f - use fewer operations

Author: jkczyz

lightning/src/routing/scoring.rs

@@ -1163,14 +1163,11 @@ impl<L: Deref<Target = u64>, BRT: Deref<Target = HistoricalBucketRangeTracker>,
 					// half life has passed, approximate an additional three-quarter life by summing
 					// the results of taking both the *next two* half lives instead. This helps
 					// smooth out the decay.
+					let decayed_offset_msat = offset_msat.checked_shr(decays as u32).unwrap_or(0);
 					if half_decays % 2 == 0 {
-						offset_msat.checked_shr(decays as u32).unwrap_or(0)
+						decayed_offset_msat
 					} else {
-						offset_msat
-							.checked_shr((decays + 1) as u32)
-							.map(|decayed_offset_msat| decayed_offset_msat
-								+ offset_msat.checked_shr((decays + 2) as u32).unwrap_or(0))
-							.unwrap_or(0)
+						(decayed_offset_msat >> 1) + (decayed_offset_msat >> 2)
 					}
 				}
 			},