4.104.114.84.95
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1 | /* Shm_Envelope_control *Shm_Locked_queue_Get( lq_cb ) |
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2 | * |
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3 | * This routine returns an envelope control block from a shared |
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4 | * memory queue. |
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5 | * |
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6 | * Input parameters: |
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7 | * lq_cb - pointer to a locked queue control block |
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8 | * |
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9 | * Output parameters: |
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10 | * returns - pointer to an envelope control block |
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11 | * - NULL if no envelopes on specified queue |
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12 | * |
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13 | * COPYRIGHT (c) 1989-1998. |
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14 | * On-Line Applications Research Corporation (OAR). |
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15 | * Copyright assigned to U.S. Government, 1994. |
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16 | * |
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17 | * The license and distribution terms for this file may be |
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18 | * found in the file LICENSE in this distribution or at |
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19 | * http://www.OARcorp.com/rtems/license.html. |
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20 | * |
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21 | * $Id$ |
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22 | */ |
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23 | |
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24 | #include <rtems.h> |
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25 | #include <shm.h> |
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26 | |
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27 | Shm_Envelope_control *Shm_Locked_queue_Get( |
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28 | Shm_Locked_queue_Control *lq_cb |
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29 | ) |
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30 | { |
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31 | Shm_Envelope_control *tmp_ecb; |
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32 | rtems_unsigned32 tmpfront; |
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33 | |
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34 | tmp_ecb = NULL; |
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35 | Shm_Lock( lq_cb ); |
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36 | |
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37 | tmpfront = Shm_Convert(lq_cb->front); |
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38 | if ( tmpfront != Shm_Locked_queue_End_of_list ) { |
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39 | tmp_ecb = &Shm_Envelopes[ tmpfront ]; |
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40 | lq_cb->front = tmp_ecb->next; |
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41 | if ( tmp_ecb->next == Shm_Locked_queue_End_of_list ) |
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42 | lq_cb->rear = Shm_Locked_queue_End_of_list; |
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43 | tmp_ecb->next = Shm_Locked_queue_Not_on_list; |
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44 | } |
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45 | |
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46 | Shm_Unlock( lq_cb ); |
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47 | return( tmp_ecb ); |
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48 | } |
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