Document caa_container_of

[urcu.git] / urcu / compiler.h

diff --git a/urcu/compiler.h b/urcu/compiler.h
index 54904cc4078ed144f8a25bc4778cea1ef7fd1319..f8fce5a6b46558fa4a4b2d50f78f91eecf229c90 100644 (file)
--- a/urcu/compiler.h
+++ b/urcu/compiler.h
@@ -55,10 +55,20 @@
 #define CAA_BITS_PER_LONG      32
 #endif
 
-#define caa_container_of(ptr, type, member)                                    \
+/*
+ * caa_container_of - Get the address of an object containing a field.
+ *
+ * @ptr: pointer to the field.
+ * @type: type of the object.
+ * @member: name of the field within the object.
+ */
+#define caa_container_of(ptr, type, member)                            \
        ({                                                              \
-               const typeof(((type *)NULL)->member) * __ptr = (ptr);   \
+               const typeof(((type *) NULL)->member) * __ptr = (ptr);  \
                (type *)((char *)__ptr - offsetof(type, member));       \
        })
 
+#define CAA_BUILD_BUG_ON_ZERO(cond) (sizeof(struct { int:-!!(cond); }))
+#define CAA_BUILD_BUG_ON(cond) ((void)BUILD_BUG_ON_ZERO(cond))
+
 #endif /* _URCU_COMPILER_H */