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#include "qutfcodec_p.h"
#include "qlist.h"
#include "qendian.h"
#include "qchar.h"

QT_BEGIN_NAMESPACE

enum { Endian = 0, Data = 1 };

static inline bool isUnicodeNonCharacter(uint ucs4)
{
    // Unicode has a couple of "non-characters" that one can use internally,
    // but are not allowed to be used for text interchange.
    //
    // Those are the last two entries each Unicode Plane (U+FFFE, U+FFFF,
    // U+1FFFE, U+1FFFF, etc.) as well as the entries between U+FDD0 and
    // U+FDEF (inclusive)

    return (ucs4 & 0xfffe) == 0xfffe
            || (ucs4 - 0xfdd0U) < 16;
}

QByteArray QUtf8::convertFromUnicode(const QChar *uc, int len, QTextCodec::ConverterState *state)
{
    uchar replacement = '?';
    int rlen = 3*len;
    int surrogate_high = -1;
    if (state) {
        if (state->flags & QTextCodec::ConvertInvalidToNull)
            replacement = 0;
        if (!(state->flags & QTextCodec::IgnoreHeader))
            rlen += 3;
        if (state->remainingChars)
            surrogate_high = state->state_data[0];
    }

    QByteArray rstr;
    rstr.resize(rlen);
    uchar* cursor = (uchar*)rstr.data();
    const QChar *ch = uc;
    int invalid = 0;
    if (state && !(state->flags & QTextCodec::IgnoreHeader)) {
        *cursor++ = 0xef;
        *cursor++ = 0xbb;
        *cursor++ = 0xbf;
    }

    const QChar *end = ch + len;
    while (ch < end) {
        uint u = ch->unicode();
        if (surrogate_high >= 0) {
            if (ch->isLowSurrogate()) {
                u = QChar::surrogateToUcs4(surrogate_high, u);
                surrogate_high = -1;
            } else {
                // high surrogate without low
                *cursor = replacement;
                ++ch;
                ++invalid;
                surrogate_high = -1;
                continue;
            }
        } else if (ch->isLowSurrogate()) {
            // low surrogate without high
            *cursor = replacement;
            ++ch;
            ++invalid;
            continue;
        } else if (ch->isHighSurrogate()) {
            surrogate_high = u;
            ++ch;
            continue;
        }

        if (u < 0x80) {
            *cursor++ = (uchar)u;
        } else {
            if (u < 0x0800) {
                *cursor++ = 0xc0 | ((uchar) (u >> 6));
            } else {
                // is it one of the Unicode non-characters?
                if (isUnicodeNonCharacter(u)) {
                    *cursor++ = replacement;
                    ++ch;
                    ++invalid;
                    continue;
                }

                if (u > 0xffff) {
                    *cursor++ = 0xf0 | ((uchar) (u >> 18));
                    *cursor++ = 0x80 | (((uchar) (u >> 12)) & 0x3f);
                } else {
                    *cursor++ = 0xe0 | (((uchar) (u >> 12)) & 0x3f);
                }
                *cursor++ = 0x80 | (((uchar) (u >> 6)) & 0x3f);
            }
            *cursor++ = 0x80 | ((uchar) (u&0x3f));
        }
        ++ch;
    }

    rstr.resize(cursor - (const uchar*)rstr.constData());
    if (state) {
        state->invalidChars += invalid;
        state->flags |= QTextCodec::IgnoreHeader;
        state->remainingChars = 0;
        if (surrogate_high >= 0) {
            state->remainingChars = 1;
            state->state_data[0] = surrogate_high;
        }
    }
    return rstr;
}

QString QUtf8::convertToUnicode(const char *chars, int len, QTextCodec::ConverterState *state)
{
    bool headerdone = false;
    ushort replacement = QChar::ReplacementCharacter;
    int need = 0;
    int error = -1;
    uint uc = 0;
    uint min_uc = 0;
    if (state) {
        if (state->flags & QTextCodec::IgnoreHeader)
            headerdone = true;
        if (state->flags & QTextCodec::ConvertInvalidToNull)
            replacement = QChar::Null;
        need = state->remainingChars;
        if (need) {
            uc = state->state_data[0];
            min_uc = state->state_data[1];
        }
    }
    if (!headerdone && len > 3
        && (uchar)chars[0] == 0xef && (uchar)chars[1] == 0xbb && (uchar)chars[2] == 0xbf) {
        // starts with a byte order mark
        chars += 3;
        len -= 3;
        headerdone = true;
    }

    QString result(need + len + 1, Qt::Uninitialized); // worst case
    ushort *qch = (ushort *)result.unicode();
    uchar ch;
    int invalid = 0;

    for (int i = 0; i < len; ++i) {
        ch = chars[i];
        if (need) {
            if ((ch&0xc0) == 0x80) {
                uc = (uc << 6) | (ch & 0x3f);
                --need;
                if (!need) {
                    // utf-8 bom composes into 0xfeff code point
                    bool nonCharacter;
                    if (!headerdone && uc == 0xfeff) {
                        // don't do anything, just skip the BOM
                    } else if (!(nonCharacter = isUnicodeNonCharacter(uc)) && uc > 0xffff && uc < 0x110000) {
                        // surrogate pair
                        Q_ASSERT((qch - (ushort*)result.unicode()) + 2 < result.length());
                        *qch++ = QChar::highSurrogate(uc);
                        *qch++ = QChar::lowSurrogate(uc);
                    } else if ((uc < min_uc) || (uc >= 0xd800 && uc <= 0xdfff) || nonCharacter || uc >= 0x110000) {
                        // error: overlong sequence, UTF16 surrogate or non-character
                        *qch++ = replacement;
                        ++invalid;
                    } else {
                        *qch++ = uc;
                    }
                    headerdone = true;
                }
            } else {
                // error
                i = error;
                *qch++ = replacement;
                ++invalid;
                need = 0;
                headerdone = true;
            }
        } else {
            if (ch < 128) {
                *qch++ = ushort(ch);
                headerdone = true;
            } else if ((ch & 0xe0) == 0xc0) {
                uc = ch & 0x1f;
                need = 1;
                error = i;
                min_uc = 0x80;
                headerdone = true;
            } else if ((ch & 0xf0) == 0xe0) {
                uc = ch & 0x0f;
                need = 2;
                error = i;
                min_uc = 0x800;
            } else if ((ch&0xf8) == 0xf0) {
                uc = ch & 0x07;
                need = 3;
                error = i;
                min_uc = 0x10000;
                headerdone = true;
            } else {
                // error
                *qch++ = replacement;
                ++invalid;
                headerdone = true;
            }
        }
    }
    if (!state && need > 0) {
        // unterminated UTF sequence
        for (int i = error; i < len; ++i) {
            *qch++ = replacement;
            ++invalid;
        }
    }
    result.truncate(qch - (ushort *)result.unicode());
    if (state) {
        state->invalidChars += invalid;
        state->remainingChars = need;
        if (headerdone)
            state->flags |= QTextCodec::IgnoreHeader;
        state->state_data[0] = need ? uc : 0;
        state->state_data[1] = need ? min_uc : 0;
    }
    return result;
}

QByteArray QUtf16::convertFromUnicode(const QChar *uc, int len, QTextCodec::ConverterState *state, DataEndianness e)
{
    DataEndianness endian = e;
    int length =  2*len;
    if (!state || (!(state->flags & QTextCodec::IgnoreHeader))) {
        length += 2;
    }
    if (e == DetectEndianness) {
        endian = (QSysInfo::ByteOrder == QSysInfo::BigEndian) ? BigEndianness : LittleEndianness;
    }

    QByteArray d;
    d.resize(length);
    char *data = d.data();
    if (!state || !(state->flags & QTextCodec::IgnoreHeader)) {
        QChar bom(QChar::ByteOrderMark);
        if (endian == BigEndianness) {
            data[0] = bom.row();
            data[1] = bom.cell();
        } else {
            data[0] = bom.cell();
            data[1] = bom.row();
        }
        data += 2;
    }
    if (endian == BigEndianness) {
        for (int i = 0; i < len; ++i) {
            *(data++) = uc[i].row();
            *(data++) = uc[i].cell();
        }
    } else {
        for (int i = 0; i < len; ++i) {
            *(data++) = uc[i].cell();
            *(data++) = uc[i].row();
        }
    }

    if (state) {
        state->remainingChars = 0;
        state->flags |= QTextCodec::IgnoreHeader;
    }
    return d;
}

QString QUtf16::convertToUnicode(const char *chars, int len, QTextCodec::ConverterState *state, DataEndianness e)
{
    DataEndianness endian = e;
    bool half = false;
    uchar buf = 0;
    bool headerdone = false;
    if (state) {
        headerdone = state->flags & QTextCodec::IgnoreHeader;
        if (endian == DetectEndianness)
            endian = (DataEndianness)state->state_data[Endian];
        if (state->remainingChars) {
            half = true;
            buf = state->state_data[Data];
        }
    }
    if (headerdone && endian == DetectEndianness)
        endian = (QSysInfo::ByteOrder == QSysInfo::BigEndian) ? BigEndianness : LittleEndianness;

    QString result(len, Qt::Uninitialized); // worst case
    QChar *qch = (QChar *)result.unicode();
    while (len--) {
        if (half) {
            QChar ch;
            if (endian == LittleEndianness) {
                ch.setRow(*chars++);
                ch.setCell(buf);
            } else {
                ch.setRow(buf);
                ch.setCell(*chars++);
            }
            if (!headerdone) {
                headerdone = true;
                if (endian == DetectEndianness) {
                    if (ch == QChar::ByteOrderSwapped) {
                        endian = LittleEndianness;
                    } else if (ch == QChar::ByteOrderMark) {
                        endian = BigEndianness;
                    } else {
                        if (QSysInfo::ByteOrder == QSysInfo::BigEndian) {
                            endian = BigEndianness;
                        } else {
                            endian = LittleEndianness;
                            ch = QChar((ch.unicode() >> 8) | ((ch.unicode() & 0xff) << 8));
                        }
                        *qch++ = ch;
                    }
                } else if (ch != QChar::ByteOrderMark) {
                    *qch++ = ch;
                }
            } else {
                *qch++ = ch;
            }
            half = false;
        } else {
            buf = *chars++;
            half = true;
        }
    }
    result.truncate(qch - result.unicode());

    if (state) {
        if (headerdone)
            state->flags |= QTextCodec::IgnoreHeader;
        state->state_data[Endian] = endian;
        if (half) {
            state->remainingChars = 1;
            state->state_data[Data] = buf;
        } else {
            state->remainingChars = 0;
            state->state_data[Data] = 0;
        }
    }
    return result;
}

QByteArray QUtf32::convertFromUnicode(const QChar *uc, int len, QTextCodec::ConverterState *state, DataEndianness e)
{
    DataEndianness endian = e;
    int length =  4*len;
    if (!state || (!(state->flags & QTextCodec::IgnoreHeader))) {
        length += 4;
    }
    if (e == DetectEndianness) {
        endian = (QSysInfo::ByteOrder == QSysInfo::BigEndian) ? BigEndianness : LittleEndianness;
    }

    QByteArray d(length, Qt::Uninitialized);
    char *data = d.data();
    if (!state || !(state->flags & QTextCodec::IgnoreHeader)) {
        if (endian == BigEndianness) {
            data[0] = 0;
            data[1] = 0;
            data[2] = (char)0xfe;
            data[3] = (char)0xff;
        } else {
            data[0] = (char)0xff;
            data[1] = (char)0xfe;
            data[2] = 0;
            data[3] = 0;
        }
        data += 4;
    }
    if (endian == BigEndianness) {
        for (int i = 0; i < len; ++i) {
            uint cp = uc[i].unicode();
            if (uc[i].isHighSurrogate() && i < len - 1)
                cp = QChar::surrogateToUcs4(cp, uc[++i].unicode());
            *(data++) = cp >> 24;
            *(data++) = (cp >> 16) & 0xff;
            *(data++) = (cp >> 8) & 0xff;
            *(data++) = cp & 0xff;
        }
    } else {
        for (int i = 0; i < len; ++i) {
            uint cp = uc[i].unicode();
            if (uc[i].isHighSurrogate() && i < len - 1)
                cp = QChar::surrogateToUcs4(cp, uc[++i].unicode());
            *(data++) = cp & 0xff;
            *(data++) = (cp >> 8) & 0xff;
            *(data++) = (cp >> 16) & 0xff;
            *(data++) = cp >> 24;
        }
    }

    if (state) {
        state->remainingChars = 0;
        state->flags |= QTextCodec::IgnoreHeader;
    }
    return d;
}

QString QUtf32::convertToUnicode(const char *chars, int len, QTextCodec::ConverterState *state, DataEndianness e)
{
    DataEndianness endian = e;
    uchar tuple[4];
    int num = 0;
    bool headerdone = false;
    if (state) {
        headerdone = state->flags & QTextCodec::IgnoreHeader;
        if (endian == DetectEndianness) {
            endian = (DataEndianness)state->state_data[Endian];
        }
        num = state->remainingChars;
        memcpy(tuple, &state->state_data[Data], 4);
    }
    if (headerdone && endian == DetectEndianness)
        endian = (QSysInfo::ByteOrder == QSysInfo::BigEndian) ? BigEndianness : LittleEndianness;

    QString result;
    result.resize((num + len) >> 2 << 1); // worst case
    QChar *qch = (QChar *)result.unicode();

    const char *end = chars + len;
    while (chars < end) {
        tuple[num++] = *chars++;
        if (num == 4) {
            if (!headerdone) {
                if (endian == DetectEndianness) {
                    if (endian == DetectEndianness) {
                        if (tuple[0] == 0xff && tuple[1] == 0xfe && tuple[2] == 0 && tuple[3] == 0 && endian != BigEndianness) {
                            endian = LittleEndianness;
                            num = 0;
                            continue;
                        } else if (tuple[0] == 0 && tuple[1] == 0 && tuple[2] == 0xfe && tuple[3] == 0xff && endian != LittleEndianness) {
                            endian = BigEndianness;
                            num = 0;
                            continue;
                        } else if (QSysInfo::ByteOrder == QSysInfo::BigEndian) {
                            endian = BigEndianness;
                        } else {
                            endian = LittleEndianness;
                        }
                    }
                } else if (((endian == BigEndianness) ? qFromBigEndian<quint32>(tuple) : qFromLittleEndian<quint32>(tuple)) == QChar::ByteOrderMark) {
                    num = 0;
                    continue;
                }
            }
            uint code = (endian == BigEndianness) ? qFromBigEndian<quint32>(tuple) : qFromLittleEndian<quint32>(tuple);
            if (code >= 0x10000) {
                *qch++ = QChar::highSurrogate(code);
                *qch++ = QChar::lowSurrogate(code);
            } else {
                *qch++ = code;
            }
            num = 0;
        }
    }
    result.truncate(qch - result.unicode());

    if (state) {
        if (headerdone)
            state->flags |= QTextCodec::IgnoreHeader;
        state->state_data[Endian] = endian;
        state->remainingChars = num;
        memcpy(&state->state_data[Data], tuple, 4);
    }
    return result;
}


#ifndef QT_NO_TEXTCODEC

QUtf8Codec::~QUtf8Codec()
{
}

QByteArray QUtf8Codec::convertFromUnicode(const QChar *uc, int len, ConverterState *state) const
{
    return QUtf8::convertFromUnicode(uc, len, state);
}

void QUtf8Codec::convertToUnicode(QString *target, const char *chars, int len, ConverterState *state) const
{
    *target += QUtf8::convertToUnicode(chars, len, state);
}

QString QUtf8Codec::convertToUnicode(const char *chars, int len, ConverterState *state) const
{
    return QUtf8::convertToUnicode(chars, len, state);
}

QByteArray QUtf8Codec::name() const
{
    return "UTF-8";
}

int QUtf8Codec::mibEnum() const
{
    return 106;
}

QUtf16Codec::~QUtf16Codec()
{
}

QByteArray QUtf16Codec::convertFromUnicode(const QChar *uc, int len, ConverterState *state) const
{
    return QUtf16::convertFromUnicode(uc, len, state, e);
}

QString QUtf16Codec::convertToUnicode(const char *chars, int len, ConverterState *state) const
{
    return QUtf16::convertToUnicode(chars, len, state, e);
}

int QUtf16Codec::mibEnum() const
{
    return 1015;
}

QByteArray QUtf16Codec::name() const
{
    return "UTF-16";
}

QList<QByteArray> QUtf16Codec::aliases() const
{
    return QList<QByteArray>();
}

int QUtf16BECodec::mibEnum() const
{
    return 1013;
}

QByteArray QUtf16BECodec::name() const
{
    return "UTF-16BE";
}

QList<QByteArray> QUtf16BECodec::aliases() const
{
    QList<QByteArray> list;
    return list;
}

int QUtf16LECodec::mibEnum() const
{
    return 1014;
}

QByteArray QUtf16LECodec::name() const
{
    return "UTF-16LE";
}

QList<QByteArray> QUtf16LECodec::aliases() const
{
    QList<QByteArray> list;
    return list;
}

QUtf32Codec::~QUtf32Codec()
{
}

QByteArray QUtf32Codec::convertFromUnicode(const QChar *uc, int len, ConverterState *state) const
{
    return QUtf32::convertFromUnicode(uc, len, state, e);
}

QString QUtf32Codec::convertToUnicode(const char *chars, int len, ConverterState *state) const
{
    return QUtf32::convertToUnicode(chars, len, state, e);
}

int QUtf32Codec::mibEnum() const
{
    return 1017;
}

QByteArray QUtf32Codec::name() const
{
    return "UTF-32";
}

QList<QByteArray> QUtf32Codec::aliases() const
{
    QList<QByteArray> list;
    return list;
}

int QUtf32BECodec::mibEnum() const
{
    return 1018;
}

QByteArray QUtf32BECodec::name() const
{
    return "UTF-32BE";
}

QList<QByteArray> QUtf32BECodec::aliases() const
{
    QList<QByteArray> list;
    return list;
}

int QUtf32LECodec::mibEnum() const
{
    return 1019;
}

QByteArray QUtf32LECodec::name() const
{
    return "UTF-32LE";
}

QList<QByteArray> QUtf32LECodec::aliases() const
{
    QList<QByteArray> list;
    return list;
}

#endif //QT_NO_TEXTCODEC

QT_END_NAMESPACE
