diff options
author | Joel Sherrill <joel.sherrill@OARcorp.com> | 2006-09-25 13:36:58 +0000 |
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committer | Joel Sherrill <joel.sherrill@OARcorp.com> | 2006-09-25 13:36:58 +0000 |
commit | 9c191eea63fd6c5511c01186297722e594220032 (patch) | |
tree | d5ad903d3005a0c24511851d829e0a00b2c1c53c /cpukit/score/src/corerwlockobtainread.c | |
parent | 2006-09-14 Joel Sherrill <joel@OARcorp.com> (diff) | |
download | rtems-9c191eea63fd6c5511c01186297722e594220032.tar.bz2 |
* score/Makefile.am, score/preinstall.am,
score/include/rtems/score/coresem.h,
score/include/rtems/score/object.h,
score/include/rtems/score/states.h,
score/inline/rtems/score/coresem.inl: Add SuperCore Barriers,
SpinLocks and a partial implementation of RWLocks.
* score/include/rtems/score/corebarrier.h,
score/include/rtems/score/corerwlock.h,
score/include/rtems/score/corespinlock.h,
score/inline/rtems/score/corebarrier.inl,
score/inline/rtems/score/corerwlock.inl,
score/inline/rtems/score/corespinlock.inl,
score/macros/rtems/score/corebarrier.inl,
score/macros/rtems/score/corerwlock.inl,
score/macros/rtems/score/corespinlock.inl, score/src/corebarrier.c,
score/src/corebarrierrelease.c, score/src/corebarrierwait.c,
score/src/corerwlock.c, score/src/corerwlockobtainread.c,
score/src/corerwlockobtainwrite.c, score/src/corerwlockrelease.c,
score/src/corespinlock.c, score/src/corespinlockrelease.c,
score/src/corespinlockwait.c: New files.
Diffstat (limited to 'cpukit/score/src/corerwlockobtainread.c')
-rw-r--r-- | cpukit/score/src/corerwlockobtainread.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/cpukit/score/src/corerwlockobtainread.c b/cpukit/score/src/corerwlockobtainread.c new file mode 100644 index 0000000000..c90bf02f07 --- /dev/null +++ b/cpukit/score/src/corerwlockobtainread.c @@ -0,0 +1,103 @@ +/* + * SuperCore RWLock Handler -- Obtain RWLock for reading + * + * COPYRIGHT (c) 1989-2006. + * On-Line Applications Research Corporation (OAR). + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + * + * $Id$ + */ + +#if HAVE_CONFIG_H +#include "config.h" +#endif + +#include <rtems/system.h> +#include <rtems/score/corerwlock.h> +#include <rtems/score/states.h> +#include <rtems/score/thread.h> +#include <rtems/score/watchdog.h> + +/*PAGE + * + * _CORE_rwlock_Obtain_for_reading + * + * This function waits for the rwlock to become available. Optionally, + * a limit may be placed on the duration of the spin. + * + * Input parameters: + * the_rwlock - the rwlock control block to initialize + * timeout_allowed - true if timeout allowed + * timeout - the maximum number of ticks to spin + * + * Output parameters: NONE + */ + +void _CORE_RWLock_Obtain_for_reading( + CORE_RWLock_Control *the_rwlock, + Objects_Id id, + boolean wait, + Watchdog_Interval timeout, + CORE_RWLock_API_mp_support_callout api_rwlock_mp_support +) +{ + ISR_Level level; + Thread_Control *executing = _Thread_Executing; + + /* + * If unlocked, then OK to read. + * If locked for reading and no waiters, then OK to read. + * If any thread is waiting, then we wait. + */ + + _ISR_Disable( level ); + switch ( the_rwlock->current_state ) { + case CORE_RWLOCK_UNLOCKED: + the_rwlock->current_state = CORE_RWLOCK_LOCKED_FOR_READING; + the_rwlock->number_of_readers += 1; + _ISR_Enable( level ); + executing->Wait.return_code = CORE_RWLOCK_SUCCESSFUL; + return; + + case CORE_RWLOCK_LOCKED_FOR_READING: { + Thread_Control *waiter; + waiter = _Thread_queue_First( &the_rwlock->Wait_queue ); + if ( !waiter ) { + the_rwlock->number_of_readers += 1; + _ISR_Enable( level ); + executing->Wait.return_code = CORE_RWLOCK_SUCCESSFUL; + return; + } + break; + } + case CORE_RWLOCK_LOCKED_FOR_WRITING: + break; + } + + /* + * If the thread is not willing to wait, then return immediately. + */ + + if ( !wait ) { + _ISR_Enable( level ); + executing->Wait.return_code = CORE_RWLOCK_UNAVAILABLE; + } + + /* + * We need to wait to enter this critical section + */ + + _Thread_queue_Enter_critical_section( &the_rwlock->Wait_queue ); + executing->Wait.queue = &the_rwlock->Wait_queue; + executing->Wait.id = id; + executing->Wait.option = CORE_RWLOCK_THREAD_WAITING_FOR_WRITE; + executing->Wait.return_code = CORE_RWLOCK_SUCCESSFUL; + _ISR_Enable( level ); + + _Thread_queue_Enqueue( &the_rwlock->Wait_queue, timeout ); + + /* return to API level so it can dispatch and we block */ +} |