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count cycle lengths in skip_max_list_cycle (#1260)

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Mark Thom
2022-01-31 18:23:16 -07:00
parent e62875ac90
commit 4b71607215
1 changed files with 10 additions and 1 deletions
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11
src/machine/system_calls.rs
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@@ -462,12 +462,21 @@ impl MachineState {
hare = step(&self.heap, self.heap[hare]); hare = step(&self.heap, self.heap[hare]);
} }
let mut count = 1;
while hare != tortoise { while hare != tortoise {
hare = step(&self.heap, self.heap[hare]); hare = step(&self.heap, self.heap[hare]);
tortoise = step(&self.heap, self.heap[tortoise]); tortoise = step(&self.heap, self.heap[tortoise]);
count += 1;
} }
unify!(self, self.registers[4], self.heap[hare]); let target_n = self.store(self.deref(self.registers[1]));
self.unify_fixnum(Fixnum::build_with(count), target_n);
if !self.fail {
unify!(self, self.registers[4], self.heap[hare]);
}
} }
fn finalize_skip_max_list(&mut self, n: i64, value: HeapCellValue) { fn finalize_skip_max_list(&mut self, n: i64, value: HeapCellValue) {