cxrsrsv1.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 function allows a task to reserve or get this resource.

 if func_mode = 1, then means get resource if free, otherwise return

 if func_mode = 0, then if the resource is "owned" by another task,
 then this task will be suspended until this resource is free or time
 period expires.
*******************************************************************/
byte K_I_Resource_Common(byte res_grp,word16 timecnt,byte func_mode)
{
	RESHDR *res_ptr;
	tcbpointer tp;

	if (res_grp >= MAX_RESOURCES)	/* see if resource number allowed */
		{
#ifdef CMXTRACKER
		if (CMXTRACKER_ON)
			{
			cmxtracker_in3(CXRSRSV_K_ERROR,res_grp,func_mode);
			}
#endif
		return(K_ERROR);	/* no, return error status */
		}

	K_I_Disable_Sched();	/* set task block */

	res_ptr = &res_que[res_grp];	/* get address of resource */

	if (res_ptr->owner)	/* does a task own this resource? */
		{
		/* yes, what function was used. */
		if (func_mode)		/* did the K_Resource_Get function call this function */
			{
#ifdef CMXTRACKER
		if (CMXTRACKER_ON)
			{
			cmxtracker_in2(CXRSRSV_K_RESOURCE_OWNED,res_grp);
			}
#endif
			 K_I_Func_Return();	/* release task block */
			 return(K_RESOURCE_OWNED);	/* return error that resource is already owned */
			}
#ifdef CMXTRACKER
		if (CMXTRACKER_ON)
			{
			cmxtracker_in4(CXRSRSV_CALL,res_grp,timecnt);
			}
#endif
		/* place the task into the resource doubly linked wait list. */

	tp = (tcbpointer)res_ptr;	/* address of resource link list. */
	do /* insert tcb at appropriate wait slot, based on priority. */
		{
		tp = tp->fwlink;
		} while ((tp != (tcbpointer)res_ptr) && (tp->priority <= activetcb->priority));
	/* We should insert it just after prevtcb, just before tp. */

		activetcb->fwlink = tp->bwlink->fwlink;
		tp->bwlink->fwlink = activetcb;
		activetcb->bwlink = tp->bwlink;
		tp->bwlink = activetcb;

		if (res_ptr->fwlink->priority < res_ptr->owner->priority)
			{
			res_ptr->owner->priority = res_ptr->fwlink->priority;
			/* update linked list to put owner in correct spot */
			K_I_Unlink(res_ptr->owner);
			K_I_Priority_In(res_ptr->owner,res_ptr->owner->priority);
			}
		/*
			res_ptr->fwlink->priority is highest priority !!!
			which we will then raise owner to highest !!!
		*/
		/* go place task into suspended state. */
		if (K_I_Time_Common(timecnt,RESOURCE))
			{
#ifdef CMXTRACKER
			if (CMXTRACKER_ON)
				{
				cmxtracker_in1(CXRSRSV_DELAY_K_TIMEOUT);
				}
#endif
			return(K_TIMEOUT);	/* return the warning: that the time period expired */
			}
			else
			{
#ifdef CMXTRACKER
			if (CMXTRACKER_ON)
				{
				cmxtracker_in2(CXRSRSV_K_OK,res_grp);
				}
#endif
			return(K_OK);	
			}
		}
	/* NO, no task owned this resource. This task is now the owner of
		this resource */
	res_ptr->fwlink = res_ptr->bwlink = (tcbpointer)(res_ptr);
	res_ptr->owner = activetcb;
	res_ptr->owner_priority = activetcb->priority;
#ifdef CMXTRACKER
		if (CMXTRACKER_ON)
			{
			cmxtracker_in3(CXRSRSV_K_OK,res_grp,func_mode);
			}
#endif
	K_I_Func_Return();	/* release task block. */
	return(K_OK);	/* return good status. */
}