65 lines
1.2 KiB
C
65 lines
1.2 KiB
C
// Cheney style stop and copy garbage collector
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#include "gc.h"
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cons_t *the_empty_list = NULL;
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static cons_t *old, *new, *scanptr, *freeptr, *eom, *root;
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size_t tos;
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void gc_init() {
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old = calloc(sizeof(cons_t), SIZE);
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freeptr = old;
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eom = old + (SIZE / 2);
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new = eom + 1;
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root = alloc();
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}
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cons_t *alloc() {
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if (freeptr < eom) {
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cons_t *retval = freeptr;
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freeptr++;
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return retval;
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} else {
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gc_run();
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return alloc();
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}
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}
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void gc_run() {
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freeptr = new;
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scanptr = new;
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// Relocate root
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relocate(root);
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// Enter the main GC loop
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gc_loop();
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// Flip old and new;
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cons_t *temp = old;
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old = new;
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new = temp;
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}
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void gc_loop() {
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while (scanptr < freeptr) {
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relocate(scanptr);
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scanptr++;
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}
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}
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void move(box_t box) {
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if (box.type == CONS && box.cons != the_empty_list) {
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if (box.cons->car.type == BROKEN_HEART) {
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box.cons = box.cons->cdr.cons;
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} else {
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memcpy(freeptr, box.cons, sizeof(cons_t));
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box.cons->car.type = BROKEN_HEART;
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box.cons->cdr.cons = freeptr;
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freeptr++;
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}
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}
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}
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void relocate(cons_t* cons) {
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move(cons->car);
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move(cons->cdr);
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}
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