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- /* Copyright (C) 1995, 1996, 1999, 2002 Aladdin Enterprises. All rights reserved.
-
- This software is provided AS-IS with no warranty, either express or
- implied.
-
- This software is distributed under license and may not be copied,
- modified or distributed except as expressly authorized under the terms
- of the license contained in the file LICENSE in this distribution.
-
- For more information about licensing, please refer to
- http://www.ghostscript.com/licensing/. For information on
- commercial licensing, go to http://www.artifex.com/licensing/ or
- contact Artifex Software, Inc., 101 Lucas Valley Road #110,
- San Rafael, CA 94903, U.S.A., +1(415)492-9861.
- */
- /* $Id: gxobj.h,v 1.7 2005/10/12 10:45:21 leonardo Exp $ */
- /* Memory manager implementation structures for Ghostscript */
- #ifndef gxobj_INCLUDED
- # define gxobj_INCLUDED
- #include "gxbitmap.h"
- #ifdef DEBUG
- #define IGC_PTR_STABILITY_CHECK 0
- #else
- #define IGC_PTR_STABILITY_CHECK 0
- #endif
- /* ================ Objects ================ */
- /*
- * Object headers have the form:
- -l- -mark/back-
- -size-
- -type/reloc-
- * l (aLone) is a single bit. Mark/back is 1 bit shorter than a uint. We
- * round the header size up to the next multiple of the most severe
- * alignment restriction (4 or 8 bytes).
- *
- * The mark/back field is used for the mark during the marking phase of
- * garbage collection, and for a back pointer value during the compaction
- * phase. Since we want to be able to collect local VM independently of
- * global VM, we need two different distinguished mark values:
- * - For local objects that have not been traced and should be freed
- * (compacted out), we use 1...11 in the mark field (o_unmarked).
- * - For global objects that have not been traced but should be kept,
- * we use 1...10 in the mark field (o_untraced).
- * Note that neither of these values is a possible real relocation value.
- *
- * The back pointer's meaning depends on whether the object is
- * free (unmarked) or in use (marked):
- * - In free objects, the back pointer is an offset from the object
- * header back to a chunk_head_t structure that contains the location
- * to which all the data in this chunk will get moved; the reloc field
- * contains the amount by which the following run of useful objects
- * will be relocated downwards.
- * - In useful objects, the back pointer is an offset from the object
- * back to the previous free object; the reloc field is not used (it
- * overlays the type field).
- * These two cases can be distinguished when scanning a chunk linearly,
- * but when simply examining an object via a pointer, the chunk pointer
- * is also needed.
- */
- #define obj_flag_bits 1
- #define obj_mb_bits (arch_sizeof_int * 8 - obj_flag_bits)
- #define o_unmarked (((uint)1 << obj_mb_bits) - 1)
- #define o_set_unmarked(pp)\
- ((pp)->o_smark = o_unmarked)
- #define o_is_unmarked(pp)\
- ((pp)->o_smark == o_unmarked)
- #define o_untraced (((uint)1 << obj_mb_bits) - 2)
- #define o_set_untraced(pp)\
- ((pp)->o_smark = o_untraced)
- #define o_is_untraced(pp)\
- ((pp)->o_smark == o_untraced)
- #define o_marked 0
- #define o_mark(pp)\
- ((pp)->o_smark = o_marked)
- #define obj_back_shift obj_flag_bits
- #define obj_back_scale (1 << obj_back_shift)
- typedef struct obj_header_data_s {
- union _f {
- struct _h {
- unsigned alone:1;
- } h;
- struct _m {
- unsigned _:1, smark:obj_mb_bits;
- } m;
- struct _b {
- unsigned _:1, back:obj_mb_bits;
- } b;
- } f;
- uint size;
- union _t {
- gs_memory_type_ptr_t type;
- uint reloc;
- } t;
- # if IGC_PTR_STABILITY_CHECK
- unsigned space_id:3; /* r_space_bits + 1 bit for "instability". */
- # endif
- } obj_header_data_t;
- /*
- * Define the alignment modulus for aligned objects. We assume all
- * alignment values are powers of 2; we can avoid nested 'max'es that way.
- * The final | is because back pointer values are divided by obj_back_scale,
- * so objects must be aligned at least 0 mod obj_back_scale.
- *
- * Note: OBJECTS ARE NOT GUARANTEED to be aligned any more strictly than
- * required by the hardware, regardless of the value of obj_align_mod.
- * See gsmemraw.h for more information about this.
- */
- #define obj_align_mod\
- (((arch_align_memory_mod - 1) |\
- (align_bitmap_mod - 1) |\
- (obj_back_scale - 1)) + 1)
- /* The only possible values for obj_align_mod are 4, 8, or 16.... */
- #if obj_align_mod == 4
- # define log2_obj_align_mod 2
- #else
- #if obj_align_mod == 8
- # define log2_obj_align_mod 3
- #else
- #if obj_align_mod == 16
- # define log2_obj_align_mod 4
- #endif
- #endif
- #endif
- #define obj_align_mask (obj_align_mod-1)
- #define obj_align_round(siz)\
- (uint)(((siz) + obj_align_mask) & -obj_align_mod)
- #define obj_size_round(siz)\
- obj_align_round((siz) + sizeof(obj_header_t))
- /* Define the real object header type, taking alignment into account. */
- struct obj_header_s { /* must be a struct because of forward reference */
- union _d {
- obj_header_data_t o;
- byte _pad[ROUND_UP(sizeof(obj_header_data_t), obj_align_mod)];
- }
- d;
- };
- /* Define some reasonable abbreviations for the fields. */
- #define o_alone d.o.f.h.alone
- #define o_back d.o.f.b.back
- #define o_smark d.o.f.m.smark
- #define o_size d.o.size
- #define o_type d.o.t.type
- #define o_nreloc d.o.t.reloc
- /*
- * The macros for getting the sizes of objects all take pointers to
- * the object header, for use when scanning storage linearly.
- */
- #define pre_obj_contents_size(pp)\
- ((pp)->o_size)
- #define pre_obj_rounded_size(pp)\
- obj_size_round(pre_obj_contents_size(pp))
- #define pre_obj_next(pp)\
- ((obj_header_t *)((byte *)(pp) + obj_align_round(\
- pre_obj_contents_size(pp) + sizeof(obj_header_t) )))
- /*
- * Define the header that free objects point back to when relocating.
- * Every chunk, including inner chunks, has one of these.
- */
- typedef struct chunk_head_s {
- byte *dest; /* destination for objects */
- #if obj_align_mod > arch_sizeof_ptr
- byte *_pad[obj_align_mod / arch_sizeof_ptr - 1];
- #endif
- obj_header_t free; /* header for a free object, */
- /* in case the first real object */
- /* is in use */
- } chunk_head_t;
- #endif /* gxobj_INCLUDED */
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