how to deal the different of qt3 and qt4 for the serial programming?

[hiuao]

I am using qt4.2.1,and I have to write serial programming.Recently,I find a kind person's serial program,anyone who need can download from the attachment of this letter and the next one,for I only can attatch 5 files one time.
My big problem is the qt4's IOdevice->readBlock(),and IOdevice->writeBlock() is not mathch the qt3's.I have changed the posix_qextserialport and qextserialbase functions,but the error is as the same as before.If someone knows the reason,can you be so kind to tell me?Thank you very much!