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/***********************************************************
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
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_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 */
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