diff options
author | Joel Sherrill <joel.sherrill@OARcorp.com> | 1999-10-04 20:41:28 +0000 |
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committer | Joel Sherrill <joel.sherrill@OARcorp.com> | 1999-10-04 20:41:28 +0000 |
commit | 19ca7978a660fd325d9a6b25f3dd964f81fe8b19 (patch) | |
tree | a06262aa2dafe8d981dcb9d7287bd1643526664f /c/src/lib/libbsp/powerpc/mvme2307/shmsupp/lock.c | |
parent | The fiels isatty.c and creat.c were copied from newlib/libc/posix to (diff) | |
download | rtems-19ca7978a660fd325d9a6b25f3dd964f81fe8b19.tar.bz2 |
Motorola MVME2307 BSP submitted by Jay Kulpinski <jskulpin@eng01.gdds.com>.
No modifications made.
Diffstat (limited to 'c/src/lib/libbsp/powerpc/mvme2307/shmsupp/lock.c')
-rw-r--r-- | c/src/lib/libbsp/powerpc/mvme2307/shmsupp/lock.c | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/powerpc/mvme2307/shmsupp/lock.c b/c/src/lib/libbsp/powerpc/mvme2307/shmsupp/lock.c new file mode 100644 index 0000000000..7101bbd4e0 --- /dev/null +++ b/c/src/lib/libbsp/powerpc/mvme2307/shmsupp/lock.c @@ -0,0 +1,86 @@ +/* Shared Memory Lock Routines + * + * This shared memory locked queue support routine need to be + * able to lock the specified locked queue. Interrupts are + * disabled while the queue is locked to prevent preemption + * and deadlock when two tasks poll for the same lock. + * previous level. + * + * COPYRIGHT (c) 1989-1998. + * On-Line Applications Research Corporation (OAR). + * Copyright assigned to U.S. Government, 1994. + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.OARcorp.com/rtems/license.html. + * + * $Id$ + */ + +#include <rtems.h> +#include <bsp.h> +#include <shm.h> + +/* + * Shm_Initialize_lock + * + * Initialize the lock for the specified locked queue. + */ + +void Shm_Initialize_lock( + Shm_Locked_queue_Control *lq_cb +) +{ + lq_cb->lock = LQ_UNLOCKED; +} + +/* void _Shm_Lock( &lq_cb ) + * + * This shared memory locked queue support routine locks the + * specified locked queue. It disables interrupts to prevent + * a deadlock condition. + */ + +void Shm_Lock( + Shm_Locked_queue_Control *lq_cb +) +{ + rtems_unsigned32 isr_level; + rtems_unsigned32 *lockptr = (rtems_unsigned32 *) &lq_cb->lock; + rtems_unsigned32 lock_value; + + lock_value = 0x80000000; + rtems_interrupt_disable( isr_level ); + + Shm_isrstat = isr_level; + while ( lock_value ) { + asm volatile( "" + : "=r" (lockptr), "=r" (lock_value) + : "0" (lockptr), "1" (lock_value) + ); + /* + * If not available, then may want to delay to reduce load on lock. + */ + + if ( lock_value ) + delay( 10 ); /* approximately 10 microseconds */ + } +} + +/* + * Shm_Unlock + * + * Unlock the lock for the specified locked queue. + */ + +void Shm_Unlock( + Shm_Locked_queue_Control *lq_cb +) +{ + rtems_unsigned32 isr_level; + + lq_cb->lock = SHM_UNLOCK_VALUE; + isr_level = Shm_isrstat; + rtems_interrupt_enable( isr_level ); +} + |