cpython/Include/pyport.h

/***********************************************************
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
**************************************************************************/


#define ANY void /* For API compatibility only. Obsolete, do not use. */

#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif

#ifdef __cplusplus
/* Move this down here since some C++ #include's don't like to be included
   inside an extern "C" */
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



/**************************************************************************
Prototypes that are missing from the standard include files on some systems
(and possibly only some versions of such systems.)

Please be conservative with adding new ones, document them and enclose them
in platform-specific #ifdefs.
**************************************************************************/

#ifdef SOLARIS
/* Unchecked */
extern int gethostname(char *, int);
#endif

#ifdef __BEOS__
/* Unchecked */
/* It's in the libs, but not the headers... - [cjh] */
int shutdown( int, int ); 
#endif

#ifdef HAVE__GETPTY
#include <sys/types.h>		/* we need to import mode_t */
extern char * _getpty(int *, int, mode_t, int);
#endif

#if defined(HAVE_OPENPTY) || defined(HAVE_FORKPTY)
#if !defined(HAVE_PTY_H) && !defined(HAVE_LIBUTIL_H)
/* BSDI does not supply a prototype for the 'openpty' and 'forkpty'
   functions, even though they are included in libutil. */
#include <termios.h>
extern int openpty(int *, int *, char *, struct termios *, struct winsize *);
extern int forkpty(int *, char *, struct termios *, struct winsize *);
#endif /* !defined(HAVE_PTY_H) && !defined(HAVE_LIBUTIL_H) */
#endif /* defined(HAVE_OPENPTY) || defined(HAVE_FORKPTY) */


/* These are pulled from various places. It isn't obvious on what platforms
   they are necessary, nor what the exact prototype should look like (which
   is likely to vary between platforms!) If you find you need one of these
   declarations, please move them to a platform-specific block and include
   proper prototypes. */
#if 0

/* From Modules/resource.c */
extern int getrusage();
extern int getpagesize();

/* From Python/sysmodule.c and Modules/posixmodule.c */
extern int fclose(FILE *);

/* From Modules/posixmodule.c */
extern int fdatasync(int);
/* XXX These are supposedly for SunOS4.1.3 but "shouldn't hurt elsewhere" */
extern int rename(const char *, const char *);
extern int pclose(FILE *);
extern int lstat(const char *, struct stat *);
extern int symlink(const char *, const char *);
extern int fsync(int fd);

#endif /* 0 */


/************************
 * WRAPPER FOR <math.h> *
 ************************/

/* On the 68K Mac, when using CFM (Code Fragment Manager),
   <math.h> requires special treatment -- we need to surround it with
   #pragma lib_export off / on...
   This is because MathLib.o is a static library, and exporting its
   symbols doesn't quite work...
   XXX Not sure now...  Seems to be something else going on as well... */

#ifndef HAVE_HYPOT
extern double hypot(double, double);
#ifdef MWERKS_BEFORE_PRO4
#define hypot we_dont_want_faulty_hypot_decl
#endif
#endif

#include <math.h>

#ifndef HAVE_HYPOT
#ifdef __MWERKS__
#undef hypot
#endif
#endif

#if defined(USE_MSL) && defined(__MC68K__)
/* CodeWarrior MSL 2.1.1 has weird define overrides that don't work
** when you take the address of math functions. If I interpret the
** ANSI C standard correctly this is illegal, but I haven't been able
** to convince the MetroWerks folks of this...
*/
#undef acos
#undef asin
#undef atan
#undef atan2
#undef ceil
#undef cos
#undef cosh
#undef exp
#undef fabs
#undef floor
#undef fmod
#undef log
#undef log10
#undef pow
#undef rint
#undef sin
#undef sinh
#undef sqrt
#undef tan
#undef tanh
#define acos acosd
#define asin asind
#define atan atand
#define atan2 atan2d
#define ceil ceild
#define cos cosd
#define cosh coshd
#define exp expd
#define fabs fabsd
#define floor floord
#define fmod fmodd
#define log logd
#define log10 log10d
#define pow powd
#define rint rintd
#define sin sind
#define sinh sinhd
#define sqrt sqrtd
#define tan tand
#define tanh tanhd
#endif 


/***********************************
 * WRAPPER FOR malloc/realloc/free *
 ***********************************/

#ifndef DL_IMPORT       /* declarations for DLL import */
#define DL_IMPORT(RTYPE) RTYPE
#endif

#ifndef NULL
#define NULL ((void *)0)
#endif

#ifdef MALLOC_ZERO_RETURNS_NULL
/* XXX Always allocate one extra byte, since some malloc's return NULL
   XXX for malloc(0) or realloc(p, 0). */
#define _PyMem_EXTRA 1
#else
#define _PyMem_EXTRA 0
#endif

/*
 * Core memory allocator
 * =====================
 */

/* To make sure the interpreter is user-malloc friendly, all memory
   APIs are implemented on top of this one.

   The PyCore_* macros can be defined to make the interpreter use a
   custom allocator. Note that they are for internal use only. Both
   the core and extension modules should use the PyMem_* API.

   See the comment block at the end of this file for two scenarios
   showing how to use this to use a different allocator. */

#ifndef PyCore_MALLOC_FUNC
#undef PyCore_REALLOC_FUNC
#undef PyCore_FREE_FUNC
#define PyCore_MALLOC_FUNC      malloc
#define PyCore_REALLOC_FUNC     realloc
#define PyCore_FREE_FUNC        free
#endif

#ifndef PyCore_MALLOC_PROTO
#undef PyCore_REALLOC_PROTO
#undef PyCore_FREE_PROTO
#define PyCore_MALLOC_PROTO    (size_t)
#define PyCore_REALLOC_PROTO   (void *, size_t)
#define PyCore_FREE_PROTO      (void *)
#endif

#ifdef NEED_TO_DECLARE_MALLOC_AND_FRIEND
extern void *PyCore_MALLOC_FUNC PyCore_MALLOC_PROTO;
extern void *PyCore_REALLOC_FUNC PyCore_REALLOC_PROTO;
extern void PyCore_FREE_FUNC PyCore_FREE_PROTO;
#endif

#ifndef PyCore_MALLOC
#undef PyCore_REALLOC
#undef PyCore_FREE
#define PyCore_MALLOC(n)        PyCore_MALLOC_FUNC(n)
#define PyCore_REALLOC(p, n)    PyCore_REALLOC_FUNC((p), (n))
#define PyCore_FREE(p)          PyCore_FREE_FUNC(p)
#endif

/* BEWARE:

   Each interface exports both functions and macros. Extension modules
   should normally use the functions for ensuring binary compatibility
   of the user's code across Python versions. Subsequently, if the
   Python runtime switches to its own malloc (different from standard
   malloc), no recompilation is required for the extensions.

   The macro versions trade compatibility for speed. They can be used
   whenever there is a performance problem, but their use implies
   recompilation of the code for each new Python release. The Python
   core uses the macros because it *is* compiled on every upgrade.
   This might not be the case with 3rd party extensions in a custom
   setup (for example, a customer does not always have access to the
   source of 3rd party deliverables). You have been warned! */

/*
 * Raw memory interface
 * ====================
 */

/* Functions */

/* Function wrappers around PyCore_MALLOC and friends; useful if you
   need to be sure that you are using the same memory allocator as
   Python.  Note that the wrappers make sure that allocating 0 bytes
   returns a non-NULL pointer, even if the underlying malloc
   doesn't. Returned pointers must be checked for NULL explicitly.
   No action is performed on failure. */
extern DL_IMPORT(void *) PyMem_Malloc(size_t);
extern DL_IMPORT(void *) PyMem_Realloc(void *, size_t);
extern DL_IMPORT(void) PyMem_Free(void *);

/* Starting from Python 1.6, the wrappers Py_{Malloc,Realloc,Free} are
   no longer supported. They used to call PyErr_NoMemory() on failure. */

/* Macros */
#define PyMem_MALLOC(n)         PyCore_MALLOC(n)
#define PyMem_REALLOC(p, n)     PyCore_REALLOC((void *)(p), (n))
#define PyMem_FREE(p)           PyCore_FREE((void *)(p))

/*
 * Type-oriented memory interface
 * ==============================
 */

/* Functions */
#define PyMem_New(type, n) \
	( (type *) PyMem_Malloc((n) * sizeof(type)) )
#define PyMem_Resize(p, type, n) \
	( (p) = (type *) PyMem_Realloc((n) * sizeof(type)) )
#define PyMem_Del(p) PyMem_Free(p)

/* Macros */
#define PyMem_NEW(type, n) \
	( (type *) PyMem_MALLOC(_PyMem_EXTRA + (n) * sizeof(type)) )
#define PyMem_RESIZE(p, type, n) \
	if ((p) == NULL) \
		(p) = (type *)(PyMem_MALLOC( \
				    _PyMem_EXTRA + (n) * sizeof(type))); \
	else \
		(p) = (type *)(PyMem_REALLOC((p), \
				    _PyMem_EXTRA + (n) * sizeof(type)))
#define PyMem_DEL(p) PyMem_FREE(p)

/* PyMem_XDEL is deprecated. To avoid the call when p is NULL,
   it is recommended to write the test explicitly in the code.
   Note that according to ANSI C, free(NULL) has no effect. */

/* SCENARIOS

   Here are two scenarios by Vladimir Marangozov (the author of the
   memory allocation redesign).

   1) Scenario A

   Suppose you want to use a debugging malloc library that collects info on
   where the malloc calls originate from. Assume the interface is:

   d_malloc(size_t n, char* src_file, unsigned long src_line) c.s.

   In this case, you would define (for example in config.h) :

   #define PyCore_MALLOC_FUNC      d_malloc
   ...
   #define PyCore_MALLOC_PROTO	(size_t, char *, unsigned long)
   ...
   #define NEED_TO_DECLARE_MALLOC_AND_FRIEND

   #define PyCore_MALLOC(n)	PyCore_MALLOC_FUNC((n), __FILE__, __LINE__)
   ...

   2) Scenario B

   Suppose you want to use malloc hooks (defined & initialized in a 3rd party
   malloc library) instead of malloc functions.  In this case, you would
   define:

   #define PyCore_MALLOC_FUNC	(*malloc_hook)
   ...
   #define NEED_TO_DECLARE_MALLOC_AND_FRIEND

   and ignore the previous definitions about PyCore_MALLOC_FUNC, etc.


*/

/********************************************
 * WRAPPER FOR <time.h> and/or <sys/time.h> *
 ********************************************/

#ifdef TIME_WITH_SYS_TIME
#include <sys/time.h>
#include <time.h>
#else /* !TIME_WITH_SYS_TIME */
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#else /* !HAVE_SYS_TIME_H */
#include <time.h>
#endif /* !HAVE_SYS_TIME_H */
#endif /* !TIME_WITH_SYS_TIME */


/******************************
 * WRAPPER FOR <sys/select.h> *
 ******************************/

/* NB caller must include <sys/types.h> */

#ifdef HAVE_SYS_SELECT_H

#include <sys/select.h>

#else /* !HAVE_SYS_SELECT_H */

#ifdef USE_GUSI1
/* If we don't have sys/select the definition may be in unistd.h */
#include <GUSI.h>
#endif

#endif /* !HAVE_SYS_SELECT_H */

/* If the fd manipulation macros aren't defined,
   here is a set that should do the job */

#ifndef	FD_SETSIZE
#define	FD_SETSIZE	256
#endif

#ifndef FD_SET

typedef long fd_mask;

#define NFDBITS	(sizeof(fd_mask) * NBBY)	/* bits per mask */
#ifndef howmany
#define	howmany(x, y)	(((x)+((y)-1))/(y))
#endif /* howmany */

typedef	struct fd_set {
	fd_mask	fds_bits[howmany(FD_SETSIZE, NFDBITS)];
} fd_set;

#define	FD_SET(n, p)	((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
#define	FD_CLR(n, p)	((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
#define	FD_ISSET(n, p)	((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
#define FD_ZERO(p)	memset((char *)(p), '\0', sizeof(*(p)))

#endif /* FD_SET */
#ifdef __cplusplus
}
#endif

#endif /* Py_PYPORT_H */