thread.h

开放源码的嵌入式开发环境

/**
 *  The following declares the dispatch critical section nesting
 *  counter which is used to prevent context switches at inopportune
 *  moments.
 */
SCORE_EXTERN volatile uint32_t   _Thread_Dispatch_disable_level;

/**
 *  If this is non-zero, then the post-task switch extension
 *  is run regardless of the state of the per thread flag.
 */
SCORE_EXTERN uint32_t   _Thread_Do_post_task_switch_extension;

/**
 *  The following holds how many user extensions are in the system.  This
 *  is used to determine how many user extension data areas to allocate
 *  per thread.
 */
SCORE_EXTERN uint32_t   _Thread_Maximum_extensions;

/**
 *  The following is used to manage the length of a timeslice quantum.
 */
SCORE_EXTERN uint32_t   _Thread_Ticks_per_timeslice;

/**
 *  The following points to the array of FIFOs used to manage the
 *  set of ready threads.
 */
SCORE_EXTERN Chain_Control *_Thread_Ready_chain;

/**
 *  The following points to the thread which is currently executing.
 *  This thread is implicitly manipulated by numerous directives.
 */
SCORE_EXTERN Thread_Control *_Thread_Executing;

/**
 *  The following points to the highest priority ready thread
 *  in the system.  Unless the current thread is not preemptibl,
 *  then this thread will be context switched to when the next
 *  dispatch occurs.
 */
SCORE_EXTERN Thread_Control *_Thread_Heir;

/**
 *  The following points to the thread whose floating point
 *  context is currently loaded.
 */
#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
SCORE_EXTERN Thread_Control *_Thread_Allocated_fp;
#endif

/**
 * The C library re-enter-rant global pointer. Some C library implementations
 * such as newlib have a single global pointer that changed during a context
 * switch. The pointer points to that global pointer. The Thread control block
 * holds a pointer to the task specific data.
 */
SCORE_EXTERN struct _reent **_Thread_libc_reent;

/**
 *  This routine performs the initialization necessary for this handler.
 */
void _Thread_Handler_initialization (
  uint32_t     ticks_per_timeslice,
  uint32_t     maximum_extensions,
  uint32_t     maximum_proxies
);

/**
 *  This routine creates the idle thread.
 *
 *  @warning No thread should be created before this one.
 */
void _Thread_Create_idle( void );

/**
 *  This routine initiates multitasking.  It is invoked only as
 *  part of initialization and its invocation is the last act of
 *  the non-multitasking part of the system initialization.
 */
void _Thread_Start_multitasking( void );

/**
 *  This routine is responsible for transferring control of the
 *  processor from the executing thread to the heir thread.  As part
 *  of this process, it is responsible for the following actions:
 *
 *     + saving the context of the executing thread
 *     + restoring the context of the heir thread
 *     + dispatching any signals for the resulting executing thread
 */
void _Thread_Dispatch( void );

/**
 *  Allocate the requested stack space for the thread.
 *  return the actual size allocated after any adjustment
 *  or return zero if the allocation failed.
 *  Set the Start.stack field to the address of the stack
 */

uint32_t   _Thread_Stack_Allocate(
  Thread_Control *the_thread,
  uint32_t   stack_size
);

/**
 *  Deallocate the Thread's stack.
 */
void _Thread_Stack_Free(
  Thread_Control *the_thread
);

/**
 *  This routine initializes the specified the thread.  It allocates
 *  all memory associated with this thread.  It completes by adding
 *  the thread to the local object table so operations on this
 *  thread id are allowed.
 *
 *  @note If stack_area is NULL, it is allocated from the workspace.
 *
 *  @note If the stack is allocated from the workspace, then it is
 *        guaranteed to be of at least minimum size.
 */
boolean _Thread_Initialize(
  Objects_Information                  *information,
  Thread_Control                       *the_thread,
  void                                 *stack_area,
  uint32_t                              stack_size,
  boolean                               is_fp,
  Priority_Control                      priority,
  boolean                               is_preemptible,
  Thread_CPU_budget_algorithms          budget_algorithm,
  Thread_CPU_budget_algorithm_callout   budget_callout,
  uint32_t                              isr_level,
  Objects_Name                          name
);

/**
 *  This routine initializes the executable information for a thread
 *  and makes it ready to execute.  After this routine executes, the
 *  thread competes with all other threads for CPU time.
 */
boolean _Thread_Start(
  Thread_Control           *the_thread,
  Thread_Start_types        the_prototype,
  void                     *entry_point,
  void                     *pointer_argument,
  uint32_t                  numeric_argument
);

/**
 *  This support routine restarts the specified task in a way that the
 *  next time this thread executes, it will begin execution at its
 *  original starting point.
 *
 *  TODO:  multiple task arg profiles
 */
boolean _Thread_Restart(
  Thread_Control           *the_thread,
  void                     *pointer_argument,
  uint32_t                  numeric_argument
);

/**
 *  This routine resets a thread to its initial state but does
 *  not restart it.
 */
void _Thread_Reset(
  Thread_Control      *the_thread,
  void                *pointer_argument,
  uint32_t             numeric_argument
);

/**
 *  This routine frees all memory associated with the specified
 *  thread and removes it from the local object table so no further
 *  operations on this thread are allowed.
 */
void _Thread_Close(
  Objects_Information  *information,
  Thread_Control       *the_thread
);

/**
 *  This routine removes any set states for the_thread.  It performs
 *  any necessary scheduling operations including the selection of
 *  a new heir thread.
 */
void _Thread_Ready(
  Thread_Control *the_thread
);

/**
 *  This routine clears the indicated STATES for the_thread.  It performs
 *  any necessary scheduling operations including the selection of
 *  a new heir thread.
 */
void _Thread_Clear_state(
  Thread_Control *the_thread,
  States_Control  state
);

/**
 *  This routine sets the indicated states for the_thread.  It performs
 *  any necessary scheduling operations including the selection of
 *  a new heir thread.
 */
void _Thread_Set_state(
  Thread_Control *the_thread,
  States_Control  state
);

/**
 *  This routine sets the TRANSIENT state for the_thread.  It performs
 *  any necessary scheduling operations including the selection of
 *  a new heir thread.
 */
void _Thread_Set_transient(
  Thread_Control *the_thread
);

/**
 *  This routine is invoked upon expiration of the currently
 *  executing thread's timeslice.  If no other thread's are ready
 *  at the priority of the currently executing thread, then the
 *  executing thread's timeslice is reset.  Otherwise, the
 *  currently executing thread is placed at the rear of the
 *  FIFO for this priority and a new heir is selected.
 */
void _Thread_Reset_timeslice( void );

/**
 *  This routine is invoked as part of processing each clock tick.
 *  It is responsible for determining if the current thread allows
 *  timeslicing and, if so, when its timeslice expires.
 */
void _Thread_Tickle_timeslice( void );

/**
 *  This routine is invoked when a thread wishes to voluntarily
 *  transfer control of the processor to another thread of equal
 *  or greater priority.
 */
void _Thread_Yield_processor( void );

/**
 *  This routine is invoked to rotate the ready queue for the
 *  given priority.  It can be used to yeild the processor
 *  by rotating the executing threads ready queue.
 */
void _Thread_Rotate_Ready_Queue(
  Priority_Control  priority
);

/**
 *  This routine initializes the context of the_thread to its
 *  appropriate starting state.
 */
void _Thread_Load_environment(
  Thread_Control *the_thread
);

/**
 *  This routine is the wrapper function for all threads.  It is
 *  the starting point for all threads.  The user provided thread
 *  entry point is invoked by this routine.  Operations
 *  which must be performed immediately before and after the user's
 *  thread executes are found here.
 */
void _Thread_Handler( void );

/**
 *  This routine is invoked when a thread must be unblocked at the
 *  end of a time based delay (i.e. wake after or wake when).
 */
void _Thread_Delay_ended(
  Objects_Id  id,
  void       *ignored
);

/**
 *  This routine changes the current priority of the_thread to
 *  new_priority.  It performs any necessary scheduling operations
 *  including the selection of a new heir thread.
 */
void _Thread_Change_priority (
  Thread_Control   *the_thread,
  Priority_Control  new_priority,
  boolean           prepend_it
);

/**
 *  This routine updates the priority related fields in the_thread
 *  control block to indicate the current priority is now new_priority.
 */
void _Thread_Set_priority(
  Thread_Control   *the_thread,
  Priority_Control  new_priority
);

/**
 *  This routine updates the related suspend fields in the_thread
 *  control block to indicate the current nested level.
 */
void _Thread_Suspend(
  Thread_Control   *the_thread
);

/**
 *  This routine updates the related suspend fields in the_thread
 *  control block to indicate the current nested level.  A force
 *  parameter of TRUE will force a resume and clear the suspend count.
 */
void _Thread_Resume(
  Thread_Control   *the_thread,
  boolean           force
);

/**
 *  This routine evaluates the current scheduling information for the
 *  system and determines if a context switch is required.  This
 *  is usually called after changing an execution mode such as preemptability
 *  for a thread.
 */
boolean _Thread_Evaluate_mode( void );

#ifndef RTEMS_INLINES
/**
 *  @note  If we are not using static inlines, this must be a real
 *         subroutine call.
 */
Thread_Control *_Thread_Get (
  Objects_Id           id,
  Objects_Locations   *location
);
#endif

#if (CPU_PROVIDES_IDLE_THREAD_BODY == FALSE)
/**
 *  This routine is the body of the system idle thread.
 */
Thread _Thread_Idle_body(
  uint32_t   ignored
);
#endif

/**  This defines the type for a method which operates on a single thread.
 */
typedef void (*rtems_per_thread_routine)( Thread_Control * );

/**
 *  This routine iterates over all threads regardless of API and
 *  invokes the specified routine.
 */
void rtems_iterate_over_all_threads(
  rtems_per_thread_routine routine
);

#ifndef __RTEMS_APPLICATION__
#include <rtems/score/thread.inl>
#endif
#if defined(RTEMS_MULTIPROCESSING)
#include <rtems/score/threadmp.h>
#endif

#ifdef __cplusplus
}
#endif

/**@}*/

#endif
/* end of include file */