From mboxrd@z Thu Jan  1 00:00:00 1970
From: tlaronde@polynum.com
Date: Mon, 19 Apr 2010 17:43:17 +0200
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Message-ID: <20100419154317.GA726@polynum.com>
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Subject: [9fans] Rounding off by one
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While verifying that I have the same result under Plan9 than under some
Unix (NetBSD), it happens that METAFONT compiles 110 of the 125 fontes,
but hence fails on some (and it should not) with something that smells
like a round off by one error on negative integer division. There is no
problem with TeX, but TeX doesn't do the same things.

Does this ring the bells to someone? It's i386 and the very same node
used for NetBSD verification (no problem on NetBSD: everything runs and
passes the test; but it was not the primary target).

Of course, it's under APE but there is no POSIX thing around: it's C89
and it even doesn't use math.h routines.

On NetBSD, the binaries are not linked against libm (whatever flavour).
Are there something "float" going under the cover?

Apparently, the APE wrapper pulls some optimization. Should I try to
look in this area?

There are conditionnals too (pre-processor: INIT, STAT etc.). Is there
problems under APE with -DINIT declarations?

There is also a suicide: divide by zero in a portion of the code doing
scaled integer arithmetic, but I think all this is linked.

If nobody has a clue, I will try to dive in the guts of METAFONT to
debug. But if I could spare some hours...

--
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                      http://www.kergis.com/
Key fingerprint = 0FF7 E906 FBAF FE95 FD89  250D 52B1 AE95 6006 F40C