From: jnc@mercury.lcs.mit.edu (Noel Chiappa)
To: tuhs@minnie.tuhs.org
Cc: jnc@mercury.lcs.mit.edu
Subject: Re: [TUHS] Using printf from Assembly Language in V6, and db.
Date: Mon, 28 Jun 2021 16:37:28 -0400 (EDT) [thread overview]
Message-ID: <20210628203728.8305818C090@mercury.lcs.mit.edu> (raw)
> From: Paul Riley <paul@rileyriot.com>
>> (I wrote a note, BITD, explaining how all this worked; I'll upload it
>> to the CHWiki when I get a chance.)
Now here:
https://gunkies.org/wiki/PDP-11_C_stack_operation
along with simple examples of args and auto variables, which are both
referenced via the FP.
> As a non-C consumer of printf, should I point R5 at some space for a
> stack and call printf in the same manner as the C example I cited?
Not necessary to do anything with R5 (you can leave it blank); the only things
a PDP-11 C routine needs are:
- a good stack
- the arguments, and return point, on the top of the stack
csv will set up the frame pointer, making no assumptions about the old
contents of R5 - see the source:
http://ana-3.lcs.mit.edu/~jnc/tech/unix/lib/csv.s
although it does save the old R5 contents, and restore them on exit.
Noel
next reply other threads:[~2021-06-28 20:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-28 20:37 Noel Chiappa [this message]
2021-06-29 12:18 ` Paul Riley
-- strict thread matches above, loose matches on Subject: below --
2021-06-28 4:48 Noel Chiappa
2021-06-28 11:27 ` Paul Riley
2021-06-28 13:48 ` Clem Cole
2021-06-28 2:34 Paul Riley
2021-06-28 3:27 ` Paul Riley
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