sark_timer.c File Reference

Timer routines for SARK. More...

#include <sark.h>

Functions
void	timer2_int_han (void)
	Interrupt handler for timer 2. Delegates to timer2_int()
void	event_register_timer (vic_slot slot)
	Register the use of the second timer on the core so that it can be used to provide delayed events via timer_schedule().
void	timer_schedule (event_t *e, uint time)
	Schedule an event to occur at some time in the future.
uint	timer_schedule_proc (event_proc proc, uint arg1, uint arg2, uint time)
	Allocates an event, initialises it with the supplied parameters and schedules it to occur at some time in the future.
void	timer_cancel (event_t *e, uint ID)
	Cancel a timer event that was previously scheduled.
void	timer_cancel_init (void)
	Initialise a statically allocated event to be used in place of an event that is cancelled at the head of the timer queue.
void	timer2_int (void)
	Interrupt handler for the timer which is handling timers.

Variables
static event_t	cancelled
	placeholder for events cancelled @ timer_queue head

Detailed Description

Timer routines for SARK.

Copyright

© The University of Manchester - 2009-2019

Author

Steve Temple, APT Group, School of Computer Science

Function Documentation

event_register_timer()

void event_register_timer

(

vic_slot

slot

)

Register the use of the second timer on the core so that it can be used to provide delayed events via timer_schedule().

A runtime error will occur if the VIC slot is already in use.

Parameters

slot	the VIC slot to use for the timer interrupt

timer_schedule()

void timer_schedule	(	event_t *	e,
		uint	time
	)

Schedule an event to occur at some time in the future.

Requires that (hardware) TIMER2 has been set up by a call to timer_register()

Note

this procedure assumes the following event conditions on entry:

e->next == NULL
e->time == 0

Parameters

e	event to execute
time	delay in microseconds (non-zero)

timer_schedule_proc()

uint timer_schedule_proc	(	event_proc	proc,
		uint	arg1,
		uint	arg2,
		uint	time
	)

Allocates an event, initialises it with the supplied parameters and schedules it to occur at some time in the future.

Requires that the second timer has been set up by a call to timer_register()

Parameters

proc	pointer to an event_proc
arg1	argument 1 to the event_proc
arg2	argument 2 to the event_proc
time	delay in microseconds (non-zero)

Returns

zero: if allocation of new event failed, one otherwise

timer_cancel()

void timer_cancel	(	event_t *	e,
		uint	ID
	)

Cancel a timer event that was previously scheduled.

The ID that was allocated when the timer was created must be given in case the timer has already executed and the event has possibly been recycled. This means that a timer event which may be cancelled must be allocated by event_new(), the ID noted and the event then scheduled with timer_schedule().

It is potentially quite difficult to cancel a timer at the head of the timer queue so in that case the timer is replaced with a placeholder with "proc" set to NULL and the placeholder is left to terminate on the timer interrupt.

Parameters

e	event to cancel
ID	ID of event to cancel

timer_cancel_init()

void timer_cancel_init

(

void

)

Initialise a statically allocated event to be used in place of an event that is cancelled at the head of the timer queue.

It is potentially quite difficult to cancel a timer at the head of the timer queue so in that case the timer is replaced with a placeholder with "proc" set to NULL and the placeholder is left to terminate on the timer interrupt.