#include<stdio.h> 
#include<stdlib.h> 
#define SIZE 100

int prog_enterd(int *,int); 

int main()
{ 
   int memory[SIZE];  //simulated memory  
   int mess;
   int acc = 0; 
   int intructcounter; 
   int operationcode,operand; 
   int instruction; 
   int loop; 
   //print welcome message first 
   printf("\n\n"); 
   
   printf("***Welcome to Simcom!***\n***Please enter your program one 
instruction word at a time**\n***I will type the location number and a 
question mark***\n***You then type the word for that 
location***\n***Type the sentinal -99999 to stop entering your 
program***\n");
   mess = prog_enterd(memory,SIZE); 
   if ( mess == 0) 
         {
           printf("You have run out of lines to enter programs or you are at the
 end of memory\n"); 
           exit (0); 
         }

         
   else 
     { printf("Great Program loading compleated\n"); 
     }
   printf("Program execution begins\n"); 
   
 for (intructcounter =0; intructcounter != 43 && intructcounter 
< 99  intructcounter++)  
      { 
         instruction = memory[intructcounter];
         operationcode = instruction / 100; 
         operand = instruction % 100; 
         
         switch (operationcode)
         {
         case 10:     scanf("%d", &memory[operand]); //read
         break; 
         
         case 20:     acc = memory[operand]; //load
         break; 
         
         case 30:     acc += memory[operand]; //add
         break; 
         
         case 43:     printf("Simcom exectution terminated\n"); //HALT
         break; 
         
         case 11:     printf("%d\n",memory[operand]; //write
         break; 
         
         case 21:     memory[operand] = acc; //store
         break; 
         
         case 31:    acc -= memory[operand]; //subtract 
         break; 
        
         case 32:    acc /= memory[operand]; //devide
         break; 

         case 33:    acc *= memory[operand]; //multiply
         break; 
   
         case 40:   intructcounter = operand; 
         break;
 
         case 41:   if (acc < 0) intructcounter = operand; 
         break; 
         
   	 case 42:   if (acc == 0) intructcounter = operand; 
	 break; 
         
     } 
     
     
}
printf("Program execution compleate\n");

printf("Memory dump information"); 

for (loop = 0; loop <= mess; loop++) 
     printf("%02d   %04d%c",loop,memory[loop],(loop % 4 == 0) ? '/n' : ' '); 

return 0;  


} 

int prog_enterd(int *mem, int size)
{ 
     int count = 0;

    do 
     { 
        
        printf("%02d ? ",count); 
        scanf("%d",&mem[count]); 
        printf("\n"); 
        if (mem[count] == -99999) 
             return count - 1; 
        count++;
     } 
     while (count < size); 
     return 0; 

}

printf("%02d   %04d%c",loop,memory[loop],(loop % 4 == 0) ? '/n' : ' ');

printf("%02d   %04d%c",loop,memory[loop],(loop % 4 == 0) ? '\n' : ' ');

for (loop = 0; loop <= mess; loop++) 
     printf("%02d   %04d%c",loop,memory[loop],(loop % 4 == 0) ? '/n' : ' ');