forked from Imagelibrary/rtems
91 lines
2.8 KiB
C
91 lines
2.8 KiB
C
/* SPDX-License-Identifier: BSD-2-Clause */
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/* Shared Memory Lock Routines
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*
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* This shared memory locked queue support routine need to be
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* able to lock the specified locked queue. Interrupts are
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* disabled while the queue is locked to prevent preemption
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* and deadlock when two tasks poll for the same lock.
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* previous level.
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*
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* COPYRIGHT (c) 1989-1999.
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* On-Line Applications Research Corporation (OAR).
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <rtems.h>
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#include <bsp.h>
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#include <shm_driver.h>
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/*
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* Shm_Initialize_lock
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*
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* Initialize the lock for the specified locked queue.
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*/
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void Shm_Initialize_lock(
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Shm_Locked_queue_Control *lq_cb
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)
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{
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lq_cb->lock = LQ_UNLOCKED;
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}
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/* void _Shm_Lock( &lq_cb )
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*
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* This shared memory locked queue support routine locks the
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* specified locked queue. It disables interrupts to prevent
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* a deadlock condition.
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*/
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void Shm_Lock(
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Shm_Locked_queue_Control *lq_cb
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)
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{
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uint32_t isr_level;
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uint32_t *lockptr = (uint32_t*)&lq_cb->lock;
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rtems_interrupt_disable( isr_level );
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Shm_isrstat = isr_level;
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__asm__ volatile( "lockit:" : : );
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__asm__ volatile( "tas %0@" : "=a" (lockptr) : "0" (lockptr) );
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__asm__ volatile( "bne lockit" : : );
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/* should delay */
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}
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/*
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* Shm_Unlock
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*
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* Unlock the lock for the specified locked queue.
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*/
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void Shm_Unlock(
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Shm_Locked_queue_Control *lq_cb
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)
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{
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uint32_t isr_level;
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lq_cb->lock = SHM_UNLOCK_VALUE;
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isr_level = Shm_isrstat;
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rtems_interrupt_enable( isr_level );
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}
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