Step by step displays the content, and the final result of the list ("buffer") of 6 elements as the initial values ??and the following elements which are produced (NEXTP) or consumed (NEXTC). This scheme allows a maximum of (Buffer_size - 1) elements.

#define BUFFER_SIZE 6

typedefstruct { ....}item;

item buffer[BUFFER_SIZE];

int    in  =  0;

int  out  =  0;

         Producer

         itemnextProduced;

                  while (true)   

                  {.../* produce an item in nextp  */

                           while  (((in + 1)  %  BUFFER_SIZE )  = =  out)   

                                                                                     /* loop, do nothing */;

                           buffer[in]  =  nextp;

                           in  =  (in + 1)  %  BUFFER_SIZE;

                  }

 Consumer

         itemnextConsumed

                  while (true)

                  {...

                           while  ( in  = = out) ;       /* loop, do nothing */;

                           nextc = buffer [out];

                           out  =  (out + 1)  %  BUFFER_SIZE;

                                    /*  consume the item in nextc  */

                  }