/* * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers * Copyright (c) 1991, 1992 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 copy this garbage collector for any purpose, * provided the above notices are retained on all copies. */ # 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 */ # define LOG_BOTTOM_SZ 10 # 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. * 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. */ 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) # ifndef HASH_TL # define BI(p) (GC_top_index \ [(word)(p) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE)]) # define HDR(p) (BI(p)->index \ [((word)(p) >> LOG_HBLKSIZE) & (BOTTOM_SZ - 1)]) # define GET_BI(p, bottom_indx) (bottom_indx) = BI(p) # define GET_HDR(p, hhdr) (hhdr) = HDR(p) # define SET_HDR(p, hhdr) HDR(p) = (hhdr) # define GET_HDR_ADDR(p, ha) (ha) = &(HDR(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) = &(bi->index[((unsigned long)(p)>>LOG_HBLKSIZE) \ & (BOTTOM_SZ - 1)]); \ } # 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(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 */