Changeset b5c5bbcf in rtems for doc/user/userext.t


Ignore:
Timestamp:
Apr 13, 2002, 4:47:23 PM (20 years ago)
Author:
Joel Sherrill <joel.sherrill@…>
Branches:
4.10, 4.11, 4.8, 4.9, 5, master
Children:
485e80fa
Parents:
18b6986
Message:

2002-04-12 Chris Johns <ccj@…>

  • doc/user/userext.t: Per PR138, updated the documentation to show how to obtain an extension table index. Also provided some extra background on the user extension API.
File:
1 edited

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  • doc/user/userext.t

    r18b6986 rb5c5bbcf  
    120120
    121121All user extensions are optional and RTEMS places no
    122 naming  restrictions on the user.
     122naming  restrictions on the user. The user extension entry points
     123are copied into an internal RTEMS structure. This means the user
     124does not need to keep the table after creating it, and changing the
     125handler entry points dynamically in a table once created has no
     126effect. Creating a table local to a function can save space in
     127space limited applications.
     128
     129Extension switches do not effect the context switch overhead if
     130no switch handler is installed.
    123131
    124132@subsection TCB Extension Area
     
    135143particular notepads.
    136144
    137 The TCB extension is an array of pointers in the TCB.
     145The TCB extension is an array of pointers in the TCB. The
     146index into the table can be obtained from the extension id
     147returned when the extension is created:
     148
     149@findex rtems extensions table index
     150@ifset is-C
     151@example
     152@group
     153index = rtems_get_index(extension_id);
     154@end group
     155@end example
     156@end ifset
     157
     158@ifset is-Ada
     159@example
     160There is currently no example for Ada.
     161@end example
     162@end ifset
     163
    138164The number of pointers in the area is the same as the number of
    139165user extension sets configured.  This allows an application to
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