source: vendor/trolltech/current/src/codecs/qisciicodec.cpp

#include "qisciicodec_p.h"
#ifndef QT_NO_CODECS

#define QValidChar(u)      ((u) ? QChar((u)) : QChar::replacement)

/*!
    \class QIsciiCodec
    \brief The QIsciiCodec class provides conversion to and from the ISCII encoding.

    \ingroup i18n
    \internal
*/

QIsciiCodec::QIsciiCodec(int i)
: idx(i)
{
}

int QIsciiCodec::mibEnum() const
{
    /* There is no MIBEnum for Iscii */
    return -3000-idx;
}


struct Codecs {
    const char *name;
    ushort base;
};

static const Codecs codecs [] = {
    { "Iscii-Dev", 0x900 },
    { "Iscii-Bng", 0x980 },
    { "Iscii-Pnj", 0xa00 },
    { "Iscii-Gjr", 0xa80 },
    { "Iscii-Ori", 0xb00 },
    { "Iscii-Tml", 0xb80 },
    { "Iscii-Tlg", 0xc00 },
    { "Iscii-Knd", 0xc80 },
    { "Iscii-Mlm", 0xd00 }
};

const char* QIsciiCodec::name() const
{
  return codecs[idx].name;
}

const char* QIsciiCodec::mimeName() const
{
  return codecs[idx].name;
}


int QIsciiCodec::heuristicNameMatch(const char* hint) const
{
    const char *p = strchr(hint, '.');
    if (p)
        p++;
    else
        p = hint;

    if (QString::fromLatin1(p).lower() == QString::fromLatin1(codecs[idx].name).lower())
        return 4;
    else
        return QTextCodec::heuristicNameMatch(hint);
}

int QIsciiCodec::heuristicContentMatch(const char*, int) const
{
    return 0;
}

#define INV 0xff

/* iscii range from 0xa0 - 0xff */
static const uchar iscii_to_uni_table[0x60] = {
    0x00, 0x01, 0x02, 0x03,
    0x05, 0x06, 0x07, 0x08,
    0x09, 0x0a, 0x0b, 0x0e,
    0x0f, 0x20, 0x0d, 0x12,

    0x13, 0x14, 0x11, 0x15,
    0x16, 0x17, 0x18, 0x19,
    0x1a, 0x1b, 0x1c, 0x1d,
    0x1e, 0x1f, 0x20, 0x21,

    0x22, 0x23, 0x24, 0x25,
    0x26, 0x27, 0x28, 0x29,
    0x2a, 0x2b, 0x2c, 0x2d,
    0x2e, 0x2f, 0x5f, 0x30,

    0x31, 0x32, 0x33, 0x34,
    0x35, 0x36, 0x37, 0x38,
    0x39,  INV, 0x3e, 0x3f,
    0x40, 0x41, 0x42, 0x43,

    0x46, 0x47, 0x48, 0x45,
    0x4a, 0x4b, 0x4c, 0x49,
    0x4d, 0x3c, 0x64, 0x00,
    0x00, 0x00, 0x00, 0x00,

    0x00, 0x66, 0x67, 0x68,
    0x69, 0x6a, 0x6b, 0x6c,
    0x6d, 0x6e, 0x6f, 0x00,
    0x00, 0x00, 0x00, 0x00
};

static const uchar uni_to_iscii_table[0x80] = {
    0x00, 0xa1, 0xa2, 0xa3,
    0x00, 0xa4, 0xa5, 0xa6,
    0xa7, 0xa8, 0xa9, 0xaa,
    0x00, 0xae, 0xab, 0xac,

    0xad, 0xb2, 0xaf, 0xb0,
    0xb1, 0xb3, 0xb4, 0xb5,
    0xb6, 0xb7, 0xb8, 0xb9,
    0xba, 0xbb, 0xbc, 0xbd,

    0xbe, 0xbf, 0xc0, 0xc1,
    0xc2, 0xc3, 0xc4, 0xc5,
    0xc6, 0xc7, 0xc8, 0xc9,
    0xca, 0xcb, 0xcc, 0xcd,

    0xcf, 0xd0, 0xd1, 0xd2,
    0xd3, 0xd4, 0xd5, 0xd6,
    0xd7, 0xd8, 0x00, 0x00,
    0xe9, 0x00, 0xda, 0xdb,

    0xdc, 0xdd, 0xde, 0xdf,
    0x00, 0xe3, 0xe0, 0xe1,
    0xe2, 0xe7, 0xe4, 0xe5,
    0xe6, 0xe8, 0x00, 0x00,

    0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00,
    0x01, 0x02, 0x03, 0x04, // decomposable into the uc codes listed here + nukta
    0x05, 0x06, 0x07, 0xce,

    0x00, 0x00, 0x00, 0x00,
    0xea, 0x08, 0xf1, 0xf2,
    0xf3, 0xf4, 0xf5, 0xf6,
    0xf7, 0xf8, 0xf9, 0xfa,

    0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00
};

static const uchar uni_to_iscii_pairs[] = {
    0x00, 0x00,
    0x15, 0x3c, // 0x958
    0x16, 0x3c, // 0x959
    0x17, 0x3c, // 0x95a
    0x1c, 0x3c, // 0x95b
    0x21, 0x3c, // 0x95c
    0x22, 0x3c, // 0x95d
    0x2b, 0x3c, // 0x95e
    0x64, 0x64  // 0x965
};


QCString QIsciiCodec::fromUnicode(const QString& uc, int& len_in_out) const
{
    int l = uc.length();
    if (len_in_out > 0)
        l = QMIN(l, len_in_out);
    QCString result(2*l); //worst case

    const QChar *data = uc.unicode();
    uchar *ch = (uchar *)result.data();

    int base = codecs[idx].base;

    bool halant = false;
    for (int i =0; i < l; ++i) {
        int pos = data[i].unicode() - base;
        if (pos > 0 && pos < 0x80) {
            uchar iscii = uni_to_iscii_table[pos];
            if (iscii > 0x80) {
                *ch++ = iscii;
            } else if (iscii) {
                const uchar *pair = uni_to_iscii_pairs + 2*iscii;
                *ch++ = *pair++;
                *ch++ = *pair++;
            } else {
                *ch++ = '?';
            }
        } else {
            if (data[i].unicode() == 0x200c) { // ZWNJ
                if (halant)
                    // Consonant Halant ZWNJ -> Consonant Halant Halant
                    *ch++ = 0xe8;
            } else if (data[i].unicode() == 0x200d) { // ZWJ
                if (halant)
                    // Consonant Halant ZWJ -> Consonant Halant Nukta
                    *ch++ = 0xe9;
            } else {
                *ch++ = '?';
            }
        }
        halant = (pos == 0x4d);
    }
    len_in_out = ch - (uchar *)result.data();
    result.truncate(len_in_out);
    return result;
}

QString QIsciiCodec::toUnicode( const char* chars, int len_in ) const
{
    QString result;
    result.setLength(len_in);

    QChar *uc = (QChar *)result.unicode();

    int base = codecs[idx].base;

    bool halant = false;
    for (int i = 0; i < len_in; ++i) {
        ushort ch = (uchar) chars[i];
        if (ch < 0xa0)
            *uc++ = QValidChar(ch);
        else {
            ushort c = iscii_to_uni_table[ch - 0xa0];
            if (halant && (c == INV || c == 0xe9)) {
                // Consonant Halant INV -> Consonant Halant ZWJ
                // Consonant Halant Nukta -> Consonant Halant ZWJ
                *uc++ = QChar(0x200d);
            } else if (halant && c == 0xe8) {
                // Consonant Halant Halant -> Consonant Halant ZWNJ
                *uc++ = QChar(0x200c);
            } else {
                *uc++ = QChar(c+base);
            }
        }
        halant = ((uchar)chars[i] == 0xe8);
    }
    return result;
}
#endif // QT_NO_CODECS