Control ports

  • PC: The current Program Counter
  • Offset


  • limit: Folding limit
  • maxSize: Size of the The Core


  • Address


This module is composed of three sub-modules:

  • Modulo is used to calculate a temporary value
  • Folding to Fold the Address into its Read (or Write) boundary.
  • Addition to make the Address Absolute. (This step also includes a Modulo)

For the two first steps, the Cref provides the following listing:

/* There is one support function used to limit the range of */
/* reading from Core and writing to Core relative to the    */
/* current instruction.  Behaviour is as expected (a small  */
/* core within Core) only if the limits are factors of the  */
/* size of Core.                                            */

static Address Fold(
   Address  pointer,    /* The pointer to fold into the desired range.  */
   Address  limit,      /* The range limit.                             */
   Address  M           /* The size of Core.                            */
) {
   Address  result;

   result = pointer % limit;
   if ( result > (limit/2) ) {
      result += M - limit;

Internal Signals

We have two internal signals to interconnect our three sub-process. Each one of them representing our output at its different stage of processing.