/*
 * Copyright (C) 2007 pluknet. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <sys/time.h>

enum {
	idle = 0,
	begin,
	work,
	end
} state_hdr;

#define NCPU 8

struct cpu_hdr {
	int state;
	struct timeval time;
	int said[4];
} cpu[NCPU];


static int
do_work(int remain) {
	int howlong;
	int i;
	struct timeval tp;

	for (i = 0; i < NCPU; ++i) {
		switch (cpu[i].state) {
		case idle:
			break;
		case begin:
			if (cpu[i].said[begin]++ == 0) {
				cpu[i].said[end] = 0;
				printf("CPU#%d: state=work ", i);
			}
			gettimeofday(&(cpu[i].time), NULL);
			howlong = random() & 7;
			printf("howlong=%d\n", howlong);
			cpu[i].time.tv_sec += howlong;
			cpu[i].state = work;
			break;
		case work:
//			if (cpu[i].said[work]++ == 0)
//				printf("i=%d state=work\n", i);
			gettimeofday(&tp, NULL);
			if (tp.tv_sec >= cpu[i].time.tv_sec)
				cpu[i].state = end;
			break;
		case end:
			if (cpu[i].said[end]++ == 0) {
				cpu[i].said[begin] = 0;
				printf("CPU#%d: state=free\n", i);
			}
			cpu[i].state = idle;
			remain--;
			break;
		default:
			printf("\n\n\t\tNOT REACHABLE!\n\n\n");
			/* ENOTREACH */
			return (-1);
		}
	}
	return remain;
}

int
main(void) {
	const int G = 40;	/* total request amount */
	int s = 0;		/* current request */
	int i, j;
	int request = 0;
	int remain = 0;

	srandomdev();

	for (i = 0; i < NCPU; ++i) {
		cpu[i].state = idle;
		for (j = 0; j < 4; ++j)
			cpu[i].said[j] = 0;
	}

	while (s++ < G) {
		if (request == 0)
			request = random() & 1;
		if (request)
			printf("s=%d presents\n", s);
		else
			printf("s=%d absents\n", s);
		if (request == 1)
			for (i = 0; i < NCPU; ++i)
				if (cpu[i].state == idle) {
					cpu[i].state = begin;
					request = 0;
					remain++;
					break;
				}
		if (request == 1) {
			s--;
			sleep(1);
		}
		if ((remain = do_work(remain)) == -1)
			return(-1);
	}
//	printf("%d\n", remain);
	while((remain = do_work(remain)))
//	printf("%d\n", remain);
		if (remain == -1)
			return(-1);
	return(0);
}