From: krewat@kilonet.net (Arthur Krewat)
Subject: [TUHS] Array index history
Date: Thu, 8 Jun 2017 09:55:49 -0400 [thread overview]
Message-ID: <be75e305-aadf-56ad-8f88-7977b5af9912@kilonet.net> (raw)
In-Reply-To: <1496929789.1143160.1002957384.3AD574C4@webmail.messagingengine.com>
On 6/8/2017 9:49 AM, Random832 wrote:
> On Wed, Jun 7, 2017, at 15:15, Arthur Krewat wrote:
>> In the days when memory and clock cycles were costly, an extra decrement
>> or subtract was not something to be taken lightly :)
> You wouldn't need a decrement per access, because the base itself could
> still be stored as the address of the "0th" element (i.e. what would be
> the "-1th" in a 0-based system). It might add some extra complexity to
> the relocator, if it's not currently possible to have a reference
> outside the bounds of an object and/or with a negative offset, but
> statically linked programs (the only kind on V7 and earlier) did not do
> any runtime relocation.
>
Shortly after making that statement, it occurred to me that the
preprocessor or assembler could take care of that easily.
Even better than worrying about whether arrays started at 0 or 1 in C
would be to institute bounds checking in the first place :) But again
would add lots of extra code that in the days of the origins of C was
not something you wanted to add to the memory footprint.
next prev parent reply other threads:[~2017-06-08 13:55 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAH_OBiewwwS6kbdWKUO-j3v=Do+Y9AzBn4ZkyVic7LOJN5WX7w@mail.gmail.com>
[not found] ` <CAH_OBid5q-YeB6UYeOfjW68s3nb3TX_icC5dFMapfo=7_q5DUQ@mail.gmail.com>
[not found] ` <CAH_OBideJeNGiiys=VOEYcU1cffSg+6zDOD39HOU74vumQF0kA@mail.gmail.com>
[not found] ` <CAH_OBie_+dQXOC2OaZii5K=j1Ljmv-OvAVXvyypoLJ10jaysWA@mail.gmail.com>
[not found] ` <CAH_OBidXd1Lpgp8ttM3sWLfXDT0ms5EGAzEjPH9QkY+bXyev2w@mail.gmail.com>
[not found] ` <CAH_OBifge2RrwcDvSV46gwLAc0wHVtH++gdMBhXi-x8C0a_2jw@mail.gmail.com>
[not found] ` <CAH_OBic3MTy-20C_T2ciT2x+EjNZvXR2PJ0OzB0qRp1gd2OL-g@mail.gmail.com>
2017-06-07 12:56 ` shawn wilson
2017-06-07 13:16 ` Ron Natalie
2017-06-07 13:20 ` arnold
2017-06-07 13:50 ` Michael Kjörling
2017-06-07 14:02 ` arnold
2017-06-08 11:28 ` Christian Neukirchen
2017-06-08 14:56 ` shawn wilson
2017-06-07 14:58 ` Tony Finch
2017-06-07 23:57 ` Dave Horsfall
2017-06-07 16:31 ` Lyndon Nerenberg
2017-06-08 0:47 ` Bakul Shah
2017-06-07 17:59 ` Tim Bradshaw
2017-06-07 18:29 ` Clem Cole
2017-06-07 18:46 ` Arthur Krewat
2017-06-07 19:03 ` Ron Natalie
2017-06-07 19:15 ` Arthur Krewat
2017-06-07 19:49 ` Ron Natalie
2017-06-08 1:58 ` ARJANEN Loïc Jean David
2017-06-08 13:49 ` Random832
2017-06-08 13:55 ` Arthur Krewat [this message]
2017-06-08 18:41 ` Tim Bradshaw
2017-06-08 2:45 ` Robert Swierczek
2017-06-08 4:05 ` Dave Horsfall
2017-06-08 6:19 ` Peter Jeremy
2017-06-08 7:02 ` Dave Horsfall
2017-06-08 13:53 ` Ron Natalie
2017-06-08 2:27 Doug McIlroy
2017-06-08 12:49 ` William Cheswick
2017-06-08 12:56 ` Michael Kjörling
2017-06-08 13:45 ` Dan Cross
2017-06-08 13:57 ` Ron Natalie
2017-06-10 21:08 ` Nemo
2017-06-08 15:04 ` Dave Horsfall
2017-06-08 15:09 ` William Pechter
2017-06-08 16:53 ` Steve Nickolas
2017-06-08 20:17 ` Larry McVoy
2017-06-09 0:03 ` Greg 'groggy' Lehey
2017-06-08 9:16 Richard Tobin
[not found] <mailman.882.1496854900.3779.tuhs@minnie.tuhs.org>
2017-06-08 18:20 ` David
2017-06-08 18:55 ` Ron Natalie
2017-06-09 21:21 ` Steve Johnson
2017-06-09 21:52 ` Arthur Krewat
2017-06-08 22:29 ` Johnny Billquist
2017-06-08 23:16 ` Ron Natalie
2017-06-08 23:41 ` Steve Nickolas
2017-06-09 15:12 ` Random832
2017-06-09 16:30 ` Ron Natalie
2017-06-09 0:21 ` Johnny Billquist
2017-06-09 0:25 ` Pete Turnbull
2017-06-09 1:19 ` Toby Thain
2017-06-09 2:14 ` Pete Turnbull
[not found] <mailman.890.1496953026.3779.tuhs@minnie.tuhs.org>
2017-06-08 22:28 ` Johnny Billquist
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=be75e305-aadf-56ad-8f88-7977b5af9912@kilonet.net \
--to=krewat@kilonet.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).