From e06b6b0a090b5d9ed8abfc012e881b3502771024 Mon Sep 17 00:00:00 2001 From: Joel Sherrill Date: Tue, 6 May 2008 20:31:33 +0000 Subject: [PATCH] 2008-05-06 Joel Sherrill * score/src/objectget.c: Improve comments and readability. --- cpukit/ChangeLog | 4 ++++ cpukit/score/src/objectget.c | 30 +++++++++++++++++++++++++++++- 2 files changed, 33 insertions(+), 1 deletion(-) diff --git a/cpukit/ChangeLog b/cpukit/ChangeLog index 28bf615748..5d510c313d 100644 --- a/cpukit/ChangeLog +++ b/cpukit/ChangeLog @@ -1,3 +1,7 @@ +2008-05-06 Joel Sherrill + + * score/src/objectget.c: Improve comments and readability. + 2008-05-06 Joel Sherrill * rtems/include/rtems/rtems/message.h, sapi/include/confdefs.h, 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)