Move substrate/serai/* to substrate/*

substrate/primitives/src/amount.rs

@@ -0,0 +1,47 @@
+use core::{
+  ops::{Add, Sub, Mul},
+  fmt::Debug,
+};
+
+#[cfg(feature = "std")]
+use zeroize::Zeroize;
+
+use scale::{Encode, Decode, MaxEncodedLen};
+use scale_info::TypeInfo;
+#[cfg(feature = "std")]
+use serde::{Serialize, Deserialize};
+
+/// The type used for amounts within Substrate.
+// Distinct from Amount due to Substrate's requirements on this type.
+// While Amount could have all the necessary traits implemented, not only are they many, it'd make
+// Amount a large type with a variety of misc functions.
+// The current type's minimalism sets clear bounds on usage.
+pub type SubstrateAmount = u64;
+/// The type used for amounts.
+#[derive(
+  Clone, Copy, PartialEq, Eq, PartialOrd, Debug, Encode, Decode, MaxEncodedLen, TypeInfo,
+)]
+#[cfg_attr(feature = "std", derive(Zeroize, Serialize, Deserialize))]
+pub struct Amount(pub SubstrateAmount);
+
+impl Add for Amount {
+  type Output = Amount;
+  fn add(self, other: Amount) -> Amount {
+    // Explicitly use checked_add so even if range checks are disabled, this is still checked
+    Amount(self.0.checked_add(other.0).unwrap())
+  }
+}
+
+impl Sub for Amount {
+  type Output = Amount;
+  fn sub(self, other: Amount) -> Amount {
+    Amount(self.0.checked_sub(other.0).unwrap())
+  }
+}
+
+impl Mul for Amount {
+  type Output = Amount;
+  fn mul(self, other: Amount) -> Amount {
+    Amount(self.0.checked_mul(other.0).unwrap())
+  }
+}