144 lines
4.1 KiB
C#
144 lines
4.1 KiB
C#
/*
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* CodeTable.cs - Implementation of the "System.Text.CodeTable" class.
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*
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* Copyright (c) 2002 Southern Storm Software, Pty Ltd
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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namespace I18N.CJK
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{
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using System;
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using System.IO;
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using System.Reflection;
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using System.Runtime.CompilerServices;
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using I18N.Common;
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// This class assists encoding classes for the large CJK character
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// sets by providing pointer access to table data in the resource
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// section of the current assembly.
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//
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// Code tables are named by their resource (e.g. "jis.table") and
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// contain one or more sections. Each section has an 8-byte header,
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// consisting of a 32-bit section number and a 32-bit section length.
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// The alignment of the data in the table is not guaranteed.
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internal unsafe sealed class CodeTable : IDisposable
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{
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// Internal state.
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private Stream stream;
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// Load a code table from the resource section of this assembly.
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public CodeTable(String name)
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{
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stream = (Assembly.GetExecutingAssembly()
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.GetManifestResourceStream(name));
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if(stream == null)
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{
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throw new NotSupportedException
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(String.Format
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(Strings.GetString("NotSupp_MissingCodeTable"),
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name));
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}
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}
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// Implement the IDisposable interface.
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public void Dispose()
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{
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if(stream != null)
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{
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stream.Close();
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stream = null;
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}
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}
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// Get the starting address for a particular section within
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// the code table. This address is guaranteed to persist
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// after "Dispose" is called.
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#if __PNET__
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public byte *GetSection(int num)
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#else
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public byte[] GetSection(int num)
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#endif
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{
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// If the table has been disposed, then bail out.
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if(stream == null)
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{
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return null;
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}
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// Scan through the stream looking for the section.
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long posn = 0;
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long length = stream.Length;
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byte[] header = new byte [8];
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int sectNum, sectLen;
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while((posn + 8) <= length)
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{
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// Read the next header block.
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stream.Position = posn;
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if(stream.Read(header, 0, 8) != 8)
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{
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break;
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}
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// Decode the fields in the header block.
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sectNum = ((int)(header[0])) |
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(((int)(header[1])) << 8) |
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(((int)(header[2])) << 16) |
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(((int)(header[3])) << 24);
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sectLen = ((int)(header[4])) |
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(((int)(header[5])) << 8) |
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(((int)(header[6])) << 16) |
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(((int)(header[7])) << 24);
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// Is this the section we are looking for?
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if(sectNum == num)
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{
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#if __PNET__
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return GetAddress(stream, posn + 8);
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#else
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byte[] buf = new byte [sectLen];
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if(stream.Read(buf, 0, sectLen) != sectLen)
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{
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break;
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}
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return buf;
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#endif
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}
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// Advance to the next section.
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posn += 8 + sectLen;
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}
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// We were unable to find the requested section.
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return null;
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}
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#if __PNET__
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// Back door access into the engine to get the address of
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// an offset within a manifest resource stream.
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[MethodImpl(MethodImplOptions.InternalCall)]
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extern private static byte *GetAddress(Stream stream, long position);
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#endif
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}; // class CodeTable
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}; // namespace I18N.CJK
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