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Groups > comp.lang.c++ > #70328
| From | Tim Rentsch <tr.17687@z991.linuxsc.com> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: What does the "L" mean |
| Date | 2019-12-06 22:36 -0800 |
| Organization | A noiseless patient Spider |
| Message-ID | <86v9qs4p7f.fsf@linuxsc.com> (permalink) |
| References | (8 earlier) <875zivzhd9.fsf@bsb.me.uk> <qsb6v7$u8q$3@dont-email.me> <87zhg6yekm.fsf@bsb.me.uk> <qsdcb3$soh$2@dont-email.me> <87o8wkyel2.fsf@bsb.me.uk> |
Ben Bacarisse <ben.usenet@bsb.me.uk> writes: > Vir Campestris <vir.campestris@invalid.invalid> writes: > <cut> > >>>>> Vir Campestris<vir.campestris@invalid.invalid> writes: >>>>> <cut> >>>>> >>>>>> The one that really strained C was the one where incrementing a >>>>>> pointer by 1 went to the next bit. Not byte or word. (TI GPU) > > <cut> > >> BTW the Dec10 - the 36 bit one I used - an int was 36 bits, but a >> character string was stored as set of 5 7-bit ASCII characters plus >> one pad bit in each word... Never used C on it though. > > It would be very expensive to implement C using that packed format for > character strings. Some C implementations on other word addressed > machines decided to make char one word; on others arithmetic was needed > to convert between word and "char" pointers. It's notable that, > programmer assumptions aside, word addressed machines are probably more > awkward for C the bit-addressed ones. The PDP-10 had a special representation for pointing to, and accessing, "bytes" within a word, and instructions for doing loads, stores, and pointer arithmetic in terms of "bytes" rather than words. A nice thing about the PDP-10 byte pointers is the width in bits of a "byte" is part of the stored representation in each byte pointer. A C implementation on a PDP-10 could choose 9-bit bytes for 'char' without too much trouble[*]. Alternatively, for a bit of fun, bytes could be 12 bits, with two bytes for int's, and three bytes for long (no longer works for C11, naturally), and two 36-bit words for long long. But 9-bit bytes would work just fine, even for C11. (Sorry folks - no uint32_t in those implementations.) [*] IIRC, "bytes" in the PDP-10 were treated as unsigned, so signed types would need sign extension on loading.
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What does the "L" mean T <T@invalid.invalid> - 2019-12-03 23:38 -0800
Re: What does the "L" mean Bonita Montero <Bonita.Montero@gmail.com> - 2019-12-04 08:43 +0100
Re: What does the "L" mean T <T@invalid.invalid> - 2019-12-04 00:05 -0800
Re: What does the "L" mean Geoff <geoff@invalid.invalid> - 2019-12-04 00:32 -0800
Re: What does the "L" mean T <T@invalid.invalid> - 2019-12-04 00:33 -0800
Re: What does the "L" mean Paavo Helde <myfirstname@osa.pri.ee> - 2019-12-04 11:11 +0200
Re: What does the "L" mean Geoff <geoff@invalid.invalid> - 2019-12-04 01:14 -0800
Re: What does the "L" mean "Fred. Zwarts" <F.Zwarts@KVI.nl> - 2019-12-04 09:39 +0100
Re: What does the "L" mean T <T@invalid.invalid> - 2019-12-04 00:51 -0800
Re: What does the "L" mean Paavo Helde <myfirstname@osa.pri.ee> - 2019-12-04 10:40 +0200
Re: What does the "L" mean T <T@invalid.invalid> - 2019-12-04 00:56 -0800
Re: What does the "L" mean Bo Persson <bo@bo-persson.se> - 2019-12-04 10:08 +0100
Re: What does the "L" mean T <T@invalid.invalid> - 2019-12-04 01:20 -0800
Re: What does the "L" mean Vir Campestris <vir.campestris@invalid.invalid> - 2019-12-04 21:46 +0000
Re: What does the "L" mean Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-12-05 01:33 +0000
Re: What does the "L" mean Vir Campestris <vir.campestris@invalid.invalid> - 2019-12-05 15:15 +0000
Re: What does the "L" mean Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-12-05 15:31 +0000
Re: What does the "L" mean Vir Campestris <vir.campestris@invalid.invalid> - 2019-12-06 10:59 +0000
Re: What does the "L" mean Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-12-07 03:55 +0000
Re: What does the "L" mean James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-06 23:38 -0500
Re: What does the "L" mean Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-12-06 22:36 -0800
Re: What does the "L" mean Vir Campestris <vir.campestris@invalid.invalid> - 2019-12-08 21:33 +0000
Re: What does the "L" mean Bart <bc@freeuk.com> - 2019-12-06 20:44 +0000
Re: What does the "L" mean Bart <bc@freeuk.com> - 2019-12-06 20:52 +0000
Re: What does the "L" mean Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-12-06 22:20 -0800
Re: What does the "L" mean Bart <bc@freeuk.com> - 2019-12-06 16:20 +0000
Re: What does the "L" mean boltar@nowhere.co.uk - 2019-12-06 16:30 +0000
Re: What does the "L" mean Bart <bc@freeuk.com> - 2019-12-06 17:50 +0000
Re: What does the "L" mean scott@slp53.sl.home (Scott Lurndal) - 2019-12-06 18:18 +0000
Re: What does the "L" mean boltar@nowhere.co.uk - 2019-12-07 11:57 +0000
Re: What does the "L" mean Bart <bc@freeuk.com> - 2019-12-07 12:04 +0000
Re: What does the "L" mean boltar@nowhere.co.uk - 2019-12-07 13:05 +0000
Re: What does the "L" mean Bart <bc@freeuk.com> - 2019-12-07 13:16 +0000
Re: What does the "L" mean Öö Tiib <ootiib@hot.ee> - 2019-12-07 05:49 -0800
Re: What does the "L" mean scott@slp53.sl.home (Scott Lurndal) - 2019-12-06 16:36 +0000
Re: What does the "L" mean Bonita Montero <Bonita.Montero@gmail.com> - 2019-12-04 13:47 +0100
Re: What does the "L" mean Thiago Adams <thiago.adams@gmail.com> - 2019-12-04 04:57 -0800
Re: What does the "L" mean "Fred. Zwarts" <F.Zwarts@KVI.nl> - 2019-12-04 14:41 +0100
Re: What does the "L" mean Bonita Montero <Bonita.Montero@gmail.com> - 2019-12-04 15:06 +0100
Re: What does the "L" mean James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-04 08:55 -0500
Re: What does the "L" mean T <T@invalid.invalid> - 2019-12-04 00:34 -0800
Re: What does the "L" mean Keith Thompson <kst-u@mib.org> - 2019-12-04 08:28 -0800
Re: What does the "L" mean Robert Wessel <robertwessel2@yahoo.com> - 2019-12-05 09:32 -0600
Re: What does the "L" mean Keith Thompson <kst-u@mib.org> - 2019-12-05 10:03 -0800
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