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1993.11.29 22:02 "Speedup of G4 FAX decoding?", by Craig Jackson
1993.11.29 23:02 "Re: Speedup of G4 FAX decoding?", by Ben Fahy
1993.11.30 12:45 "Re: Speedup of G4 FAX decoding?", by Karsten Spang
1993.12.01 13:30 "Re: Speedup of G4 FAX decoding?", by Karsten Spang

1993.11.29 22:02 "Speedup of G4 FAX decoding?", by Craig Jackson

My profiling of G4 FAX decoding with 3.3beta2 seems to point a finger at subroutine call overhead as a significant factor using VAX C on VMS. In particular, the finddiff routine in tif_fax3.c, which is a wrapper for the findspan routine in the same file, shows up a lot in the profiling.

Has anybody considered replacing finddiff with an equivalent macro?

Tried it and found any benefit?

I know that VAX C and VMS have a heavy calling overhead by today's standards, but would this be a generally interesting change?

Craig Jackson
craigj@epub.ziff.com
Electronic Publishing,
Ziff Information Services