Reads the source and transforms it with the bitfields pattern file
C:circle rad 40px "$(SOURCE_IN)" fit
arrow right 100%
E:box rad 10px "$(TEXT_PROC)" fit
arrow right 100%
G: circle rad 40px "$(BITFIELDS_OUT)" fit
F:circle rad 40px "$(BITFIELDS_PAT)" fit at 1.5 s of C
arrow from F.e \
then right until even with E \
then to E.s