From 4890190de68fd7020c870d971f4a3e3bc40addef Mon Sep 17 00:00:00 2001
From: rameel <rameel-b@hotmail.com>
Date: Mon, 14 Jul 2025 18:33:50 +0500
Subject: [PATCH] Backport ExtractMostSignificantBits and drop .NET7.0 target

---
 .../Ramstack.Globbing.Tests.csproj             |  2 +-
 .../SimdConfigurationTests.cs                  |  1 +
 Ramstack.Globbing/Internal/PathHelper.cs       | 18 +++++++++++++-----
 Ramstack.Globbing/Ramstack.Globbing.csproj     |  2 +-
 4 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/Ramstack.Globbing.Tests/Ramstack.Globbing.Tests.csproj b/Ramstack.Globbing.Tests/Ramstack.Globbing.Tests.csproj
index 2f124f9..2a75b0b 100644
--- a/Ramstack.Globbing.Tests/Ramstack.Globbing.Tests.csproj
+++ b/Ramstack.Globbing.Tests/Ramstack.Globbing.Tests.csproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
+    <TargetFramework>net6.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <LangVersion>preview</LangVersion>
diff --git a/Ramstack.Globbing.Tests/SimdConfigurationTests.cs b/Ramstack.Globbing.Tests/SimdConfigurationTests.cs
index 7371115..e76671b 100644
--- a/Ramstack.Globbing.Tests/SimdConfigurationTests.cs
+++ b/Ramstack.Globbing.Tests/SimdConfigurationTests.cs
@@ -15,6 +15,7 @@ public void VerifySimdConfiguration()
             Assert.That(Sse2.IsSupported, Is.False);
             Assert.That(Sse41.IsSupported, Is.False);
             Assert.That(Avx2.IsSupported, Is.False);
+            Assert.That(AdvSimd.Arm64.IsSupported, Is.False);
             Assert.That(AdvSimd.IsSupported, Is.False);
         }
 
diff --git a/Ramstack.Globbing/Internal/PathHelper.cs b/Ramstack.Globbing/Internal/PathHelper.cs
index 2cff6c5..a03a128 100644
--- a/Ramstack.Globbing/Internal/PathHelper.cs
+++ b/Ramstack.Globbing/Internal/PathHelper.cs
@@ -334,7 +334,7 @@ public PathSegmentIterator() =>
 
             while ((int)_position < length)
             {
-                if ((Avx2.IsSupported || Sse2.IsSupported || AdvSimd.IsSupported) && _mask != 0)
+                if ((Avx2.IsSupported || Sse2.IsSupported || AdvSimd.Arm64.IsSupported) && _mask != 0)
                 {
                     var offset = BitOperations.TrailingZeroCount(_mask);
                     if (AdvSimd.IsSupported)
@@ -446,8 +446,7 @@ public PathSegmentIterator() =>
                     if (_mask == 0)
                         _position += Vector128<ushort>.Count;
                 }
-                #if NET7_0_OR_GREATER
-                else if (AdvSimd.IsSupported && (int)_position + Vector128<ushort>.Count <= length)
+                else if (AdvSimd.Arm64.IsSupported && (int)_position + Vector128<ushort>.Count <= length)
                 {
                     var chunk = LoadVector128(ref source, _position);
                     var backslashMask = CreateBackslash128Bitmask(flags);
@@ -466,15 +465,24 @@ public PathSegmentIterator() =>
                     // This avoids reloading SIMD registers and repeating comparisons
                     // on the same chunk of data.
                     //
-                    _mask = comparison.ExtractMostSignificantBits();
+                    _mask = ExtractMostSignificantBits(comparison);
 
                     //
                     // Advance position to the next chunk when no separators found
                     //
                     if (_mask == 0)
                         _position += Vector128<ushort>.Count;
+
+                    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                    static uint ExtractMostSignificantBits(Vector128<ushort> v)
+                    {
+                        var sum = AdvSimd.Arm64.AddAcross(
+                            AdvSimd.ShiftLogical(
+                                AdvSimd.And(v, Vector128.Create((ushort)0x8000)),
+                                Vector128.Create((short)-15, -14, -13, -12, -11, -10, -9, -8)));
+                        return sum.ToScalar();
+                    }
                 }
-                #endif
                 else
                 {
                     for (; (int)_position < length; _position++)
diff --git a/Ramstack.Globbing/Ramstack.Globbing.csproj b/Ramstack.Globbing/Ramstack.Globbing.csproj
index 78e0e99..9be81d9 100644
--- a/Ramstack.Globbing/Ramstack.Globbing.csproj
+++ b/Ramstack.Globbing/Ramstack.Globbing.csproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
+    <TargetFramework>net6.0</TargetFramework>
     <Description>Fast and zero-allocation .NET globbing library for matching file paths using glob patterns.</Description>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>