# DSPs, DPMs, and DPFs

DSP programs are distributed in files called data processing modules (DPMs). These files use the extension .f41, and contain executable code for a family of algorithms. Algorithms in the family are called data processing functions (DPFs). They can be referenced by a unique string generated by combining the family string ID that corresponds to the DPM with the function ID string that corresponds to the DPF. The string is formatted as dpm.dpt. Both the DPM and DPF have associated hexadecimal IDs that can be combined to uniquely identify the DSP function.

For example, the file ptf.f41 is the DPM for precise tone filters. All of the DPFs in ptf.f41 provide precise tone filtering functionality. The precise tone filter DPM ID is ptf and the associated hexadecimal ID is 0x1C. For a precise tone filter that has a pair of filters, the DPF ID is det_2f and the associated hexadecimal ID is 0x0700. Therefore, the precise tone DPF is identified by the string ID ptf.det_2f or the hexadecimal ID 0x1C0700.

To list all function IDs in a family and their associated hexadecimal IDs, run the f41info program and specify the DPM file name for the family. For example, for the echo cancellation family of functions, type the following command at the prompt:

f41info ptf

For more information about f41info and about DPM and DPF hexadecimal IDs, refer to f41info - Displaying DPF file resource usage.