private void FindInputState(byte[] buf, int len)
{
for (int i = 0; i < len; i++)
{
// other than 0xa0, if every other character is ascii, the page is ascii
if ((buf[i] & 0x80) != 0 && buf[i] != 0xA0)
{
// we got a non-ascii byte (high-byte)
if (InputState != InputState.Highbyte)
{
InputState = InputState.Highbyte;
// kill EscCharsetProber if it is active
_escCharsetProber = null;
// start multibyte and singlebyte charset prober
if (_charsetProbers[0] == null)
{
_charsetProbers[0] = new MBCSGroupProber();
}
if (_charsetProbers[1] == null)
{
_charsetProbers[1] = new SBCSGroupProber();
}
if (_charsetProbers[2] == null)
{
_charsetProbers[2] = new Latin1Prober();
}
}
}
else
{
if (InputState == InputState.PureASCII &&
(buf[i] == 0x1B || (buf[i] == 0x7B && _lastChar == 0x7E)))
{
// found escape character or HZ "~{"
InputState = InputState.EscASCII;
}
_lastChar = buf[i];
}
}
}
public virtual void Feed(byte[] buf, int offset, int len)
{
if (done)
{
return;
}
if (len > 0)
{
gotData = true;
}
// If the data starts with BOM, we know it is UTF
if (start)
{
start = false;
if (len > 3)
{
switch (buf[0])
{
case 0xEF:
if (0xBB == buf[1] && 0xBF == buf[2])
{
detectedCharset = "UTF-8";
}
break;
case 0xFE:
if (0xFF == buf[1] && 0x00 == buf[2] && 0x00 == buf[3])
{
// FE FF 00 00 UCS-4, unusual octet order BOM (3412)
detectedCharset = "X-ISO-10646-UCS-4-3412";
}
else if (0xFF == buf[1])
{
detectedCharset = "UTF-16BE";
}
break;
case 0x00:
if (0x00 == buf[1] && 0xFE == buf[2] && 0xFF == buf[3])
{
detectedCharset = "UTF-32BE";
}
else if (0x00 == buf[1] && 0xFF == buf[2] && 0xFE == buf[3])
{
// 00 00 FF FE UCS-4, unusual octet order BOM (2143)
detectedCharset = "X-ISO-10646-UCS-4-2143";
}
break;
case 0xFF:
if (0xFE == buf[1] && 0x00 == buf[2] && 0x00 == buf[3])
{
detectedCharset = "UTF-32LE";
}
else if (0xFE == buf[1])
{
detectedCharset = "UTF-16LE";
}
break;
} // switch
}
if (detectedCharset != null)
{
done = true;
return;
}
}
for (int i = 0; i < len; i++)
{
// other than 0xa0, if every other character is ascii, the page is ascii
if ((buf[i] & 0x80) != 0 && buf[i] != 0xA0)
{
// we got a non-ascii byte (high-byte)
if (inputState != InputState.Highbyte)
{
inputState = InputState.Highbyte;
// kill EscCharsetProber if it is active
if (escCharsetProber != null)
{
escCharsetProber = null;
}
// start multibyte and singlebyte charset prober
if (charsetProbers[0] == null)
{
charsetProbers[0] = new MBCSGroupProber();
}
if (charsetProbers[1] == null)
{
charsetProbers[1] = new SBCSGroupProber();
}
if (charsetProbers[2] == null)
{
charsetProbers[2] = new Latin1Prober();
}
}
}
else
{
if (inputState == InputState.PureASCII &&
(buf[i] == 0x33 || (buf[i] == 0x7B && lastChar == 0x7E)))
{
// found escape character or HZ "~{"
inputState = InputState.EscASCII;
}
lastChar = buf[i];
}
}
ProbingState st = ProbingState.NotMe;
switch (inputState)
{
case InputState.EscASCII:
if (escCharsetProber == null)
{
escCharsetProber = new EscCharsetProber();
}
st = escCharsetProber.HandleData(buf, offset, len);
if (st == ProbingState.FoundIt)
{
done = true;
detectedCharset = escCharsetProber.GetCharsetName();
}
break;
case InputState.Highbyte:
for (int i = 0; i < PROBERS_NUM; i++)
{
if (charsetProbers[i] != null)
{
st = charsetProbers[i].HandleData(buf, offset, len);
#if DEBUG
charsetProbers[i].DumpStatus();
#endif
if (st == ProbingState.FoundIt)
{
done = true;
detectedCharset = charsetProbers[i].GetCharsetName();
return;
}
}
}
break;
default:
// pure ascii
break;
}
return;
}
