class/corlib/System.Text/ASCIIEncoding.cs

   1 /*
   2  * ASCIIEncoding.cs - Implementation of the "System.Text.ASCIIEncoding" class.
   3  *
   4  * Copyright (c) 2001  Southern Storm Software, Pty Ltd
   5  * Copyright (C) 2003 Novell, Inc.
   6  * Copyright (C) 2004 Novell, Inc (http://www.novell.com)
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining
   9  * a copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  21  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  22  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  23  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  * OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27 namespace System.Text
  28 {
  29
  30 using System;
  31 using System.Runtime.InteropServices;
  32
  33 [Serializable]
  34 [ComVisible (true)]
  35 [MonoLimitation ("Serialization format not compatible with .NET")]
  36 public class ASCIIEncoding : Encoding
  37 {
  38         // Magic number used by Windows for "ASCII".
  39         internal const int ASCII_CODE_PAGE = 20127;
  40
  41         // Constructor.
  42         public ASCIIEncoding () : base(ASCII_CODE_PAGE) {
  43                 body_name = header_name = web_name= "us-ascii";
  44                 encoding_name = "US-ASCII";
  45                 is_mail_news_display = true;
  46                 is_mail_news_save = true;
  47         }
  48
  49         [ComVisible (false)]
  50         public override bool IsSingleByte {
  51                 get { return true; }
  52         }
  53
  54         // Get the number of bytes needed to encode a character buffer.
  55         public override int GetByteCount (char[] chars, int index, int count)
  56         {
  57                 if (chars == null) {
  58                         throw new ArgumentNullException ("chars");
  59                 }
  60                 if (index < 0 || index > chars.Length) {
  61                         throw new ArgumentOutOfRangeException ("index", _("ArgRange_Array"));
  62                 }
  63                 if (count < 0 || count > (chars.Length - index)) {
  64                         throw new ArgumentOutOfRangeException ("count", _("ArgRange_Array"));
  65                 }
  66                 return count;
  67         }
  68
  69         // Convenience wrappers for "GetByteCount".
  70         public override int GetByteCount (String chars)
  71         {
  72                 if (chars == null) {
  73                         throw new ArgumentNullException ("chars");
  74                 }
  75                 return chars.Length;
  76         }
  77
  78         // Get the bytes that result from encoding a character buffer.
  79         public override int GetBytes (char[] chars, int charIndex, int charCount,
  80                                       byte[] bytes, int byteIndex)
  81         {
  82                 EncoderFallbackBuffer buffer = null;
  83                 char [] fallback_chars = null;
  84
  85                 return GetBytes (chars, charIndex, charCount, bytes, byteIndex,
  86                                  ref buffer, ref fallback_chars);
  87         }
  88
  89         int GetBytes (char[] chars, int charIndex, int charCount,
  90                       byte[] bytes, int byteIndex,
  91                       ref EncoderFallbackBuffer buffer,
  92                       ref char [] fallback_chars)
  93         {
  94                 if (chars == null)
  95                         throw new ArgumentNullException ("chars");
  96
  97                 unsafe {
  98                         fixed (char *cptr = chars) {
  99                                 return InternalGetBytes (cptr, chars.Length, charIndex, charCount, bytes, byteIndex, ref buffer, ref fallback_chars);
 100                         }
 101                 }
 102         }
 103
 104         // Convenience wrappers for "GetBytes".
 105         public override int GetBytes (String chars, int charIndex, int charCount, byte[] bytes, int byteIndex)
 106         {
 107                 EncoderFallbackBuffer buffer = null;
 108                 char [] fallback_chars = null;
 109                 return GetBytes (chars, charIndex, charCount, bytes, byteIndex,
 110                         ref buffer, ref fallback_chars);
 111         }
 112
 113         int GetBytes (String chars, int charIndex, int charCount,
 114                       byte[] bytes, int byteIndex,
 115                       ref EncoderFallbackBuffer buffer,
 116                       ref char [] fallback_chars)
 117         {
 118                 if (chars == null)
 119                         throw new ArgumentNullException ("chars");
 120
 121                 unsafe {
 122                         fixed (char *cptr = chars) {
 123                                 return InternalGetBytes (cptr, chars.Length, charIndex, charCount, bytes, byteIndex, ref buffer, ref fallback_chars);
 124                         }
 125                 }
 126         }
 127
 128         unsafe int InternalGetBytes (char *chars, int charLength, int charIndex, int charCount,
 129                       byte[] bytes, int byteIndex,
 130                       ref EncoderFallbackBuffer buffer,
 131                       ref char [] fallback_chars)
 132         {
 133                 if (bytes == null)
 134                         throw new ArgumentNullException ("bytes");
 135                 if (charIndex < 0 || charIndex > charLength)
 136                         throw new ArgumentOutOfRangeException ("charIndex", _("ArgRange_StringIndex"));
 137                 if (charCount < 0 || charCount > (charLength - charIndex))
 138                         throw new ArgumentOutOfRangeException ("charCount", _("ArgRange_StringRange"));
 139                 if (byteIndex < 0 || byteIndex > bytes.Length)
 140                         throw new ArgumentOutOfRangeException ("byteIndex", _("ArgRange_Array"));
 141                 if ((bytes.Length - byteIndex) < charCount)
 142                         throw new ArgumentException (_("Arg_InsufficientSpace"));
 143
 144                 int count = charCount;
 145                 char ch;
 146                 while (count-- > 0) {
 147                         ch = chars [charIndex++];
 148                         if (ch < (char)0x80) {
 149                                 bytes [byteIndex++] = (byte)ch;
 150                         } else {
 151                                 if (buffer == null)
 152                                         buffer = EncoderFallback.CreateFallbackBuffer ();
 153                                 if (Char.IsSurrogate (ch) && count > 1 &&
 154                                     Char.IsSurrogate (chars [charIndex]))
 155                                         buffer.Fallback (ch, chars [charIndex], charIndex++ - 1);
 156                                 else
 157                                         buffer.Fallback (ch, charIndex - 1);
 158                                 if (fallback_chars == null || fallback_chars.Length < buffer.Remaining)
 159                                         fallback_chars = new char [buffer.Remaining];
 160                                 for (int i = 0; i < fallback_chars.Length; i++)
 161                                         fallback_chars [i] = buffer.GetNextChar ();
 162                                 byteIndex += GetBytes (fallback_chars, 0,
 163                                         fallback_chars.Length, bytes, byteIndex,
 164                                         ref buffer, ref fallback_chars);
 165                         }
 166                 }
 167                 return charCount;
 168         }
 169
 170         // Get the number of characters needed to decode a byte buffer.
 171         public override int GetCharCount (byte[] bytes, int index, int count)
 172         {
 173                 if (bytes == null) {
 174                         throw new ArgumentNullException ("bytes");
 175                 }
 176                 if (index < 0 || index > bytes.Length) {
 177                         throw new ArgumentOutOfRangeException ("index", _("ArgRange_Array"));
 178                 }
 179                 if (count < 0 || count > (bytes.Length - index)) {
 180                         throw new ArgumentOutOfRangeException ("count", _("ArgRange_Array"));
 181                 }
 182                 return count;
 183         }
 184
 185         // Get the characters that result from decoding a byte buffer.
 186         public override int GetChars (byte[] bytes, int byteIndex, int byteCount, char[] chars, int charIndex)
 187         {
 188                 DecoderFallbackBuffer buffer = null;
 189                 return GetChars (bytes, byteIndex, byteCount, chars,
 190                         charIndex, ref buffer);
 191         }
 192
 193         int GetChars (byte[] bytes, int byteIndex, int byteCount,
 194                       char[] chars, int charIndex,
 195                       ref DecoderFallbackBuffer buffer)
 196         {
 197                 if (bytes == null)
 198                         throw new ArgumentNullException ("bytes");
 199                 if (chars == null)
 200                         throw new ArgumentNullException ("chars");
 201                 if (byteIndex < 0 || byteIndex > bytes.Length)
 202                         throw new ArgumentOutOfRangeException ("byteIndex", _("ArgRange_Array"));
 203                 if (byteCount < 0 || byteCount > (bytes.Length - byteIndex))
 204                         throw new ArgumentOutOfRangeException ("byteCount", _("ArgRange_Array"));
 205                 if (charIndex < 0 || charIndex > chars.Length)
 206                         throw new ArgumentOutOfRangeException ("charIndex", _("ArgRange_Array"));
 207
 208                 if ((chars.Length - charIndex) < byteCount)
 209                         throw new ArgumentException (_("Arg_InsufficientSpace"));
 210
 211                 int count = byteCount;
 212                 while (count-- > 0) {
 213                         char c = (char) bytes [byteIndex++];
 214                         if (c < '\x80')
 215                                 chars [charIndex++] = c;
 216                         else {
 217                                 if (buffer == null)
 218                                         buffer = DecoderFallback.CreateFallbackBuffer ();
 219                                 buffer.Fallback (bytes, byteIndex);
 220                                 while (buffer.Remaining > 0)
 221                                         chars [charIndex++] = buffer.GetNextChar ();
 222                         }
 223                 }
 224                 return byteCount;
 225         }
 226
 227         // Get the maximum number of bytes needed to encode a
 228         // specified number of characters.
 229         public override int GetMaxByteCount (int charCount)
 230         {
 231                 if (charCount < 0) {
 232                         throw new ArgumentOutOfRangeException ("charCount", _("ArgRange_NonNegative"));
 233                 }
 234                 return charCount;
 235         }
 236
 237         // Get the maximum number of characters needed to decode a
 238         // specified number of bytes.
 239         public override int GetMaxCharCount (int byteCount)
 240         {
 241                 if (byteCount < 0) {
 242                         throw new ArgumentOutOfRangeException ("byteCount", _("ArgRange_NonNegative"));
 243                 }
 244                 return byteCount;
 245         }
 246
 247         // Decode a buffer of bytes into a string.
 248         public override String GetString (byte[] bytes, int byteIndex, int byteCount)
 249         {
 250                 if (bytes == null) {
 251                         throw new ArgumentNullException ("bytes");
 252                 }
 253                 if (byteIndex < 0 || byteIndex > bytes.Length) {
 254                         throw new ArgumentOutOfRangeException ("byteIndex", _("ArgRange_Array"));
 255                 }
 256                 if (byteCount < 0 || byteCount > (bytes.Length - byteIndex)) {
 257                         throw new ArgumentOutOfRangeException ("byteCount", _("ArgRange_Array"));
 258                 }
 259                 if (byteCount == 0)
 260                         return String.Empty;
 261
 262                 unsafe {
 263                         fixed (byte* bytePtr = bytes) {
 264                                 string s = string.InternalAllocateStr (byteCount);
 265
 266                                 fixed (char* charPtr = s) {
 267                                         byte* currByte = bytePtr + byteIndex;
 268                                         byte* lastByte = currByte + byteCount;
 269                                         char* currChar = charPtr;
 270
 271                                         while (currByte < lastByte) {
 272                                                 byte b = currByte++ [0];
 273                                                 currChar++ [0] = b <= 0x7F ? (char) b : (char) '?';
 274                                         }
 275                                 }
 276
 277                                 return s;
 278                         }
 279                 }
 280         }
 281
 282         [CLSCompliantAttribute (false)]
 283         [ComVisible (false)]
 284         public unsafe override int GetBytes (char *chars, int charCount, byte *bytes, int byteCount)
 285         {
 286                 if (chars == null)
 287                         throw new ArgumentNullException ("chars");
 288                 if (bytes == null)
 289                         throw new ArgumentNullException ("bytes");
 290                 if (charCount < 0)
 291                         throw new ArgumentOutOfRangeException ("charCount");
 292                 if (byteCount < 0)
 293                         throw new ArgumentOutOfRangeException ("byteCount");
 294
 295                 if (byteCount < charCount)
 296                         throw new ArgumentException ("bytecount is less than the number of bytes required", "byteCount");
 297
 298                 for (int i = 0; i < charCount; i++){
 299                         char c = chars [i];
 300                         bytes [i] = (byte) ((c < (char) 0x80) ? c : '?');
 301                 }
 302                 return charCount;
 303         }
 304
 305         [CLSCompliantAttribute(false)]
 306         [ComVisible (false)]
 307         public unsafe override int GetChars (byte *bytes, int byteCount, char *chars, int charCount)
 308         {
 309                 if (bytes == null)
 310                         throw new ArgumentNullException ("bytes");
 311                 if (chars == null)
 312                         throw new ArgumentNullException ("chars");
 313                 if (charCount < 0)
 314                         throw new ArgumentOutOfRangeException ("charCount");
 315                 if (byteCount < 0)
 316                         throw new ArgumentOutOfRangeException ("byteCount");
 317                 if (charCount < byteCount)
 318                         throw new ArgumentException ("charcount is less than the number of bytes required", "charCount");
 319
 320                 for (int i = 0; i < byteCount; i++){
 321                         byte b = bytes [i];
 322                         chars [i] = b > 127 ? '?' : (char) b;
 323                 }
 324                 return byteCount;
 325
 326         }
 327
 328         [CLSCompliantAttribute(false)]
 329         [ComVisible (false)]
 330         public unsafe override int GetCharCount (byte *bytes, int count)
 331         {
 332                 return count;
 333         }
 334
 335         [CLSCompliantAttribute(false)]
 336         [ComVisible (false)]
 337         public unsafe override int GetByteCount (char *chars, int count)
 338         {
 339                 return count;
 340         }
 341
 342         [ComVisible (false)]
 343         public override Decoder GetDecoder ()
 344         {
 345                 return base.GetDecoder ();
 346         }
 347
 348         [ComVisible (false)]
 349         public override Encoder GetEncoder ()
 350         {
 351                 return base.GetEncoder ();
 352         }
 353 }; // class ASCIIEncoding
 354
 355 }; // namespace System.Text