core/macros: add math helper macros

core/include/macros/math.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2022 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     core_macros
+ * @{
+ *
+ * @file
+ * @brief       Math helper macros
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ */
+
+#ifndef MACROS_MATH_H
+#define MACROS_MATH_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Returns the sign of @p a, either -1 or 1
+ */
+#define SIGNOF(a) _Generic(a, unsigned char: 1,          \
+                              unsigned short: 1,         \
+                              unsigned int: 1,           \
+                              unsigned long: 1,          \
+                              unsigned long long: 1,     \
+                              default: (long long)(a) < 0 ? -1 : 1)
+/**
+ * @brief Calculates @p a/ @p b with arithmetic rounding
+ */
+#define DIV_ROUND(a, b) (((a) + SIGNOF(a) * (b) / 2) / (b))
+
+/**
+ * @brief Calculates @p a/ @p b, always rounding up to the
+ *        next whole number
+ */
+#define DIV_ROUND_UP(a, b) (((a) + SIGNOF(a) * ((b) - SIGNOF(b))) / (b))
+
+/**
+ * @brief Align @p num with the next multiple of @p chunk
+ */
+#define MATH_ALIGN(num, chunk) ((chunk) * DIV_ROUND_UP(num, chunk))
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MACROS_MATH_H */
+/** @} */