Shared data between two process

shared_file.c

#define buff_max 25 
#define mod % 
  
    struct item{ 
  
        // diffrent member of the produced data  
        // or consumed data     
        --------- 
    } 
      
    // An array is needed for holding the items.  
    // This is the shared place which will be   
    // access by both process    
    // item shared_buff [ buff_max ]; 
       
    // Two variables which will keep track of  
    // the indexes of the items produced by producer  
    // and consumer The free index points to  
    // the next free index. The full index points to  
    // the first full index.  
    int free_index = 0; 
    int full_index = 0; 

item nextProduced; 
      
    while(1){ 
          
        // check if there is no space  
        // for production. 
        // if so keep waiting. 
        while((free_index+1) mod buff_max == full_index); 
          
        shared_buff[free_index] = nextProduced; 
        free_index = (free_index + 1) mod buff_max; 
    } 

item nextConsumed; 
      
    while(1){ 
          
        // check if there is an available  
        // item  for consumption.  
        // if not keep on waiting for  
        // get them produced. 
        while((free_index == full_index); 
          
        nextConsumed = shared_buff[full_index]; 
        full_index = (full_index + 1) mod buff_max; 
    }