1 Feb
2017
1 Feb
'17
6:30 p.m.
From: Paul Koning
Yes, GCC should do that correctly. ... Dealing with
the output might be
a nuisance ... You may need some post-processing to cast the output
into the syntax that V6 "as" expects.
Actually, dealing with the _input_ is going to be a PITA (so my suggestion
was, in retrospect, not really a plausible one). The problem is that V6 is
written in an early dialect of C, one which I am sure would cause GCC would
toss its cookies, if fed to it.
Some things, like "a =+ b;" would be easy to fix; likewise "int a 1;"
instead
of "int a = 1;". But the Unix kernel is shot through with places where are
int is used as a structure pointer, etc, without benefit of a cast (casts
weren't invented until later). And a lot of stuff like that.
Noel
2 Feb
2 Feb
6:34 a.m.
On Feb 1, 2017, at 9:30 PM, Noel Chiappa <jnc at
mercury.lcs.mit.edu> wrote:
Yes, that would be an interesting issue. One answer would be to write a new front end
("Old C"). That's probably more work than can easily be justified, though.
paul
From: Paul Koning
Yes, GCC should do that correctly. ... Dealing
with the output might be
a nuisance ... You may need some post-processing to cast the output
into the syntax that V6 "as" expects.
Actually, dealing with the _input_ is going to be a PITA (so my suggestion
was, in retrospect, not really a plausible one). The problem is that V6 is
written in an early dialect of C, one which I am sure would cause GCC would
toss its cookies, if fed to it.
Some things, like "a =+ b;" would be easy to fix; likewise "int a 1;"
instead
of "int a = 1;". But the Unix kernel is shot through with places where are
int is used as a structure pointer, etc, without benefit of a cast (casts
weren't invented until later). And a lot of stuff like that. 
9:25 a.m.
From: cctalk [cctalk-bounces at classiccmp.org] on behalf of Paul Koning [paulkoning at
comcast.net]
Sent: Thursday, February 2, 2017 9:34 AM
To: General Discussion: On-Topic and Off-Topic Posts
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: RL02 version of UNIX6?
On Feb 1, 2017, at 9:30 PM, Noel Chiappa <jnc at
mercury.lcs.mit.edu> wrote:
Yes, that would be an interesting issue. One answer would be to write a new front end
("Old C"). That's probably more work than can easily be justified, though.
__________________________________________________________________
What version of GCC is being used here? I thought they removed support
for the PDP-11 more than a deacde ago.
And, while I am at it, based on what people are saying here I assume they also
removed the switch for K&R mode.
bill
From: Paul Koning
Yes, GCC should do that correctly. ... Dealing
with the output might be
a nuisance ... You may need some post-processing to cast the output
into the syntax that V6 "as" expects.
Actually, dealing with the _input_ is going to be a PITA (so my suggestion
was, in retrospect, not really a plausible one). The problem is that V6 is
written in an early dialect of C, one which I am sure would cause GCC would
toss its cookies, if fed to it.
Some things, like "a =+ b;" would be easy to fix; likewise "int a 1;"
instead
of "int a = 1;". But the Unix kernel is shot through with places where are
int is used as a structure pointer, etc, without benefit of a cast (casts
weren't invented until later). And a lot of stuff like that. 
9:58 a.m.
On Feb 2, 2017, at 9:25 AM, Bill Gunshannon
<bill.gunshannon at hotmail.com> wrote:
From: cctalk [cctalk-bounces at classiccmp.org] on behalf of Paul Koning [paulkoning at
comcast.net]
Sent: Thursday, February 2, 2017 9:34 AM
To: General Discussion: On-Topic and Off-Topic Posts
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: RL02 version of UNIX6?
It?s not just K&R mode. It?s v6 mode. C had some deficiencies prior to the release
of v7. The most notable was that <larg> <op=> <expression> (e.g. a +=
1) was in
v6 actually <larg><=op><expression> (e.g a =+ 1). This led to
ambiguities:
if you have a=+1 do you mean to increment a by 1 or assign +1 to a? I don?t recall
if v7 cc was transitory (in that it allowed both forms) but I do know the earlier form
was phased out fairly quickly.
TTFN - Guy
On Feb 1, 2017, at 9:30 PM, Noel Chiappa <jnc
at mercury.lcs.mit.edu> wrote:
Yes, that would be an interesting issue. One answer would be to write a new front end
("Old C"). That's probably more work than can easily be justified, though.
__________________________________________________________________
What version of GCC is being used here? I thought they removed support
for the PDP-11 more than a deacde ago.
And, while I am at it, based on what people are saying here I assume they also
removed the switch for K&R mode. From: Paul Koning
Yes, GCC should do that correctly. ... Dealing
with the output might be
a nuisance ... You may need some post-processing to cast the output
into the syntax that V6 "as" expects.
Actually, dealing with the _input_ is going to be a PITA (so my suggestion
was, in retrospect, not really a plausible one). The problem is that V6 is
written in an early dialect of C, one which I am sure would cause GCC would
toss its cookies, if fed to it.
Some things, like "a =+ b;" would be easy to fix; likewise "int a 1;"
instead
of "int a = 1;". But the Unix kernel is shot through with places where are
int is used as a structure pointer, etc, without benefit of a cast (casts
weren't invented until later). And a lot of stuff like that.
10:12 a.m.
On Feb 2, 2017, at 12:25 PM, Bill Gunshannon
<bill.gunshannon at hotmail.com> wrote:
What version of GCC is being used here? I thought they removed support
for the PDP-11 more than a deacde ago.
No, it's still there. I'm the target maintainer for it, not that I've done a
whole lot of work on it recently. But I signed up for that role partly to prevent its
being removed.
What did get removed (though it could be restored) is the 2bsd target variant.
The float support is a bit flaky because of the complications created by ac4 and ac5. But
in general it does a decent job, and passes a large fraction of the GCC unit test
scripts.
And, while I am at it, based on what people are saying
here I assume they also
removed the switch for K&R mode.
That sounds familiar.
paul
10:16 a.m.
On Thu, 2017-02-02 at 17:25 +0000, Bill Gunshannon wrote:
What version of GCC is being used here? I thought they removed
support for the PDP-11 more than a deacde ago.
GCC does still have a pdp11 backend today. It doesn't seem to be very
actively maintained, and how well it works nowadays is possibly another
question, but it should at least be buildable.
I assume they also removed the switch for K&R
mode.
I'm not sure there ever was such a switch. If there was, it was
removed a long time ago. "-std=c90" still works and should accept
some, maybe most, K&R code. As others have noted, GCC has no option to
accept pre-K&R C, though I suspect it would probably not be all that
hard to write some sort of preprocessor to convert such code to either
K&R or C90 dialect.
p.
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days inactive
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