context: //-----------------------------------------------------------------------------
  //
  // 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;
  using System.Collections;
  using System.Collections.Generic;
  
  namespace Microsoft.Cci.Pdb {
    internal class PdbFunction {
      static internal readonly Guid msilMetaData = new Guid(0xc6ea3fc9, 0x59b3, 0x49d6, 0xbc, 0x25,
                                                          0x09, 0x02, 0xbb, 0xab, 0xb4, 0x60);
      static internal readonly IComparer byAddress = new PdbFunctionsByAddress();
      static internal readonly IComparer byAddressAndToken = new PdbFunctionsByAddressAndToken();
      //static internal readonly IComparer byToken = new PdbFunctionsByToken();
  
      internal uint token;
      internal uint slotToken;
      internal uint tokenOfMethodWhoseUsingInfoAppliesToThisMethod;
      //internal string name;
      //internal string module;
      //internal ushort flags;
  
      internal uint segment;
      internal uint address;
      //internal uint length;
  
      //internal byte[] metadata;
      internal PdbScope[] scopes;
      internal PdbSlot[] slots;
      internal PdbConstant[] constants;
      internal string[] usedNamespaces;
      internal PdbLines[] lines;
      internal ushort[]/*?*/ usingCounts;
      internal IEnumerable<INamespaceScope>/*?*/ namespaceScopes;
      internal string/*?*/ iteratorClass;
      internal List<ILocalScope>/*?*/ iteratorScopes;
      internal PdbSynchronizationInformation/*?*/ synchronizationInformation;
  
      private static string StripNamespace(string module) {
        int li = module.LastIndexOf('.');
        if (li > 0) {
          return module.Substring(li + 1);
        }
        return module;
      }
  
  
      internal static PdbFunction[] LoadManagedFunctions(/*string module,*/
                                                         BitAccess bits, uint limit,
                                                         bool readStrings) {
        //string mod = StripNamespace(module);
        int begin = bits.Position;
        int count = 0;
  
        while (bits.Position < limit) {
          ushort siz;
          ushort rec;
  
          bits.ReadUInt16(out siz);
          int star = bits.Position;
          int stop = bits.Position + siz;
          bits.Position = star;
          bits.ReadUInt16(out rec);
  
          switch ((SYM)rec) {
            case SYM.S_GMANPROC:
            case SYM.S_LMANPROC:
              ManProcSym proc;
              bits.ReadUInt32(out proc.parent);
              bits.ReadUInt32(out proc.end);
              bits.Position = (int)proc.end;
              count++;
              break;
  
            case SYM.S_END:
              bits.Position = stop;
              break;
  
            default:
              //Console.WriteLine("{0,6}: {1:x2} {2}",
              //                  bits.Position, rec, (SYM)rec);
              bits.Position = stop;
              break;
          }
        }
        if (count == 0) {
          return null;
        }
  
        bits.Position = begin;
        PdbFunction[] funcs = new PdbFunction[count];
        int func = 0;
  
        while (bits.Position < limit) {
          ushort siz;
          ushort rec;
  
          bits.ReadUInt16(out siz);
          int star = bits.Position;
          int stop = bits.Position + siz;
          bits.ReadUInt16(out rec);
  
          switch ((SYM)rec) {
  
            case SYM.S_GMANPROC:
            case SYM.S_LMANPROC:
              ManProcSym proc;
              //int offset = bits.Position;
  
              bits.ReadUInt32(out proc.parent);
              bits.ReadUInt32(out proc.end);
              bits.ReadUInt32(out proc.next);
              bits.ReadUInt32(out proc.len);
              bits.ReadUInt32(out proc.dbgStart);
              bits.ReadUInt32(out proc.dbgEnd);
              bits.ReadUInt32(out proc.token);
              bits.ReadUInt32(out proc.off);
              bits.ReadUInt16(out proc.seg);
              bits.ReadUInt8(out proc.flags);
              bits.ReadUInt16(out proc.retReg);
              if (readStrings) {
                bits.ReadCString(out proc.name);
              } else {
                bits.SkipCString(out proc.name);
              }
              //Console.WriteLine("token={0:X8} [{1}::{2}]", proc.token, module, proc.name);
  
              bits.Position = stop;
              funcs[func++] = new PdbFunction(/*module,*/ proc, bits);
              break;
  
            default: {
                //throw new PdbDebugException("Unknown SYMREC {0}", (SYM)rec);
                bits.Position = stop;
                break;
              }
          }
        }
        return funcs;
      }
  
      internal static void CountScopesAndSlots(BitAccess bits, uint limit,
                                               out int constants, out int scopes, out int slots, out int usedNamespaces) {
        int pos = bits.Position;
        BlockSym32 block;
        constants = 0;
        slots = 0;
        scopes = 0;
        usedNamespaces = 0;
  
        while (bits.Position < limit) {
          ushort siz;
          ushort rec;
  
          bits.ReadUInt16(out siz);
          int star = bits.Position;
          int stop = bits.Position + siz;
          bits.Position = star;
          bits.ReadUInt16(out rec);
  
          switch ((SYM)rec) {
            case SYM.S_BLOCK32: {
                bits.ReadUInt32(out block.parent);
                bits.ReadUInt32(out block.end);
  
                scopes++;
                bits.Position = (int)block.end;
                break;
              }
  
            case SYM.S_MANSLOT:
              slots++;
              bits.Position = stop;
              break;
  
            case SYM.S_UNAMESPACE:
              usedNamespaces++;
              bits.Position = stop;
              break;
  
            case SYM.S_MANCONSTANT:
              constants++;
              bits.Position = stop;
              break;
  
            default:
              bits.Position = stop;
              break;
          }
        }
        bits.Position = pos;
      }
  
      internal PdbFunction() {
      }
  
      internal PdbFunction(/*string module, */ManProcSym proc, BitAccess bits) {
        this.token = proc.token;
        //this.module = module;
        //this.name = proc.name;
        //this.flags = proc.flags;
        this.segment = proc.seg;
        this.address = proc.off;
        //this.length = proc.len;
  
        if (proc.seg != 1) {
          throw new PdbDebugException("Segment is {0}, not 1.", proc.seg);
        }
        if (proc.parent != 0 || proc.next != 0) {
          throw new PdbDebugException("Warning parent={0}, next={1}",
                                      proc.parent, proc.next);
        }
        //if (proc.dbgStart != 0 || proc.dbgEnd != 0) {
        //  throw new PdbDebugException("Warning DBG start={0}, end={1}",
        //                              proc.dbgStart, proc.dbgEnd);
        //}
  
        int constantCount;
        int scopeCount;
        int slotCount;
        int usedNamespacesCount;
        CountScopesAndSlots(bits, proc.end, out constantCount, out scopeCount, out slotCount, out usedNamespacesCount);
        int scope = constantCount > 0 || slotCount > 0 || usedNamespacesCount > 0 ? 1 : 0;
        int slot = 0;
        int constant = 0;
        int usedNs = 0;
        scopes = new PdbScope[scopeCount+scope];
        slots = new PdbSlot[slotCount];
        constants = new PdbConstant[constantCount];
        usedNamespaces = new string[usedNamespacesCount];
  
        if (scope > 0)
          scopes[0] = new PdbScope(this.address, proc.len, slots, constants, usedNamespaces);
  
        while (bits.Position < proc.end) {
          ushort siz;
          ushort rec;
  
          bits.ReadUInt16(out siz);
          int star = bits.Position;
          int stop = bits.Position + siz;
          bits.Position = star;
          bits.ReadUInt16(out rec);
  
          switch ((SYM)rec) {
            case SYM.S_OEM: {          // 0x0404
                OemSymbol oem;
  
                bits.ReadGuid(out oem.idOem);
                bits.ReadUInt32(out oem.typind);
                // internal byte[]   rgl;        // user data, force 4-byte alignment
  
                if (oem.idOem == msilMetaData) {
                  string name = bits.ReadString();
                  if (name == "MD2") {
                    byte version;
                    bits.ReadUInt8(out version);
                    if (version == 4) {
                      byte count;
                      bits.ReadUInt8(out count);
                      bits.Align(4);
                      while (count-- > 0)
                        this.ReadCustomMetadata(bits);
                    }
                  } else if (name == "asyncMethodInfo") {
                    this.synchronizationInformation = new PdbSynchronizationInformation(bits);
                  }
                  bits.Position = stop;
                  break;
                } else {
                  throw new PdbDebugException("OEM section: guid={0} ti={1}",
                                              oem.idOem, oem.typind);
                  // bits.Position = stop;
                }
              }
  
            case SYM.S_BLOCK32: {
                BlockSym32 block = new BlockSym32();
  
                bits.ReadUInt32(out block.parent);
                bits.ReadUInt32(out block.end);
                bits.ReadUInt32(out block.len);
                bits.ReadUInt32(out block.off);
                bits.ReadUInt16(out block.seg);
                bits.SkipCString(out block.name);
                bits.Position = stop;
  
                scopes[scope++] = new PdbScope(this.address, block, bits, out slotToken);
  
gt:               bits.Position = (int)block.end;