Why do I remember The C Programming Language book by K&R explaining how to write a version of cdecl? I just checked the second edition of the book and my memory seems to be wrong.
It's not listed as cdecl and (therefore?) not findable in the index, but in chapter 5 - Pointers and Arrays - the book presents the programs dcl and undcl that translate between C declarations and English renderings of them.
I believe dcl mimics the cdecl program.