[ac7d5ef0] | 1 | /* Shared Memory Lock Routines |
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| 2 | * |
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| 3 | * This shared memory locked queue support routine need to be |
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| 4 | * able to lock the specified locked queue. Interrupts are |
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| 5 | * disabled while the queue is locked to prevent preemption |
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| 6 | * and deadlock when two tasks poll for the same lock. |
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| 7 | * previous level. |
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| 8 | * |
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| 9 | * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. |
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| 10 | * On-Line Applications Research Corporation (OAR). |
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| 11 | * All rights assigned to U.S. Government, 1994. |
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| 12 | * |
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| 13 | * This material may be reproduced by or for the U.S. Government pursuant |
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| 14 | * to the copyright license under the clause at DFARS 252.227-7013. This |
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| 15 | * notice must appear in all copies of this file and its derivatives. |
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| 16 | * |
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| 17 | * $Id$ |
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| 18 | */ |
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| 19 | |
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| 20 | #include <bsp.h> |
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| 21 | #include <shm.h> |
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| 22 | |
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| 23 | /* |
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| 24 | * Shm_Initialize_lock |
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| 25 | * |
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| 26 | * Initialize the lock for the specified locked queue. |
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| 27 | */ |
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| 28 | |
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| 29 | void Shm_Initialize_lock( |
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| 30 | Shm_Locked_queue_Control *lq_cb |
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| 31 | ) |
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| 32 | { |
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| 33 | lq_cb->lock = LQ_UNLOCKED; |
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| 34 | } |
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| 35 | |
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| 36 | /* Shm_Lock( &lq_cb ) |
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| 37 | * |
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| 38 | * This shared memory locked queue support routine locks the |
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| 39 | * specified locked queue. It disables interrupts to prevent |
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| 40 | * a deadlock condition. |
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| 41 | */ |
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| 42 | |
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| 43 | void Shm_Lock( |
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| 44 | Shm_Locked_queue_Control *lq_cb |
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| 45 | ) |
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| 46 | { |
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| 47 | rtems_unsigned32 isr_level; |
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| 48 | vol_u32 *lockptr = &lq_cb->lock; |
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| 49 | rtems_unsigned32 lock_value; |
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| 50 | |
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| 51 | rtems_interrupt_disable( isr_level ); |
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| 52 | |
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| 53 | Shm_isrstat = isr_level; |
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| 54 | |
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| 55 | do { |
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| 56 | HPPA_ASM_LDCWS( 0, 0, lockptr, lock_value ); |
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| 57 | } while (lock_value == SHM_LOCK_VALUE); |
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| 58 | } |
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| 59 | |
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| 60 | /* |
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| 61 | * Shm_Unlock |
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| 62 | * |
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| 63 | * Unlock the lock for the specified locked queue. |
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| 64 | */ |
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| 65 | |
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| 66 | void Shm_Unlock( |
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| 67 | Shm_Locked_queue_Control *lq_cb |
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| 68 | ) |
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| 69 | { |
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| 70 | rtems_unsigned32 isr_level; |
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| 71 | |
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| 72 | lq_cb->lock = SHM_UNLOCK_VALUE; |
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| 73 | isr_level = Shm_isrstat; |
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| 74 | rtems_interrupt_enable( isr_level ); |
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| 75 | } |
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