/*
 * Pierre Hyvernat, exemple de programme pour le TP2 du cours info803.  C'est
 * presque une correction...
 */

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

typedef unsigned char octet ;
octet masque[8] = { 1,2,4,8,16,32,64,128 };



#define INVERSE


/* pour inverser l'ordre des bits dans un octet */
octet inverse_octet(octet o) {
 octet u=o; octet v=0;
 int i,b;
 for(i=0;i<8;i++) {
  b=u&1; u=u>>1;
   v=v<<1;v=v|b;
 }
 return v;
}

void process_octets(octet*T,int n) {
 int i;
#ifdef INVERSE
 int o;
 for(i=0;i<n/2;i++) { o=T[i] ; T[i] = T[n-i-1] ; T[n-i-1]=o ; }
#endif
 for(i=0;i<n;i++) T[i] = inverse_octet(T[i]) ;
}

void print_byte(octet o) {
 int i;
 for(i=0;i<8;i++) {
  printf("%u",o&1);
  o=o>>1;
 }
}

void print_float(const float x) {
 octet X[4] ;
 memcpy(X,&x, sizeof x) ;
 process_octets(X,4) ;

 octet w ;
 int i ;

 for(i=0;i<34;i++) { if((i==0) | (i==9) | (i==18) | (i==26)) printf("."); else printf(" "); } printf("\n");

/* bit de signe */
 w=X[0] ;
 printf("%u ",w&masque[0]);
 w=w>>1;

/* exposant */
 for(i=0;i<7;i++) {
 printf("%u",w&masque[0]);
 w=w>>1;
 }
 w=X[1];
 printf("%u ",w&masque[0]);
 w=w>>1;

/* mantisse */
 for(i=0;i<7;i++) {
 printf("%u",w&masque[0]);
 w=w>>1;
 }
 w=X[2];
 for(i=0;i<8;i++) {
 printf("%u",w&masque[0]);
 w=w>>1;
 }
 w=X[3];
 for(i=0;i<8;i++) {
 printf("%u",w&masque[0]);
 w=w>>1;
 }
 printf("\n");

}





int main (void) {

 octet xo[4] ;
 float x=0;
 float y=0;
 float res=0;
 float t;

 char c;
 int i,j;

 while(1) {
  c = getchar();
  switch(c) {

   case 'q' : printf("Quitting...\n") ; return(1) ; break ;

   case 'r' : printf("Representation of X:\n") ; print_float(x) ;
              printf("\nRepresentation of Y:\n") ; print_float(y) ;
              printf("\nRepresentation of R:\n") ; print_float(res) ;
              break ;

   case 'v' : printf("Value of X: %f\n",x) ;
              printf("\nValue of Y: %f\n",y) ;
              printf("\nValue of R: %f\n",res) ; break ;

   case 'X' : printf("Set value of X:  "); scanf("%f",&x) ; break ;
   case 'Y' : printf("Set value of Y:  "); scanf("%f",&y) ; break ;

   case 'b' : printf("Modify bit in X:\n") ;
              printf("  Which byte?  ") ; i=getchar()-48;
              printf("  Which bit?  ") ; j=getchar()-48;
              if ((i>0) && (i<5) && (j>0) && (j<9)) {
               memcpy(xo,&x,4) ;
               process_octets(xo,4);
               xo[i-1] = xo[i-1] ^ masque[j-1] ;
               process_octets(xo,4);
               memcpy(&x,xo,4) ;
              }
              break ;

   case 'S' : printf("Swap X and Y.\n") ; t=x; x=y; y=t; break ;
   case 'R' : printf("Swap X and R.\n") ; t=x; x=res; res=t; break ;

   case 'C' : if (y<x) printf("Y < X.\n") ;
              else if (y>x) printf("X < Y.\n") ;
              else if (y==x) printf("X == Y.\n") ;
              else printf("Comparison failed!!!\n") ;
              break ;

   case 'M' : printf("Multiply X and Y in R.\n") ; res = x*y ; break ;
   case 'A' : printf("Add X and Y in R.\n") ; res = x+y ; break ;
   case 'D' : printf("Divide X by Y in R.\n") ; res = x/y ; break ;

   case '\n' : break ;

   case 'h' : printf("Help: press \'q\'(uit), \'r\'(epresentation), \'v\'(alues), \'X\' or \'Y\' (set value of X or Y), \'b\' (modify bit in X), \'S\'(wap X and Y), \'R\' (swap X and R), \'C\'(ompare X and Y), \'A\'(dd X and Y), \'M\'(ultiply X and Y), \'D\'(ivide X by Y) or \'h\'(elp).\n"); break ;
/* rajouter : 3 registres : x,y et res, multiplication, addition, division */

   default : printf("???\n") ; break ;
  }

 }




 return(-1);
}