Answering some of my own question:

For receive:
1) phy interface to a/d
2) symbol decoding
3) chip rate despreading
4) bpsk demodulation
5) sync

For transmit:
1) phy interface to d/a
2) symbol encoding
3) chip rate spreading
4) power control
5) bpsk modulation

What else goes on? TIA.

In a baseband processor, 802.11b 1Mb/s (bpsk) for example, what are the 
tasks done?

For receive, I am guessing
a) demodulation
b) sync

Is there source code somewhere for an audio bpsk modem somewhere to 
inspect? Something that might be compiled for a blackfin and used to 
play on a test bench...

TIA.