From 595f6129b680bfb1b69d172c128ea8e81495d3a8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Lema=C5=84czyk?= <marek@lemanczyk.eu>
Date: Tue, 9 Sep 2025 22:22:23 +0200
Subject: [PATCH] Fix subtraction borrow in GpuUInt128

---
 PerfectNumbers.Core/Gpu/GpuUInt128.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/PerfectNumbers.Core/Gpu/GpuUInt128.cs b/PerfectNumbers.Core/Gpu/GpuUInt128.cs
index 4528a74..45d68c3 100644
--- a/PerfectNumbers.Core/Gpu/GpuUInt128.cs
+++ b/PerfectNumbers.Core/Gpu/GpuUInt128.cs
@@ -246,7 +246,7 @@ public readonly struct GpuUInt128 : IComparable<GpuUInt128>, IEquatable<GpuUInt1
     public GpuUInt128 Sub(GpuUInt128 other)
     {
         ulong borrow = Low < other.Low ? 1UL : 0UL;
-        return new(High - other.High + borrow, Low - other.Low);
+        return new(High - other.High - borrow, Low - other.Low);
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]