New upstream version 4.19upstream/4.19

1 files changed, 129 insertions, 0 deletions

diff --git a/include/libHX/cast.h b/include/libHX/cast.h
new file mode 100644
index 0000000..cb2cba5
--- /dev/null
+++ b/include/libHX/cast.h
@@ -0,0 +1,129 @@
+#ifndef _LIBHX_CAST_H
+#define _LIBHX_CAST_H 1
+
+#ifdef __cplusplus
+#	ifndef const_cast
+#		define const_cast(T, x) const_cast<T>(x)
+#	endif
+#	ifndef static_cast
+#		define static_cast(T, x) static_cast<T>(x)
+#	endif
+#	define const_cast1(type, expr)      const_cast<type>(expr)
+#	define const_cast2(type, expr)      const_cast<type>(expr)
+#	define const_cast3(type, expr)      const_cast<type>(expr)
+
+template<typename new_type>
+static __inline__ new_type signed_cast(const char *expr)
+{
+	return reinterpret_cast<new_type>(expr);
+}
+
+template<typename new_type>
+static __inline__ new_type signed_cast(const signed char *expr)
+{
+	return reinterpret_cast<new_type>(expr);
+}
+
+template<typename new_type>
+static __inline__ new_type signed_cast(const unsigned char *expr)
+{
+	return reinterpret_cast<new_type>(expr);
+}
+
+template<typename new_type>
+static __inline__ new_type signed_cast(char *expr)
+{
+	return reinterpret_cast<new_type>(expr);
+}
+
+template<typename new_type>
+static __inline__ new_type signed_cast(signed char *expr)
+{
+	return reinterpret_cast<new_type>(expr);
+}
+
+template<typename new_type>
+static __inline__ new_type signed_cast(unsigned char *expr)
+{
+	return reinterpret_cast<new_type>(expr);
+}
+
+#else
+	/* N.B. signed_cast<> does not exist in C++. */
+#	define __signed_cast_compatible(a, b) \
+		__builtin_choose_expr( \
+			__builtin_types_compatible_p(b, const char *) || \
+			__builtin_types_compatible_p(b, const signed char *) || \
+			__builtin_types_compatible_p(b, const unsigned char *), \
+			/* if src has a const qualifier */ \
+			__builtin_types_compatible_p(a, const char *) || \
+			__builtin_types_compatible_p(a, const signed char *) || \
+			__builtin_types_compatible_p(a, const unsigned char *), \
+			/* and if it has none... */ \
+			__builtin_types_compatible_p(a, const char *) || \
+			__builtin_types_compatible_p(a, const signed char *) || \
+			__builtin_types_compatible_p(a, const unsigned char *) || \
+			__builtin_types_compatible_p(a, char *) || \
+			__builtin_types_compatible_p(a, signed char *) || \
+			__builtin_types_compatible_p(a, unsigned char *) \
+		)
+
+#	if defined(__GNUC__) && !defined(__clang__) && !defined(signed_cast)
+#		define signed_cast(type, expr) ({ \
+			BUILD_BUG_ON(!__signed_cast_compatible(__typeof__(type), __typeof__(expr))); \
+			(type)(expr); \
+		})
+#	endif
+#	if defined(__GNUC__) && !defined(__clang__) && !defined(static_cast)
+#		define static_cast(type, expr) \
+			((struct { type x; }){(expr)}.x)
+#	endif
+#	if defined(__GNUC__) && !defined(__clang__) && !defined(const_cast1)
+		/*
+		 * The idea starts with (in abstract notation)
+		 * 	typeof deref typeof expr
+		 * To deref something, we need an object, which we can get by
+		 * creating a temporary aggregate, such as a union, of which
+		 * the member is accessed and dereferenced.
+		 * 	*(union { __typeof__(expr) x; }){init}.x
+		 * union has two nice properties:
+		 * - with an additional dummy member, we do not have to
+		 *   initialize x according to its type, which, if expr is
+		 *   an array type, may want extra braces.
+		 * - and with that dummy member, we also avoid the ugly
+		 *   "literal 0 is implicitly convertible to a pointer".
+		 * Unfortunately, this all requires C99 compound initializers.
+		 * That's ok - gcc and clang only treat it as a warning even
+		 * under strict C89 - and if you still force strict C89 on
+		 * yourself, you have a lot to answer for either way.
+		 */
+#		define __const_cast_strip(ptrs, expr) \
+			__typeof__(ptrs(union { int z; __typeof__(expr) x; }){0}.x)
+#		define __const_cast_p(ptrs, new_type, expr) ((new_type)( \
+			(expr) + \
+			BUILD_BUG_ON_EXPR(!__builtin_types_compatible_p(__const_cast_strip(ptrs, expr), __const_cast_strip(ptrs, new_type))) \
+		))
+#		define const_cast1(new_type, expr) __const_cast_p(*, new_type, expr)
+#		define const_cast2(new_type, expr) __const_cast_p(**, new_type, expr)
+#		define const_cast3(new_type, expr) __const_cast_p(***, new_type, expr)
+#	endif
+#	ifndef signed_cast
+#		define signed_cast(type, expr)      ((type)(expr))
+#	endif
+#	ifndef static_cast
+#		define static_cast(type, expr)      ((type)(expr))
+#	endif
+#	ifndef const_cast
+#		define const_cast(type, expr)       ((type)(expr))
+#	endif
+#	ifndef const_cast1
+#		define const_cast1(type, expr)      ((type)(expr))
+#		define const_cast2(type, expr)      ((type)(expr))
+#		define const_cast3(type, expr)      ((type)(expr))
+#	endif
+#	ifndef reinterpret_cast
+#		define reinterpret_cast(type, expr) ((type)(expr))
+#	endif
+#endif
+
+#endif /* _LIBHX_CAST_H */