Add amount conversion for Orchard values.

zcash_primitives/src/transaction/components/amount.rs

@@ -2,6 +2,8 @@ use std::convert::TryFrom;
 use std::iter::Sum;
 use std::ops::{Add, AddAssign, Neg, Sub, SubAssign};
 
+use orchard::value as orchard;
+
 pub const COIN: i64 = 1_0000_0000;
 pub const MAX_MONEY: i64 = 21_000_000 * COIN;
 
@@ -180,6 +182,14 @@ impl Neg for Amount {
     }
 }
 
+impl TryFrom<orchard::ValueSum> for Amount {
+    type Error = ();
+
+    fn try_from(v: orchard::ValueSum) -> Result<Amount, Self::Error> {
+        i64::try_from(v).map_err(|_| ()).and_then(Amount::try_from)
+    }
+}
+
 #[cfg(any(test, feature = "test-dependencies"))]
 pub mod testing {
     use proptest::prelude::prop_compose;