cxrsrel.c

CMEX source code RTOS for atmel atmega128

/*********************************************************

Copyright (c) CMX Company. 1999. All rights reserved

*********************************************************/
/* version 5.30 */

#define CMXMODULE 1

#include <cxfuncs.h>	/* get cmx include header file */
#include <cxextern.h>	/* get cmx include header file */

#ifdef CMXTRACKER
#include <cmxtrack.h>	/* get cmx include header file */
#endif

/*****************************************************************
 This lets a task that owns a resource, to release it. Once the resource
 is released, if another task is waiting for it, then that task will
 automatically become the owner.
******************************************************************/
byte K_Resource_Release(byte res_grp)
{
	RESHDR *res_ptr;

	if (res_grp >= MAX_RESOURCES)	/* see if resource group OK */
		{
#ifdef CMXTRACKER
		if (CMXTRACKER_ON)
			{
			cmxtracker_in2(CXRSREL_K_ERROR,res_grp);
			}
#endif
		return(K_ERROR);	/* no, return error status */
		}

	res_ptr = &res_que[res_grp];	/* get address of resource */
	if (res_ptr->owner != activetcb)	/* see if task really "owns" this. */
		{
#ifdef CMXTRACKER
		if (CMXTRACKER_ON)
			{
			cmxtracker_in2(CXRSREL_K_RESOURCE_NOT_OWNED,res_grp);
			}
#endif
		return(K_RESOURCE_NOT_OWNED);	/* resource not owned by this task */
		}
	K_I_Disable_Sched();	/* set task block */
	/* restore original task's priority */
	active_priority = res_ptr->owner_priority;
	if (res_ptr->owner->priority != active_priority)
		{
		/* update linked list to put owner in correct spot */
		K_I_Unlink(res_ptr->owner);
		K_I_Priority_In(res_ptr->owner,active_priority);
		}
	/* see if another task waiting for this resource. */
	if ((res_ptr->owner = res_ptr->fwlink) != (tcbpointer)res_ptr)
		{
		/* properly adjust the linked list. */
		res_ptr->fwlink = res_ptr->fwlink->fwlink;
		res_ptr->fwlink->bwlink = res_ptr->owner->bwlink;
		res_ptr->owner->tcbstate = RESUME;	/* wake task that was sleeping. */
		if (res_ptr->owner->priority < active_priority) 
			PREEMPTED;	/* yes, set the preempted scheduling flag */
		res_ptr->owner_priority = res_ptr->owner->priority;
		}
	else
		{
		res_ptr->owner = NULL;
		}
#ifdef CMXTRACKER
		if (CMXTRACKER_ON)
			{
			cmxtracker_in2(CXRSREL_K_OK,res_grp);
			}
#endif
	K_I_Func_Return();	/* release task block */
	return(K_OK);	/* return good status to caller */
}