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Diffstat (limited to '')
| -rw-r--r-- | gc/gc_hdrs.h | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/gc/gc_hdrs.h b/gc/gc_hdrs.h new file mode 100644 index 0000000..60dc2ad --- /dev/null +++ b/gc/gc_hdrs.h @@ -0,0 +1,135 @@ +/* + * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers + * Copyright (c) 1991-1994 by Xerox Corporation. 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. + */ +/* Boehm, July 11, 1995 11:54 am PDT */ +# ifndef GC_HEADERS_H +# define GC_HEADERS_H +typedef struct hblkhdr hdr; + +# if CPP_WORDSZ != 32 && CPP_WORDSZ < 36 + --> Get a real machine. +# endif + +/* + * The 2 level tree data structure that is used to find block headers. + * If there are more than 32 bits in a pointer, the top level is a hash + * table. + */ + +# if CPP_WORDSZ > 32 +# define HASH_TL +# endif + +/* Define appropriate out-degrees for each of the two tree levels */ +# ifdef SMALL_CONFIG +# define LOG_BOTTOM_SZ 11 + /* Keep top index size reasonable with smaller blocks. */ +# else +# define LOG_BOTTOM_SZ 10 +# endif +# ifndef HASH_TL +# define LOG_TOP_SZ (WORDSZ - LOG_BOTTOM_SZ - LOG_HBLKSIZE) +# else +# define LOG_TOP_SZ 11 +# endif +# define TOP_SZ (1 << LOG_TOP_SZ) +# define BOTTOM_SZ (1 << LOG_BOTTOM_SZ) + +typedef struct bi { + hdr * index[BOTTOM_SZ]; + /* + * The bottom level index contains one of three kinds of values: + * 0 means we're not responsible for this block, + * or this is a block other than the first one in a free block. + * 1 < (long)X <= MAX_JUMP means the block starts at least + * X * HBLKSIZE bytes before the current address. + * A valid pointer points to a hdr structure. (The above can't be + * valid pointers due to the GET_MEM return convention.) + */ + struct bi * asc_link; /* All indices are linked in */ + /* ascending order... */ + struct bi * desc_link; /* ... and in descending order. */ + word key; /* high order address bits. */ +# ifdef HASH_TL + struct bi * hash_link; /* Hash chain link. */ +# endif +} bottom_index; + +/* extern bottom_index GC_all_nils; - really part of GC_arrays */ + +/* extern bottom_index * GC_top_index []; - really part of GC_arrays */ + /* Each entry points to a bottom_index. */ + /* On a 32 bit machine, it points to */ + /* the index for a set of high order */ + /* bits equal to the index. For longer */ + /* addresses, we hash the high order */ + /* bits to compute the index in */ + /* GC_top_index, and each entry points */ + /* to a hash chain. */ + /* The last entry in each chain is */ + /* GC_all_nils. */ + + +# define MAX_JUMP (HBLKSIZE - 1) + +# define HDR_FROM_BI(bi, p) \ + ((bi)->index[((word)(p) >> LOG_HBLKSIZE) & (BOTTOM_SZ - 1)]) +# ifndef HASH_TL +# define BI(p) (GC_top_index \ + [(word)(p) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE)]) +# define HDR_INNER(p) HDR_FROM_BI(BI(p),p) +# ifdef SMALL_CONFIG +# define HDR(p) GC_find_header((ptr_t)(p)) +# else +# define HDR(p) HDR_INNER(p) +# endif +# define GET_BI(p, bottom_indx) (bottom_indx) = BI(p) +# define GET_HDR(p, hhdr) (hhdr) = HDR(p) +# define SET_HDR(p, hhdr) HDR_INNER(p) = (hhdr) +# define GET_HDR_ADDR(p, ha) (ha) = &(HDR_INNER(p)) +# else /* hash */ +/* Hash function for tree top level */ +# define TL_HASH(hi) ((hi) & (TOP_SZ - 1)) +/* Set bottom_indx to point to the bottom index for address p */ +# define GET_BI(p, bottom_indx) \ + { \ + register word hi = \ + (word)(p) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE); \ + register bottom_index * _bi = GC_top_index[TL_HASH(hi)]; \ + \ + while (_bi -> key != hi && _bi != GC_all_nils) \ + _bi = _bi -> hash_link; \ + (bottom_indx) = _bi; \ + } +# define GET_HDR_ADDR(p, ha) \ + { \ + register bottom_index * bi; \ + \ + GET_BI(p, bi); \ + (ha) = &(HDR_FROM_BI(bi, p)); \ + } +# define GET_HDR(p, hhdr) { register hdr ** _ha; GET_HDR_ADDR(p, _ha); \ + (hhdr) = *_ha; } +# define SET_HDR(p, hhdr) { register hdr ** _ha; GET_HDR_ADDR(p, _ha); \ + *_ha = (hhdr); } +# define HDR(p) GC_find_header((ptr_t)(p)) +# endif + +/* Is the result a forwarding address to someplace closer to the */ +/* beginning of the block or NIL? */ +# define IS_FORWARDING_ADDR_OR_NIL(hhdr) ((unsigned long) (hhdr) <= MAX_JUMP) + +/* Get an HBLKSIZE aligned address closer to the beginning of the block */ +/* h. Assumes hhdr == HDR(h) and IS_FORWARDING_ADDR(hhdr). */ +# define FORWARDED_ADDR(h, hhdr) ((struct hblk *)(h) - (unsigned long)(hhdr)) +# endif /* GC_HEADERS_H */ |