Remember that IrDa protocol is a vaste and several layers communication
protocol. It is based on the HDLC (SDLC), and it uses several flow
controls, identifiers and so on. I made a partial subset at the 8051 uC
family to control a wireles printer, it took aprox 6 kbytes of code
(assembler).

The IrDa chips (controller and the transceiver) can also be programmed
to work in "Raw InfraRed" mode, that is similar to the VCR remote
controls IR modulation, and some other way.   But to ensure a real
communication mode, with multi devices and protocol confirmation, you
need to go for real IrDa.

I used chips from Temic, as the TOIM3232 and TFDS4000, but the last one
is a pain in the neck to get from the distributors, except if you want
to buy in 750 pieces a time (whole reel). Their explanation is that once
you open the sealed package the transceivers start to suffer from
humidity and can not be restocked...  I wonder what happens after you
solder them at the PCB... it must be some magic that stops the humidity
attack.  Talking to someone at Temic, this person said that during the
SMD reflow the unit cooks again and fix the humidity problem... then I
asked him "what about if I solder it by hand"?... the guy probably
entered in "duhhhh state" because I heard a long silence at the other
side of the phone.