Hello Hina.
The Viterbi decoder functions are built into VisualDSP and CCES. I am not sure which toolset you are using, but you can find the appropriate documentation in the associated compiler manual...for example, if using VisualDSP, it is located in this manual on p1-253:
http://www.analog.com/static/imported-files/software_manuals/50_bf_cc_rtl_mn_rev_5.4.pdf
Similarly, convolution encoding is also supported natively in our DSP run-time libraries. Again, using VisualDSP as the reference, it is in the same manual above on p4-125.
-Joe