/*************************************/
/* Demonstrate amdc semaphores       */
/* Kristi Cablk			     */
/*************************************/

/*
*/

#include "amdc96.h"
#include <stdio.h>

#define FETCHED 1
#define DATA    2
#define FETCH   3

/* initial value for the semaphore */
#define SEMCOUNT 3

Location	my_loc;

LocName		Sema;

Message fetch(LocName L);
void    doFetch(Message m, Location loc);
void    doStore(Message m, Location loc);
void    storeAt(Message m, LocName L);
void	initSemaphore(LocName sema, int c);
void	up(LocName sema);
void	down(LocName sema);

/*
 * This procedure is called by a process to 
 * fetch a record.
 */
Message fetch(LocName L)
{
  Message p;
  Destiny *d = (Destiny *)amdc_rawMsg(sizeof(Destiny));
  *d = amdc_makeDest(amdc_getNameOfLoc(my_loc),FETCHED,
		     (Script)amdc_rawScript);
  amdc_sendToAsDo(d,L,FETCH,(Script)doFetch);
  while ((p=amdc_getLoc(my_loc, FETCHED))==NULL)
    amdc_pollBlock();
  return p;
}

/*
 * This is a script to fetch a record.
 */
void doFetch(Message m, Location loc)
{
  Message p;
  Destiny d;
  LocName loc_name = amdc_getNameOfLoc(loc);
  memcpy(&d,m,sizeof(Destiny));
  if ((p=amdc_getLoc(loc,DATA))!=NULL) {
    amdc_sendToDest(p,d);
    amdc_freeMsg(m);
  } else amdc_putLoc(loc,m);
}

/*
 * This is a script to store a record - it will execute
 * the scripts of waiting "fetch" messages immediately.
 */
void doStore(Message m, Location loc)
{
  Message p;
  amdc_putLoc(loc,m);
  if ((p=amdc_getLoc(loc,FETCH)) != NULL) {
    (amdc_getScript(p))(p,loc);
  }
}

/*
 * This procedure is used by a process to store a 
 * record at a location.
 */
void storeAt(Message m, LocName L)
{
	amdc_sendToAsDo(m, L, DATA, (Script) doStore);
}

/*
 * This is a procedure to initialize the semaphore.  It should be called 
 * by only one process.
 */
void initSemaphore(LocName sema, int c)
{
	for (;c>0;c--) storeAt(amdc_rawMsg(0), sema);
}

/*
 * This is the procedure used to decrement the semaphore.
 */
void down(LocName sema)
{
	amdc_freeMsg(fetch(sema));
}

/*
 * This is the procedure used to increment the semaphore.
 */
void up(LocName sema)
{
	storeAt(amdc_rawMsg(0), sema);
}

Main()
{
  my_loc=amdc_getMyLoc();

  /* Create the location name of the semaphore */
  Sema = amdc_0DLocName(AMDC_AbsoluteSymbol(1,AMDC_SYMB_HASH));

  printf("I am node %d\n", amdc_getMyId());

  if (amdc_getMyId() == 0) {
	/* This is the master process */

	/* Initialize the semaphore to SEMCOUNT */
  	/* Call this only once! */
	initSemaphore(Sema, SEMCOUNT);

	/* Do some stuff... */

	down(Sema);
	/* perform critical section */
	up(Sema);

	/* Do some more stuff ... */
  }
  else {
	/* All other processes */

	/* Do some stuff... */

	down(Sema);
	/* perform critical section */
	up(Sema);

	/* Do some more stuff ... */
  }
}