[OpenSPARC-T2-DV] / tools / src / nas,5.n2.os.2 / lib / python / include / python2.4 / objimpl.h

#ifndef Py_OBJIMPL_H
#define Py_OBJIMPL_H

#include "pymem.h"

#ifdef __cplusplus
extern "C" {
#endif

/* BEWARE:

   Each interface exports both functions and macros.  Extension modules should
   use the functions, to ensure binary compatibility across Python versions.
   Because the Python implementation is free to change internal details, and
   the macros may (or may not) expose details for speed, if you do use the
   macros you must recompile your extensions with each Python release.

   Never mix calls to PyObject_ memory functions with calls to the platform
   malloc/realloc/ calloc/free, or with calls to PyMem_.
*/

/*
Functions and macros for modules that implement new object types.

 - PyObject_New(type, typeobj) allocates memory for a new object of the given
   type, and initializes part of it.  'type' must be the C structure type used
   to represent the object, and 'typeobj' the address of the corresponding
   type object.  Reference count and type pointer are filled in; the rest of
   the bytes of the object are *undefined*!  The resulting expression type is
   'type *'.  The size of the object is determined by the tp_basicsize field
   of the type object.

 - PyObject_NewVar(type, typeobj, n) is similar but allocates a variable-size
   object with room for n items.  In addition to the refcount and type pointer
   fields, this also fills in the ob_size field.

 - PyObject_Del(op) releases the memory allocated for an object.  It does not
   run a destructor -- it only frees the memory.  PyObject_Free is identical.

 - PyObject_Init(op, typeobj) and PyObject_InitVar(op, typeobj, n) don't
   allocate memory.  Instead of a 'type' parameter, they take a pointer to a
   new object (allocated by an arbitrary allocator), and initialize its object
   header fields.

Note that objects created with PyObject_{New, NewVar} are allocated using the
specialized Python allocator (implemented in obmalloc.c), if WITH_PYMALLOC is
enabled.  In addition, a special debugging allocator is used if PYMALLOC_DEBUG
is also #defined.

In case a specific form of memory management is needed (for example, if you
must use the platform malloc heap(s), or shared memory, or C++ local storage or
operator new), you must first allocate the object with your custom allocator,
then pass its pointer to PyObject_{Init, InitVar} for filling in its Python-
specific fields:  reference count, type pointer, possibly others.  You should
be aware that Python no control over these objects because they don't
cooperate with the Python memory manager.  Such objects may not be eligible
for automatic garbage collection and you have to make sure that they are
released accordingly whenever their destructor gets called (cf. the specific
form of memory management you're using).

Unless you have specific memory management requirements, use
PyObject_{New, NewVar, Del}.
*/

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

/* Functions to call the same malloc/realloc/free as used by Python's
   object allocator.  If WITH_PYMALLOC is enabled, these may differ from
   the platform malloc/realloc/free.  The Python object allocator is
   designed for fast, cache-conscious allocation of many "small" objects,
   and with low hidden memory overhead.

   PyObject_Malloc(0) returns a unique non-NULL pointer if possible.

   PyObject_Realloc(NULL, n) acts like PyObject_Malloc(n).
   PyObject_Realloc(p != NULL, 0) does not return  NULL, or free the memory
   at p.

   Returned pointers must be checked for NULL explicitly; no action is
   performed on failure other than to return NULL (no warning it printed, no
   exception is set, etc).

   For allocating objects, use PyObject_{New, NewVar} instead whenever
   possible.  The PyObject_{Malloc, Realloc, Free} family is exposed
   so that you can exploit Python's small-block allocator for non-object
   uses.  If you must use these routines to allocate object memory, make sure
   the object gets initialized via PyObject_{Init, InitVar} after obtaining
   the raw memory.
*/
PyAPI_FUNC(void *) PyObject_Malloc(size_t);
PyAPI_FUNC(void *) PyObject_Realloc(void *, size_t);
PyAPI_FUNC(void) PyObject_Free(void *);


/* Macros */
#ifdef WITH_PYMALLOC
#ifdef PYMALLOC_DEBUG
PyAPI_FUNC(void *) _PyObject_DebugMalloc(size_t nbytes);
PyAPI_FUNC(void *) _PyObject_DebugRealloc(void *p, size_t nbytes);
PyAPI_FUNC(void) _PyObject_DebugFree(void *p);
PyAPI_FUNC(void) _PyObject_DebugDumpAddress(const void *p);
PyAPI_FUNC(void) _PyObject_DebugCheckAddress(const void *p);
PyAPI_FUNC(void) _PyObject_DebugMallocStats(void);
#define PyObject_MALLOC		_PyObject_DebugMalloc
#define PyObject_Malloc		_PyObject_DebugMalloc
#define PyObject_REALLOC	_PyObject_DebugRealloc
#define PyObject_Realloc	_PyObject_DebugRealloc
#define PyObject_FREE		_PyObject_DebugFree
#define PyObject_Free		_PyObject_DebugFree

#else	/* WITH_PYMALLOC && ! PYMALLOC_DEBUG */
#define PyObject_MALLOC		PyObject_Malloc
#define PyObject_REALLOC	PyObject_Realloc
#define PyObject_FREE		PyObject_Free
#endif

#else	/* ! WITH_PYMALLOC */
#define PyObject_MALLOC		PyMem_MALLOC
#define PyObject_REALLOC	PyMem_REALLOC
/* This is an odd one!  For backward compatibility with old extensions, the
   PyMem "release memory" functions have to invoke the object allocator's
   free() function.  When pymalloc isn't enabled, that leaves us using
   the platform free(). */
#define PyObject_FREE		free

#endif	/* WITH_PYMALLOC */

#define PyObject_Del		PyObject_Free
#define PyObject_DEL		PyObject_FREE

/* for source compatibility with 2.2 */
#define _PyObject_Del		PyObject_Free

/*
 * Generic object allocator interface
 * ==================================
 */

/* Functions */
PyAPI_FUNC(PyObject *) PyObject_Init(PyObject *, PyTypeObject *);
PyAPI_FUNC(PyVarObject *) PyObject_InitVar(PyVarObject *,
                                                 PyTypeObject *, int);
PyAPI_FUNC(PyObject *) _PyObject_New(PyTypeObject *);
PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, int);

#define PyObject_New(type, typeobj) \
		( (type *) _PyObject_New(typeobj) )
#define PyObject_NewVar(type, typeobj, n) \
		( (type *) _PyObject_NewVar((typeobj), (n)) )

/* Macros trading binary compatibility for speed. See also pymem.h.
   Note that these macros expect non-NULL object pointers.*/
#define PyObject_INIT(op, typeobj) \
	( (op)->ob_type = (typeobj), _Py_NewReference((PyObject *)(op)), (op) )
#define PyObject_INIT_VAR(op, typeobj, size) \
	( (op)->ob_size = (size), PyObject_INIT((op), (typeobj)) )

#define _PyObject_SIZE(typeobj) ( (typeobj)->tp_basicsize )

/* _PyObject_VAR_SIZE returns the number of bytes (as size_t) allocated for a
   vrbl-size object with nitems items, exclusive of gc overhead (if any).  The
   value is rounded up to the closest multiple of sizeof(void *), in order to
   ensure that pointer fields at the end of the object are correctly aligned
   for the platform (this is of special importance for subclasses of, e.g.,
   str or long, so that pointers can be stored after the embedded data).

   Note that there's no memory wastage in doing this, as malloc has to
   return (at worst) pointer-aligned memory anyway.
*/
#if ((SIZEOF_VOID_P - 1) & SIZEOF_VOID_P) != 0
#   error "_PyObject_VAR_SIZE requires SIZEOF_VOID_P be a power of 2"
#endif

#define _PyObject_VAR_SIZE(typeobj, nitems)	\
	(size_t)				\
	( ( (typeobj)->tp_basicsize +		\
	    (nitems)*(typeobj)->tp_itemsize +	\
	    (SIZEOF_VOID_P - 1)			\
	  ) & ~(SIZEOF_VOID_P - 1)		\
	)

#define PyObject_NEW(type, typeobj) \
( (type *) PyObject_Init( \
	(PyObject *) PyObject_MALLOC( _PyObject_SIZE(typeobj) ), (typeobj)) )

#define PyObject_NEW_VAR(type, typeobj, n) \
( (type *) PyObject_InitVar( \
      (PyVarObject *) PyObject_MALLOC(_PyObject_VAR_SIZE((typeobj),(n)) ),\
      (typeobj), (n)) )

/* This example code implements an object constructor with a custom
   allocator, where PyObject_New is inlined, and shows the important
   distinction between two steps (at least):
       1) the actual allocation of the object storage;
       2) the initialization of the Python specific fields
          in this storage with PyObject_{Init, InitVar}.

   PyObject *
   YourObject_New(...)
   {
       PyObject *op;

       op = (PyObject *) Your_Allocator(_PyObject_SIZE(YourTypeStruct));
       if (op == NULL)
           return PyErr_NoMemory();

       PyObject_Init(op, &YourTypeStruct);

       op->ob_field = value;
       ...
       return op;
   }

   Note that in C++, the use of the new operator usually implies that
   the 1st step is performed automatically for you, so in a C++ class
   constructor you would start directly with PyObject_Init/InitVar
*/

/*
 * Garbage Collection Support
 * ==========================
 */

/* C equivalent of gc.collect(). */
long PyGC_Collect(void);

/* Test if a type has a GC head */
#define PyType_IS_GC(t) PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC)

/* Test if an object has a GC head */
#define PyObject_IS_GC(o) (PyType_IS_GC((o)->ob_type) && \
	((o)->ob_type->tp_is_gc == NULL || (o)->ob_type->tp_is_gc(o)))

PyAPI_FUNC(PyVarObject *) _PyObject_GC_Resize(PyVarObject *, int);
#define PyObject_GC_Resize(type, op, n) \
		( (type *) _PyObject_GC_Resize((PyVarObject *)(op), (n)) )

/* for source compatibility with 2.2 */
#define _PyObject_GC_Del PyObject_GC_Del

/* GC information is stored BEFORE the object structure. */
typedef union _gc_head {
	struct {
		union _gc_head *gc_next;
		union _gc_head *gc_prev;
		int gc_refs;
	} gc;
	long double dummy;  /* force worst-case alignment */
} PyGC_Head;

extern PyGC_Head *_PyGC_generation0;

#define _Py_AS_GC(o) ((PyGC_Head *)(o)-1)

#define _PyGC_REFS_UNTRACKED			(-2)
#define _PyGC_REFS_REACHABLE			(-3)
#define _PyGC_REFS_TENTATIVELY_UNREACHABLE	(-4)

/* Tell the GC to track this object.  NB: While the object is tracked the
 * collector it must be safe to call the ob_traverse method. */
#define _PyObject_GC_TRACK(o) do { \
	PyGC_Head *g = _Py_AS_GC(o); \
	if (g->gc.gc_refs != _PyGC_REFS_UNTRACKED) \
		Py_FatalError("GC object already tracked"); \
	g->gc.gc_refs = _PyGC_REFS_REACHABLE; \
	g->gc.gc_next = _PyGC_generation0; \
	g->gc.gc_prev = _PyGC_generation0->gc.gc_prev; \
	g->gc.gc_prev->gc.gc_next = g; \
	_PyGC_generation0->gc.gc_prev = g; \
    } while (0);

/* Tell the GC to stop tracking this object.
 * gc_next doesn't need to be set to NULL, but doing so is a good
 * way to provoke memory errors if calling code is confused.
 */
#define _PyObject_GC_UNTRACK(o) do { \
	PyGC_Head *g = _Py_AS_GC(o); \
	assert(g->gc.gc_refs != _PyGC_REFS_UNTRACKED); \
	g->gc.gc_refs = _PyGC_REFS_UNTRACKED; \
	g->gc.gc_prev->gc.gc_next = g->gc.gc_next; \
	g->gc.gc_next->gc.gc_prev = g->gc.gc_prev; \
	g->gc.gc_next = NULL; \
    } while (0);

PyAPI_FUNC(PyObject *) _PyObject_GC_Malloc(size_t);
PyAPI_FUNC(PyObject *) _PyObject_GC_New(PyTypeObject *);
PyAPI_FUNC(PyVarObject *) _PyObject_GC_NewVar(PyTypeObject *, int);
PyAPI_FUNC(void) PyObject_GC_Track(void *);
PyAPI_FUNC(void) PyObject_GC_UnTrack(void *);
PyAPI_FUNC(void) PyObject_GC_Del(void *);

#define PyObject_GC_New(type, typeobj) \
		( (type *) _PyObject_GC_New(typeobj) )
#define PyObject_GC_NewVar(type, typeobj, n) \
		( (type *) _PyObject_GC_NewVar((typeobj), (n)) )


/* Utility macro to help write tp_traverse functions.
 * To use this macro, the tp_traverse function must name its arguments
 * "visit" and "arg".  This is intended to keep tp_traverse functions
 * looking as much alike as possible.
 */
#define Py_VISIT(op)					\
        do { 						\
                if (op) {				\
                        int vret = visit((op), arg);	\
                        if (vret)			\
                                return vret;		\
                }					\
        } while (0)

/* This is here for the sake of backwards compatibility.  Extensions that
 * use the old GC API will still compile but the objects will not be
 * tracked by the GC. */
#define PyGC_HEAD_SIZE 0
#define PyObject_GC_Init(op)
#define PyObject_GC_Fini(op)
#define PyObject_AS_GC(op) (op)
#define PyObject_FROM_GC(op) (op)


/* Test if a type supports weak references */
#define PyType_SUPPORTS_WEAKREFS(t) \
        (PyType_HasFeature((t), Py_TPFLAGS_HAVE_WEAKREFS) \
         && ((t)->tp_weaklistoffset > 0))

#define PyObject_GET_WEAKREFS_LISTPTR(o) \
	((PyObject **) (((char *) (o)) + (o)->ob_type->tp_weaklistoffset))

#ifdef __cplusplus
}
#endif
#endif /* !Py_OBJIMPL_H */
Commit	Line	Data
86530b38 AT	1	#ifndef Py_OBJIMPL_H
	2	#define Py_OBJIMPL_H
	3
	4	#include "pymem.h"
	5
	6	#ifdef __cplusplus
	7	extern "C" {
	8	#endif
	9
	10	/* BEWARE:
	11
	12	Each interface exports both functions and macros. Extension modules should
	13	use the functions, to ensure binary compatibility across Python versions.
	14	Because the Python implementation is free to change internal details, and
	15	the macros may (or may not) expose details for speed, if you do use the
	16	macros you must recompile your extensions with each Python release.
	17
	18	Never mix calls to PyObject_ memory functions with calls to the platform
	19	malloc/realloc/ calloc/free, or with calls to PyMem_.
	20	*/
	21
	22	/*
	23	Functions and macros for modules that implement new object types.
	24
	25	- PyObject_New(type, typeobj) allocates memory for a new object of the given
	26	type, and initializes part of it. 'type' must be the C structure type used
	27	to represent the object, and 'typeobj' the address of the corresponding
	28	type object. Reference count and type pointer are filled in; the rest of
	29	the bytes of the object are undefined! The resulting expression type is
	30	'type *'. The size of the object is determined by the tp_basicsize field
	31	of the type object.
	32
	33	- PyObject_NewVar(type, typeobj, n) is similar but allocates a variable-size
	34	object with room for n items. In addition to the refcount and type pointer
	35	fields, this also fills in the ob_size field.
	36
	37	- PyObject_Del(op) releases the memory allocated for an object. It does not
	38	run a destructor -- it only frees the memory. PyObject_Free is identical.
	39
	40	- PyObject_Init(op, typeobj) and PyObject_InitVar(op, typeobj, n) don't
	41	allocate memory. Instead of a 'type' parameter, they take a pointer to a
	42	new object (allocated by an arbitrary allocator), and initialize its object
	43	header fields.
	44
	45	Note that objects created with PyObject_{New, NewVar} are allocated using the
	46	specialized Python allocator (implemented in obmalloc.c), if WITH_PYMALLOC is
	47	enabled. In addition, a special debugging allocator is used if PYMALLOC_DEBUG
	48	is also #defined.
	49
	50	In case a specific form of memory management is needed (for example, if you
	51	must use the platform malloc heap(s), or shared memory, or C++ local storage or
	52	operator new), you must first allocate the object with your custom allocator,
	53	then pass its pointer to PyObject_{Init, InitVar} for filling in its Python-
	54	specific fields: reference count, type pointer, possibly others. You should
	55	be aware that Python no control over these objects because they don't
	56	cooperate with the Python memory manager. Such objects may not be eligible
	57	for automatic garbage collection and you have to make sure that they are
	58	released accordingly whenever their destructor gets called (cf. the specific
	59	form of memory management you're using).
	60
	61	Unless you have specific memory management requirements, use
	62	PyObject_{New, NewVar, Del}.
	63	*/
	64
65	/*
66	* Raw object memory interface
67	* ===========================
68	*/
69
70	/* Functions to call the same malloc/realloc/free as used by Python's
71	object allocator. If WITH_PYMALLOC is enabled, these may differ from
72	the platform malloc/realloc/free. The Python object allocator is
73	designed for fast, cache-conscious allocation of many "small" objects,
74	and with low hidden memory overhead.
75
76	PyObject_Malloc(0) returns a unique non-NULL pointer if possible.
77
78	PyObject_Realloc(NULL, n) acts like PyObject_Malloc(n).
79	PyObject_Realloc(p != NULL, 0) does not return NULL, or free the memory
80	at p.
81
82	Returned pointers must be checked for NULL explicitly; no action is
83	performed on failure other than to return NULL (no warning it printed, no
84	exception is set, etc).
85
86	For allocating objects, use PyObject_{New, NewVar} instead whenever
87	possible. The PyObject_{Malloc, Realloc, Free} family is exposed
88	so that you can exploit Python's small-block allocator for non-object
89	uses. If you must use these routines to allocate object memory, make sure
90	the object gets initialized via PyObject_{Init, InitVar} after obtaining
91	the raw memory.
92	*/
93	PyAPI_FUNC(void *) PyObject_Malloc(size_t);
94	PyAPI_FUNC(void ) PyObject_Realloc(void , size_t);
95	PyAPI_FUNC(void) PyObject_Free(void *);
96
97
98	/* Macros */
99	#ifdef WITH_PYMALLOC
100	#ifdef PYMALLOC_DEBUG
101	PyAPI_FUNC(void *) _PyObject_DebugMalloc(size_t nbytes);
102	PyAPI_FUNC(void ) _PyObject_DebugRealloc(void p, size_t nbytes);
103	PyAPI_FUNC(void) _PyObject_DebugFree(void *p);
104	PyAPI_FUNC(void) _PyObject_DebugDumpAddress(const void *p);
105	PyAPI_FUNC(void) _PyObject_DebugCheckAddress(const void *p);
106	PyAPI_FUNC(void) _PyObject_DebugMallocStats(void);
107	#define PyObject_MALLOC _PyObject_DebugMalloc
108	#define PyObject_Malloc _PyObject_DebugMalloc
109	#define PyObject_REALLOC _PyObject_DebugRealloc
110	#define PyObject_Realloc _PyObject_DebugRealloc
111	#define PyObject_FREE _PyObject_DebugFree
112	#define PyObject_Free _PyObject_DebugFree
113
114	#else /* WITH_PYMALLOC && ! PYMALLOC_DEBUG */
115	#define PyObject_MALLOC PyObject_Malloc
116	#define PyObject_REALLOC PyObject_Realloc
117	#define PyObject_FREE PyObject_Free
118	#endif
119
120	#else /* ! WITH_PYMALLOC */
121	#define PyObject_MALLOC PyMem_MALLOC
122	#define PyObject_REALLOC PyMem_REALLOC
123	/* This is an odd one! For backward compatibility with old extensions, the
124	PyMem "release memory" functions have to invoke the object allocator's
125	free() function. When pymalloc isn't enabled, that leaves us using
126	the platform free(). */
127	#define PyObject_FREE free
128
129	#endif /* WITH_PYMALLOC */
130
131	#define PyObject_Del PyObject_Free
132	#define PyObject_DEL PyObject_FREE
133
134	/* for source compatibility with 2.2 */
135	#define _PyObject_Del PyObject_Free
136
137	/*
138	* Generic object allocator interface
139	* ==================================
140	*/
141
142	/* Functions */
143	PyAPI_FUNC(PyObject ) PyObject_Init(PyObject , PyTypeObject *);
144	PyAPI_FUNC(PyVarObject ) PyObject_InitVar(PyVarObject ,
145	PyTypeObject *, int);
146	PyAPI_FUNC(PyObject ) _PyObject_New(PyTypeObject );
147	PyAPI_FUNC(PyVarObject ) _PyObject_NewVar(PyTypeObject , int);
148
149	#define PyObject_New(type, typeobj) \
150	( (type *) _PyObject_New(typeobj) )
151	#define PyObject_NewVar(type, typeobj, n) \
152	( (type *) _PyObject_NewVar((typeobj), (n)) )
153
154	/* Macros trading binary compatibility for speed. See also pymem.h.
155	Note that these macros expect non-NULL object pointers.*/
156	#define PyObject_INIT(op, typeobj) \
157	( (op)->ob_type = (typeobj), _Py_NewReference((PyObject *)(op)), (op) )
158	#define PyObject_INIT_VAR(op, typeobj, size) \
159	( (op)->ob_size = (size), PyObject_INIT((op), (typeobj)) )
160
161	#define _PyObject_SIZE(typeobj) ( (typeobj)->tp_basicsize )
162
163	/* _PyObject_VAR_SIZE returns the number of bytes (as size_t) allocated for a
164	vrbl-size object with nitems items, exclusive of gc overhead (if any). The
165	value is rounded up to the closest multiple of sizeof(void *), in order to
166	ensure that pointer fields at the end of the object are correctly aligned
167	for the platform (this is of special importance for subclasses of, e.g.,
168	str or long, so that pointers can be stored after the embedded data).
169
170	Note that there's no memory wastage in doing this, as malloc has to
171	return (at worst) pointer-aligned memory anyway.
172	*/
173	#if ((SIZEOF_VOID_P - 1) & SIZEOF_VOID_P) != 0
174	# error "_PyObject_VAR_SIZE requires SIZEOF_VOID_P be a power of 2"
175	#endif
176
177	#define _PyObject_VAR_SIZE(typeobj, nitems) \
178	(size_t) \
179	( ( (typeobj)->tp_basicsize + \
180	(nitems)*(typeobj)->tp_itemsize + \
181	(SIZEOF_VOID_P - 1) \
182	) & ~(SIZEOF_VOID_P - 1) \
183	)
184
185	#define PyObject_NEW(type, typeobj) \
186	( (type *) PyObject_Init( \
187	(PyObject *) PyObject_MALLOC( _PyObject_SIZE(typeobj) ), (typeobj)) )
188
189	#define PyObject_NEW_VAR(type, typeobj, n) \
190	( (type *) PyObject_InitVar( \
191	(PyVarObject *) PyObject_MALLOC(_PyObject_VAR_SIZE((typeobj),(n)) ),\
192	(typeobj), (n)) )
193
194	/* This example code implements an object constructor with a custom
195	allocator, where PyObject_New is inlined, and shows the important
196	distinction between two steps (at least):
197	1) the actual allocation of the object storage;
198	2) the initialization of the Python specific fields
199	in this storage with PyObject_{Init, InitVar}.
200
201	PyObject *
202	YourObject_New(...)
203	{
204	PyObject *op;
205
206	op = (PyObject *) Your_Allocator(_PyObject_SIZE(YourTypeStruct));
207	if (op == NULL)
208	return PyErr_NoMemory();
209
210	PyObject_Init(op, &YourTypeStruct);
211
212	op->ob_field = value;
213	...
214	return op;
215	}
216
217	Note that in C++, the use of the new operator usually implies that
218	the 1st step is performed automatically for you, so in a C++ class
219	constructor you would start directly with PyObject_Init/InitVar
220	*/
221
222	/*
223	* Garbage Collection Support
224	* ==========================
225	*/
226
227	/* C equivalent of gc.collect(). */
228	long PyGC_Collect(void);
229
230	/* Test if a type has a GC head */
231	#define PyType_IS_GC(t) PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC)
232
233	/* Test if an object has a GC head */
234	#define PyObject_IS_GC(o) (PyType_IS_GC((o)->ob_type) && \
235	((o)->ob_type->tp_is_gc == NULL \|\| (o)->ob_type->tp_is_gc(o)))
236
237	PyAPI_FUNC(PyVarObject ) _PyObject_GC_Resize(PyVarObject , int);
238	#define PyObject_GC_Resize(type, op, n) \
239	( (type ) _PyObject_GC_Resize((PyVarObject )(op), (n)) )
240
241	/* for source compatibility with 2.2 */
242	#define _PyObject_GC_Del PyObject_GC_Del
243
244	/* GC information is stored BEFORE the object structure. */
245	typedef union _gc_head {
246	struct {
247	union _gc_head *gc_next;
248	union _gc_head *gc_prev;
249	int gc_refs;
250	} gc;
251	long double dummy; /* force worst-case alignment */
252	} PyGC_Head;
253
254	extern PyGC_Head *_PyGC_generation0;
255
256	#define _Py_AS_GC(o) ((PyGC_Head *)(o)-1)
257
258	#define _PyGC_REFS_UNTRACKED (-2)
259	#define _PyGC_REFS_REACHABLE (-3)
260	#define _PyGC_REFS_TENTATIVELY_UNREACHABLE (-4)
261
262	/* Tell the GC to track this object. NB: While the object is tracked the
263	* collector it must be safe to call the ob_traverse method. */
264	#define _PyObject_GC_TRACK(o) do { \
265	PyGC_Head *g = _Py_AS_GC(o); \
266	if (g->gc.gc_refs != _PyGC_REFS_UNTRACKED) \
267	Py_FatalError("GC object already tracked"); \
268	g->gc.gc_refs = _PyGC_REFS_REACHABLE; \
269	g->gc.gc_next = _PyGC_generation0; \
270	g->gc.gc_prev = _PyGC_generation0->gc.gc_prev; \
271	g->gc.gc_prev->gc.gc_next = g; \
272	_PyGC_generation0->gc.gc_prev = g; \
273	} while (0);
274
275	/* Tell the GC to stop tracking this object.
276	* gc_next doesn't need to be set to NULL, but doing so is a good
277	* way to provoke memory errors if calling code is confused.
278	*/
279	#define _PyObject_GC_UNTRACK(o) do { \
280	PyGC_Head *g = _Py_AS_GC(o); \
281	assert(g->gc.gc_refs != _PyGC_REFS_UNTRACKED); \
282	g->gc.gc_refs = _PyGC_REFS_UNTRACKED; \
283	g->gc.gc_prev->gc.gc_next = g->gc.gc_next; \
284	g->gc.gc_next->gc.gc_prev = g->gc.gc_prev; \
285	g->gc.gc_next = NULL; \
286	} while (0);
287
288	PyAPI_FUNC(PyObject *) _PyObject_GC_Malloc(size_t);
289	PyAPI_FUNC(PyObject ) _PyObject_GC_New(PyTypeObject );
290	PyAPI_FUNC(PyVarObject ) _PyObject_GC_NewVar(PyTypeObject , int);
291	PyAPI_FUNC(void) PyObject_GC_Track(void *);
292	PyAPI_FUNC(void) PyObject_GC_UnTrack(void *);
293	PyAPI_FUNC(void) PyObject_GC_Del(void *);
294
295	#define PyObject_GC_New(type, typeobj) \
296	( (type *) _PyObject_GC_New(typeobj) )
297	#define PyObject_GC_NewVar(type, typeobj, n) \
298	( (type *) _PyObject_GC_NewVar((typeobj), (n)) )
299
300
301	/* Utility macro to help write tp_traverse functions.
302	* To use this macro, the tp_traverse function must name its arguments
303	* "visit" and "arg". This is intended to keep tp_traverse functions
304	* looking as much alike as possible.
305	*/
306	#define Py_VISIT(op) \
307	do { \
308	if (op) { \
309	int vret = visit((op), arg); \
310	if (vret) \
311	return vret; \
312	} \
313	} while (0)
314
315	/* This is here for the sake of backwards compatibility. Extensions that
316	* use the old GC API will still compile but the objects will not be
317	* tracked by the GC. */
318	#define PyGC_HEAD_SIZE 0
319	#define PyObject_GC_Init(op)
320	#define PyObject_GC_Fini(op)
321	#define PyObject_AS_GC(op) (op)
322	#define PyObject_FROM_GC(op) (op)
323
324
325	/* Test if a type supports weak references */
326	#define PyType_SUPPORTS_WEAKREFS(t) \
327	(PyType_HasFeature((t), Py_TPFLAGS_HAVE_WEAKREFS) \
328	&& ((t)->tp_weaklistoffset > 0))
329
330	#define PyObject_GET_WEAKREFS_LISTPTR(o) \
331	((PyObject *) (((char ) (o)) + (o)->ob_type->tp_weaklistoffset))
332
333	#ifdef __cplusplus
334	}
335	#endif
336	#endif /* !Py_OBJIMPL_H */