//
// Programmer:    Craig Stuart Sapp <craig@ccrma.stanford.edu>
// Creation Date: Sat Feb  1 08:50:37 PST 2003
// Last Modified: Sat Feb  1 08:50:37 PST 2003
// Filename:      /usr/web/peabody/class/dmp2/lab/markov1/markov1.cpp
// Syntax:        C++ 
// $Smake:        g++ -O3 -o %b %f && strip %b
//
// Description:   Realizes Markov chain values for example.
//

#include <stdlib.h>
#include <iostream.h>

#define STATES 3

int transitionTable[STATES][STATES];

// function declarations:
double randfloat                 (void);
int    chooseNextEventFromTable  (int current, int table[STATES][STATES]);
void   setTable                  (int value, int table[STATES][STATES]);


//////////////////////////////////////////////////////////////////////////

int main(void) { 
   int i;

   // for demo purposes:
   transitionTable[0][0] = 20;
   transitionTable[0][1] = 50;
   transitionTable[0][2] = 30;
   transitionTable[1][0] = 35;
   transitionTable[1][1] = 25;
   transitionTable[1][2] = 40;
   transitionTable[2][0] = 70;
   transitionTable[2][1] = 14;
   transitionTable[2][2] = 16;

   int currentState = 0;
   for (i=0; i<1000; i++) {
      cout << currentState << " ";
      currentState = chooseNextEventFromTransitionTable(currentState);
   }
   return 0;
};


//////////////////////////////////////////////////////////////////////////


//////////////////////////////
//
// chooseNextEventFromTransitionTable -- choose the next note.
//

int chooseNextEventFromTransitionTable(int currentState) {
   int targetSum   = 0;
   int sum         = 0;
   int targetNote  = 0;
   int totalevents = 0;
   int i;

   currentState = currentState % STATES;  // remove any octave value
   for (i=0; i<STATES; i++) {
      totalevents += transitionTable[currentState][i];
   }
   targetSum   = (int)(randfloat() * totalevents + 0.5);
   while (targetNote < STATES &&
      sum+transitionTable[currentState][targetNote] < targetSum) {
      sum += transitionTable[currentState][targetNote];
      targetNote++;
   }

   return targetNote;
}



//////////////////////////////
//
// randfloat -- returns a random number between 0.0 and 1.0.
//

double randfloat(void) {
   return (double)rand()/RAND_MAX;
}



//////////////////////////////
//
// setTable -- set all values in the transition table to the given value.
//

void setTable(int value, int table[STATES][STATES]) {
   int i, j;
   for (i=0; i<STATES; i++) {
      for (j=0; j<STATES; j++) {
         table[i][j] = value;
      }
   }
}