From afe99c27dbac7e76118108b5f33a5b0fc930580e Mon Sep 17 00:00:00 2001 From: Joel Sherrill Date: Wed, 18 Sep 1996 14:17:54 +0000 Subject: new file submitted by Dominique le Campion. --- c/src/lib/libbsp/m68k/mvme147s/shmsupp/lock.c | 75 +++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 c/src/lib/libbsp/m68k/mvme147s/shmsupp/lock.c (limited to 'c/src/lib/libbsp/m68k/mvme147s/shmsupp/lock.c') diff --git a/c/src/lib/libbsp/m68k/mvme147s/shmsupp/lock.c b/c/src/lib/libbsp/m68k/mvme147s/shmsupp/lock.c new file mode 100644 index 0000000000..5ccc406af5 --- /dev/null +++ b/c/src/lib/libbsp/m68k/mvme147s/shmsupp/lock.c @@ -0,0 +1,75 @@ +/* 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, 1990, 1991, 1992, 1993, 1994. + * On-Line Applications Research Corporation (OAR). + * All rights assigned to U.S. Government, 1994. + * + * This material may be reproduced by or for the U.S. Government pursuant + * to the copyright license under the clause at DFARS 252.227-7013. This + * notice must appear in all copies of this file and its derivatives. + * + * $Id$ + */ + +#include +#include +#include + +/* + * 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_interrupt_disable( isr_level ); + Shm_isrstat = isr_level; + asm volatile( "lockit:" : : ); + asm volatile( "tas %0@" : "=a" (lockptr) : "0" (lockptr) ); + asm volatile( "bne lockit" : : ); +/* should delay */ +} + +/* + * 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 ); +} + -- cgit v1.2.3