cxsempd1.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

/*
mode 0 : wait if semaphore not present 
mode 1 : do NOT wait if semaphore not present, return immediatedly
*/

byte K_I_Semaphore_Get_Common(byte sem_num, word16 timecnt, byte mode)	
{
	SEM *sem_ptr;

	if (sem_num >= MAX_SEMAPHORES)
		{
		return(K_ERROR);	/* return good status to caller */
		}
	K_I_Disable_Sched();
	sem_ptr = &sem_array[sem_num];	/* CMX semaphore handler. */
	if (sem_ptr->fwlink == NULL)
		{
		K_I_Func_Return();	/* release task block */
		return(K_ERROR);	/* return good status to caller */
		}
	if (!sem_ptr->sem_count)
		{
		if (mode)
			{
			K_I_Func_Return();	/* release task block */
			return(K_SEMAPHORE_NONE);	/* return error that semaphore
											had not been posted to */
			}
		if (sem_ptr->fwlink != (tcbpointer)sem_ptr)	/* is at least one task waiting
																		on is semaphore */
			{
			activetcb->fwlink = sem_ptr->bwlink->fwlink;
			sem_ptr->bwlink->fwlink = activetcb;
			activetcb->bwlink = sem_ptr->bwlink;
			sem_ptr->bwlink = activetcb;
			}
		else
			{
			sem_ptr->fwlink = sem_ptr->bwlink = activetcb;
			activetcb->fwlink = activetcb->bwlink = (tcbpointer)sem_ptr;
			}
		if (K_I_Time_Common(timecnt,SEMAPHORE))	/* go suspend task. */
			return(K_TIMEOUT);	/* return the warning: that the time period expired */
		else
			return(K_OK);
		}
	--sem_ptr->sem_count;
	K_I_Func_Return();
	return(K_OK);
}	/* K_I_Semaphore_Get_Common */