Add an Add bench!

Author: Coding-Enthusiast

Src/Benchmarks/Bitcoin/Cryptography/EllipticCurve/Scalar8x32Alt.cs

@@ -125,6 +125,66 @@ public bool IsHigh
             }
         }
 
+
+        public Scalar8x32Alt Add(in Scalar8x32Alt other, out bool overflow)
+        {
+            ulong t = (ulong)b0 + other.b0;
+            uint r0 = (uint)t; t >>= 32;
+            t += (ulong)b1 + other.b1;
+            uint r1 = (uint)t; t >>= 32;
+            t += (ulong)b2 + other.b2;
+            uint r2 = (uint)t; t >>= 32;
+            t += (ulong)b3 + other.b3;
+            uint r3 = (uint)t; t >>= 32;
+            t += (ulong)b4 + other.b4;
+            uint r4 = (uint)t; t >>= 32;
+            t += (ulong)b5 + other.b5;
+            uint r5 = (uint)t; t >>= 32;
+            t += (ulong)b6 + other.b6;
+            uint r6 = (uint)t; t >>= 32;
+            t += (ulong)b7 + other.b7;
+            uint r7 = (uint)t; t >>= 32;
+
+            int yes = 0;
+            int no = 0;
+            no |= (r7 < N7 ? 1 : 0);
+            no |= (r6 < N6 ? 1 : 0);
+            no |= (r5 < N5 ? 1 : 0);
+            no |= (r4 < N4 ? 1 : 0);
+            yes |= (r4 > N4 ? 1 : 0) & ~no;
+            no |= (r3 < N3 ? 1 : 0) & ~yes;
+            yes |= (r3 > N3 ? 1 : 0) & ~no;
+            no |= (r2 < N2 ? 1 : 0) & ~yes;
+            yes |= (r2 > N2 ? 1 : 0) & ~no;
+            no |= (r1 < N1 ? 1 : 0) & ~yes;
+            yes |= (r1 > N1 ? 1 : 0) & ~no;
+            yes |= (r0 >= N0 ? 1 : 0) & ~no;
+
+            uint of = (uint)yes + (uint)t;
+            overflow = of != 0;
+
+            Debug.Assert(of == 0 || of == 1);
+
+            t = (ulong)r0 + (of * NC0);
+            r0 = (uint)t; t >>= 32;
+            t += (ulong)r1 + (of * NC1);
+            r1 = (uint)t; t >>= 32;
+            t += (ulong)r2 + (of * NC2);
+            r2 = (uint)t; t >>= 32;
+            t += (ulong)r3 + (of * NC3);
+            r3 = (uint)t; t >>= 32;
+            t += (ulong)r4 + (of * NC4);
+            r4 = (uint)t; t >>= 32;
+            t += r5;
+            r5 = (uint)t; t >>= 32;
+            t += r6;
+            r6 = (uint)t; t >>= 32;
+            t += r7;
+            r7 = (uint)t;
+
+            return new Scalar8x32Alt(r0, r1, r2, r3, r4, r5, r6, r7);
+        }
+
         public Scalar8x32Alt Multiply(in Scalar8x32Alt b)
         {
             uint[] l = new uint[16];

Src/Benchmarks/Bitcoin/Cryptography/EllipticCurve/Scalar8x32_AddBench.cs

@@ -0,0 +1,53 @@
+// Autarkysoft Benchmarks
+// Copyright (c) 2020 Autarkysoft
+// Distributed under the MIT software license, see the accompanying
+// file LICENCE or http://www.opensource.org/licenses/mit-license.php.
+
+using Autarkysoft.Bitcoin.Cryptography.EllipticCurve;
+using BenchmarkDotNet.Attributes;
+using System;
+
+namespace Benchmarks.Bitcoin.Cryptography.EllipticCurve
+{
+    [InProcess]
+    [RankColumn]
+    public class Scalar8x32_AddBench
+    {
+        [GlobalSetup]
+        public void Setup()
+        {
+            byte[] ba1 = new byte[32];
+            byte[] ba2 = new byte[32];
+            Random rng = new(17);
+            rng.NextBytes(ba1);
+            rng.NextBytes(ba2);
+
+            lib1 = new(ba1, out bool of1);
+            lib2 = new(ba1, out bool of2);
+            if (of1 || of2)
+            {
+                throw new Exception("Unexpected overflow.");
+            }
+            alt1 = new(ba1);
+            alt2 = new(ba1);
+
+            Scalar8x32 res1 = lib1.Add(lib2, out _);
+            Scalar8x32Alt res2 = alt1.Add(alt2, out _);
+
+            if (!res2.Equals(res1))
+            {
+                throw new Exception("Not equal.");
+            }
+        }
+
+        Scalar8x32 lib1, lib2;
+        Scalar8x32Alt alt1, alt2;
+
+
+        [Benchmark(Baseline = true)]
+        public Scalar8x32 LibAdd() => lib1.Add(lib2, out _);
+
+        [Benchmark]
+        public Scalar8x32Alt AltAdd() => alt1.Add(alt2, out _);
+    }
+}