output reg [3:0] st_read,
        input [31:0] st_data,
        
+       /* Coprocessor interface */
+       output reg cp_req,
+       input cp_ack,
+       input cp_busy,
+       output cp_rnw,  /* 1 = read from CP, 0 = write to CP */
+       input [31:0] cp_read,
+       output reg [31:0] cp_write,
+       
        /* stage inputs */
        input inbubble,
        input [31:0] pc,
                next_outbubble = inbubble;
                outstall = 1'b0;
                next_regs = regs;
+               cp_req = 1'b0;
+               cp_rnw = 1'bx;
+               cp_write = 32'hxxxxxxxx;
                offset = prev_offset;
                next_outcpsr = lsm_state == 3'b010 ? out_cpsr : cpsr;
                next_lsm_state = lsm_state;
                        default: begin end
                        endcase
                end
+               `DECODE_LDCSTC: begin
+                       $display("WARNING: Unimplemented LDCSTC");
+               end
+               `DECODE_CDP: begin
+                       cp_req = 1;
+                       if (cp_busy) begin
+                               outstall = 1;
+                               next_outbubble = 1;
+                       end
+                       if (!cp_ack) begin
+                               /* XXX undefined instruction trap */
+                               $display("WARNING: Possible CDP undefined instruction");
+                       end
+               end
+               `DECODE_MRCMCR: begin
+                       cp_req = 1;
+                       cp_rnw = insn[20] /* L */;
+                       if (insn[20] == 0 /* store to coprocessor */)
+                               cp_write = op0;
+                       else begin
+                               next_write_reg = 1'b1;
+                               next_write_num = insn[15:12];
+                               next_write_data = cp_read;
+                       end
+                       if (cp_busy) begin
+                               outstall = 1;
+                               next_outbubble = 1;
+                       end
+                       if (!cp_ack) begin
+                               $display("WARNING: Possible MRCMCR undefined instruction");
+                       end
+               end
                default: begin end
                endcase
        end
 
        wire [3:0] memory_out_write_num;
        wire [31:0] memory_out_write_data;
        
+       wire cp_req;
+       wire cp_ack = 0;
+       wire cp_busy = 0;
+       wire cp_rnw;
+       wire [31:0] cp_read = 0;
+       wire [31:0] cp_write;
+       
        wire stall_cause_issue;
        wire stall_cause_execute;
        wire stall_cause_memory;
                .outstall(stall_cause_memory), .outbubble(bubble_out_memory), 
                .outpc(pc_out_memory), .outinsn(insn_out_memory),
                .out_write_reg(memory_out_write_reg), .out_write_num(memory_out_write_num), 
-               .out_write_data(memory_out_write_data));
+               .out_write_data(memory_out_write_data),
+               .cp_req(cp_req), .cp_ack(cp_ack), .cp_busy(cp_busy), .cp_rnw(cp_rnw), .cp_read(cp_read), .cp_write(cp_write));
 
        reg [31:0] clockno = 0;
        always @(posedge clk)