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//
// I18N.CJK.CP950
//
// Author:
// Alan Tam Siu Lung (Tam@SiuLung.com)
//
using System;
using System.Text;
using I18N.Common;
namespace I18N.CJK
{
[Serializable]
internal class CP950 : DbcsEncoding
{
// Magic number used by Windows for the Big5 code page.
private const int BIG5_CODE_PAGE = 950;
// Constructor.
public CP950() : base(BIG5_CODE_PAGE) {
}
internal override DbcsConvert GetConvert ()
{
return Big5Convert.Convert;
}
// Get the bytes that result from encoding a character buffer.
public unsafe override int GetBytesImpl (char* chars, int charCount,
byte* bytes, int byteCount)
{
DbcsConvert convert = GetConvert ();
int charIndex = 0;
int byteIndex = 0;
#if NET_2_0
EncoderFallbackBuffer buffer = null;
#endif
int origIndex = byteIndex;
while (charCount-- > 0) {
char c = chars[charIndex++];
if (c <= 0x80 || c == 0xFF) { // ASCII
bytes[byteIndex++] = (byte)c;
continue;
}
byte b1 = convert.u2n[((int)c) * 2 + 1];
byte b2 = convert.u2n[((int)c) * 2];
if (b1 == 0 && b2 == 0) {
#if NET_2_0
HandleFallback (ref buffer, chars,
ref charIndex, ref charCount,
bytes, ref byteIndex, ref byteCount);
#else
bytes[byteIndex++] = (byte)'?';
#endif
} else {
bytes[byteIndex++] = b1;
bytes[byteIndex++] = b2;
}
}
return byteIndex - origIndex;
}
// Get the characters that result from decoding a byte buffer.
public override int GetChars(byte[] bytes, int byteIndex, int byteCount,
char[] chars, int charIndex)
{
DbcsConvert convert = GetConvert ();
// A1 40 - FA FF
base.GetChars(bytes, byteIndex, byteCount, chars, charIndex);
int origIndex = charIndex;
int lastByte = 0;
while (byteCount-- > 0) {
int b = bytes[byteIndex++];
if (lastByte == 0) {
if (b <= 0x80 || b == 0xFF) { // ASCII
chars[charIndex++] = (char)b;
} else if (b < 0xA1 || b >= 0xFA) {
// incorrect first byte.
chars[charIndex++] = '?';
byteCount--; // cut one more byte.
} else {
lastByte = b;
}
continue;
}
int ord = ((lastByte - 0xA1) * 191 + b - 0x40) * 2;
char c1 = ord < 0 || ord > convert.n2u.Length ?
'\0' :
(char)(convert.n2u[ord] + convert.n2u[ord + 1] * 256);
if (c1 == 0)
chars[charIndex++] = '?';
else
chars[charIndex++] = c1;
lastByte = 0;
}
if (lastByte != 0)
chars[charIndex++] = '?';
return charIndex - origIndex;
}
// Get a decoder that handles a rolling Big5 state.
public override Decoder GetDecoder()
{
return new CP950Decoder(GetConvert ());
}
// Get the mail body name for this encoding.
public override String BodyName
{
get { return "big5"; }
}
// Get the human-readable name for this encoding.
public override String EncodingName
{
get { return "Chinese Traditional (Big5)"; }
}
// Get the mail agent header name for this encoding.
public override String HeaderName
{
get { return "big5"; }
}
// Get the IANA-preferred Web name for this encoding.
public override String WebName
{
get { return "big5"; }
}
/*
// Get the Windows code page represented by this object.
public override int WindowsCodePage
{
get { return BIG5_PAGE; }
}
*/
// Decoder that handles a rolling Big5 state.
private sealed class CP950Decoder : DbcsDecoder
{
// Constructor.
public CP950Decoder(DbcsConvert convert) : base(convert) {}
public override int GetChars(byte[] bytes, int byteIndex, int byteCount,
char[] chars, int charIndex)
{
base.GetChars(bytes, byteIndex, byteCount, chars, charIndex);
int origIndex = charIndex;
while (byteCount-- > 0) {
int b = bytes[byteIndex++];
if (lastByte == 0) {
if (b <= 0x80 || b == 0xFF) { // ASCII
chars[charIndex++] = (char)b;
continue;
} else if (b < 0xA1 || b >= 0xFA) {
continue;
} else {
lastByte = b;
continue;
}
}
int ord = ((lastByte - 0xA1) * 191 + b - 0x40) * 2;
char c1 = (char)(convert.n2u[ord] + convert.n2u[ord + 1] * 256);
if (c1 == 0) {
chars[charIndex++] = '?';
} else {
chars[charIndex++] = c1;
}
lastByte = 0;
}
return charIndex - origIndex;
}
}
}
[Serializable]
internal class ENCbig5 : CP950
{
public ENCbig5() {}
}
}
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