KERNEL DESIGN ISSUES - Hard Real-Time Computing Systems: Predictable Scheduling Algorithms and Applications - page 375

10.5.4 TASK MANAGEMENT

It concerns creation, activation, suspension, and termination of tasks. The create prim-
itive allocates and initializes all data structures needed by a task and puts the task in
SLEEP. A guarantee is performed for HARD tasks.

/*-----------------------------------------------------------*/
/* create -- creates a task and puts it in sleep state */
/*-----------------------------------------------------------*/
proc

create (
char name[MAXLEN+1], /* task name */

proc (*addr)(), /* task address */

int type, /* type (HARD, NRT) */

float period, /* period or priority */

float wcet) /* execution time */

proc p;
<disable cpu interrupts>
p = getfirst(&freetcb);
if (p == NIL) abort(NO TCB);
if (vdes[p].type == HARD)
if (!guarantee(p)) return(NO GUARANTEE);
vdes[p].name = name;
vdes[p].addr = addr;
vdes[p].type = type;
vdes[p].state = SLEEP;
vdes[p].period = (int)(period / time unit);
vdes[p].wcet = (int)(wcet / time unit);
vdes[p].util = wcet / period;
vdes[p].prt = (int)period;
vdes[p].dline = MAX LONG + (long)(period - PRT LEV);
<initialize process stack>
<enable cpu interrupts>
return(p);

}