oh/common/hdl/oh_arbiter.v

/* Simple combinatorial priority arbiter
 * bit[0] has highest priority
 *
 */

module oh_arbiter(/*AUTOARG*/
   // Outputs
   grants,
   // Inputs
   requests
   );
   
   parameter N    = 99;
   parameter TYPE = "FIXED"; //arbiter type
                             //"FIXED"
                             //"ROUNDROBIN"
                             //"FAIR"
   
       
   input  [N-1:0] requests;  //request vector
   output [N-1:0] grants;    //grant (one hot)

   wire [N-1:0]   waitmask; 
   genvar 	  j;     
   generate       
      if(TYPE=="FIXED")
	begin
	   assign waitmask[0]   = 1'b0;      
	   for (j=N-1; j>=1; j=j-1) 
	     begin : gen_arbiter     
		assign waitmask[j] = |requests[j-1:0];
	     end
	end
   endgenerate
      
   //grant circuit
   assign grants[N-1:0] = requests[N-1:0] & ~waitmask[N-1:0];
   
endmodule // oh_arbiter