1 | /* |
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2 | * CORE Semaphore Handler |
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3 | * |
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4 | * DESCRIPTION: |
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5 | * |
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6 | * This package is the implementation of the CORE Semaphore Handler. |
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7 | * This core object utilizes standard Dijkstra counting semaphores to provide |
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8 | * synchronization and mutual exclusion capabilities. |
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9 | * |
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10 | * COPYRIGHT (c) 1989-1999. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * |
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13 | * The license and distribution terms for this file may be |
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14 | * found in the file LICENSE in this distribution or at |
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15 | * http://www.rtems.com/license/LICENSE. |
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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 | #if HAVE_CONFIG_H |
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21 | #include "config.h" |
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22 | #endif |
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23 | |
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24 | #include <rtems/system.h> |
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25 | #include <rtems/score/isr.h> |
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26 | #include <rtems/score/coresem.h> |
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27 | #include <rtems/score/states.h> |
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28 | #include <rtems/score/thread.h> |
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29 | #include <rtems/score/threadq.h> |
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30 | #if defined(RTEMS_MULTIPROCESSING) |
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31 | #include <rtems/score/mpci.h> |
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32 | #endif |
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33 | |
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34 | /*PAGE |
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35 | * |
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36 | * _CORE_semaphore_Seize |
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37 | * |
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38 | * This routine attempts to allocate a core semaphore to the calling thread. |
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39 | * |
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40 | * Input parameters: |
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41 | * the_semaphore - pointer to semaphore control block |
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42 | * id - id of object to wait on |
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43 | * wait - TRUE if wait is allowed, FALSE otherwise |
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44 | * timeout - number of ticks to wait (0 means forever) |
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45 | * |
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46 | * Output parameters: NONE |
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47 | * |
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48 | * INTERRUPT LATENCY: |
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49 | * available |
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50 | * wait |
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51 | */ |
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52 | |
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53 | void _CORE_semaphore_Seize( |
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54 | CORE_semaphore_Control *the_semaphore, |
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55 | Objects_Id id, |
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56 | boolean wait, |
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57 | Watchdog_Interval timeout |
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58 | ) |
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59 | { |
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60 | Thread_Control *executing; |
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61 | ISR_Level level; |
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62 | |
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63 | executing = _Thread_Executing; |
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64 | executing->Wait.return_code = CORE_SEMAPHORE_STATUS_SUCCESSFUL; |
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65 | _ISR_Disable( level ); |
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66 | if ( the_semaphore->count != 0 ) { |
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67 | the_semaphore->count -= 1; |
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68 | _ISR_Enable( level ); |
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69 | return; |
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70 | } |
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71 | |
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72 | if ( !wait ) { |
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73 | _ISR_Enable( level ); |
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74 | executing->Wait.return_code = CORE_SEMAPHORE_STATUS_UNSATISFIED_NOWAIT; |
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75 | return; |
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76 | } |
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77 | |
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78 | /* |
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79 | * If the semaphore is not available and the caller is willing to |
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80 | * block, then we now block the caller with optional timeout. |
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81 | */ |
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82 | _Thread_queue_Enter_critical_section( &the_semaphore->Wait_queue ); |
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83 | executing->Wait.queue = &the_semaphore->Wait_queue; |
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84 | executing->Wait.id = id; |
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85 | _ISR_Enable( level ); |
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86 | _Thread_queue_Enqueue( &the_semaphore->Wait_queue, timeout ); |
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87 | |
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88 | } |
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