[Discuss-GnuRadio]: tx_chain.v module in usrp_std.v

[Oussama Sekkat]

Hello everybody,

I am still a beginner in the project so bare with me if my questions have obvious answers.
I
was looking at the verilog code for usrp_std.v module. that module
containes the tx_chain.v module which uses a module called phase_acc. I
am not sure what this later module does? It takes as inputs (among
others) a 7bit serial address and 32 bit serial data and outputs the
32bit phase. 
Does anyone have any idea what that module does and what its purpose is in the tx_chain?

Thank you,

Oussama.