Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Configuration/System/Configuration/SimpleBitVector32.cs

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+//------------------------------------------------------------------------------
+// <copyright file="SimpleBitVector32.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Configuration {
+    using System;
+
+    //
+    // This is a cut down copy of System.Collections.Specialized.BitVector32. The
+    // reason this is here is because it is used rather intensively by Control and
+    // WebControl. As a result, being able to inline this operations results in a
+    // measurable performance gain, at the expense of some maintainability.
+    //
+    [Serializable]
+    internal struct SimpleBitVector32 {
+        private int data;
+
+        internal SimpleBitVector32(int data) {
+            this.data = data;
+        }
+
+        internal int Data {
+            get { return data; }
+#if UNUSED_CODE
+            set { data = value; }
+#endif
+        }
+
+        internal bool this[int bit] {
+            get {
+                return (data & bit) == bit;
+            }
+            set {
+                int _data = data;
+                if(value) {
+                    data = _data | bit;
+                }
+                else {
+                    data = _data & ~bit;
+                }
+            }
+        }
+
+#if UNUSED_CODE
+        internal void Set(int bit) {
+            data |= bit;
+        }
+
+        internal void Clear(int bit) {
+            data &= ~bit;
+        }
+
+        internal void Toggle(int bit) {
+            data ^= bit;
+        }
+
+        /*
+         * COPY_FLAG copies the value of flags from a source field
+         * into a destination field.
+         *
+         * In the macro:
+         * + "&flag" limits the outer xor operation to just the flag we're interested in.
+         * + These are the results of the two xor operations:
+         *
+         * fieldDst    fieldSrc    inner xor   outer xor
+         * 0           0           0           0
+         * 0           1           1           1
+         * 1           0           1           0
+         * 1           1           0           1
+         */
+        internal void Copy(SimpleBitVector32 src, int bit) {
+            data ^= (data ^ src.data) & bit;
+        }
+#endif
+    }
+}