char* ptr = _msgbuffer;
    char buffer[512];
    int tmp = 0;

    // read until all is read
    while(data_read < size) {
        if(size-data_read > 512)
            tmp = read(sd, buffer, 512);
        else
            tmp = read(sd, buffer, size-data_read);

        memcpy(ptr, buffer, tmp);
        ptr += tmp;
        data_read += tmp;
    }