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From: Hyman Rosen <hyrosen@mail.com>
Subject: Re: How do I write directly to a memory address?
Date: Wed, 09 Feb 2011 10:49:37 -0500
Date: 2011-02-09T10:49:37-05:00	[thread overview]
Message-ID: <4d52b82f$0$19486$882e7ee2@usenet-news.net> (raw)
In-Reply-To: <6cf0950a-d2a3-4df4-9f19-23474d568c28@q40g2000prh.googlegroups.com>

On 2/8/2011 9:33 PM, Adam Beneschan wrote:
>  Dmitry asks, "How do you set the third
> bit?", and you say, "Well, if the third bit is a Ready bit in a
> hardware I/O register, I'd define a struct with bit components [yes, I
> think C has those] and just assign 1 to the component, which would be
> more readable than using a mask."

This can be considerably more complicated depending on
the hardware and the compiler; you are trying to assign
to a single bit, but the compiler may do this by reading
an entire word, setting the bit in the result, and
assigning the entire word back. That could have dire
effects if writing adjacent bits does something.



  reply	other threads:[~2011-02-09 15:49 UTC|newest]

Thread overview: 381+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-03  5:52 How do I write directly to a memory address? Syntax Issues
2011-02-03  8:00 ` Georg Bauhaus
2011-02-03  8:01   ` Georg Bauhaus
2011-02-08 13:34   ` Yannick Duchêne (Hibou57)
2011-02-03  8:08 ` mockturtle
2011-02-03 18:07   ` Jeffrey Carter
2011-02-08 13:43   ` Yannick Duchêne (Hibou57)
2011-02-08 21:07     ` Vinzent Hoefler
2011-02-10  2:21     ` Randy Brukardt
2011-02-03  8:24 ` Ludovic Brenta
2011-02-03 10:50   ` Syntax Issues
2011-02-03 11:03   ` Georg Bauhaus
2011-02-03 18:24   ` Jeffrey Carter
2011-02-04  9:21     ` Ludovic Brenta
2011-02-03 21:30   ` Florian Weimer
2011-02-04  9:24   ` Ludovic Brenta
2011-02-04 10:31     ` Georg Bauhaus
2011-02-04 11:07       ` Dmitry A. Kazakov
2011-02-04 17:35       ` Jeffrey Carter
2011-02-04 16:00     ` Hyman Rosen
2011-02-04 17:40       ` Dmitry A. Kazakov
2011-02-04 18:35         ` Hyman Rosen
2011-02-05  5:17           ` Randy Brukardt
2011-02-04 21:36       ` Shark8
2011-02-04 23:00       ` Adam Beneschan
2011-02-05  0:20         ` John B. Matthews
2011-02-05 14:56       ` Pascal Obry
2011-02-07 14:59         ` Hyman Rosen
2011-02-07 16:24           ` Robert A Duff
2011-02-07 16:44             ` Hyman Rosen
2011-02-07 17:02               ` Ludovic Brenta
2011-03-01 20:27             ` Hyman Rosen
2011-03-01 20:47               ` Dmitry A. Kazakov
2011-03-01 21:17                 ` Hyman Rosen
2011-03-01 21:37                   ` Dmitry A. Kazakov
2011-03-01 21:54                     ` Hyman Rosen
2011-03-02  8:42                       ` Dmitry A. Kazakov
2011-03-02 14:36                         ` Hyman Rosen
2011-03-02 15:30                           ` Dmitry A. Kazakov
2011-03-02 15:40                             ` Hyman Rosen
2011-03-02 16:25                               ` Georg Bauhaus
2011-03-02 16:40                                 ` Hyman Rosen
2011-03-02 18:44                                   ` Georg Bauhaus
2011-03-02 18:59                                     ` Hyman Rosen
2011-03-02 17:21                               ` Dmitry A. Kazakov
2011-03-02 17:40                                 ` Hyman Rosen
2011-03-02 18:04                                   ` Dmitry A. Kazakov
2011-03-02 18:29                                     ` Hyman Rosen
2011-03-02 21:55                                       ` Dmitry A. Kazakov
2011-03-02 22:10                                         ` Hyman Rosen
2011-03-03  8:14                                           ` Dmitry A. Kazakov
2011-03-03  8:04                                 ` Simon Wright
2011-03-03  8:23                                   ` Dmitry A. Kazakov
2011-03-03  8:50                                   ` Hyman Rosen
2011-03-03  7:54                               ` Simon Wright
2011-03-02 20:34                   ` KK6GM
2011-03-02 20:59                     ` Hyman Rosen
2011-03-02 21:03                       ` Vinzent Hoefler
2011-03-02 21:13                         ` Hyman Rosen
2011-03-02 21:34                           ` KK6GM
2011-03-03  1:09                             ` Hyman Rosen
2011-03-03  1:38                               ` KK6GM
2011-03-03  2:42                               ` Randy Brukardt
2011-03-02 23:18                           ` Vinzent Hoefler
2011-03-02 23:26                             ` Hyman Rosen
2011-03-03  0:46                               ` Edward Fish
2011-03-03  1:03                                 ` Hyman Rosen
2011-03-03  3:01                                   ` Randy Brukardt
2011-03-03  6:05                                     ` Hyman Rosen
2011-03-03  8:52                                       ` Dmitry A. Kazakov
2011-03-03 17:51                                         ` Hyman Rosen
2011-03-03 18:32                                           ` Dmitry A. Kazakov
2011-03-03 20:08                                             ` Hyman Rosen
2011-03-03 21:55                                               ` Dmitry A. Kazakov
2011-03-03 22:08                                                 ` Hyman Rosen
2011-03-03 20:34                                             ` Hyman Rosen
2011-03-04  0:22                                       ` Randy Brukardt
2011-03-04  3:21                                         ` Nasser M. Abbasi
2011-03-04 16:48                                         ` Hyman Rosen
2011-03-03 21:24                               ` Vinzent Hoefler
2011-03-03 21:32                                 ` Hyman Rosen
2011-03-03 21:39                                   ` Vinzent Hoefler
2011-03-03 21:44                                     ` Hyman Rosen
2011-03-03 22:28                                   ` Georg Bauhaus
2011-03-01 21:52               ` Pascal Obry
2011-03-01 22:08                 ` Hyman Rosen
2011-03-02  0:41                   ` Randy Brukardt
2011-03-02  2:59                     ` Nasser M. Abbasi
2011-03-03  1:44                       ` Randy Brukardt
2011-03-02 14:26                     ` Hyman Rosen
2011-03-02 14:34                       ` Ludovic Brenta
2011-03-02 14:59                         ` Hyman Rosen
2011-03-02 15:19                           ` Pascal Obry
2011-03-02 15:35                             ` Hyman Rosen
2011-03-02 15:49                           ` Ludovic Brenta
2011-03-02 16:03                             ` Hyman Rosen
2011-03-03  2:23                       ` Randy Brukardt
2011-03-03  5:48                         ` Hyman Rosen
2011-03-02  9:19                   ` Pascal Obry
2011-03-02  9:31                     ` Dmitry A. Kazakov
2011-03-02  9:45                       ` Nasser M. Abbasi
2011-03-02 10:24                         ` Georg Bauhaus
2011-03-02 11:16                         ` Dmitry A. Kazakov
2011-03-02 14:51                     ` Hyman Rosen
2011-02-06 17:49     ` Simon Clubley
2011-02-06 18:18       ` Niklas Holsti
2011-02-06 19:05         ` Simon Clubley
2011-02-06 20:01           ` Dmitry A. Kazakov
2011-02-06 21:27             ` Maciej Sobczak
2011-02-06 23:08               ` Shark8
2011-02-07  6:38                 ` Niklas Holsti
2011-02-07  7:23                   ` Shark8
2011-02-07  8:31                     ` Niklas Holsti
2011-02-07 12:31                       ` Simon Clubley
2011-02-07 12:42                         ` Simon Clubley
2011-02-07 21:54                           ` Randy Brukardt
2011-02-08  0:21                             ` Bill Findlay
2011-02-08  1:06                             ` Adam Beneschan
2011-02-21  7:17                               ` David Thompson
2011-02-08 12:46                             ` Simon Clubley
2011-02-08 13:12                             ` J-P. Rosen
2011-02-08 18:03                               ` Jeffrey Carter
2011-02-07  8:38               ` Dmitry A. Kazakov
2011-02-07  9:05                 ` Maciej Sobczak
2011-02-07  9:24                   ` Dmitry A. Kazakov
2011-02-07 23:11                     ` Maciej Sobczak
2011-02-08 18:14                       ` Dmitry A. Kazakov
2011-02-08 21:48                         ` Maciej Sobczak
2011-02-09  8:43                           ` Dmitry A. Kazakov
2011-02-09 21:07                             ` Maciej Sobczak
2011-02-09 21:38                               ` Dmitry A. Kazakov
2011-03-01 21:45                                 ` Maciej Sobczak
2011-02-07  9:00             ` Ludovic Brenta
2011-02-07 13:43               ` Georg Bauhaus
2011-02-07 13:56                 ` Ludovic Brenta
2011-02-07 14:58                   ` Georg Bauhaus
2011-02-07 15:21                     ` Dmitry A. Kazakov
2011-02-07 16:14                       ` Robert A Duff
2011-02-07 17:23                         ` Dmitry A. Kazakov
2011-02-07 18:38                         ` Jeffrey Carter
2011-02-07 21:38                           ` Robert A Duff
2011-02-07 22:41                             ` Simon Wright
2011-02-07 18:10                       ` Georg Bauhaus
2011-02-07 19:27                         ` Simon Wright
2011-02-07 19:29                         ` Dmitry A. Kazakov
2011-02-07 16:54                     ` Ludovic Brenta
2011-02-07 17:55                       ` Georg Bauhaus
2011-02-08  8:04                         ` Ludovic Brenta
2011-02-08  9:01                           ` Nasser M. Abbasi
2011-02-08  9:08                             ` Ludovic Brenta
2011-02-08  9:43                           ` Georg Bauhaus
2011-02-08 19:53                             ` Shark8
2011-02-08  9:46                           ` Georg Bauhaus
2011-02-08  9:58                             ` Ludovic Brenta
2011-02-08 10:03                               ` Georg Bauhaus
2011-02-08 10:08                                 ` Ludovic Brenta
2011-02-08 10:27                                   ` Georg Bauhaus
2011-02-08 10:15                                 ` Nasser M. Abbasi
2011-02-08 16:48                                 ` Adam Beneschan
2011-02-08 18:25                                   ` Georg Bauhaus
2011-02-08 20:48                                     ` Vinzent Hoefler
2011-02-08 21:24                                       ` Georg Bauhaus
2011-02-08 21:41                                         ` Vinzent Hoefler
2011-02-09  8:59                                           ` Dmitry A. Kazakov
2011-02-09 18:25                                             ` Vinzent Hoefler
2011-02-09 20:03                                               ` Dmitry A. Kazakov
2011-02-09 20:19                                                 ` Vinzent Hoefler
2011-02-09 21:10                                                   ` Hyman Rosen
2011-02-09 21:42                                                     ` Vinzent Hoefler
2011-02-08 17:11                             ` Pascal Obry
2011-02-08 17:11                             ` Pascal Obry
2011-02-08 17:11                             ` Pascal Obry
2011-02-08 17:24                               ` Hyman Rosen
2011-02-08 18:27                                 ` Dmitry A. Kazakov
2011-02-08 18:43                                   ` Hyman Rosen
2011-02-08 10:10                           ` Georg Bauhaus
2011-02-08 10:14                             ` Ludovic Brenta
2011-02-08 10:31                               ` Georg Bauhaus
2011-02-08 18:30                               ` Jeffrey Carter
2011-02-08 18:47                                 ` Hyman Rosen
2011-02-08 20:11                                   ` Shark8
2011-02-08 20:27                                     ` Hyman Rosen
2011-02-08 20:52                                       ` Shark8
2011-02-08 21:21                                         ` Jeffrey Carter
2011-02-08 21:35                                           ` Shark8
2011-02-09  0:03                                       ` Randy Brukardt
2011-02-09  0:14                                         ` Shark8
2011-02-10  2:51                                           ` Randy Brukardt
2011-02-10  4:30                                             ` Shark8
2011-02-11  2:16                                               ` Randy Brukardt
2011-02-09 15:34                                         ` Hyman Rosen
2011-02-09 16:15                                           ` Dmitry A. Kazakov
2011-02-09 16:43                                             ` KK6GM
2011-02-09 17:49                                               ` Dmitry A. Kazakov
2011-02-09 17:54                                                 ` Hyman Rosen
2011-02-09 18:15                                                   ` Dmitry A. Kazakov
2011-02-09 18:25                                                   ` Shark8
2011-02-09 20:16                                                   ` Simon Wright
2011-02-09 20:33                                                     ` Vinzent Hoefler
2011-02-09 16:48                                             ` Hyman Rosen
2011-02-09 17:49                                               ` Dmitry A. Kazakov
2011-02-09 18:07                                                 ` Hyman Rosen
2011-02-09 18:36                                                   ` Dmitry A. Kazakov
2011-02-09 19:12                                                     ` Hyman Rosen
2011-02-09 19:41                                                       ` Shark8
2011-02-09 20:00                                                         ` Hyman Rosen
2011-02-09 20:25                                                           ` Shark8
2011-02-09 21:20                                                             ` Hyman Rosen
2011-02-09 21:23                                                               ` Shark8
2011-02-09 21:40                                                                 ` Hyman Rosen
2011-02-09 23:59                                                                   ` Robert A Duff
2011-02-09 20:01                                                       ` Dmitry A. Kazakov
2011-02-09 20:56                                                         ` Hyman Rosen
2011-02-09 21:47                                                           ` Dmitry A. Kazakov
2011-02-09 21:51                                                             ` Simon Wright
2011-02-09 21:56                                                             ` Hyman Rosen
2011-02-09 22:01                                                               ` Dmitry A. Kazakov
2011-02-10  3:08                                                       ` Randy Brukardt
2011-02-09 22:31                                                   ` Anonymous
2011-02-09 22:34                                                     ` Hyman Rosen
2011-02-09 22:41                                                       ` Vinzent Hoefler
2011-02-09 22:52                                                         ` Hyman Rosen
     [not found]                                                 ` <4d52d7d9$0$18057$882e7ee2@usenet-news.ne t>
2011-02-10  3:03                                                   ` Randy Brukardt
2011-02-09 18:23                                               ` Shark8
2011-02-09 18:31                                                 ` Hyman Rosen
2011-02-09 19:20                                                   ` Shark8
2011-02-09 19:43                                                     ` Hyman Rosen
2011-02-09 20:29                                                       ` Shark8
2011-02-09 21:26                                                         ` Hyman Rosen
2011-02-09 21:40                                                           ` Shark8
2011-02-09 22:09                                                             ` Hyman Rosen
2011-02-09 22:23                                                               ` Shark8
2011-02-09 22:31                                                                 ` Hyman Rosen
2011-02-09 22:38                                                                   ` Vinzent Hoefler
2011-02-09 22:50                                                                     ` Hyman Rosen
2011-02-10  0:16                                                                       ` Shark8
2011-02-10 15:28                                                                         ` Hyman Rosen
2011-02-10 16:38                                                                           ` Shark8
2011-02-10 16:46                                                                             ` Hyman Rosen
2011-02-10  3:23                                                                       ` Randy Brukardt
2011-02-10 17:33                                                                       ` Vinzent Hoefler
2011-02-09 23:07                                                                   ` Shark8
2011-02-09 23:24                                                                     ` Hyman Rosen
2011-02-10  0:35                                                                       ` Shark8
2011-02-10 15:38                                                                         ` Hyman Rosen
2011-02-10 17:05                                                                           ` Shark8
2011-02-10 17:40                                                                             ` Hyman Rosen
2011-02-10 18:22                                                                               ` Shark8
2011-02-10 19:20                                                                               ` Georg Bauhaus
2011-02-11  8:26                                                                               ` Ludovic Brenta
2011-02-11 10:22                                                                                 ` Nasser M. Abbasi
2011-02-11 16:10                                                                                 ` Hyman Rosen
2011-02-11 18:04                                                                                   ` Dmitry A. Kazakov
2011-02-11 18:31                                                                                     ` Hyman Rosen
2011-02-11 18:42                                                                                       ` Vinzent Hoefler
2011-02-11 18:52                                                                                         ` Hyman Rosen
2011-02-11 20:02                                                                                           ` Vinzent Hoefler
2011-02-11 19:41                                                                                       ` Dmitry A. Kazakov
2011-02-11 18:43                                                                                   ` Vinzent Hoefler
2011-02-11 18:57                                                                                     ` Hyman Rosen
2011-02-11 20:15                                                                                       ` Vinzent Hoefler
2011-02-11 20:29                                                                                         ` Hyman Rosen
2011-02-11 20:42                                                                                           ` Vinzent Hoefler
2011-02-11 18:52                                                                                   ` Georg Bauhaus
2011-02-11 19:02                                                                                     ` Hyman Rosen
2011-02-10 17:30                                                                           ` Georg Bauhaus
2011-02-09 18:10                                             ` Shark8
2011-02-10  2:56                                           ` Randy Brukardt
2011-02-09 21:15                                         ` Anonymous
2011-02-08 19:43                                 ` Dmitry A. Kazakov
2011-02-08 20:01                                   ` Hyman Rosen
2011-02-08 20:27                                     ` Dmitry A. Kazakov
2011-02-08 20:41                                       ` Hyman Rosen
2011-02-08 21:06                                     ` Adam Beneschan
2011-02-08 21:13                                       ` Hyman Rosen
2011-02-08 21:16                                       ` Vinzent Hoefler
2011-02-08 22:41                                         ` Adam Beneschan
2011-02-09 18:39                                           ` Vinzent Hoefler
2011-02-09 20:29                                             ` Simon Wright
2011-02-09 20:44                                               ` Vinzent Hoefler
2011-02-10  3:03                                                 ` Adam Beneschan
2011-02-10 19:07                                                   ` Vinzent Hoefler
2011-02-11  7:19                                                     ` Stephen Leake
2011-02-11 18:43                                                       ` Vinzent Hoefler
2011-02-09 10:42                                         ` Simon Wright
2011-02-09 18:39                                           ` Vinzent Hoefler
2011-02-09 18:48                                             ` J-P. Rosen
2011-02-09 18:55                                               ` Vinzent Hoefler
2011-02-09 22:03                                                 ` J-P. Rosen
2011-02-09 22:25                                                   ` Vinzent Hoefler
2011-02-10  3:07                                                     ` Adam Beneschan
2011-02-10  6:09                                                     ` J-P. Rosen
2011-02-10 17:48                                                       ` Vinzent Hoefler
2011-02-09 21:30                                             ` Simon Wright
2011-02-09 22:05                                               ` Vinzent Hoefler
2011-02-09 18:42                                           ` Vinzent Hoefler
2011-02-08 21:09                                     ` Shark8
2011-02-08 21:25                                       ` Hyman Rosen
2011-02-08 21:46                                         ` Vinzent Hoefler
2011-02-08 21:59                                           ` Hyman Rosen
2011-02-09 18:44                                             ` Vinzent Hoefler
2011-02-09 18:54                                               ` Hyman Rosen
2011-02-09 18:59                                                 ` Vinzent Hoefler
2011-02-09 19:21                                                   ` Hyman Rosen
2011-02-09 19:30                                                     ` Vinzent Hoefler
2011-02-09 19:44                                                       ` Hyman Rosen
2011-02-09 20:08                                                         ` Vinzent Hoefler
2011-02-08 21:49                                         ` Simon Clubley
2011-02-08 21:51                                           ` Vinzent Hoefler
2011-02-08 22:13                                             ` Hyman Rosen
2011-02-09 18:04                                               ` Vinzent Hoefler
2011-02-08 22:12                                           ` Hyman Rosen
2011-02-08 23:03                                             ` Simon Clubley
2011-02-08 22:30                                         ` Shark8
2011-02-09 10:19                                         ` Ludovic Brenta
2011-02-09 15:09                                         ` KK6GM
2011-02-09  0:13                                       ` Randy Brukardt
2011-02-09  1:56                                         ` Shark8
2011-02-09  2:33                                           ` Adam Beneschan
2011-02-09 15:49                                             ` Hyman Rosen [this message]
2011-02-10  3:29                                               ` Randy Brukardt
2011-02-21  7:17                                             ` David Thompson
2011-02-08 20:04                                   ` Simon Clubley
2011-02-08 20:44                                     ` Dmitry A. Kazakov
2011-02-08 21:19                                       ` Simon Clubley
2011-02-09  9:21                                         ` Dmitry A. Kazakov
2011-02-09 15:20                                           ` KK6GM
2011-02-09 16:39                                             ` Hyman Rosen
2011-02-09 16:46                                               ` KK6GM
2011-02-09 17:15                                                 ` Hyman Rosen
2011-02-09 17:46                                                   ` Shark8
2011-02-09 18:02                                                   ` Dmitry A. Kazakov
2011-02-09 18:17                                                     ` Hyman Rosen
2011-02-09 18:34                                                       ` Dmitry A. Kazakov
2011-02-09 18:52                                                         ` Hyman Rosen
2011-02-09 19:48                                                           ` Dmitry A. Kazakov
2011-02-09 20:09                                                             ` Vinzent Hoefler
2011-02-09 20:52                                                             ` Hyman Rosen
2011-02-09 21:45                                                               ` Simon Wright
2011-02-09 22:13                                                                 ` Shark8
2011-02-09 18:53                                                   ` KK6GM
2011-02-09 19:20                                                     ` Hyman Rosen
2011-02-08 21:31                                       ` Shark8
2011-02-08 21:50                                         ` Vinzent Hoefler
2011-02-08 21:56                                           ` Simon Clubley
2011-02-08 22:41                                             ` Shark8
2011-02-09 18:12                                               ` Vinzent Hoefler
2011-02-09 18:29                                                 ` Shark8
2011-02-09 18:49                                                   ` Vinzent Hoefler
2011-02-09 18:36                                                 ` Hyman Rosen
2011-02-09 18:51                                                   ` Vinzent Hoefler
2011-02-21  7:17                                         ` David Thompson
2011-02-08 20:55                                   ` Georg Bauhaus
2011-02-08 21:26                                   ` Jeffrey Carter
2011-02-09  7:59                                   ` Mart van de Wege
2011-02-09  9:16                                     ` Dmitry A. Kazakov
2011-02-09 10:28                                       ` Mart van de Wege
2011-02-09 15:57                                         ` Hyman Rosen
2011-02-10  3:36                                           ` Randy Brukardt
2011-02-10  6:35                                             ` J-P. Rosen
2011-02-08 10:11                           ` Georg Bauhaus
2011-02-08 10:16                             ` Ludovic Brenta
2011-02-08 10:36                               ` Georg Bauhaus
2011-02-08 10:43                                 ` Ludovic Brenta
2011-02-08 12:20                                   ` Georg Bauhaus
2011-02-08 20:21                             ` Shark8
2011-02-08 21:46                               ` Georg Bauhaus
2011-02-08 22:35                                 ` Shark8
2011-02-10  2:18                             ` Randy Brukardt
2011-02-08 15:36               ` Hyman Rosen
2011-02-08 16:44                 ` Adam Beneschan
2011-02-08 17:13                   ` Hyman Rosen
2011-02-08 18:33                     ` Georg Bauhaus
2011-02-08 18:39                       ` Hyman Rosen
2011-02-03 17:43 ` John McCormick
2011-02-12  4:47 ` Edward Fish
2011-02-12  8:02   ` Niklas Holsti
2011-02-14  0:09   ` Hyman Rosen
2011-02-15  0:25     ` Randy Brukardt
2011-02-19  4:21       ` Edward Fish
2011-02-13  1:04 ` anon
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