Task Scheduling in PiR2  v04
as of 2020 E May 05
by D@CC

Schedule of Tasks
The actual schedule is an array (named a_t) of future tasks. Each row contains
	1. launch-time (earliest time that it can be launched
	2. task name to launch
	3. parameter1 for the task when launched

Callable Tasks
**************
Add_TASK()			#done --
Next_Launchable_TASK_Number()
Remove_TASK()			#done --
TASK_Sleep()			#done   actually runs the task
Next_TASK()
init_TASK()			#done --
launch_TASK()			#done --

Add_TASK(a_t,dT, task_name, parameter1)
    self -explanatory, will launch after dT sec

Next_Launchable_TASK_Number(a_t)
# returns the number of the next task that can be launched at this time or -1

Launch_TASK(a_t,n)
 actually runs task n

Remove_TASK_Number(a_t, n)
 remove task number n from the task schedule

TASK_Sleep(a_t,dT)
# This will run any launchable tasks, if none it will sleep
 this will 1) time_in= time  (actual clock time)
	   2) time_resume = time + dT
	      # launch any launchable tasks while time not expired
	   3) while time < time_resume  #(time is actual clock time)
		#run 1 launchable task
		Next_Task= Next_Launchable_Task_Number
		if Next_Task == -1 :
				# no more tasks so
			break	# out of the while
		else :
			3) Remove_Task(a_t,Next_task)
	   		4) Launch_Task(a_t,Next_task)
		#end if
	      #end while
	      # there is no more time or no more launchable tasks
	   4) if time_resume > time :  #if there is more time
		sleep (time_resume - time)
	      #end if
#end def

NexT_TASK(a_t)
# this will return the # of the Next Task to run
#    NB its launch-time might be in the future
# if returns 0, there are no tasks in the schedule

**********************************************************************************************************

Main PiR2 routine
def pir2_main()
	#############################################################
	# ????
	#############################################################
	array a_t[100,3]		#define the schedule array
	sec1=1
	sec2=2
	sec15=15
	process1() #init
	init_TASK(a_t,100)
	add_TASK(a_t,0,"PiR2_Init","")
	TASK_Sleep(-1)	#schedule PiR2_Init for "yesterday"		# Initialize PiR2 main
	#subrB()

	add_TASK(a_t,0,"PiR2_Sound_Detected","")
	# at end it will  reschedule itself then TASK_Sleep(sec(1))  # keep doing this every 1 sec until ^C

	add_TASK(a_t,0,"PiR2_Loop","")
	# at end it will  reschedule itself then TASK_Sleep(sec(15))  # keep doing this every 15 sec until ^C

	while True :
	   try :
		while True ;
		    #			#Launch any launchable tasks
		    TASK_Sleep(sec2)	# if none, sleep for 2 seconds
		#end while
	   escape:
		break #out of while
	#end while
	# exit from program
	n=Next_TASK(a_t)
	if n>0 :
		name=a_t(n, 1)
		print("^C but task:",name," remains unlaunched")
	#end if
	return 0
# end def

def PiR2_Sound_Detected(parm1)
	print("in PiR2_Sound_Detected")
	add_TASK(a_t,sec1,'PiR2_Sound_Detected',"SD")
	return
#end def

def PiR2_Loop(parm1)
	print("in PiR2_Loop")
	input("reschedule this Task"), answer
	if answer != "n"
		add_TASK(a_t,sec15,'PiR2_Loop',"L")
	#end if
	return
#end def

def PiR2_Init(parm1)
	print("in PiR2_Init")
	return
#end def



**********************************************************************************************************

def init_TASK(a_t,n)
# Purpose:  to initialize the schedule array
	###################################
	#
	###################################
	a_t=[n,3]
	for i = 0 to len(a_t) :
		remove_TASK(a_t,i)
	#end for
#end def

def add_TASK(a_t,dT,task_name,parm1_value)
	is_room = False
	for i=0 to len(a_t):
		if a_t[i,0]="" :
			is_room = True
			##############################################
			# time
			##############################################
			a_t[i,0]=time+dT
			a_t[i,1]=task_name
			a_t[i,2]=parm1_value
		#end if
	# end for
	if is_room == False : 
		print("PiR2 warning - No room in schedule array: a_t[]")
	#end if
	return
#end def

def launch_TASK(a_t,n)
#Purpose:	to launch a task
	if time > a_t[n,0] :	#is it time to launch it
		name= a_t[n,1]
		parm1 = a_t[n,2]
		#
		# launched tasks don't return any result
		# parameters are "called by value"
		#
		if name="PiR2SoundDetected"	:call PiR2_SoundDetected(parm1)
		if name="PiR2Loop" 		:call PiR2_Loop(parm1)
		if name="PiR2Init"		:call PiR2_Init(parm1)
	else :
		print("PiR2 Warning: Its too early to launch task:",n)
	#end if
	return
#end def

def remove_TASK(a_t,n)
#Purpose:	to remove task n from the array
	if n > len(a_t) :
		a_t[n,0]=""
		a_t[n,1]=""
		a_t[n,2]=""
	else :
		print ("Pir2 warning:", n, " is too large")
	#end if
	# removed it whether it was already romoved or not
	return
# end def

def display_TASK_array(a_t)
#Purpose : To display all non-null rows of the TASK array
	is_empty= True
	###########################################
	# syntax of for
	###########################################
	print("row","   time         , name         parm1")
	for i=0 to len(a_t) :
		if (a_t[i,0] != "" ) :
			is_empty= False
			print (i,",",a_t[i,0],",",a_t[i,1],",",a_t[i,2])
		#end if
	#end for
	if is_empty =="" :
		print"a_t is empty")
	#end if
	return
#end def

/PiR2_Task_Scheduling_04.txt