From: Jens Staal <staal1978@gmail.com>
To: 9fans@9fans.net
Subject: [9fans] a jmp_buf in APE question
Date: Mon, 7 Jan 2013 06:45:42 +0100 [thread overview]
Message-ID: <1752877.EVzC7FFEmr@krypton> (raw)
Hi all. Perhaps I have been looking at completely the wrong places and perhaps
I am just not grasping it at all.
For a package that I want to build under APE, I need to put in the stack
pointer (sp) and the program counter (pc) part of jmp_buf specific for Plan9
(since APE does not expose any stack-related functions that could have been
used)
according to /sys/include/ape/setjmp.h, jmp_buf is an array of 10 int:s.
I then went to check out /sys/src/ape/lib/ap/$objtype/setjmp.s
but I could not really understand anything in those files
luckily, I also looked at the GAS-formatted setjmp.s in the GCC-port of the
APE libs.
There, it seems that each function with a jmp_buf variable as an argument has
a set of 10 rows of operations (which I guess correspond to the 10 values in
jmp_buf). Based on that, it would seem that the value for sp is in jmp_buf[2]
and for pc in jmp_buf[3].
Am I correct or have I totally misunderstood how these things work? I am a
self-taught hobbyist so sometimes really basic stuff can have eluded me.
The second question would be, is the position of those two values in jmp_buf
architecture-specific so that I should make a note of that it is working on
i386 only?
next reply other threads:[~2013-01-07 5:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-07 5:45 Jens Staal [this message]
2013-01-07 10:31 ` erik quanstrom
2013-01-07 11:05 ` Jens Staal
2013-01-07 11:15 ` erik quanstrom
2013-01-07 16:43 ` Jens Staal
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