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author | Joel Sherrill <joel.sherrill@OARcorp.com> | 2008-05-06 20:31:33 +0000 |
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committer | Joel Sherrill <joel.sherrill@OARcorp.com> | 2008-05-06 20:31:33 +0000 |
commit | e06b6b0a090b5d9ed8abfc012e881b3502771024 (patch) | |
tree | f6511aab25578380fdb315353daf7af20748c3b6 /cpukit/score/src/objectget.c | |
parent | 2008-05-06 Joel Sherrill <joel.sherrill@OARcorp.com> (diff) | |
download | rtems-e06b6b0a090b5d9ed8abfc012e881b3502771024.tar.bz2 |
2008-05-06 Joel Sherrill <joel.sherrill@OARcorp.com>
* score/src/objectget.c: Improve comments and readability.
Diffstat (limited to 'cpukit/score/src/objectget.c')
-rw-r--r-- | cpukit/score/src/objectget.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/cpukit/score/src/objectget.c b/cpukit/score/src/objectget.c index d0414113eb..a0aa3465b2 100644 --- a/cpukit/score/src/objectget.c +++ b/cpukit/score/src/objectget.c @@ -57,18 +57,46 @@ Objects_Control *_Objects_Get( Objects_Control *the_object; uint32_t index; + /* + * Extract the index portion of an Id in a way that produces a valid + * index for objects within this class and an invalid value for objects + * outside this class. + * + * If the Id matches the api, class, and node but index portion is 0, + * then the subtraction will underflow and the addition of 1 will + * result in a 0 index. The zeroth element in the local_table is + * always NULL. + * + * If the Id is valid but the object has not been created yet, then + * the local_table entry will be NULL. + */ index = id - information->minimum_id + 1; - if ( information->maximum >= index ) { + /* + * If the index is less than maximum, then it is OK to use it to + * index into the local_table array. + */ + if ( index <= information->maximum ) { _Thread_Disable_dispatch(); if ( (the_object = information->local_table[ index ]) != NULL ) { *location = OBJECTS_LOCAL; return the_object; } + + /* + * Valid Id for this API, Class and Node but the object has not + * been allocated yet. + */ _Thread_Enable_dispatch(); *location = OBJECTS_ERROR; return NULL; } + + /* + * Object Id is not within this API and Class on this node. So + * it may be global in a multiprocessing system. But it is clearly + * invalid on a single processor system. + */ *location = OBJECTS_ERROR; #if defined(RTEMS_MULTIPROCESSING) |