From cb1a40859029f33184355475e51fec95afb79a73 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Yaroslav=20de=20la=20Pe=C3=B1a=20Smirnov?=
 <yps@yaroslavps.com>
Date: Sat, 22 Jul 2023 03:03:09 +0300
Subject: init

Just some C wares; hmap, list, optional, unit tests.
---
 utils.h | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 utils.h

(limited to 'utils.h')

diff --git a/utils.h b/utils.h
new file mode 100644
index 0000000..cb7d795
--- /dev/null
+++ b/utils.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: MIT */
+/**
+ * utils.h - useful macros for compile-time magic
+ *
+ * Inspired by similar macros in the Linux Kernel.
+ *
+ * Copyright (c) 2023 - Yaroslav de la Peña Smirnov
+ */
+#ifndef CWARE_UTILS_H
+#define CWARE_UTILS_H
+
+#include <stddef.h>
+
+#ifndef static_assert
+#define static_assert(exp, msg) _Static_assert(exp, msg)
+#endif
+
+#define same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
+
+#define container_of(ptr, T, member)                      \
+	({                                                    \
+		static_assert(same_type(*(ptr), ((T *)0)->member) \
+							  || same_type(*(ptr), void), \
+					  "type mismatch in container_of()"); \
+		(T *)((void *)(ptr)-offsetof(T, member));         \
+	})
+
+#define ARRAY_SIZE(arr)                             \
+	({                                              \
+		static_assert(!same_type((arr), &(arr)[0]), \
+					  "variable is not an array");  \
+		sizeof(arr) / sizeof(*arr);                 \
+	})
+
+#endif
-- 
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