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authorJörg Frings-Fürst <debian@jff-webhosting.net>2023-12-17 14:18:48 +0100
committerJörg Frings-Fürst <debian@jff-webhosting.net>2023-12-17 14:18:48 +0100
commiteece9692d707ccb20356ec06955f8308c4e59ca7 (patch)
tree55186434884960d25d11736c8f846876d568fa08 /include/libHX/cast.h
parent987942a206ef0f2342bf81d5de6432c6af42b7e7 (diff)
New upstream version 4.19upstream/4.19
Diffstat (limited to 'include/libHX/cast.h')
-rw-r--r--include/libHX/cast.h129
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 */