1 | /* |
---|
2 | * Thread Handler |
---|
3 | * |
---|
4 | * |
---|
5 | * COPYRIGHT (c) 1989-1999. |
---|
6 | * On-Line Applications Research Corporation (OAR). |
---|
7 | * |
---|
8 | * The license and distribution terms for this file may be |
---|
9 | * found in found in the file LICENSE in this distribution or at |
---|
10 | * http://www.OARcorp.com/rtems/license.html. |
---|
11 | * |
---|
12 | * $Id$ |
---|
13 | */ |
---|
14 | |
---|
15 | #include <rtems/system.h> |
---|
16 | #include <rtems/score/apiext.h> |
---|
17 | #include <rtems/score/context.h> |
---|
18 | #include <rtems/score/interr.h> |
---|
19 | #include <rtems/score/isr.h> |
---|
20 | #include <rtems/score/object.h> |
---|
21 | #include <rtems/score/priority.h> |
---|
22 | #include <rtems/score/states.h> |
---|
23 | #include <rtems/score/sysstate.h> |
---|
24 | #include <rtems/score/thread.h> |
---|
25 | #include <rtems/score/threadq.h> |
---|
26 | #include <rtems/score/userext.h> |
---|
27 | #include <rtems/score/wkspace.h> |
---|
28 | |
---|
29 | /*PAGE |
---|
30 | * |
---|
31 | * _Thread_Dispatch |
---|
32 | * |
---|
33 | * This kernel routine determines if a dispatch is needed, and if so |
---|
34 | * dispatches to the heir thread. Once the heir is running an attempt |
---|
35 | * is made to dispatch any ASRs. |
---|
36 | * |
---|
37 | * ALTERNATE ENTRY POINTS: |
---|
38 | * void _Thread_Enable_dispatch(); |
---|
39 | * |
---|
40 | * Input parameters: NONE |
---|
41 | * |
---|
42 | * Output parameters: NONE |
---|
43 | * |
---|
44 | * INTERRUPT LATENCY: |
---|
45 | * dispatch thread |
---|
46 | * no dispatch thread |
---|
47 | */ |
---|
48 | |
---|
49 | #if ( CPU_INLINE_ENABLE_DISPATCH == FALSE ) |
---|
50 | void _Thread_Enable_dispatch( void ) |
---|
51 | { |
---|
52 | if ( --_Thread_Dispatch_disable_level ) |
---|
53 | return; |
---|
54 | _Thread_Dispatch(); |
---|
55 | } |
---|
56 | #endif |
---|
57 | |
---|
58 | void _Thread_Dispatch( void ) |
---|
59 | { |
---|
60 | Thread_Control *executing; |
---|
61 | Thread_Control *heir; |
---|
62 | ISR_Level level; |
---|
63 | |
---|
64 | executing = _Thread_Executing; |
---|
65 | _ISR_Disable( level ); |
---|
66 | while ( _Context_Switch_necessary == TRUE ) { |
---|
67 | heir = _Thread_Heir; |
---|
68 | _Thread_Dispatch_disable_level = 1; |
---|
69 | _Context_Switch_necessary = FALSE; |
---|
70 | _Thread_Executing = heir; |
---|
71 | executing->rtems_ada_self = rtems_ada_self; |
---|
72 | rtems_ada_self = heir->rtems_ada_self; |
---|
73 | _ISR_Enable( level ); |
---|
74 | |
---|
75 | heir->ticks_executed++; |
---|
76 | |
---|
77 | _User_extensions_Thread_switch( executing, heir ); |
---|
78 | |
---|
79 | if ( heir->budget_algorithm == THREAD_CPU_BUDGET_ALGORITHM_RESET_TIMESLICE ) |
---|
80 | heir->cpu_time_budget = _Thread_Ticks_per_timeslice; |
---|
81 | |
---|
82 | /* |
---|
83 | * If the CPU has hardware floating point, then we must address saving |
---|
84 | * and restoring it as part of the context switch. |
---|
85 | * |
---|
86 | * The second conditional compilation section selects the algorithm used |
---|
87 | * to context switch between floating point tasks. The deferred algorithm |
---|
88 | * can be significantly better in a system with few floating point tasks |
---|
89 | * because it reduces the total number of save and restore FP context |
---|
90 | * operations. However, this algorithm can not be used on all CPUs due |
---|
91 | * to unpredictable use of FP registers by some compilers for integer |
---|
92 | * operations. |
---|
93 | */ |
---|
94 | |
---|
95 | #if ( CPU_HARDWARE_FP == TRUE ) |
---|
96 | #if ( CPU_USE_DEFERRED_FP_SWITCH == TRUE ) |
---|
97 | if ( (heir->fp_context != NULL) && !_Thread_Is_allocated_fp( heir ) ) { |
---|
98 | if ( _Thread_Allocated_fp != NULL ) |
---|
99 | _Context_Save_fp( &_Thread_Allocated_fp->fp_context ); |
---|
100 | _Context_Restore_fp( &heir->fp_context ); |
---|
101 | _Thread_Allocated_fp = heir; |
---|
102 | } |
---|
103 | #else |
---|
104 | if ( executing->fp_context != NULL ) |
---|
105 | _Context_Save_fp( &executing->fp_context ); |
---|
106 | |
---|
107 | if ( heir->fp_context != NULL ) |
---|
108 | _Context_Restore_fp( &heir->fp_context ); |
---|
109 | #endif |
---|
110 | #endif |
---|
111 | |
---|
112 | _Context_Switch( &executing->Registers, &heir->Registers ); |
---|
113 | |
---|
114 | executing = _Thread_Executing; |
---|
115 | |
---|
116 | _ISR_Disable( level ); |
---|
117 | } |
---|
118 | |
---|
119 | _Thread_Dispatch_disable_level = 0; |
---|
120 | |
---|
121 | _ISR_Enable( level ); |
---|
122 | |
---|
123 | if ( _Thread_Do_post_task_switch_extension || |
---|
124 | executing->do_post_task_switch_extension ) { |
---|
125 | executing->do_post_task_switch_extension = FALSE; |
---|
126 | _API_extensions_Run_postswitch(); |
---|
127 | } |
---|
128 | |
---|
129 | } |
---|