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From: Will Senn <will.senn@gmail.com>
To: Dan Cross <crossd@gmail.com>
Cc: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] asm helper routines in v7
Date: Tue, 4 Jan 2022 15:24:18 -0600	[thread overview]
Message-ID: <54ec532a-6603-6b25-fa9f-40aa9d111687@gmail.com> (raw)
In-Reply-To: <CAEoi9W5dz_rk0KEzhxTpH8_AR4A3AH46S5WaK5KF==xG7_ZeBQ@mail.gmail.com>

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On 1/4/22 3:12 PM, Dan Cross wrote:
> 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.
Yep, that worked... you make it look so easy, and your rationales are 
definitely believable :).

Will

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  reply	other threads:[~2022-01-04 21:24 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
2022-01-04 21:24   ` Will Senn [this message]
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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