Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Workflow.ComponentModel/Shared/DigestComparer.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Diagnostics;
+using System.Collections.Generic;
+using System.Globalization;
+
+internal class DigestComparer : IComparer<byte[]>, IEqualityComparer<byte[]>
+{
+    int IComparer<byte[]>.Compare(byte[] digest1, byte[] digest2)
+    {
+        Debug.Assert(digest1.Length == 16 && digest2.Length == 16, "Invalid digest!");
+
+        for (int index = 0; index < 16; index++)
+            if (digest1[index] != digest2[index])
+                return (digest1[index] < digest2[index]) ? -1 : 1;
+
+        return 0;
+    }
+
+    bool IEqualityComparer<byte[]>.Equals(byte[] digest1, byte[] digest2)
+    {
+        Debug.Assert(digest1.Length == 16 && digest2.Length == 16, "Invalid digest!");
+
+        for (int index = 0; index < 16; index++)
+            if (digest1[index] != digest2[index])
+                return false;
+
+        return true;
+    }
+
+    int IEqualityComparer<byte[]>.GetHashCode(byte[] checksumBytes)
+    {
+        return GetMD5DigestString(checksumBytes).GetHashCode();
+    }
+
+    internal static string GetMD5DigestString(byte[] md5Digest)
+    {
+        return string.Format(CultureInfo.InvariantCulture, "{0}{1}{2}{3}{4}{5}{6}{7}{8}{9}{10}{11}{12}{13}{14}{15}", md5Digest[0].ToString("X2", CultureInfo.InvariantCulture), md5Digest[1].ToString("X2", CultureInfo.InvariantCulture), md5Digest[2].ToString("X2", CultureInfo.InvariantCulture), md5Digest[3].ToString("X2", CultureInfo.InvariantCulture), md5Digest[4].ToString("X2", CultureInfo.InvariantCulture), md5Digest[5].ToString("X2", CultureInfo.InvariantCulture), md5Digest[6].ToString("X2", CultureInfo.InvariantCulture), md5Digest[7].ToString("X2", CultureInfo.InvariantCulture), md5Digest[8].ToString("X2", CultureInfo.InvariantCulture), md5Digest[9].ToString("X2", CultureInfo.InvariantCulture), md5Digest[10].ToString("X2", CultureInfo.InvariantCulture), md5Digest[11].ToString("X2", CultureInfo.InvariantCulture), md5Digest[12].ToString("X2", CultureInfo.InvariantCulture), md5Digest[13].ToString("X2", CultureInfo.InvariantCulture), md5Digest[14].ToString("X2", CultureInfo.InvariantCulture), md5Digest[15].ToString("X2", CultureInfo.InvariantCulture));
+    }
+}