/*********************************************************** Copyright (c) 2000, BeOpen.com. All rights reserved. See the file "Misc/COPYRIGHT" for information on usage and redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES. ******************************************************************/ #ifndef Py_PYPORT_H #define Py_PYPORT_H /************************************************************************** Symbols and macros to supply platform-independent interfaces to basic C language & library operations whose spellings vary across platforms. Please try to make documentation here as clear as possible: by definition, the stuff here is trying to illuminate C's darkest corners. Config #defines referenced here: SIGNED_RIGHT_SHIFT_ZERO_FILLS Meaning: To be defined iff i>>j does not extend the sign bit when i is a signed integral type and i < 0. Used in: Py_ARITHMETIC_RIGHT_SHIFT RETSIGTYPE Meaning: Expands to void or int, depending on what the platform wants signal handlers to return. Note that only void is ANSI! Used in: Py_RETURN_FROM_SIGNAL_HANDLER Py_DEBUG Meaning: Extra checks compiled in for debug mode. Used in: Py_SAFE_DOWNCAST **************************************************************************/ #ifdef __cplusplus extern "C" { #endif /* Py_ARITHMETIC_RIGHT_SHIFT * C doesn't define whether a right-shift of a signed integer sign-extends * or zero-fills. Here a macro to force sign extension: * Py_ARITHMETIC_RIGHT_SHIFT(TYPE, I, J) * Return I >> J, forcing sign extension. * Requirements: * I is of basic signed type TYPE (char, short, int, long, or long long). * TYPE is one of char, short, int, long, or long long, although long long * must not be used except on platforms that support it. * J is an integer >= 0 and strictly less than the number of bits in TYPE * (because C doesn't define what happens for J outside that range either). * Caution: * I may be evaluated more than once. */ #ifdef SIGNED_RIGHT_SHIFT_ZERO_FILLS #define Py_ARITHMETIC_RIGHT_SHIFT(TYPE, I, J) \ ((I) < 0 ? ~((~(unsigned TYPE)(I)) >> (J)) : (I) >> (J)) #else #define Py_ARITHMETIC_RIGHT_SHIFT(TYPE, I, J) ((I) >> (J)) #endif /* Py_FORCE_EXPANSION * "Simply" returns its argument. However, macro expansions within the * argument are evaluated. This unfortunate trickery is needed to get * token-pasting to work as desired in some cases. */ #define Py_FORCE_EXPANSION(X) X /* Py_RETURN_FROM_SIGNAL_HANDLER * The return from a signal handler varies depending on whether RETSIGTYPE * is int or void. The macro Py_RETURN_FROM_SIGNAL_HANDLER(VALUE) expands * to * return VALUE * if RETSIGTYPE is int, else to nothing if RETSIGTYPE is void. */ #define int_PySIGRETURN(VALUE) return VALUE #define void_PySIGRETURN(VALUE) #define Py_RETURN_FROM_SIGNAL_HANDLER(VALUE) \ Py_FORCE_EXPANSION(RETSIGTYPE) ## _PySIGRETURN(VALUE) /* Py_SAFE_DOWNCAST(VALUE, WIDE, NARROW) * Cast VALUE to type NARROW from type WIDE. In Py_DEBUG mode, this * assert-fails if any information is lost. * Caution: * VALUE may be evaluated more than once. */ #ifdef Py_DEBUG #define Py_SAFE_DOWNCAST(VALUE, WIDE, NARROW) \ (assert((WIDE)(NARROW)(VALUE) == (VALUE)), (NARROW)(VALUE)) #else #define Py_SAFE_DOWNCAST(VALUE, WIDE, NARROW) (NARROW)(VALUE) #endif #ifdef __cplusplus } #endif #endif /* Py_PYPORT_H */