1 | /* |
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2 | * Region Manager |
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3 | * |
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4 | * |
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5 | * COPYRIGHT (c) 1989-1999. |
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6 | * On-Line Applications Research Corporation (OAR). |
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7 | * |
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8 | * The license and distribution terms for this file may be |
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9 | * found in the file LICENSE in this distribution or at |
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10 | * http://www.rtems.com/license/LICENSE. |
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11 | * |
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12 | * $Id$ |
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13 | */ |
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14 | |
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15 | #if HAVE_CONFIG_H |
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16 | #include "config.h" |
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17 | #endif |
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18 | |
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19 | #include <rtems/system.h> |
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20 | #include <rtems/rtems/status.h> |
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21 | #include <rtems/rtems/support.h> |
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22 | #include <rtems/score/object.h> |
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23 | #include <rtems/rtems/options.h> |
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24 | #include <rtems/rtems/region.h> |
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25 | #include <rtems/score/states.h> |
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26 | #include <rtems/score/thread.h> |
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27 | #include <rtems/score/apimutex.h> |
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28 | |
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29 | /*PAGE |
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30 | * |
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31 | * _Region_Process_queue |
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32 | * |
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33 | * If enough memory is available to satisfy the rtems_region_get_segment of |
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34 | * the first blocked task, then that task and as many subsequent tasks as |
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35 | * possible will be unblocked with their requests satisfied. |
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36 | * |
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37 | * Input parameters: |
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38 | * the_region - the region |
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39 | * |
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40 | * Output parameters: |
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41 | * none |
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42 | */ |
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43 | |
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44 | void _Region_Process_queue( |
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45 | Region_Control *the_region |
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46 | ) |
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47 | { |
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48 | Thread_Control *the_thread; |
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49 | void *the_segment; |
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50 | /* |
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51 | * Switch from using the memory allocation mutex to using a |
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52 | * dispatching disabled critical section. We have to do this |
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53 | * because this thread may unblock one or more threads that were |
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54 | * waiting on memory. |
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55 | * |
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56 | * NOTE: Be sure to disable dispatching before unlocking the mutex |
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57 | * since we do not want to open a window where a context |
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58 | * switch could occur. |
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59 | */ |
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60 | _Thread_Disable_dispatch(); |
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61 | _RTEMS_Unlock_allocator(); |
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62 | |
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63 | /* |
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64 | * NOTE: The following loop is O(n) where n is the number of |
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65 | * threads whose memory request is satisfied. |
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66 | */ |
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67 | for ( ; ; ) { |
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68 | the_thread = _Thread_queue_First( &the_region->Wait_queue ); |
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69 | |
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70 | if ( the_thread == NULL ) |
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71 | break; |
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72 | |
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73 | the_segment = (void **) _Region_Allocate_segment( |
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74 | the_region, |
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75 | the_thread->Wait.count |
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76 | ); |
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77 | |
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78 | if ( the_segment == NULL ) |
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79 | break; |
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80 | |
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81 | *(void **)the_thread->Wait.return_argument = the_segment; |
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82 | the_region->number_of_used_blocks += 1; |
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83 | _Thread_queue_Extract( &the_region->Wait_queue, the_thread ); |
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84 | the_thread->Wait.return_code = RTEMS_SUCCESSFUL; |
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85 | } |
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86 | _Thread_Enable_dispatch(); |
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87 | } |
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