Fix: accept variable list of arguments from SIDE_PTR_INIT

[libside.git] / include / side / macros.h

diff --git a/include/side/macros.h b/include/side/macros.h
index 2f2181252eb2ffa660210a548b86dc43b81f4fda..20fa97e804f07d76aae19d2afe1fe765620e6812 100644 (file)
--- a/include/side/macros.h
+++ b/include/side/macros.h
@@ -7,6 +7,7 @@
 #define _SIDE_MACROS_H
 
 #include <stddef.h>
+#include <limits.h>
 
 /* Helper macros */
 
@@ -29,6 +30,30 @@
 
 #define SIDE_PARAM(...)        __VA_ARGS__
 
+/*
+ * SIDE_PARAM_SELECT_ARG1
+ *
+ * Select second argument. Use inside macros to implement optional last
+ * macro argument, such as:
+ *
+ * #define macro(_a, _b, _c, _optional...) \
+ *     SIDE_PARAM_SELECT_ARG1(_, ##_optional, do_default_macro())
+ *
+ * This macro is far from pretty, but attempts to create a cleaner layer
+ * on top fails for various reasons:
+ *
+ * - The libside API needs to use the default argument selection as an
+ *   argument to itself (recursively), e.g. for fields and for types, so
+ *   using the argument selection within an extra layer of macro fails
+ *   because the extra layer cannot expand recursively.
+ * - Attempts to make the extra layer of macro support recursion through
+ *   another layer of macros which expands all arguments failed because
+ *   the optional argument may contain commas, and is therefore expanded
+ *   into multiple arguments before argument selection, which fails to
+ *   select the optional argument content after its first comma.
+ */
+#define SIDE_PARAM_SELECT_ARG1(_arg0, _arg1, ...) _arg1
+
 /*
  * side_container_of - Get the address of an object containing a field.
  *
@@ -43,12 +68,59 @@
                (type *)((char *)__ptr - offsetof(type, member));       \
        })
 
+#define side_struct_field_sizeof(_struct, _field) \
+       sizeof(((_struct * )NULL)->_field)
+
 #if defined(__SIZEOF_LONG__)
-#define SIDE_BITS_PER_LONG     (__SIZEOF_LONG__ * 8)
+# define SIDE_BITS_PER_LONG    (__SIZEOF_LONG__ * 8)
 #elif defined(_LP64)
-#define SIDE_BITS_PER_LONG     64
+# define SIDE_BITS_PER_LONG    64
 #else
-#define SIDE_BITS_PER_LONG     32
+# define SIDE_BITS_PER_LONG    32
 #endif
 
+#define SIDE_PACKED    __attribute__((packed))
+
+/*
+ * The side_ptr macros allow defining a pointer type which is suitable
+ * for use by 32-bit and 64-bit kernels without compatibility code,
+ * while preserving information about the pointer type.
+ *
+ * Those pointers are stored as 64-bit integers, and the type of the
+ * actual pointer is kept alongside with the 64-bit pointer value in a
+ * 0-len array within a union.
+ *
+ * uintptr_t will fit within a uint64_t except on architectures with
+ * 128-bit pointers. This provides fixed-size pointers on architectures
+ * with pointer size of 64-bit or less. Architectures with larger
+ * pointer size will have to handle the ABI offset specifics explicitly.
+ */
+#if (__SIZEOF_POINTER__ <= 8)
+# define side_ptr_t(_type)                                     \
+       union {                                                 \
+               uint64_t v;                                     \
+               _type *t[0];                                    \
+       }
+# define side_ptr_get(_field)                                  \
+       ((__typeof__((_field).t[0]))(uintptr_t)(_field).v)
+# define side_ptr_set(_field, _ptr)                            \
+       do {                                                    \
+               (_field).v = (uint64_t)(uintptr_t)(_ptr);       \
+       } while (0)
+#else
+# define side_ptr_t(_type)                                     \
+       union {                                                 \
+               uintptr_t v;                                    \
+               _type *t[0];                                    \
+       }
+# define side_ptr_get(_field)                                  \
+       ((__typeof__((_field).t[0]))(_field).v)
+# define side_ptr_set(_field, _ptr)                            \
+       do {                                                    \
+               (_field).v = (uintptr_t)(_ptr);                 \
+       } while (0)
+#endif
+
+#define SIDE_PTR_INIT(...)     { .v = (uintptr_t) (__VA_ARGS__) }
+
 #endif /* _SIDE_MACROS_H */