *
+ * You can use this function after filling a map to increase access performance.
+ *
+ * @note If the specified map is not a hash map, the behavior is undefined.
+ *
+ * @param map the map to rehash
+ * @return zero on success, non-zero if a memory allocation error occurred
+ */
+__attribute__((__nonnull__))
+int cxMapRehash(CxMap *map);
+
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif // UCX_HASH_MAP_H