Fix folder names in primitives (#4358)

* sr-arithmetic -> arithmetic

* sr-sandbox -> sandbox

* primitives/sr-staking-primitives -> primitives/staking

* primitives/sr-version -> primitives/version

* primitives/block-builder/runtime-api -> primitives/block-builder

substrate/primitives/arithmetic/benches/bench.rs

@@ -0,0 +1,80 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use criterion::{Criterion, Throughput, BenchmarkId, criterion_group, criterion_main};
+use sp_arithmetic::biguint::{BigUint, Single};
+use rand::Rng;
+
+fn random_big_uint(size: usize) -> BigUint {
+	let mut rng = rand::thread_rng();
+	let digits: Vec<_> = (0..size).map(|_| rng.gen_range(0, Single::max_value())).collect();
+	BigUint::from_limbs(&digits)
+}
+
+fn bench_op<F: Fn(&BigUint, &BigUint)>(c: &mut Criterion, name: &str, op: F) {
+	let mut group = c.benchmark_group(name);
+
+	for size in [2, 4, 6, 8, 10].iter() {
+		group.throughput(Throughput::Elements(*size));
+		group.bench_with_input(BenchmarkId::from_parameter(size), size, |bencher, &size| {
+			let a = random_big_uint(size as usize);
+			let b = random_big_uint(size as usize);
+
+			bencher.iter(|| op(&a, &b));
+		});
+	}
+}
+
+fn bench_addition(c: &mut Criterion) {
+	bench_op(c, "addition", |a, b| {
+		let _ = a.clone().add(&b);
+	});
+}
+
+fn bench_subtraction(c: &mut Criterion) {
+	bench_op(c, "subtraction", |a, b| {
+		let _ = a.clone().sub(&b);
+	});
+}
+
+fn bench_multiplication(c: &mut Criterion) {
+	bench_op(c, "multiplication", |a, b| {
+		let _ = a.clone().mul(&b);
+	});
+}
+
+fn bench_division(c: &mut Criterion) {
+	let mut group = c.benchmark_group("division");
+
+	for size in [4, 6, 8, 10].iter() {
+		group.throughput(Throughput::Elements(*size));
+		group.bench_with_input(BenchmarkId::from_parameter(size), size, |bencher, &size| {
+			let a = random_big_uint(size as usize);
+			let b = random_big_uint(rand::thread_rng().gen_range(2, size as usize));
+
+			bencher.iter(|| {
+				let _ = a.clone().div(&b, true);
+			});
+		});
+	}
+}
+
+criterion_group!{
+    name = benches;
+    config = Criterion::default();
+    targets = bench_addition, bench_subtraction, bench_multiplication, bench_division
+}
+criterion_main!(benches);