/* -------------------------------------------------------------------------  * This program is a next-event simulation of a multi-user time-sharing * system.  All users begin with the thinking task and the simulation ends  * when the simulation clock time meets or exceeds the terminal time STOP. *  * Name              : ttr.c (Think-Type-Receive) * Author            : Larry Leemis  * Language          : ANSI C  * Latest Revision   : 10-12-04  * Compile with      : gcc -lm ttr.c rngs.c  * -------------------------------------------------------------------------  */#include <stdio.h>#include <math.h>#include "rngs.h"#define START    0.0                    /* initial simulation clock time  */#define STOP     100.0                  /* terminal time                  */#define N        5                      /* number of servers              */   long Equilikely(long a, long b)/* =================================================================== * Returns an equilikely distributed integer between a and b inclusive.  * NOTE: use a < b * =================================================================== */{  return (a + (long) ((b - a + 1) * Random()));}   double Uniform(double a, double b)/* ===========================================================  * Returns a uniformly distributed real number between a and b.  * NOTE: use a < b * =========================================================== */{   return (a + (b - a) * Random());}      double GetThinkTime(void)/* ---------------------------- * generate the next think time  * ---------------------------- */ {       SelectStream(0);  return (Uniform(0.0, 10.0));}      double GetKeystrokeTime(void)/* ------------------------------- * generate the next keystroke time  * ------------------------------- */ {       SelectStream(1);  return (Uniform(0.15, 0.35));}      long GetNumKeystrokes(void)/* --------------------------------- * generate the number of keystrokes  * --------------------------------- */ {       SelectStream(2);  return (Equilikely(5, 15));}      long GetNumCharacters(void)/* --------------------------------- * generate the number of characters  * --------------------------------- */ {       SelectStream(3);  return (Equilikely(50, 300));}  int main(void){  int i;                             /* loop parameter                         */  int j;                             /* index for the next event               */  long nevents = 0;                  /* number of events during the simulation */  long nsearches = 0;                /* number of event list searches          */  double tnow;                       /* simulation clock                       */  double temp;                       /* used to find time of next event        */  double ReceiveRate = 1.0 / 120.0;  /* time to transmit a character           */  struct {    double time;                     /* event time                             */    int    type;                     /* event type                             */    int    info;                     /* ancillary information                  */  } event[N];  PlantSeeds(0);  tnow = START;  for (i = 0; i < N; i++) {    event[i].time = GetThinkTime();    event[i].type = 1;    event[i].info = 0;  }  while (tnow < STOP) {     nevents++;    temp = 100.0 * STOP;    for (i = 0; i < N; i++) {      nsearches++;      if (event[i].time <= temp) {        temp = event[i].time;        j = i;      }    }    tnow = event[j].time;       if (event[j].type == 1) {           /* complete thinking event  */      event[j].time = tnow + GetKeystrokeTime();      event[j].type = 2;      event[j].info = GetNumKeystrokes();    }    else if (event[j].type == 2) {      /* complete keystroke event */      event[j].info--;       if (event[j].info > 0) {        event[j].time = tnow + GetKeystrokeTime();      }      else {                            /* last keystroke           */        event[j].time = tnow + ReceiveRate;         event[j].type = 3;        event[j].info = GetNumCharacters();      }    }    else if (event[j].type == 3) {      /* complete character recpt */      event[j].info--;       if (event[j].info > 0) {        event[j].time = tnow + ReceiveRate;       }      else {                            /* last character           */        event[j].time = tnow + GetThinkTime();         event[j].type = 1;        event[j].info = 0;      }    }    else {      printf("\nerror: event type must be 1, 2, or 3\n");      }  }   printf("\nsimulation end time .... = %6.2f\n", tnow);  printf("\nfinal status of the event list:\n");    for (i = 0; i < N; i++)    printf("%8d %14.3f %8d %8d\n", i, event[i].time, event[i].type, event[i].info);   printf("\nnumber of events ....... = %ld\n", nevents);  printf("\nnumber of searches ..... = %ld\n", nsearches);  printf("\n");  return (0);}