void DataWriter::writeUTF8()

in src/dxapi/native/tickdb/data_writer.cpp [73:144]
56 lines of code
12 McCabe index (conditional complexity)

void DataWriter::writeUTF8(const wchar_t * data, uintptr length)
{
    assert(length == 0 || NULL != data);
    if (length >= 0xFFFF) {
        THROW_DBGLOG("putUTF8(wchar_t *): UTF8 string length is too big: %llu", (ulonglong)length);
    }

    byte * header = dataPtr;
    putUInt16(0);
    if (0 == length) {
        setNotNull();
        return;
    }

    data += length;
    intptr i = -(intptr)length;
    unsigned c, cc;

    // TODO: Possible perf. improvement: estimate max. length and preallocate bytes

    do {
        c = data[i];
        if (c < 0x80) {
            putByte((byte)c);
            continue;
        }

        if (c < 0x800) {
            putByte((byte)(0xC0 | ((c >> 6) & 0x1F)));
            putByte((byte)(0x80 | (c & 0x3F)));
            continue;
        }

        if (0xD800 != (c & 0xF800)) {
            putByte((byte)(0xE0 | ((c >> 12) & 0x0F)));
            putByte((byte)(0x80 | ((c >> 6) & 0x3F)));
            putByte((byte)(0x80 | (c & 0x3F)));
            continue;
        }

        if (0x400 & c) {
            THROW_DBGLOG("putUTF8(wchar *): UTF-16 High surrogate pair encountered before low");
        }

        if (0 == ++i) {
            THROW_DBGLOG("putUTF8(wchar *): String ends on UTF-16 High surrogate");
        }

        cc = data[i];
        c = (c << 10) + (0x10000U - (0xD800 << 10) - 0xDC00);
        if (0xDC00 != (cc & 0xFC00)) {
            THROW_DBGLOG("putUTF8(wchar *): UTF-16 High surrogate is not followed by Low surrogate");
        }

        c += cc;

        // Encode 20-bit codepoint (which is guaranteed to be > 0xFFFF)
        putByte((byte)(0xF0 | ((c >> 18) & 0x07)));
        putByte((byte)(0x80 | ((c >> 12) & 0x3F)));
        putByte((byte)(0x80 | ((c >> 6) & 0x3F)));
        putByte((byte)(0x80 | (c & 0x3F)));

    } while (0 != ++i);

    length = (dataPtr - header - 2);
    if (length >= 0xFFFF) {
        THROW_DBGLOG("putUTF8(wchar *): after conversion to UTF8, length >= 0xFFFF: %llu", (ulonglong)length);
    }

    _storeBE<uint16>(header, (uint16)length);
    setNotNull();
}