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From: brucee@runx.ips.oz (Bruce Evans)
Newsgroups: comp.os.minix
Subject: Re: 1.3c upgrade results[LONG]
Message-ID: <1773@runx.ips.oz>
Date: 6 Oct 88 18:36:50 GMT
References: <1429@ast.cs.vu.nl> <14243@comp.vuw.ac.nz>
Reply-To: brucee@runx.OZ (Bruce Evans)
Organization: RUNX  Un*x Timeshare. Sydney, Australia.
Lines: 34

jonathan@comp.vuw.ac.nz (Jonathan) writes:

>	(5) the patch to sed.c causes the preprocessor symbol
>	"CMASK" to be multiply #defined.  The standard definition
>	in <stdio.h> is 0377, to defeat sign extension of characters.
>	Is it safe to ignore the warning message this causes?

Since I "fixed" it, let me reply. Sed.c didn't compile (here) because
it was missing the #define for CMASK. I supplied the value 0x7F after
examining old multi-file sed where it is hard-coded. I was trusted
(too much :-)) and fix got into 1.3c. CMASK became multiply defined
(harmless, but should have been caught).

How standard is the CMASK in stdio.h? I don't use Minix stdio, having
written a better one :-). Hence the "fix". My stdio.h also has cruft
to handle sign extensions, but done more portably with casts, and more
or less private to the library. Signed chars are bad and undefined
signed-ness is worse.

>X| peek(seg, offset) reads a word from seg:offset and returns it in ax.
>X| it must have been written by a long-time BASIC addict.

BASIC addict is right. peek() returns a word and not a byte in some DOS C
compilers. peekb() is for bytes. Actually, these are not so bad, they are
just small model's far pointers.

>X| FIXME: need interrupts be disabled in here while we fiddle with segment resisters?

Interrupt routines now preserve segment registers. Was there a prehistoric
version of Minix where they didn't? The comments in the assembler code are
out of date and aimed too low.

Bruce Evans
Internet: brucee@runx.ips.oz.au    UUCP: uunet!runx.ips.oz.au!brucee