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#ifndef _LIBHX_CAST_H
#define _LIBHX_CAST_H 1
#ifndef BUILD_BUG_ON_EXPR
# define BUILD_BUG_ON_EXPR(condition) (sizeof(char[1 - 2 * !!(condition)]) - 1)
#endif
#ifndef BUILD_BUG_ON
# define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_EXPR(condition))
#endif
#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 */
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