+STATIC word GC_faulted[NSUMS]; /* Record of pages on which we saw a write */
+ /* fault. */
+STATIC size_t GC_n_faulted = 0;
+
+void GC_record_fault(struct hblk * h)
+{
+ word page = (word)h;
+
+ page += GC_page_size - 1;
+ page &= ~(GC_page_size - 1);
+ if (GC_n_faulted >= NSUMS) ABORT("write fault log overflowed");
+ GC_faulted[GC_n_faulted++] = page;
+}
+
+STATIC GC_bool GC_was_faulted(struct hblk *h)
+{
+ size_t i;
+ word page = (word)h;
+
+ page += GC_page_size - 1;
+ page &= ~(GC_page_size - 1);
+ for (i = 0; i < GC_n_faulted; ++i) {
+ if (GC_faulted[i] == page) return TRUE;
+ }
+ return FALSE;
+}
+
+STATIC word GC_checksum(struct hblk *h)