Imported Upstream version 5.0.0.42

Former-commit-id: fd56571888259555122d8a0f58c68838229cea2b

external/linker/cecil/symbols/pdb/Microsoft.Cci.Pdb/MsfDirectory.cs

@@ -0,0 +1,58 @@
+//-----------------------------------------------------------------------------
+//
+// Copyright (c) Microsoft. All rights reserved.
+// This code is licensed under the Microsoft Public License.
+// THIS CODE IS PROVIDED *AS IS* WITHOUT WARRANTY OF
+// ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY
+// IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR
+// PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.
+//
+//-----------------------------------------------------------------------------
+using System;
+
+namespace Microsoft.Cci.Pdb {
+  internal class MsfDirectory {
+    internal MsfDirectory(PdbReader reader, PdbFileHeader head, BitAccess bits) {
+      int pages = reader.PagesFromSize(head.directorySize);
+
+      // 0..n in page of directory pages.
+      bits.MinCapacity(head.directorySize);
+      int directoryRootPages = head.directoryRoot.Length;
+      int pagesPerPage = head.pageSize / 4;
+      int pagesToGo = pages;
+      for (int i = 0; i < directoryRootPages; i++) {
+        int pagesInThisPage = pagesToGo <= pagesPerPage ? pagesToGo : pagesPerPage;
+        reader.Seek(head.directoryRoot[i], 0);
+        bits.Append(reader.reader, pagesInThisPage * 4);
+        pagesToGo -= pagesInThisPage;
+      }
+      bits.Position = 0;
+
+      DataStream stream = new DataStream(head.directorySize, bits, pages);
+      bits.MinCapacity(head.directorySize);
+      stream.Read(reader, bits);
+
+      // 0..3 in directory pages
+      int count;
+      bits.ReadInt32(out count);
+
+      // 4..n
+      int[] sizes = new int[count];
+      bits.ReadInt32(sizes);
+
+      // n..m
+      streams = new DataStream[count];
+      for (int i = 0; i < count; i++) {
+        if (sizes[i] <= 0) {
+          streams[i] = new DataStream();
+        } else {
+          streams[i] = new DataStream(sizes[i], bits,
+                                      reader.PagesFromSize(sizes[i]));
+        }
+      }
+    }
+
+    internal DataStream[] streams;
+  }
+
+}