X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=blobdiff_plain;f=mcs%2Fclass%2Fcorlib%2FSystem.Text%2FUTF8Encoding.cs;h=2c00c72eeaf43682588adfc19c1a40b9b3c86417;hb=7e18ed47c9606f3981e7b18cbc238d6781843153;hp=eb7ddffaf7dfce38e13809fb8d4d1b66a032f8f8;hpb=6b52f461498739c8995311450bbb0d0dbf3b46a4;p=mono.git

diff --git a/mcs/class/corlib/System.Text/UTF8Encoding.cs b/mcs/class/corlib/System.Text/UTF8Encoding.cs
old mode 100755
new mode 100644
index eb7ddffaf7d..2c00c72eeaf
--- a/mcs/class/corlib/System.Text/UTF8Encoding.cs
+++ b/mcs/class/corlib/System.Text/UTF8Encoding.cs
@@ -1,40 +1,913 @@
-//
-// System.Text.UTF8Encoding.cs
-//
-// Author:
-//   Sean MacIsaac (macisaac@ximian.com)
-//
-// (C) Ximian, Inc.  http://www.ximian.com
-//
-
-
-namespace System.Text {
-        
-        public class UTF8Encoding : Encoding {
-                public override int GetByteCount(char[] chars, int index, int count) {
-                        // FIXME
-                        return 0;
-                }
-
-                public override int GetBytes(char[] chars, int charIndex, int charCount, byte[] bytes, int byteIndex) {
-                        // FIXME
-                        return 0;
-                }
-
-                public override char[] GetChars(byte[] bytes, int byteIndex, int byteCount, char[] chars, int charIndex) {
-                        // FIXME
-                        return null;
-                }
-
-                public override int GetMaxByteCount(int charCount) {
-                        // FIXME
-                        return 0;
-                }
-
-                public override int GetMaxCharCount(int byteCount) {
-                        // FIXME
-                        return 0;
-                }
-        }
-}
+/*
+ * UTF8Encoding.cs - Implementation of the "System.Text.UTF8Encoding" class.
+ *
+ * Copyright (c) 2001, 2002  Southern Storm Software, Pty Ltd
+ * Copyright (C) 2004 Novell, Inc (http://www.novell.com)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
 
+namespace System.Text
+{
+
+using System;
+
+[Serializable]
+[MonoTODO ("Fix serialization compatibility with MS.NET")]
+#if NET_2_0
+[MonoTODO ("EncoderFallback is not handled")]
+#endif
+public class UTF8Encoding : Encoding
+{
+	// Magic number used by Windows for UTF-8.
+	internal const int UTF8_CODE_PAGE = 65001;
+
+	// Internal state.
+	private bool emitIdentifier;
+#if !NET_2_0
+	private bool throwOnInvalid;
+#endif
+
+	// Constructors.
+	public UTF8Encoding () : this (false, false) {}
+	public UTF8Encoding (bool encoderShouldEmitUTF8Identifier)
+			: this (encoderShouldEmitUTF8Identifier, false) {}
+	
+	public UTF8Encoding (bool encoderShouldEmitUTF8Identifier, bool throwOnInvalidBytes)
+		: base (UTF8_CODE_PAGE)
+	{
+		emitIdentifier = encoderShouldEmitUTF8Identifier;
+#if NET_2_0
+		if (throwOnInvalidBytes)
+			SetFallbackInternal (null, new DecoderExceptionFallback ());
+		else
+			SetFallbackInternal (null, new DecoderReplacementFallback (String.Empty));
+#else
+		throwOnInvalid = throwOnInvalidBytes;
+#endif
+
+		web_name = body_name = header_name = "utf-8";
+		encoding_name = "Unicode (UTF-8)";
+		is_browser_save = true;
+		is_browser_display = true;
+		is_mail_news_display = true;
+		windows_code_page = UnicodeEncoding.UNICODE_CODE_PAGE;
+	}
+
+	// Internal version of "GetByteCount" which can handle a rolling
+	// state between multiple calls to this method.
+	private static int InternalGetByteCount (char[] chars, int index, int count, uint leftOver, bool flush)
+	{
+		// Validate the parameters.
+		if (chars == null) {
+			throw new ArgumentNullException ("chars");
+		}
+		if (index < 0 || index > chars.Length) {
+			throw new ArgumentOutOfRangeException ("index", _("ArgRange_Array"));
+		}
+		if (count < 0 || count > (chars.Length - index)) {
+			throw new ArgumentOutOfRangeException ("count", _("ArgRange_Array"));
+		}
+
+		// Determine the lengths of all characters.
+		char ch;
+		int length = 0;
+		uint pair = leftOver;
+		while (count > 0) {
+			ch = chars[index];
+			if (pair == 0) {
+				if (ch < '\u0080') {
+					++length;
+				} else if (ch < '\u0800') {
+					length += 2;
+				} else if (ch >= '\uD800' && ch <= '\uDBFF') {
+					// This is the start of a surrogate pair.
+					pair = (uint)ch;
+				} else {
+					length += 3;
+				}
+			} else if (ch >= '\uDC00' && ch <= '\uDFFF') {
+				// We have a surrogate pair.
+				length += 4;
+				pair = 0;
+			} else {
+				// We have a surrogate start followed by a
+				// regular character.  Technically, this is
+				// invalid, but we have to do something.
+				// We write out the surrogate start and then
+				// re-visit the current character again.
+				length += 3;
+				pair = 0;
+				continue;
+			}
+			++index;
+			--count;
+		}
+		if (flush && pair != 0) {
+			// Flush the left-over surrogate pair start.
+			length += 3;
+		}
+
+		// Return the final length to the caller.
+		return length;
+	}
+
+	// Get the number of bytes needed to encode a character buffer.
+	public override int GetByteCount (char[] chars, int index, int count)
+	{
+		return InternalGetByteCount (chars, index, count, 0, true);
+	}
+
+	// Convenience wrappers for "GetByteCount".
+	public override int GetByteCount (String s)
+	{
+		// Validate the parameters.
+		if (s == null) {
+			throw new ArgumentNullException ("s");
+		}
+
+		// Determine the lengths of all characters.
+		char ch;
+		int index = 0;
+		int count = s.Length;
+		int length = 0;
+		uint pair;
+		while (count > 0) {
+			ch = s[index++];
+			if (ch < '\u0080') {
+				++length;
+			} else if (ch < '\u0800') {
+				length += 2;
+			} else if (ch >= '\uD800' && ch <= '\uDBFF' && count > 1) {
+				// This may be the start of a surrogate pair.
+				pair = (uint)(s[index]);
+				if (pair >= (uint)0xDC00 && pair <= (uint)0xDFFF) {
+					length += 4;
+					++index;
+					--count;
+				} else {
+					length += 3;
+				}
+			} else {
+				length += 3;
+			}
+			--count;
+		}
+
+		// Return the final length to the caller.
+		return length;
+	}
+
+	// Internal version of "GetBytes" which can handle a rolling
+	// state between multiple calls to this method.
+	private static int InternalGetBytes (char[] chars, int charIndex,
+					     int charCount, byte[] bytes,
+					     int byteIndex, ref uint leftOver,
+					     bool flush)
+	{
+		// Validate the parameters.
+		if (chars == null) {
+			throw new ArgumentNullException ("chars");
+		}
+		if (bytes == null) {
+			throw new ArgumentNullException ("bytes");
+		}
+		if (charIndex < 0 || charIndex > chars.Length) {
+			throw new ArgumentOutOfRangeException ("charIndex", _("ArgRange_Array"));
+		}
+		if (charCount < 0 || charCount > (chars.Length - charIndex)) {
+			throw new ArgumentOutOfRangeException ("charCount", _("ArgRange_Array"));
+		}
+		if (byteIndex < 0 || byteIndex > bytes.Length) {
+			throw new ArgumentOutOfRangeException ("byteIndex", _("ArgRange_Array"));
+		}
+
+		// Convert the characters into bytes.
+		char ch;
+		int length = bytes.Length;
+		uint pair;
+		uint left = leftOver;
+		int posn = byteIndex;
+		while (charCount > 0) {
+			// Fetch the next UTF-16 character pair value.
+			ch = chars[charIndex++];
+			--charCount;
+			if (left == 0) {
+				if (ch >= '\uD800' && ch <= '\uDBFF') {
+					// This is the start of a surrogate pair.
+					left = (uint)ch;
+					continue;
+				} else {
+					// This is a regular character.
+					pair = (uint)ch;
+				}
+			} else if (ch >= '\uDC00' && ch <= '\uDFFF') {
+				// We have a surrogate pair.
+				pair = ((left - (uint)0xD800) << 10) +
+					   (((uint)ch) - (uint)0xDC00) +
+					   (uint)0x10000;
+				left = 0;
+			} else {
+				// We have a surrogate start followed by a
+				// regular character.  Technically, this is
+				// invalid, but we have to do something.
+				// We write out the surrogate start and then
+				// re-visit the current character again.
+				pair = (uint)left;
+				left = 0;
+				--charIndex;
+				++charCount;
+			}
+
+			// Encode the character pair value.
+			if (pair < (uint)0x0080) {
+				if (posn >= length) {
+					throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+				}
+				bytes[posn++] = (byte)pair;
+			} else if (pair < (uint)0x0800) {
+				if ((posn + 2) > length) {
+					throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+				}
+				bytes[posn++] = (byte)(0xC0 | (pair >> 6));
+				bytes[posn++] = (byte)(0x80 | (pair & 0x3F));
+			} else if (pair < (uint)0x10000) {
+				if ((posn + 3) > length) {
+					throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+				}
+				bytes[posn++] = (byte)(0xE0 | (pair >> 12));
+				bytes[posn++] = (byte)(0x80 | ((pair >> 6) & 0x3F));
+				bytes[posn++] = (byte)(0x80 | (pair & 0x3F));
+			} else {
+				if ((posn + 4) > length) {
+					throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+				}
+				bytes[posn++] = (byte)(0xF0 | (pair >> 18));
+				bytes[posn++] = (byte)(0x80 | ((pair >> 12) & 0x3F));
+				bytes[posn++] = (byte)(0x80 | ((pair >> 6) & 0x3F));
+				bytes[posn++] = (byte)(0x80 | (pair & 0x3F));
+			}
+		}
+		if (flush && left != 0) {
+			// Flush the left-over surrogate pair start.
+			if ((posn + 3) > length) {
+				throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+			}
+			bytes[posn++] = (byte)(0xE0 | (left >> 12));
+			bytes[posn++] = (byte)(0x80 | ((left >> 6) & 0x3F));
+			bytes[posn++] = (byte)(0x80 | (left & 0x3F));
+			left = 0;
+		}
+		leftOver = left;
+
+		// Return the final count to the caller.
+		return posn - byteIndex;
+	}
+
+	// Get the bytes that result from encoding a character buffer.
+	public override int GetBytes (char[] chars, int charIndex, int charCount,
+								 byte[] bytes, int byteIndex)
+	{
+		uint leftOver = 0;
+		return InternalGetBytes (chars, charIndex, charCount, bytes, byteIndex, ref leftOver, true);
+	}
+
+	// Convenience wrappers for "GetBytes".
+	public override int GetBytes (String s, int charIndex, int charCount,
+								 byte[] bytes, int byteIndex)
+	{
+		// Validate the parameters.
+		if (s == null) {
+			throw new ArgumentNullException ("s");
+		}
+		if (bytes == null) {
+			throw new ArgumentNullException ("bytes");
+		}
+		if (charIndex < 0 || charIndex > s.Length) {
+			throw new ArgumentOutOfRangeException ("charIndex", _("ArgRange_StringIndex"));
+		}
+		if (charCount < 0 || charCount > (s.Length - charIndex)) {
+			throw new ArgumentOutOfRangeException ("charCount", _("ArgRange_StringRange"));
+		}
+		if (byteIndex < 0 || byteIndex > bytes.Length) {
+			throw new ArgumentOutOfRangeException ("byteIndex", _("ArgRange_Array"));
+		}
+
+		// Convert the characters into bytes.
+		char ch;
+		int length = bytes.Length;
+		uint pair;
+		int posn = byteIndex;
+		while (charCount > 0) {
+			// Fetch the next UTF-16 character pair value.
+			ch = s[charIndex++];
+			if (ch >= '\uD800' && ch <= '\uDBFF' && charCount > 1) {
+				// This may be the start of a surrogate pair.
+				pair = (uint)(s[charIndex]);
+				if (pair >= (uint)0xDC00 && pair <= (uint)0xDFFF) {
+					pair = (pair - (uint)0xDC00) +
+						   ((((uint)ch) - (uint)0xD800) << 10) +
+						   (uint)0x10000;
+					++charIndex;
+					--charCount;
+				} else {
+					pair = (uint)ch;
+				}
+			} else {
+				pair = (uint)ch;
+			}
+			--charCount;
+
+			// Encode the character pair value.
+			if (pair < (uint)0x0080) {
+				if (posn >= length) {
+					throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+				}
+				bytes[posn++] = (byte)pair;
+			} else if (pair < (uint)0x0800) {
+				if ((posn + 2) > length) {
+					throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+				}
+				bytes[posn++] = (byte)(0xC0 | (pair >> 6));
+				bytes[posn++] = (byte)(0x80 | (pair & 0x3F));
+			} else if (pair < (uint)0x10000) {
+				if ((posn + 3) > length) {
+					throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+				}
+				bytes[posn++] = (byte)(0xE0 | (pair >> 12));
+				bytes[posn++] = (byte)(0x80 | ((pair >> 6) & 0x3F));
+				bytes[posn++] = (byte)(0x80 | (pair & 0x3F));
+			} else {
+				if ((posn + 4) > length) {
+					throw new ArgumentException (_("Arg_InsufficientSpace"), "bytes");
+				}
+				bytes[posn++] = (byte)(0xF0 | (pair >> 18));
+				bytes[posn++] = (byte)(0x80 | ((pair >> 12) & 0x3F));
+				bytes[posn++] = (byte)(0x80 | ((pair >> 6) & 0x3F));
+				bytes[posn++] = (byte)(0x80 | (pair & 0x3F));
+			}
+		}
+
+		// Return the final count to the caller.
+		return posn - byteIndex;
+	}
+
+	// Internal version of "GetCharCount" which can handle a rolling
+	// state between multiple calls to this method.
+#if NET_2_0
+	// Internal version of "GetCharCount" which can handle a rolling
+	// state between multiple calls to this method.
+	private static int InternalGetCharCount (
+		byte[] bytes, int index, int count, uint leftOverBits,
+		uint leftOverCount, DecoderFallbackBuffer fallbackBuffer, bool flush)
+#else
+	private static int InternalGetCharCount (
+		byte[] bytes, int index, int count, uint leftOverBits,
+		uint leftOverCount, bool throwOnInvalid, bool flush)
+#endif
+	{
+		// Validate the parameters.
+		if (bytes == null) {
+			throw new ArgumentNullException ("bytes");
+		}
+		if (index < 0 || index > bytes.Length) {
+			throw new ArgumentOutOfRangeException ("index", _("ArgRange_Array"));
+		}
+		if (count < 0 || count > (bytes.Length - index)) {
+			throw new ArgumentOutOfRangeException ("count", _("ArgRange_Array"));
+		}
+
+		// Determine the number of characters that we have.
+		uint ch;
+		int length = 0;
+		uint leftBits = leftOverBits;
+		uint leftSoFar = (leftOverCount & (uint)0x0F);
+		uint leftSize = ((leftOverCount >> 4) & (uint)0x0F);
+		while (count > 0) {
+			ch = (uint)(bytes[index++]);
+			--count;
+			if (leftSize == 0) {
+				// Process a UTF-8 start character.
+				if (ch < (uint)0x0080) {
+					// Single-byte UTF-8 character.
+					++length;
+				} else if ((ch & (uint)0xE0) == (uint)0xC0) {
+					// Double-byte UTF-8 character.
+					leftBits = (ch & (uint)0x1F);
+					leftSoFar = 1;
+					leftSize = 2;
+				} else if ((ch & (uint)0xF0) == (uint)0xE0) {
+					// Three-byte UTF-8 character.
+					leftBits = (ch & (uint)0x0F);
+					leftSoFar = 1;
+					leftSize = 3;
+				} else if ((ch & (uint)0xF8) == (uint)0xF0) {
+					// Four-byte UTF-8 character.
+					leftBits = (ch & (uint)0x07);
+					leftSoFar = 1;
+					leftSize = 4;
+				} else if ((ch & (uint)0xFC) == (uint)0xF8) {
+					// Five-byte UTF-8 character.
+					leftBits = (ch & (uint)0x03);
+					leftSoFar = 1;
+					leftSize = 5;
+				} else if ((ch & (uint)0xFE) == (uint)0xFC) {
+					// Six-byte UTF-8 character.
+					leftBits = (ch & (uint)0x03);
+					leftSoFar = 1;
+					leftSize = 6;
+				} else {
+					// Invalid UTF-8 start character.
+#if NET_2_0
+					length += Fallback (fallbackBuffer, bytes, index - 1);
+#else
+					if (throwOnInvalid)
+						throw new ArgumentException (_("Arg_InvalidUTF8"), "bytes");
+#endif
+				}
+			} else {
+				// Process an extra byte in a multi-byte sequence.
+				if ((ch & (uint)0xC0) == (uint)0x80) {
+					leftBits = ((leftBits << 6) | (ch & (uint)0x3F));
+					if (++leftSoFar >= leftSize) {
+						// We have a complete character now.
+						if (leftBits < (uint)0x10000) {
+							// is it an overlong ?
+							bool overlong = false;
+							switch (leftSize) {
+							case 2:
+								overlong = (leftBits <= 0x7F);
+								break;
+							case 3:
+								overlong = (leftBits <= 0x07FF);
+								break;
+							case 4:
+								overlong = (leftBits <= 0xFFFF);
+								break;
+							case 5:
+								overlong = (leftBits <= 0x1FFFFF);
+								break;
+							case 6:
+								overlong = (leftBits <= 0x03FFFFFF);
+								break;
+							}
+							if (overlong) {
+#if NET_2_0
+								length += Fallback (fallbackBuffer, bytes, index - 1);
+#else
+								if (throwOnInvalid)
+									throw new ArgumentException (_("Overlong"), leftBits.ToString ());
+#endif
+							}
+							else
+								++length;
+						} else if (leftBits < (uint)0x110000) {
+							length += 2;
+						} else {
+#if NET_2_0
+							length += Fallback (fallbackBuffer, bytes, index - 1);
+#else
+							if (throwOnInvalid)
+								throw new ArgumentException (_("Arg_InvalidUTF8"), "bytes");
+#endif
+						}
+						leftSize = 0;
+					}
+				} else {
+					// Invalid UTF-8 sequence: clear and restart.
+#if NET_2_0
+					length += Fallback (fallbackBuffer, bytes, index - 1);
+#else
+					if (throwOnInvalid)
+						throw new ArgumentException (_("Arg_InvalidUTF8"), "bytes");
+#endif
+					leftSize = 0;
+					--index;
+					++count;
+				}
+			}
+		}
+		if (flush && leftSize != 0) {
+			// We had left-over bytes that didn't make up
+			// a complete UTF-8 character sequence.
+#if NET_2_0
+			length += Fallback (fallbackBuffer, bytes, index - 1);
+#else
+			if (throwOnInvalid)
+				throw new ArgumentException (_("Arg_InvalidUTF8"), "bytes");
+#endif
+		}
+
+		// Return the final length to the caller.
+		return length;
+	}
+
+#if NET_2_0
+	// for GetCharCount()
+	static int Fallback (DecoderFallbackBuffer buffer, byte [] bytes, int index)
+	{
+		buffer.Fallback (bytes, index - 1);
+		return buffer.Remaining;
+	}
+
+	// for GetChars()
+	static void Fallback (DecoderFallbackBuffer buffer, byte [] bytes, int byteIndex,
+		char [] chars, ref int charIndex)
+	{
+		buffer.Fallback (bytes, byteIndex - 1);
+		while (buffer.Remaining > 0)
+			chars [charIndex++] = buffer.GetNextChar ();
+	}
+#endif
+
+	// Get the number of characters needed to decode a byte buffer.
+	public override int GetCharCount (byte[] bytes, int index, int count)
+	{
+#if NET_2_0
+		return InternalGetCharCount (bytes, index, count, 0, 0, DecoderFallback.CreateFallbackBuffer (), true);
+#else
+		return InternalGetCharCount (bytes, index, count, 0, 0, throwOnInvalid, true);
+#endif
+	}
+
+	// Get the characters that result from decoding a byte buffer.
+#if NET_2_0
+	private static int InternalGetChars (
+		byte[] bytes, int byteIndex, int byteCount, char[] chars,
+		int charIndex, ref uint leftOverBits, ref uint leftOverCount,
+		DecoderFallbackBuffer fallbackBuffer, bool flush)
+#else
+	private static int InternalGetChars (
+		byte[] bytes, int byteIndex, int byteCount, char[] chars,
+		int charIndex, ref uint leftOverBits, ref uint leftOverCount,
+		bool throwOnInvalid, bool flush)
+#endif
+	{
+		// Validate the parameters.
+		if (bytes == null) {
+			throw new ArgumentNullException ("bytes");
+		}
+		if (chars == null) {
+			throw new ArgumentNullException ("chars");
+		}
+		if (byteIndex < 0 || byteIndex > bytes.Length) {
+			throw new ArgumentOutOfRangeException ("byteIndex", _("ArgRange_Array"));
+		}
+		if (byteCount < 0 || byteCount > (bytes.Length - byteIndex)) {
+			throw new ArgumentOutOfRangeException ("byteCount", _("ArgRange_Array"));
+		}
+		if (charIndex < 0 || charIndex > chars.Length) {
+			throw new ArgumentOutOfRangeException ("charIndex", _("ArgRange_Array"));
+		}
+
+		if (charIndex == chars.Length)
+			return 0;
+
+		// Convert the bytes into the output buffer.
+		uint ch;
+		int length = chars.Length;
+		int posn = charIndex;
+		uint leftBits = leftOverBits;
+		uint leftSoFar = (leftOverCount & (uint)0x0F);
+		uint leftSize = ((leftOverCount >> 4) & (uint)0x0F);
+		while (byteCount > 0) {
+			// Fetch the next character from the byte buffer.
+			ch = (uint)(bytes[byteIndex++]);
+			--byteCount;
+			if (leftSize == 0) {
+				// Process a UTF-8 start character.
+				if (ch < (uint)0x0080) {
+					// Single-byte UTF-8 character.
+					if (posn >= length) {
+						throw new ArgumentException (_("Arg_InsufficientSpace"), "chars");
+					}
+					chars[posn++] = (char)ch;
+				} else if ((ch & (uint)0xE0) == (uint)0xC0) {
+					// Double-byte UTF-8 character.
+					leftBits = (ch & (uint)0x1F);
+					leftSoFar = 1;
+					leftSize = 2;
+				} else if ((ch & (uint)0xF0) == (uint)0xE0) {
+					// Three-byte UTF-8 character.
+					leftBits = (ch & (uint)0x0F);
+					leftSoFar = 1;
+					leftSize = 3;
+				} else if ((ch & (uint)0xF8) == (uint)0xF0) {
+					// Four-byte UTF-8 character.
+					leftBits = (ch & (uint)0x07);
+					leftSoFar = 1;
+					leftSize = 4;
+				} else if ((ch & (uint)0xFC) == (uint)0xF8) {
+					// Five-byte UTF-8 character.
+					leftBits = (ch & (uint)0x03);
+					leftSoFar = 1;
+					leftSize = 5;
+				} else if ((ch & (uint)0xFE) == (uint)0xFC) {
+					// Six-byte UTF-8 character.
+					leftBits = (ch & (uint)0x03);
+					leftSoFar = 1;
+					leftSize = 6;
+				} else {
+					// Invalid UTF-8 start character.
+#if NET_2_0
+					Fallback (fallbackBuffer, bytes, byteIndex, chars, ref posn);
+#else
+					if (throwOnInvalid)
+						throw new ArgumentException (_("Arg_InvalidUTF8"), "bytes");
+#endif
+				}
+			} else {
+				// Process an extra byte in a multi-byte sequence.
+				if ((ch & (uint)0xC0) == (uint)0x80) {
+					leftBits = ((leftBits << 6) | (ch & (uint)0x3F));
+					if (++leftSoFar >= leftSize) {
+						// We have a complete character now.
+						if (leftBits < (uint)0x10000) {
+							// is it an overlong ?
+							bool overlong = false;
+							switch (leftSize) {
+							case 2:
+								overlong = (leftBits <= 0x7F);
+								break;
+							case 3:
+								overlong = (leftBits <= 0x07FF);
+								break;
+							case 4:
+								overlong = (leftBits <= 0xFFFF);
+								break;
+							case 5:
+								overlong = (leftBits <= 0x1FFFFF);
+								break;
+							case 6:
+								overlong = (leftBits <= 0x03FFFFFF);
+								break;
+							}
+							if (overlong) {
+#if NET_2_0
+								Fallback (fallbackBuffer, bytes, byteIndex, chars, ref posn);
+#else
+								if (throwOnInvalid)
+									throw new ArgumentException (_("Overlong"), leftBits.ToString ());
+#endif
+							}
+							else {
+								if (posn >= length) {
+									throw new ArgumentException
+										(_("Arg_InsufficientSpace"), "chars");
+								}
+								chars[posn++] = (char)leftBits;
+							}
+						} else if (leftBits < (uint)0x110000) {
+							if ((posn + 2) > length) {
+								throw new ArgumentException
+									(_("Arg_InsufficientSpace"), "chars");
+							}
+							leftBits -= (uint)0x10000;
+							chars[posn++] = (char)((leftBits >> 10) +
+												   (uint)0xD800);
+							chars[posn++] =
+								(char)((leftBits & (uint)0x3FF) + (uint)0xDC00);
+						} else {
+#if NET_2_0
+							Fallback (fallbackBuffer, bytes, byteIndex, chars, ref posn);
+#else
+							if (throwOnInvalid)
+								throw new ArgumentException (_("Arg_InvalidUTF8"), "bytes");
+#endif
+						}
+						leftSize = 0;
+					}
+				} else {
+					// Invalid UTF-8 sequence: clear and restart.
+#if NET_2_0
+					Fallback (fallbackBuffer, bytes, byteIndex, chars, ref posn);
+#else
+					if (throwOnInvalid)
+						throw new ArgumentException (_("Arg_InvalidUTF8"), "bytes");
+#endif
+					leftSize = 0;
+					--byteIndex;
+					++byteCount;
+				}
+			}
+		}
+		if (flush && leftSize != 0) {
+			// We had left-over bytes that didn't make up
+			// a complete UTF-8 character sequence.
+#if NET_2_0
+			Fallback (fallbackBuffer, bytes, byteIndex, chars, ref posn);
+#else
+			if (throwOnInvalid)
+				throw new ArgumentException (_("Arg_InvalidUTF8"), "bytes");
+#endif
+		}
+		leftOverBits = leftBits;
+		leftOverCount = (leftSoFar | (leftSize << 4));
+
+		// Return the final length to the caller.
+		return posn - charIndex;
+	}
+
+	// Get the characters that result from decoding a byte buffer.
+	public override int GetChars (byte[] bytes, int byteIndex, int byteCount,
+								 char[] chars, int charIndex)
+	{
+		uint leftOverBits = 0;
+		uint leftOverCount = 0;
+#if NET_2_0
+		return InternalGetChars (bytes, byteIndex, byteCount, chars, 
+				charIndex, ref leftOverBits, ref leftOverCount, DecoderFallback.CreateFallbackBuffer (), true);
+#else
+		return InternalGetChars (bytes, byteIndex, byteCount, chars, 
+				charIndex, ref leftOverBits, ref leftOverCount, throwOnInvalid, true);
+#endif
+	}
+
+	// Get the maximum number of bytes needed to encode a
+	// specified number of characters.
+	public override int GetMaxByteCount (int charCount)
+	{
+		if (charCount < 0) {
+			throw new ArgumentOutOfRangeException ("charCount", _("ArgRange_NonNegative"));
+		}
+		return charCount * 4;
+	}
+
+	// Get the maximum number of characters needed to decode a
+	// specified number of bytes.
+	public override int GetMaxCharCount (int byteCount)
+	{
+		if (byteCount < 0) {
+			throw new ArgumentOutOfRangeException ("byteCount", _("ArgRange_NonNegative"));
+		}
+		return byteCount;
+	}
+
+	// Get a UTF8-specific decoder that is attached to this instance.
+	public override Decoder GetDecoder ()
+	{
+#if NET_2_0
+		return new UTF8Decoder (DecoderFallback);
+#else
+		return new UTF8Decoder (throwOnInvalid);
+#endif
+	}
+
+	// Get a UTF8-specific encoder that is attached to this instance.
+	public override Encoder GetEncoder ()
+	{
+		return new UTF8Encoder (emitIdentifier);
+	}
+
+	// Get the UTF8 preamble.
+	public override byte[] GetPreamble ()
+	{
+		if (emitIdentifier) {
+			byte[] pre = new byte [3];
+			pre[0] = (byte)0xEF;
+			pre[1] = (byte)0xBB;
+			pre[2] = (byte)0xBF;
+			return pre;
+		} else {
+			return new byte [0];
+		}
+	}
+
+	// Determine if this object is equal to another.
+	public override bool Equals (Object value)
+	{
+		UTF8Encoding enc = (value as UTF8Encoding);
+		if (enc != null) {
+#if NET_2_0
+			return (codePage == enc.codePage &&
+					emitIdentifier == enc.emitIdentifier &&
+					DecoderFallback == enc.DecoderFallback &&
+					EncoderFallback == enc.EncoderFallback);
+#else
+			return (codePage == enc.codePage &&
+					emitIdentifier == enc.emitIdentifier &&
+					throwOnInvalid == enc.throwOnInvalid);
+#endif
+		} else {
+			return false;
+		}
+	}
+
+	// Get the hash code for this object.
+	public override int GetHashCode ()
+	{
+		return base.GetHashCode ();
+	}
+	
+	public override byte [] GetBytes (String s)
+	{
+		if (s == null)
+			throw new ArgumentNullException ("s");
+		
+		int length = GetByteCount (s);
+		byte [] bytes = new byte [length];
+		GetBytes (s, 0, s.Length, bytes, 0);
+		return bytes;
+	}
+
+	// UTF-8 decoder implementation.
+	[Serializable]
+	private class UTF8Decoder : Decoder
+	{
+#if !NET_2_0
+		private bool throwOnInvalid;
+#endif
+		private uint leftOverBits;
+		private uint leftOverCount;
+
+		// Constructor.
+#if NET_2_0
+		public UTF8Decoder (DecoderFallback fallback)
+#else
+		public UTF8Decoder (bool throwOnInvalid)
+#endif
+		{
+#if NET_2_0
+			Fallback = fallback;
+#else
+			this.throwOnInvalid = throwOnInvalid;
+#endif
+			leftOverBits = 0;
+			leftOverCount = 0;
+		}
+
+		// Override inherited methods.
+		public override int GetCharCount (byte[] bytes, int index, int count)
+		{
+#if NET_2_0
+			return InternalGetCharCount (bytes, index, count,
+				leftOverBits, leftOverCount, FallbackBuffer, false);
+#else
+			return InternalGetCharCount (bytes, index, count,
+					leftOverBits, leftOverCount, throwOnInvalid, false);
+#endif
+		}
+		public override int GetChars (byte[] bytes, int byteIndex,
+						 int byteCount, char[] chars, int charIndex)
+		{
+#if NET_2_0
+			return InternalGetChars (bytes, byteIndex, byteCount,
+				chars, charIndex, ref leftOverBits, ref leftOverCount, FallbackBuffer, false);
+#else
+			return InternalGetChars (bytes, byteIndex, byteCount,
+				chars, charIndex, ref leftOverBits, ref leftOverCount, throwOnInvalid, false);
+#endif
+		}
+
+	} // class UTF8Decoder
+
+	// UTF-8 encoder implementation.
+	[Serializable]
+	private class UTF8Encoder : Encoder
+	{
+		private bool emitIdentifier;
+		private uint leftOver;
+
+		// Constructor.
+		public UTF8Encoder (bool emitIdentifier)
+		{
+			this.emitIdentifier = emitIdentifier;
+			leftOver = 0;
+		}
+
+		// Override inherited methods.
+		public override int GetByteCount (char[] chars, int index,
+					 int count, bool flush)
+		{
+			return InternalGetByteCount (chars, index, count, leftOver, flush);
+		}
+		public override int GetBytes (char[] chars, int charIndex,
+					 int charCount, byte[] bytes, int byteCount, bool flush)
+		{
+			int result;
+			result = InternalGetBytes (chars, charIndex, charCount, bytes, byteCount, ref leftOver, flush);
+			emitIdentifier = false;
+			return result;
+		}
+
+	} // class UTF8Encoder
+
+}; // class UTF8Encoding
+
+}; // namespace System.Text