#include "stdinc.h"
#include "uth.h"

//
// Purpose:	Like mileB.c except RR scheduling
//		2 threads independently compute fibonacci numbers but
//		scheduler interrupts periodically to give control to other
//		thread (i.e., preemption).  Also, a high-priority monitor
//		thread periodically records CPU usage progress
// Usage:	mileC [-d debug]
// Notes:	none
// Functions:	uth_init, uth_create, uth_yield, uth_exit, uth_join, uth_self,
//		uth_usage
// History:
// o 10 Apr 2007	kenw: creation
//

typedef void (func_t)(void);	// 0-arg function

struct th_arg {
  int	id;
  int	n;
};
typedef struct th_arg th_arg_t;

// --| constants |--
const int	nworkers = 2;	// # fibFiber
const int	TickSz = 10;	// tick size (msec); 0 ==> no clock
const int	Nperiods = 4;	// # monitoring periods

// --| globals |--
int		debug = 0;
u_int64_t	fib[nworkers];	// result for each thrd
uth_tid_t	tid[nworkers];
int		usage[nworkers][Nperiods];

// --| prototypes |--
void getArgs(int argc, char *argv[]);

// --| fib thread |-- 
//	compute fibonacci number
//	fib(5)  = fib(4) + fib(3)
//		= fib (3) + fib(2) + fib(2) + fib(1)
//		= fib (2) + fib(1) + fib(2) + fib(2) + fib(1)
//		= fib (1) + fib(1) + fib(1) + fib(1) + fib(1) + 3 fib(0)
//		= 5
void
fibFiber( void *myarg ) {
  int	whoami = ((th_arg_t *)myarg)->id;
  int	n = ((th_arg_t *)myarg)->n;
  int	ncall = 0;
  u_int64_t	a, b, tmp;

printf( "+ BEGIN fibFiber %d (tid %d), n = %d\n", whoami, uth_self(), n );

  for (int i=0; i<1000; i++) {	// compute 1000 times
    if ( n == 0)	b = 0;
    else {
      a = 0;	b = 1;
      for (int i=1; i<n; i++) {
        tmp = a + b;
        a = b;
        b = tmp;
        fib[whoami] = b;
      }
    }
  }

  Tab(1+whoami);
  printf( "+++++ END fibFiber %d with fib(%d) = %ld +++++\n", whoami, n, b );
  uth_exit( 0 );
}

// --| usage monitor |--
void
usage_mon( void ) {
  for (int i=0; i<4; i++) {
    uth_sleep( 100 );
    for (int j=0; j<nworkers; j++)	usage[j][i] = uth_usage( tid[j] );
  }
  uth_exit( 0 );
}

// --| root of all evil |--
int
main(int argc, char *argv[]) {
  th_arg_t	fibArg[nworkers];
  int		result;
  uth_tid_t	montid;
  int		debug;

  setlinebuf(stdout);
  printf( "+ BEGIN:  Parent fiber\n" );
  getArgs( argc, argv );
  uth_init( nworkers+4, TickSz, debug = 1 );

  for (int i=0; i<nworkers; i++) {	// create fib fibers
    fibArg[i].id = i;
    fibArg[i].n = 10000;
    Uth_create( &tid[i], LO_PRI, (func_t *)&fibFiber, &fibArg[i] );
  }
  Uth_create( &montid, HI_PRI, (func_t *)&usage_mon, NULL );

  for (int i=0; i<nworkers; i++) {	// wait for fibers
    uth_join( tid[i], &result );
  }

  uth_join( montid, &result );
  printf( "\nUsage Statistics:\n" );
  for (int i=0; i<nworkers; i++) {
    printf( "\tThread %2d:", i );
    for (int j=0; j<Nperiods; j++) {
      printf( "  %4d", usage[i][j] );
    }
    printf( "\n" );
  }

  printf( "+++ DONE:  Parent fiber\n" );
}

void
getArgs(int argc, char *argv[]) {
  int	c;
  int	ok = 1;
       
  while ((c = getopt(argc, argv, "d:")) != -1) {
    switch(c) {
      case 'd':
        debug = atoi(optarg);
      	break;
      default:	
        ok = 0;
	fprintf( stderr, "getArgs:  Unknown flag %c\n", c );
        break;
    }
  }

  if (!ok) {
    fprintf(stderr, "Usage: fib-rr [-d debug]\n");
    exit(1);
  }
}