From de1f0c3ef824fca91036875a22c9afc6ab44e4d2 Mon Sep 17 00:00:00 2001
From: Gav <gavin@parity.io>
Date: Mon, 14 May 2018 17:52:12 +0200
Subject: [PATCH] Balance is 128-bit value.

---
 Cargo.lock                                 |  2 +-
 polkadot/primitives/src/lib.rs             | 19 +++++++++++++------
 substrate/codec/src/slicable.rs            |  2 +-
 substrate/runtime/primitives/src/traits.rs |  4 ++--
 4 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 84210a9849164..7dab36dd0285d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -797,7 +797,7 @@ dependencies = [
 [[package]]
 name = "integer-sqrt"
 version = "0.1.0"
-source = "git+https://github.com/paritytech/integer-sqrt-rs.git#f4cf61482096dc98c1273f46a10849d182b4c23c"
+source = "git+https://github.com/paritytech/integer-sqrt-rs.git#886e9cb983c46498003878afe965d55caa762025"
 
 [[package]]
 name = "interleaved-ordered"
diff --git a/polkadot/primitives/src/lib.rs b/polkadot/primitives/src/lib.rs
index 012cf57b3d21a..f9438c4dc5d5b 100644
--- a/polkadot/primitives/src/lib.rs
+++ b/polkadot/primitives/src/lib.rs
@@ -50,7 +50,8 @@ pub use primitives::block::Id as BlockId;
 pub use primitives::block::Log as Log;
 
 /// An index to a block.
-pub type BlockNumber = u64;
+/// 32-bits will allow for 136 years of blocks assuming 1 block per second.
+pub type BlockNumber = u32;
 
 /// Alias to Ed25519 pubkey that identifies an account on the relay chain. This will almost
 /// certainly continue to be the same as the substrate's `AuthorityId`.
@@ -60,11 +61,11 @@ pub type AccountId = primitives::AuthorityId;
 /// exactly equivalent to what the substrate calls an "authority".
 pub type SessionKey = primitives::AuthorityId;
 
-/// Indentifier for a chain.
-pub type ChainId = u64;
+/// Indentifier for a chain. 32-bit should be plenty.
+pub type ChainId = u32;
 
-/// Index of a transaction in the relay chain.
-pub type Index = u64;
+/// Index of a transaction in the relay chain. 32-bit should be plenty.
+pub type Index = u32;
 
 /// A hash of some data used by the relay chain.
 pub type Hash = primitives::H256;
@@ -76,4 +77,10 @@ pub type Signature = runtime_primitives::Ed25519Signature;
 pub type Timestamp = u64;
 
 /// The balance of an account.
-pub type Balance = u64;
+/// 128-bits (or 38 significant decimal figures) will allow for 10m currency (10^7) at a resolution
+/// to all for one second's worth of an annualised 50% reward be paid to a unit holder (10^11 unit
+/// denomination), or 10^18 total atomic units, to grow at 50%/year for 51 years (10^9 multiplier)
+/// for an eventual total of 10^27 units (27 significant decimal figures).
+/// We round denomination to 10^12 (12 sdf), and leave the other redundancy at the upper end so
+/// that 32 bits may be multiplied with a balance in 128 bits without worrying about overflow.
+pub type Balance = u128;
diff --git a/substrate/codec/src/slicable.rs b/substrate/codec/src/slicable.rs
index 8c3d8f4330dce..4054b5ef5eccb 100644
--- a/substrate/codec/src/slicable.rs
+++ b/substrate/codec/src/slicable.rs
@@ -344,7 +344,7 @@ macro_rules! impl_non_endians {
 	)* }
 }
 
-impl_endians!(u16, u32, u64, usize, i16, i32, i64, isize);
+impl_endians!(u16, u32, u64, u128, usize, i16, i32, i64, i128, isize);
 impl_non_endians!(i8, [u8; 1], [u8; 2], [u8; 3], [u8; 4], [u8; 5], [u8; 6], [u8; 7], [u8; 8],
 	[u8; 10], [u8; 12], [u8; 14], [u8; 16], [u8; 20], [u8; 24], [u8; 28], [u8; 32], [u8; 40],
 	[u8; 48], [u8; 56], [u8; 64], [u8; 80], [u8; 96], [u8; 112], [u8; 128], bool);
diff --git a/substrate/runtime/primitives/src/traits.rs b/substrate/runtime/primitives/src/traits.rs
index bcd5707f1fd83..4b7530e6db70c 100644
--- a/substrate/runtime/primitives/src/traits.rs
+++ b/substrate/runtime/primitives/src/traits.rs
@@ -61,7 +61,7 @@ pub trait As<T> {
 macro_rules! impl_numerics {
 	( $( $t:ty ),* ) => {
 		$(
-			impl_numerics!($t: u8, u16, u32, u64, usize, i8, i16, i32, i64, isize,);
+			impl_numerics!($t: u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize,);
 		)*
 	};
 	( $f:ty : $t:ty, $( $rest:ty, )* ) => {
@@ -74,7 +74,7 @@ macro_rules! impl_numerics {
 	( $f:ty : ) => {}
 }
 
-impl_numerics!(u8, u16, u32, u64, usize, i8, i16, i32, i64, isize);
+impl_numerics!(u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize);
 
 pub struct Identity;
 impl<T> Convert<T, T> for Identity {