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* gc.c (scm_cellp): New function: C predicate to determine if an

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SCM value can be regarded as a pointer to a cell on the heap.
This commit is contained in:
Mikael Djurfeldt 1996-09-04 23:59:46 +00:00
parent 7f907b02be
commit 2e11a5778a
1 changed files with 71 additions and 0 deletions
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71
libguile/gc.c
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@ -767,6 +767,77 @@ scm_mark_locations (x, n)
} }
/* The following is a C predicate which determines if an SCM value can be
regarded as a pointer to a cell on the heap. The code is duplicated
from scm_mark_locations. */
#ifdef __STDC__
int
scm_cellp (SCM value)
#else
int
scm_cellp (value)
SCM value;
#endif
{
register int i, j;
register SCM_CELLPTR ptr;
if SCM_CELLP (*(SCM **) & value)
{
ptr = (SCM_CELLPTR) SCM2PTR ((*(SCM **) & value));
i = 0;
j = scm_n_heap_segs - 1;
if ( SCM_PTR_LE (scm_heap_table[i].bounds[0], ptr)
&& SCM_PTR_GT (scm_heap_table[j].bounds[1], ptr))
{
while (i <= j)
{
int seg_id;
seg_id = -1;
if ( (i == j)
|| SCM_PTR_GT (scm_heap_table[i].bounds[1], ptr))
seg_id = i;
else if (SCM_PTR_LE (scm_heap_table[j].bounds[0], ptr))
seg_id = j;
else
{
int k;
k = (i + j) / 2;
if (k == i)
break;
if (SCM_PTR_GT (scm_heap_table[k].bounds[1], ptr))
{
j = k;
++i;
if (SCM_PTR_LE (scm_heap_table[i].bounds[0], ptr))
continue;
else
break;
}
else if (SCM_PTR_LE (scm_heap_table[k].bounds[0], ptr))
{
i = k;
--j;
if (SCM_PTR_GT (scm_heap_table[j].bounds[1], ptr))
continue;
else
break;
}
}
if ( !scm_heap_table[seg_id].valid
|| scm_heap_table[seg_id].valid (ptr,
&scm_heap_table[seg_id]))
return 1;
break;
}
}
}
return 0;
}
static void static void
scm_mark_weak_vector_spines () scm_mark_weak_vector_spines ()
{ {