From: Dan Cross <crossd@gmail.com>
To: Will Senn <will.senn@gmail.com>
Cc: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] asm helper routines in v7
Date: Tue, 4 Jan 2022 16:12:08 -0500 [thread overview]
Message-ID: <CAEoi9W5dz_rk0KEzhxTpH8_AR4A3AH46S5WaK5KF==xG7_ZeBQ@mail.gmail.com> (raw)
In-Reply-To: <10197622-30fe-7553-2f2d-edc9637ff489@gmail.com>
On Tue, Jan 4, 2022 at 3:38 PM Will Senn <will.senn@gmail.com> wrote:
> [snip]
> My questions are:
>
> 1. Is mesg or an equivalent available in v7?
Perhaps just call printf?
> 2. If not, what was the v7 way of putting strings out?
Here's what I did:
$ rm -f h h.o
$ cat h.s
.globl _printf, _exit
mov sp, r5
mov $hi,(sp)
jsr pc,*$_printf
mov $0, (sp)
jsr pc,*$_exit
hi: <Hello, World!\n\0>
$ as -o h.o h.s
$ ld -o h h.o -lc
$ ./h
Hello, World!
$ rm h h.o
> 3. Why aren't the system call names defined?
If I had to hazard a guess, it would have been to de-emphasize the use
of assembler for user code, particularly as 7th Edition was starting
to be portable beyond the PDP-11.
> 4. What was the v7 way of naming system calls?
I imagine the canonical way to invoke system calls from assembler was
invoking calling functions in the C library and linking against that.
- Dan C.
next prev parent reply other threads:[~2022-01-04 21:13 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-04 20:37 Will Senn
2022-01-04 21:12 ` Dan Cross [this message]
2022-01-04 21:24 ` Will Senn
2022-01-04 21:28 ` Warner Losh
2022-01-05 17:35 ` Dan Cross
2022-01-04 21:38 ` Clem Cole
2022-01-06 3:26 Douglas McIlroy
2022-01-06 3:37 ` Warner Losh
2022-01-06 16:00 ` Clem Cole
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