Method seekoff

src/Abyss/FileSystem/MPQ.cpp:65–90

std::streambuf::pos_type MPQStream::seekpos(const pos_type pos, const std::ios_base::openmode which) { return seekoff(pos, std::ios_base::beg, which); }

std::streambuf::pos_type MPQStream::seekoff(const off_type off, const std::ios_base::seekdir dir, std::ios_base::openmode which) {
    std::streamsize newPos = 0;
    switch (dir) {
    case std::ios_base::beg:
        newPos = off;
        break;
    case std::ios_base::cur:
        newPos = _startOfBlock + (gptr() - eback()) + off;
        break;
    case std::ios_base::end:
        newPos = size() + off;
        break;
    default:
        break;
    }
    if (newPos >= _startOfBlock && newPos < _startOfBlock + (egptr() - eback())) {
        // The new position is already in the buffer, just repoint the pointer to it
        setg(eback(), eback() + newPos - _startOfBlock, egptr());
    } else {
        // Drop buffer, it will be read in underflow
        SFileSetFilePointer(_mpqFile, static_cast<int>(newPos), nullptr, 0);
        setg(nullptr, nullptr, nullptr);
        _startOfBlock = newPos;
    }
    return _startOfBlock + (gptr() - eback());
}

std::streamsize MPQStream::size() const { return SFileGetFileSize(_mpqFile, nullptr); }