From: Alexander Voropay <alec@sensi.org>
To: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] as(1) on Ultrix-11 vs 2.11BSD
Date: Fri, 1 May 2020 00:49:35 +0300 [thread overview]
Message-ID: <CAGqcPWAX_N4tvg4DCDC5CWHNnYAmObz0cn7hHU95Po5m7j-8bA@mail.gmail.com> (raw)
In-Reply-To: <a5bcdfa7c2f7388ede9ccdfba62c9055.squirrel@squirrelmail.tuffmail.net>
Can anyone please explain the last $0 pushed to the stack ?
Early SysIII ans SYSV on the i386 (and may be on i286) used
similar syscall convention.
I wrote about this:
https://minnie.tuhs.org/pipermail/tuhs/2019-October/019274.html
https://minnie.tuhs.org/pipermail/tuhs/2019-October/019294.html
Example:
===
.file "test.s"
.version "02.01"
.set WRITE,4
.set EXIT,1
.text
.align 4
.globl entry
entry:
pushl %ebp
movl %esp,%ebp
subl $8,%esp
pushl $14 /length
pushl $hello
pushl $1 /STDOUT
pushl $0
movl $WRITE,%eax
lcall $0x07,$0
addl $16,%esp
pushl $0
movl $EXIT,%eax
lcall 0x07,$0
.data
.align 4
hello:
.byte 0x48,0x65,0x6c,0x6c,0x6f,0x2c, 0x20,0x77,0x6f,0x72
.byte 0x6c,0x64,0x21,0x0a,0x00
ср, 29 апр. 2020 г. в 17:19, <ron@ronnatalie.com>:
>
> Thanks for the link. With that help, I fixed the bug in the program:
>
> mov $6., -(sp)
> mov $1f, -(sp)
> mov $1,-(sp)
> mov $0,-(sp)
> sys 4
> add $8., sp
> mov $0,-(sp)
> mov $0,-(sp)
> sys 1
> 1: <hello>
>
>
> >> Sorry, I typed that in haste without testing. I don’t have a 2.11 system
> >> to try it on. However, reading the source code, I did that wrong. The
> >> args go on the stack, not in line with the code.
> >> mov $6, -(sp)
> >> mov a, -(sp)
> >> mov $1,-(sp)
> >> sys 4
> >
> > Without suggesting that every helpful post should be tested, I find the
> > superb https://unix50.org web emulator excellent for such things.
> >
> > Many thanks to the folks hosting & maintaining this great resource!
> >
> >
>
>
next prev parent reply other threads:[~2020-04-30 21:50 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-29 13:55 Paul Ruizendaal
2020-04-29 14:18 ` ron
2020-04-30 21:49 ` Alexander Voropay [this message]
2020-04-30 22:06 ` Clem Cole
2020-04-30 22:09 ` Clem Cole
2020-05-01 0:12 ` Ronald Natalie
-- strict thread matches above, loose matches on Subject: below --
2020-04-29 2:26 Noel Chiappa
2020-04-29 4:08 ` Jacob Ritorto
2020-04-29 12:20 ` Ronald Natalie
2020-04-28 1:56 Jacob Ritorto
2020-04-28 13:03 ` Ronald Natalie
2020-04-29 0:17 ` Jacob Ritorto
2020-04-29 0:54 ` ron
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