source: rtems/cpukit/score/src/threaddispatch.c @ a4819530

4.104.114.84.9
Last change on this file since a4819530 was 63f786e, checked in by Joel Sherrill <joel.sherrill@…>, on Apr 5, 2007 at 10:13:08 PM

2007-04-05 Joel Sherrill <joel@…>

  • itron/src/itrontime.c: Fix typo.
  • score/include/rtems/score/tod.h: Add TOD_TICKS_PER_SECOND macro.
  • score/src/iterateoverthreads.c: Safely take NULL as argument.
  • score/src/threaddispatch.c: Formatting.
  • Property mode set to 100644
File size: 3.9 KB
Line 
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.rtems.com/license/LICENSE.
11 *
12 *  $Id$
13 */
14
15#if HAVE_CONFIG_H
16#include "config.h"
17#endif
18
19#include <rtems/system.h>
20#include <rtems/score/apiext.h>
21#include <rtems/score/context.h>
22#include <rtems/score/interr.h>
23#include <rtems/score/isr.h>
24#include <rtems/score/object.h>
25#include <rtems/score/priority.h>
26#include <rtems/score/states.h>
27#include <rtems/score/sysstate.h>
28#include <rtems/score/thread.h>
29#include <rtems/score/threadq.h>
30#include <rtems/score/userext.h>
31#include <rtems/score/wkspace.h>
32
33/*PAGE
34 *
35 *  _Thread_Dispatch
36 *
37 *  This kernel routine determines if a dispatch is needed, and if so
38 *  dispatches to the heir thread.  Once the heir is running an attempt
39 *  is made to dispatch any ASRs.
40 *
41 *  ALTERNATE ENTRY POINTS:
42 *    void _Thread_Enable_dispatch();
43 *
44 *  Input parameters:  NONE
45 *
46 *  Output parameters:  NONE
47 *
48 *  INTERRUPT LATENCY:
49 *    dispatch thread
50 *    no dispatch thread
51 */
52
53#if ( CPU_INLINE_ENABLE_DISPATCH == FALSE )
54void _Thread_Enable_dispatch( void )
55{
56  if ( --_Thread_Dispatch_disable_level )
57    return;
58  _Thread_Dispatch();
59}
60#endif
61
62void _Thread_Dispatch( void )
63{
64  Thread_Control   *executing;
65  Thread_Control   *heir;
66  ISR_Level         level;
67
68  executing   = _Thread_Executing;
69  _ISR_Disable( level );
70  while ( _Context_Switch_necessary == TRUE ) {
71    heir = _Thread_Heir;
72    _Thread_Dispatch_disable_level = 1;
73    _Context_Switch_necessary = FALSE;
74    _Thread_Executing = heir;
75    executing->rtems_ada_self = rtems_ada_self;
76    rtems_ada_self = heir->rtems_ada_self;
77    if ( heir->budget_algorithm == THREAD_CPU_BUDGET_ALGORITHM_RESET_TIMESLICE )
78      heir->cpu_time_budget = _Thread_Ticks_per_timeslice;
79    _ISR_Enable( level );
80
81    heir->ticks_executed++;
82
83    /*
84     * Switch libc's task specific data.
85     */
86    if ( _Thread_libc_reent ) {
87      executing->libc_reent = *_Thread_libc_reent;
88      *_Thread_libc_reent = heir->libc_reent;
89    }
90
91    _User_extensions_Thread_switch( executing, heir );
92
93    /*
94     *  If the CPU has hardware floating point, then we must address saving
95     *  and restoring it as part of the context switch.
96     *
97     *  The second conditional compilation section selects the algorithm used
98     *  to context switch between floating point tasks.  The deferred algorithm
99     *  can be significantly better in a system with few floating point tasks
100     *  because it reduces the total number of save and restore FP context
101     *  operations.  However, this algorithm can not be used on all CPUs due
102     *  to unpredictable use of FP registers by some compilers for integer
103     *  operations.
104     */
105
106#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
107#if ( CPU_USE_DEFERRED_FP_SWITCH != TRUE )
108    if ( executing->fp_context != NULL )
109      _Context_Save_fp( &executing->fp_context );
110#endif
111#endif
112
113    _Context_Switch( &executing->Registers, &heir->Registers );
114
115#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
116#if ( CPU_USE_DEFERRED_FP_SWITCH == TRUE )
117    if ( (executing->fp_context != NULL) &&
118         !_Thread_Is_allocated_fp( executing ) ) {
119      if ( _Thread_Allocated_fp != NULL )
120        _Context_Save_fp( &_Thread_Allocated_fp->fp_context );
121      _Context_Restore_fp( &executing->fp_context );
122      _Thread_Allocated_fp = executing;
123    }
124#else
125    if ( executing->fp_context != NULL )
126      _Context_Restore_fp( &executing->fp_context );
127#endif
128#endif
129
130    executing = _Thread_Executing;
131
132    _ISR_Disable( level );
133  }
134
135  _Thread_Dispatch_disable_level = 0;
136
137  _ISR_Enable( level );
138
139  if ( _Thread_Do_post_task_switch_extension ||
140       executing->do_post_task_switch_extension ) {
141    executing->do_post_task_switch_extension = FALSE;
142    _API_extensions_Run_postswitch();
143  }
144
145}
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