Make by-divisor GPU kernels reuse read-only operands

PerfectNumbers.Core/Gpu/ReadOnlyGpuUInt128.cs

@@ -0,0 +1,90 @@
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+
+namespace PerfectNumbers.Core.Gpu;
+
+public readonly struct ReadOnlyGpuUInt128 : IEquatable<ReadOnlyGpuUInt128>
+{
+    public readonly ulong High;
+    public readonly ulong Low;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ReadOnlyGpuUInt128(ulong high, ulong low)
+    {
+        High = high;
+        Low = low;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ReadOnlyGpuUInt128(ulong low)
+        : this(0UL, low)
+    {
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ReadOnlyGpuUInt128(UInt128 value)
+    {
+        High = (ulong)(value >> 64);
+        Low = (ulong)value;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ReadOnlyGpuUInt128(GpuUInt128 value)
+    {
+        High = value.High;
+        Low = value.Low;
+    }
+
+    public bool IsZero
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => High == 0UL && Low == 0UL;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public int GetBitLength()
+    {
+        if (High != 0UL)
+        {
+            return 64 + (64 - BitOperations.LeadingZeroCount(High));
+        }
+
+        if (Low == 0UL)
+        {
+            return 0;
+        }
+
+        return 64 - BitOperations.LeadingZeroCount(Low);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public GpuUInt128 ToMutable() => new(High, Low);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public bool Equals(ReadOnlyGpuUInt128 other) => High == other.High && Low == other.Low;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public override bool Equals(object? obj) => obj is ReadOnlyGpuUInt128 other && Equals(other);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public override int GetHashCode() => HashCode.Combine(High, Low);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static implicit operator ReadOnlyGpuUInt128(ulong value) => new(value);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static implicit operator ReadOnlyGpuUInt128(UInt128 value) => new(value);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static implicit operator ReadOnlyGpuUInt128(GpuUInt128 value) => new(value);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static implicit operator UInt128(ReadOnlyGpuUInt128 value) => ((UInt128)value.High << 64) | value.Low;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ReadOnlyGpuUInt128 WithHigh(ulong high) => new(high, Low);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ReadOnlyGpuUInt128 WithLow(ulong low) => new(High, low);
+}