1 | /* |
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2 | * Thread Handler |
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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 found in the file LICENSE in this distribution or at |
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10 | * http://www.OARcorp.com/rtems/license.html. |
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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 | #include <rtems/system.h> |
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16 | #include <rtems/score/apiext.h> |
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17 | #include <rtems/score/context.h> |
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18 | #include <rtems/score/interr.h> |
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19 | #include <rtems/score/isr.h> |
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20 | #include <rtems/score/object.h> |
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21 | #include <rtems/score/priority.h> |
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22 | #include <rtems/score/states.h> |
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23 | #include <rtems/score/sysstate.h> |
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24 | #include <rtems/score/thread.h> |
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25 | #include <rtems/score/threadq.h> |
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26 | #include <rtems/score/userext.h> |
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27 | #include <rtems/score/wkspace.h> |
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28 | |
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29 | /*PAGE |
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30 | * |
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31 | * _Thread_Rotate_Ready_Queue |
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32 | * |
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33 | * This kernel routine will rotate the ready queue. |
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34 | * remove the running THREAD from the ready chain |
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35 | * and place it immediatly at the rear of this chain. Reset timeslice |
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36 | * and yield the processor functions both use this routine, therefore if |
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37 | * reset is TRUE and this is the only thread on the chain then the |
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38 | * timeslice counter is reset. The heir THREAD will be updated if the |
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39 | * running is also the currently the heir. |
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40 | * |
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41 | * Input parameters: |
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42 | * Priority of the queue we wish to modify. |
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43 | * |
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44 | * Output parameters: NONE |
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45 | * |
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46 | * INTERRUPT LATENCY: |
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47 | * ready chain |
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48 | * select heir |
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49 | */ |
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50 | |
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51 | void _Thread_Rotate_Ready_Queue( |
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52 | Priority_Control priority |
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53 | ) |
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54 | { |
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55 | ISR_Level level; |
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56 | Thread_Control *executing; |
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57 | Chain_Control *ready; |
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58 | Chain_Node *node; |
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59 | |
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60 | ready = &_Thread_Ready_chain[ priority ]; |
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61 | executing = _Thread_Executing; |
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62 | |
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63 | if ( ready == executing->ready ) { |
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64 | _Thread_Yield_processor(); |
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65 | return; |
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66 | } |
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67 | |
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68 | _ISR_Disable( level ); |
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69 | |
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70 | if ( !_Chain_Is_empty( ready ) ) { |
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71 | if (!_Chain_Has_only_one_node( ready ) ) { |
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72 | node = _Chain_Get_first_unprotected( ready ); |
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73 | _Chain_Append_unprotected( ready, node ); |
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74 | } |
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75 | } |
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76 | |
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77 | _ISR_Flash( level ); |
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78 | |
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79 | if ( _Thread_Heir->ready == ready ) |
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80 | _Thread_Heir = (Thread_Control *) ready->first; |
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81 | |
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82 | if ( executing != _Thread_Heir ) |
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83 | _Context_Switch_necessary = TRUE; |
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84 | |
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85 | _ISR_Enable( level ); |
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86 | } |
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87 | |
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88 | |
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89 | |
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90 | |
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91 | |
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92 | |
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