Date: Wed, 15 Oct 1997 21:44:40 +0930 From: Mike Smith <mike@smith.net.au> To: stesin@gu.net Cc: Mike Smith <mike@smith.net.au>, hackers@FreeBSD.ORG Subject: Re: Call for Fortran assistance. Message-ID: <199710151214.VAA00326@word.smith.net.au> In-Reply-To: Your message of "Wed, 15 Oct 1997 12:37:25 %2B0300." <Pine.BSF.3.96.971015121206.1265F-100000@trifork.gu.net>
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> On Wed, 15 Oct 1997, Mike Smith wrote:
>
> > Our second design threw the data through a FIFO, but Fortran has funny
> > formatting requirements for sequential-access data that have stymied us.
>
> What was so strange there with the formatting?
To quote from /usr/src/lib/libI77/README:
Unformatted sequential records consist of a length of record
contents, the record contents themselves, and the length of
record contents again (for backspace). Prior to 17 Oct. 1991,
the length was of type int; now it is of type long, but you
can change it back to int by inserting
> > We tried converting to ASCII and then parsing it back in, but that's
> > too slow.
>
> As far as I recall, Fortran is able to handle "binary"
> input records (in a way like one do read(2)/write(2)
> of a memory buffer containig a C struct foo { ... };
> or some kind of an array)
You can do this with an unformatted file open for direct access, but
this fails (blocks forever) on a FIFO. Worse, you can't vary the size
of the entity read. 8(
> Anyway you will be
> able to fill a Fortran array with bytes from an input
> stream without any conversion and use the buffer' content
> in any way you like then, using Fortran' equivalent
> of C union xxx { ... }; that is a COMMON construct.
This would be OK if it worked (forgive any syntax, I'm not a Fortran
programmer):
character*1 foo
open(unit=16,file='/tmp/fifo',form='unformatted',access='direct',
$ recl=1,status='old')
do irec = 0, 10000
read(unit=16,rec=irec,end=200)foo
...
enddo
but given a FIFO; eg. in a test case:
# mkfifo /tmp/fifo
# cat /kernel > /tmp/fifo &
# ./testprogram
it just sits there doing nothing.
mike
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