I have reconstituted Jon Bentley's DFORMAT preprocessor (troff and awk
source) and made it available on GitHub. See
This is an awk program that reads a description of data layouts, such
as registers or network packets, and generates PIC descriptions.
A Makefile generates PDF from the dformat.ms file using GNU troff.
Jon Bentley was helpful in the final stages, including contributing
his original files.