[Info-vax] C limitations, was: Re: VMS process communication

[Steven Schweda]

   This thread left the rails so long ago that I don't feel very bad
about including the following slightly related story.

   Back in the eighties, I worked on a (FORTRAN) program for digital
logic and fault simulation.  Circuits were described in text, and only a
limited character set was allowed.  Part of the input parsing involved
detecting invalid characters.

   One day we ran some performance analysis (VAXset PCA?), and
discovered that much time was spent in an input-parsing function.  A
glance at the code showed why.  There was an array of all the legal
characters, and that array was searched sequentially for each character
in the input.  (Is it an "A"?  Is it a "B"  Is it a "C"  ...)

   Replacing that atrocity with a (256-character) look-up table reduced
the time spent in that function to approximately zero, and, as I recall,
cut about 2% off of the total design-compilation time.