From 3a85f3f45e4a0baa101c902f2caa35bce4a7c1ca Mon Sep 17 00:00:00 2001
From: qiuhao <qiuhao951@gmail.com>
Date: Sun, 8 Dec 2019 10:45:28 +0800
Subject: [PATCH] add recip for FixedU128 (#61)
---
utilities/src/fixed128.rs | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/utilities/src/fixed128.rs b/utilities/src/fixed128.rs
index 1de4ab4..d611c11 100644
--- a/utilities/src/fixed128.rs
+++ b/utilities/src/fixed128.rs
@@ -53,6 +53,11 @@ impl FixedU128 {
self.0
}
+ /// Takes the reciprocal(inverse) of FixedU128, 1/x
+ pub fn recip(&self) -> Option<Self> {
+ Self::from_natural(1u128).checked_div(self)
+ }
+
/// Checked add. Same semantic to `num_traits::CheckedAdd`.
pub fn checked_add(&self, rhs: &Self) -> Option<Self> {
self.0.checked_add(rhs.0).map(Self)
@@ -290,4 +295,22 @@ mod tests {
let ten_percent_perquintill: FixedU128 = Perquintill::from_percent(10).into();
assert_eq!(ten_percent_perquintill.deconstruct(), DIV / 10);
}
+
+ #[test]
+ fn recip_should_work() {
+ let a = FixedU128::from_natural(2);
+ assert_eq!(a.recip(), Some(FixedU128::from_rational(1, 2)));
+
+ let a = FixedU128::from_natural(2);
+ assert_eq!(a.recip().unwrap().checked_mul_int(&4i32), Some(2i32));
+
+ let a = FixedU128::from_rational(100, 121);
+ assert_eq!(a.recip(), Some(FixedU128::from_rational(121, 100)));
+
+ let a = FixedU128::from_rational(1, 2);
+ assert_eq!(a.recip().unwrap().checked_mul(&a), Some(FixedU128::from_natural(1)));
+
+ let a = FixedU128::from_natural(0);
+ assert_eq!(a.recip(), None);
+ }
}
--
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