diff -r 99a34860c105 -r d938228c382e src/ucx/cx/utils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ucx/cx/utils.h	Sun Nov 06 15:53:32 2022 +0100
@@ -0,0 +1,125 @@
+/*
+ * 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 utils.h
+ *
+ * \brief General purpose utility functions.
+ *
+ * \author Mike Becker
+ * \author Olaf Wintermann
+ * \version 3.0
+ * \copyright 2-Clause BSD License
+ */
+
+#ifndef UCX_UTILS_H
+#define UCX_UTILS_H
+
+#include "common.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Convenience macro for a for loop that counts from zero to n-1.
+ */
+#define cx_for_n(varname, n) for (size_t varname = 0 ; (varname) < (n) ; (varname)++)
+
+/* ----------------------
+ * cx_szmul() definition.
+ * ---------------------- */
+
+#if (__GNUC__ >= 5 || defined(__clang__)) && !defined(CX_NO_SZMUL_BUILTIN)
+#define CX_SZMUL_BUILTIN
+
+#if __WORDSIZE == 32
+/**
+ * Alias for \c __builtin_umul_overflow.
+ *
+ * Performs a multiplication of size_t values and checks for overflow.
+ *
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t, where the result should
+ * be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+#define cx_szmul(a, b, result) __builtin_umul_overflow(a, b, result)
+#else /* __WORDSIZE != 32 */
+/**
+ * Alias for \c __builtin_umull_overflow.
+ *
+ * Performs a multiplication of size_t values and checks for overflow.
+ *
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t, where the result should
+ * be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+#define cx_szmul(a, b, result) __builtin_umull_overflow(a, b, result)
+#endif /* __WORDSIZE */
+
+#else /* no GNUC or clang bultin */
+
+/**
+ * Performs a multiplication of size_t values and checks for overflow.
+  *
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t, where the result should
+ * be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+#define cx_szmul(a, b, result) cx_szmul_impl(a, b, result)
+
+/**
+ * Performs a multiplication of size_t values and checks for overflow.
+ *
+ * This is a custom implementation in case there is no compiler builtin
+ * available.
+ *
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t where the result should be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+int cx_szmul_impl(size_t a, size_t b, size_t *result);
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* UCX_UTILS_H */