Use ref byte for compression input pointers

Snappier.Benchmarks/FindMatchLength.cs

@@ -1,4 +1,5 @@
-using BenchmarkDotNet.Attributes;
+using System.Runtime.CompilerServices;
+using BenchmarkDotNet.Attributes;
 using Snappier.Internal;
 
 namespace Snappier.Benchmarks
@@ -15,13 +16,12 @@ public class FindMatchLength
         public unsafe (long, bool) Regular()
         {
             ulong data = 0;
-            fixed (byte* s1 = _array)
-            {
-                var s2 = s1 + 12;
-                var s2Limit = s1 + _array.Length;
 
-                return SnappyCompressor.FindMatchLength(s1, s2, s2Limit, ref data);
-            }
+            ref byte s1 = ref _array[0];
+            ref byte s2 = ref Unsafe.Add(ref s1, 12);
+            ref byte s2Limit = ref Unsafe.Add(ref s1, _array.Length - 1);
+
+            return SnappyCompressor.FindMatchLength(ref s1, ref s2, ref s2Limit, ref data);
         }
     }
 }

Snappier.Tests/Internal/SnappyCompressorTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 using System.Text;
 using Snappier.Internal;
 using Xunit;
@@ -87,16 +88,14 @@ public unsafe void FindMatchLength(int expectedResult, string s1String, string s
                                                          + new string('\0', Math.Max(0, length - s2String.Length)));
 
             ulong data = 0;
-            fixed (byte* s1 = array)
-            {
-                byte* s2 = s1 + s1String.Length;
+            ref byte s1 = ref array[0];
+            ref byte s2 = ref Unsafe.Add(ref s1, s1String.Length);
 
-                var result =
-                    SnappyCompressor.FindMatchLength(s1, s2, s2 + length, ref data);
+            var result =
+                SnappyCompressor.FindMatchLength(ref s1, ref s2, ref Unsafe.Add(ref s2, length - 1), ref data);
 
-                Assert.Equal(result.matchLength < 8, result.matchLengthLessThan8);
-                Assert.Equal(expectedResult, result.matchLength);
-            }
+            Assert.Equal(result.matchLength < 8, result.matchLengthLessThan8);
+            Assert.Equal(expectedResult, result.matchLength);
         }
 
         #endregion

Snappier/Internal/Constants.cs

@@ -20,7 +20,7 @@ public enum ChunkType : byte
 
         public const int BlockLog = 16;
         public const long BlockSize = 1 << BlockLog;
-        public const long InputMarginBytes = 15;
+        public const nint InputMarginBytes = 15;
 
         /// <summary>
         /// Data stored per entry in lookup table:

Snappier/Internal/Helpers.cs

@@ -123,9 +123,9 @@ public static uint UnsafeReadUInt32(ref byte ptr)
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static unsafe ulong UnsafeReadUInt64(void* ptr)
+        public static ulong UnsafeReadUInt64(ref byte ptr)
         {
-            var result = Unsafe.ReadUnaligned<ulong>(ptr);
+            var result = Unsafe.ReadUnaligned<ulong>(ref ptr);
             if (!BitConverter.IsLittleEndian)
             {
                 result = BinaryPrimitives.ReverseEndianness(result);