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The Scheduler
[Multitasking]

Functions
void	sched_enter_critical_region ()
	Disable the scheduling of the other tasks. Warning: ATTENTION!!! Remember to call sched_leave_critical_region() when the task exits from the critical region. Otherwise the whole system could be blocked, because the scheduling of the other tasks is disabled after a task calls this function.
void	sched_leave_critical_region ()
	Re-enable scheduling for the other tasks.
bool	is_sched_enabled ()
	Return if the scheduling is enabled or not. Returns: TRUE if the scheduling is enabled FALSE otherwise.
__inline__ void	scheduler ()
	This is a simple round robin scheduler.
Variables
semaphore_t	sched_enabled
	A semaphore to enable or disable scheduling (used to manage critical regions).

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Detailed Description

The routines for the tasks scheduling.

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Function Documentation

bool is_sched_enabled (    )

Return if the scheduling is enabled or not. Returns: TRUE if the scheduling is enabled FALSE otherwise. Definition at line 1070 of file task.c. { if( atomic_read(&sched_enabled) ) return( TRUE ); else return( FALSE ); }

void sched_enter_critical_region (    )

Disable the scheduling of the other tasks. Warning: ATTENTION!!! Remember to call sched_leave_critical_region() when the task exits from the critical region. Otherwise the whole system could be blocked, because the scheduling of the other tasks is disabled after a task calls this function. Definition at line 1055 of file task.c. { DOWN( &sched_enabled ); }

void sched_leave_critical_region (    )

Re-enable scheduling for the other tasks. Definition at line 1061 of file task.c. { UP( &sched_enabled ); }

__inline__ void scheduler (    )  [static]

This is a simple round robin scheduler. This routine is called by the dispatcher() every time a task must be scheduled. Definition at line 1083 of file task.c. { task_t *p=NULL; int count; // Look for the tasks that need to sleep. count = count_queue( &ready_queue ); for ( ; count; --count ) { p = pick_queue( &ready_queue ); if ( p->state==WAIT ) { rem_queue( &ready_queue, p ); add_queue( &wait_queue, p ); } } // Look for the tasks that need to wake-up. count = count_queue( &wait_queue ); for ( ; count; --count ) { p = pick_queue( &wait_queue ); if ( p->state==READY ) { rem_queue( &wait_queue, p ); add_queue( &ready_queue, p ); } } // Select a new task to run (Round Robin). curr_task = pick_queue( &ready_queue ); if (curr_task == NULL) curr_task=idle_task; }

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Variable Documentation

semaphore_t sched_enabled

A semaphore to enable or disable scheduling (used to manage critical regions). Definition at line 1047 of file task.c.

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