hal/include/hal_stddef.h: add convenient container_of macro

5e33eaf5 · Lucas Russo · d2a6bee4 · 5e33eaf5
Commit 5e33eaf5 authored Aug 12, 2014 by Lucas Russo
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hal_stddef.h hal/include/hal_stddef.h +37 -0

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--- a/hal/include/hal_stddef.h
+++ b/hal/include/hal_stddef.h
+/*
+ * Copyright (C) 2014 LNLS (www.lnls.br)
+ * Author: Lucas Russo <lucas.russo@lnls.br>
+ *
+ * Released according to the GNU LGPL, version 3 or any later version.
+ */
+
+/* Cut from Linux sources */
+
+#ifndef _HAL_STDDEF_H_
+#define _HAL_STDDEF_H_
+
+#undef offsetof
+#ifdef __compiler_offsetof
+#define offsetof(type,member) __compiler_offsetof(type, member)
+#else
+#define offsetof(type, member) ((size_t) &((type *)0)->member)
+#endif
+
+/*
+* swap - swap value of @a and @b
+*/
+#define swap(a, b) \
+        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
+
+/*
+ * container_of - cast a member of a structure out to the containing structure
+ * @ptr:        the pointer to the member.
+ * @type:       the type of the container struct this is embedded in.
+ * @member:     the name of the member within the struct.
+ *
+ */
+#define container_of(ptr, type, member) ({                      \
+        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
+        (type *)( (char *)__mptr - offsetof(type,member) );})
+
+#endif