H1B transfer - urgent

[singus]

I resigned from company A and joined company B. Company B had
applied for tranfer of H1B. It is still pending. Meanwhile company
A had cancelled my H1B. Now I am planning to join back company
A and they are willing to take me back.
What is the procedure? Since my h1b transfer is still pending for
company B , can company A apply for a transfer or can company
A go back and revalidate my original H1B which was cancelled?

Any input appreciated.

thanks

singus