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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright 1996 Silicon Graphics. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
/*
* Some simple primitives for allocation with explicit type information.
* Facilities for dynamic type inference may be added later.
* Should be used only for extremely performance critical applications,
* or if conservative collector leakage is otherwise a problem (unlikely).
* Note that this is implemented completely separately from the rest
* of the collector, and is not linked in unless referenced.
* This does not currently support GC_DEBUG in any interesting way.
*/
#ifndef GC_TYPED_H
#define GC_TYPED_H
#ifndef GC_H
# include "gc.h"
#endif
#ifdef __cplusplus
extern "C" {
#endif
typedef GC_word * GC_bitmap;
/* The least significant bit of the first word is one if */
/* the first word in the object may be a pointer. */
#define GC_WORDSZ (8 * sizeof(GC_word))
#define GC_get_bit(bm, index) \
(((bm)[(index) / GC_WORDSZ] >> ((index) % GC_WORDSZ)) & 1)
#define GC_set_bit(bm, index) \
((bm)[(index) / GC_WORDSZ] |= (GC_word)1 << ((index) % GC_WORDSZ))
#define GC_WORD_OFFSET(t, f) (offsetof(t,f) / sizeof(GC_word))
#define GC_WORD_LEN(t) (sizeof(t) / sizeof(GC_word))
#define GC_BITMAP_SIZE(t) ((GC_WORD_LEN(t) + GC_WORDSZ - 1) / GC_WORDSZ)
typedef GC_word GC_descr;
GC_API GC_descr GC_CALL GC_make_descriptor(const GC_word * /* GC_bitmap bm */,
size_t /* len (number_of_bits_in_bitmap) */);
/* Return a type descriptor for the object whose layout */
/* is described by the argument. */
/* The least significant bit of the first word is one */
/* if the first word in the object may be a pointer. */
/* The second argument specifies the number of */
/* meaningful bits in the bitmap. The actual object */
/* may be larger (but not smaller). Any additional */
/* words in the object are assumed not to contain */
/* pointers. */
/* Returns a conservative approximation in the */
/* (unlikely) case of insufficient memory to build */
/* the descriptor. Calls to GC_make_descriptor */
/* may consume some amount of a finite resource. This */
/* is intended to be called once per type, not once */
/* per allocation. */
/* It is possible to generate a descriptor for a C type T with */
/* word aligned pointer fields f1, f2, ... as follows: */
/* */
/* GC_descr T_descr; */
/* GC_word T_bitmap[GC_BITMAP_SIZE(T)] = {0}; */
/* GC_set_bit(T_bitmap, GC_WORD_OFFSET(T,f1)); */
/* GC_set_bit(T_bitmap, GC_WORD_OFFSET(T,f2)); */
/* ... */
/* T_descr = GC_make_descriptor(T_bitmap, GC_WORD_LEN(T)); */
GC_API GC_ATTR_MALLOC GC_ATTR_ALLOC_SIZE(1) void * GC_CALL
GC_malloc_explicitly_typed(size_t /* size_in_bytes */,
GC_descr /* d */);
/* Allocate an object whose layout is described by d. */
/* The size may NOT be less than the number of */
/* meaningful bits in the bitmap of d multiplied by */
/* sizeof GC_word. The returned object is cleared. */
/* The returned object may NOT be passed to GC_realloc. */
GC_API GC_ATTR_MALLOC GC_ATTR_ALLOC_SIZE(1) void * GC_CALL
GC_malloc_explicitly_typed_ignore_off_page(size_t /* size_in_bytes */,
GC_descr /* d */);
GC_API GC_ATTR_MALLOC GC_ATTR_CALLOC_SIZE(1, 2) void * GC_CALL
GC_calloc_explicitly_typed(size_t /* nelements */,
size_t /* element_size_in_bytes */,
GC_descr /* d */);
/* Allocate an array of nelements elements, each of the */
/* given size, and with the given descriptor. */
/* The element size must be a multiple of the byte */
/* alignment required for pointers. E.g. on a 32-bit */
/* machine with 16-bit aligned pointers, size_in_bytes */
/* must be a multiple of 2. The element size may NOT */
/* be less than the number of meaningful bits in the */
/* bitmap of d multiplied by sizeof GC_word. */
/* Returned object is cleared. */
#define GC_CALLOC_TYPED_DESCR_WORDS 8
#ifdef GC_BUILD
struct GC_calloc_typed_descr_s;
#else
struct GC_calloc_typed_descr_s {
GC_word opaque[GC_CALLOC_TYPED_DESCR_WORDS];
};
#endif
GC_API int GC_CALL GC_calloc_prepare_explicitly_typed(
struct GC_calloc_typed_descr_s * /* pctd */,
size_t /* sizeof_ctd */, size_t /* nelements */,
size_t /* element_size_in_bytes */, GC_descr);
/* This is same as GC_calloc_explicitly_typed but more optimal */
/* in terms of the performance and memory usage if the client */
/* needs to allocate multiple typed object arrays with the */
/* same layout and number of elements. The client should call */
/* it to be prepared for the subsequent allocations by */
/* GC_calloc_do_explicitly_typed, one or many. The result of */
/* the preparation is stored to *pctd, even in case of */
/* a failure. The prepared structure could be just dropped */
/* when no longer needed. Returns 0 on failure, 1 on success; */
/* the result could be ignored (as it is also stored to *pctd */
/* and checked later by GC_calloc_do_explicitly_typed). */
GC_API GC_ATTR_MALLOC void * GC_CALL GC_calloc_do_explicitly_typed(
const struct GC_calloc_typed_descr_s * /* pctd */,
size_t /* sizeof_ctd */);
/* The actual object allocation for the prepared description. */
#ifdef GC_DEBUG
# define GC_MALLOC_EXPLICITLY_TYPED(bytes, d) ((void)(d), GC_MALLOC(bytes))
# define GC_MALLOC_EXPLICITLY_TYPED_IGNORE_OFF_PAGE(bytes, d) \
GC_MALLOC_EXPLICITLY_TYPED(bytes, d)
# define GC_CALLOC_EXPLICITLY_TYPED(n, bytes, d) \
((void)(d), GC_MALLOC((n) * (bytes)))
#else
# define GC_MALLOC_EXPLICITLY_TYPED(bytes, d) \
GC_malloc_explicitly_typed(bytes, d)
# define GC_MALLOC_EXPLICITLY_TYPED_IGNORE_OFF_PAGE(bytes, d) \
GC_malloc_explicitly_typed_ignore_off_page(bytes, d)
# define GC_CALLOC_EXPLICITLY_TYPED(n, bytes, d) \
GC_calloc_explicitly_typed(n, bytes, d)
#endif
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* GC_TYPED_H */
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