unroff/src/gcroot.c

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2023-02-13 08:45:50 -05:00
/* $Revision: 1.5 $
*/
#include "unroff.h"
/* Functions to register Scheme objects in a vector that has been added
* to the GC root set to avoid having to deal with weak pointers.
* Code using these functions works with indexes into the vector.
*
* register_object(obj) -- registers an object and returns index
* deregister_object(inx) -- deregisters object specified by index
* get_object(inx) -- returns object specified by index
*/
static int max_objects = 32; /* initial size */
static int num_objects;
static Object objects;
static int inx;
int register_object(Object x) {
Object v;
int n;
GC_Node;
if (num_objects == max_objects) {
max_objects *= 2;
GC_Link(x);
v = Make_Vector(max_objects, Null);
GC_Unlink;
memcpy(VECTOR(v)->data, VECTOR(objects)->data,
num_objects * sizeof(Object));
objects = v;
inx = num_objects;
}
for (n = 0; !Nullp(VECTOR(objects)->data[inx]);
inx++, inx %= max_objects) {
n++;
assert(n < max_objects);
}
VECTOR(objects)->data[inx] = x;
num_objects++;
return inx;
}
void deregister_object(int i) {
VECTOR(objects)->data[i] = Null;
--num_objects;
assert(num_objects >= 0);
}
Object get_object(int i) {
return VECTOR(objects)->data[i];
}
void init_gcroot(void) {
objects = Make_Vector(max_objects, Null);
Global_GC_Link(objects);
}