/*
 * ASCIIEncoding.cs - Implementation of the "System.Text.ASCIIEncoding" class.
 *
 * Copyright (c) 2001  Southern Storm Software, Pty Ltd
 *
 * 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]
public class ASCIIEncoding : Encoding
{
	// Magic number used by Windows for "ASCII".
	internal const int ASCII_CODE_PAGE = 20127;

	// Constructor.
	public ASCIIEncoding() : base(ASCII_CODE_PAGE) {}

	// Get the number of bytes needed to encode a character buffer.
	public override int GetByteCount(char[] chars, int index, int count)
			{
				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"));
				}
				return count;
			}

	// Convenience wrappers for "GetByteCount".
	public override int GetByteCount(String s)
			{
				if(s == null)
				{
					throw new ArgumentNullException("s");
				}
				return s.Length;
			}

	// Get the bytes that result from encoding a character buffer.
	public override int GetBytes(char[] chars, int charIndex, int charCount,
								 byte[] bytes, int byteIndex)
			{
				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"));
				}
				if((bytes.Length - byteIndex) < charCount)
				{
					throw new ArgumentException
						(_("Arg_InsufficientSpace"));
				}
				int count = charCount;
				char ch;
				while(count-- > 0)
				{
					ch = chars[charIndex++];
					if(ch < (char)0x80)
					{
						bytes[byteIndex++] = (byte)ch;
					}
					else
					{
						bytes[byteIndex++] = (byte)'?';
					}
				}
				return charCount;
			}

	// Convenience wrappers for "GetBytes".
	public override int GetBytes(String s, int charIndex, int charCount,
								 byte[] bytes, int byteIndex)
			{
				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"));
				}
				if((bytes.Length - byteIndex) < charCount)
				{
					throw new ArgumentException(_("Arg_InsufficientSpace"));
				}
				int count = charCount;
				char ch;
				while(count-- > 0)
				{
					ch = s[charIndex++];
					if(ch < (char)0x80)
					{
						bytes[byteIndex++] = (byte)ch;
					}
					else
					{
						bytes[byteIndex++] = (byte)'?';
					}
				}
				return charCount;
			}

	// Get the number of characters needed to decode a byte buffer.
	public override int GetCharCount(byte[] bytes, int index, int count)
			{
				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"));
				}
				return count;
			}

	// Get the characters that result from decoding a byte buffer.
	public override int GetChars(byte[] bytes, int byteIndex, int byteCount,
								 char[] chars, int charIndex)
			{
				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((chars.Length - charIndex) < byteCount)
				{
					throw new ArgumentException(_("Arg_InsufficientSpace"));
				}
				int count = byteCount;
				while(count-- > 0)
				{
					chars[charIndex++] = (char)(bytes[byteIndex++]);
				}
				return byteCount;
			}

	// 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;
			}

	// 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;
			}

	// Decode a buffer of bytes into a string.
	public override String GetString(byte[] bytes, int index, int count)
			{
				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"));
				}
				/*String s = String.NewString(count);
				int posn = 0;
				while(count-- > 0)
				{
					s.SetChar(posn++, (char)(bytes[index++]));
				}
				return s;*/
				unsafe {
					fixed (byte *ss = &bytes [0]) {
						return new String ((sbyte*)ss, index, count);
					}
				}
			}
	public override String GetString(byte[] bytes)
			{
				if(bytes == null)
				{
					throw new ArgumentNullException("bytes");
				}
				int count = bytes.Length;
				/*int posn = 0;
				String s = String.NewString(count);
				while(count-- > 0)
				{
					s.SetChar(posn, (char)(bytes[posn]));
					++posn;
				}
				return s;*/
				unsafe {
					fixed (byte *ss = &bytes [0]) {
						return new String ((sbyte*)ss, 0, count);
					}
				}
			}

#if !ECMA_COMPAT

	// Get the mail body name for this encoding.
	public override String BodyName
			{
				get
				{
					return "us-ascii";
				}
			}

	// Get the human-readable name for this encoding.
	public override String EncodingName
			{
				get
				{
					return "US-ASCII";
				}
			}

	// Get the mail agent header name for this encoding.
	public override String HeaderName
			{
				get
				{
					return "us-ascii";
				}
			}

	// Determine if this encoding can be displayed in a mail/news agent.
	public override bool IsMailNewsDisplay
			{
				get
				{
					return true;
				}
			}

	// Determine if this encoding can be saved from a mail/news agent.
	public override bool IsMailNewsSave
			{
				get
				{
					return true;
				}
			}

	// Get the IANA-preferred Web name for this encoding.
	public override String WebName
			{
				get
				{
					return "us-ascii";
				}
			}

#endif // !ECMA_COMPAT

}; // class ASCIIEncoding

}; // namespace System.Text