RL02 version of UNIX6?

jim stephens jwsmail at jwsss.com
Thu Feb 2 13:15:59 CST 2017

On 2/2/2017 10:50 AM, Paul Koning wrote:
>> On Feb 2, 2017, at 1:41 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
>>> From: Phil Blundell
>>> I suspect it would probably not be all that hard to write some
>>> sort of preprocessor to convert such code
>> Really? Check out:
>>   http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/sys/ken/pipe.c
>> (Needless to say, none of the 'int *' things are actually pointers to
>> integers!)
>> In particular, what will lines like this:
>>   sleep(ip+2, PPIPE);
>> do, depending on what 'ip' is declared as?
> If "ip" is an int *, it would pass the address in ip plus 2 * 2.  If ip is actually the address of some struct, then hopefully that address offset by 4 is a meaningful address.  I'm guessing that the 2 in there represents sizeof(foo)/sizeof(int).  Right?
> 	paul
The listings I've read of early unix have assembly files, mixed c + 
assembly, and in this case ip is

register *ip;

so things get to be quite a lot of fun.  BTW I recall seeing assembly in 
the compiler phases as well as the system code, so things require a lot 
of the code between the assembly interface and the C to line up.  Not 
sure if gcc does that, or if the conventions between early unix and gcc 
would line up or not.

There are also wake calls as well with ip+1 as a parameter, FWIW. I've 
not gone hunting to what those calls do.  I'd need to read the sleep and 
wake code, which may be assembly.  More useful parts of the puzzle to know.


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