+               `DECODE_ALU_HDATA_REG,
+               `DECODE_ALU_HDATA_IMM: if(!inbubble) begin
+                       next_outbubble = rw_wait;
+                       outstall = rw_wait;
+                       addr = insn[23] ? op0 + op1 : op0 - op1; /* up/down select */
+                       raddr = insn[24] ? op0 : addr; /* pre/post increment */
+                       busaddr = raddr;
+                       /* rotate to correct position */
+                       case(insn[6:5])
+                       2'b00: begin end /* swp */
+                       2'b01: begin /* unsigned half */
+                               wr_data = {2{op2[15:0]}}; /* XXX need to store halfword */
+                               lsrh_rddata = {16'b0, raddr[1] ? rd_data[31:16] : rd_data[15:0]};
+                       end
+                       2'b10: begin /* signed byte */
+                               wr_data = {4{op2[7:0]}};
+                               lsrh_rddata_s1 = raddr[1] ? rd_data[31:16] : rd_data[15:0];
+                               lsrh_rddata_s2 = raddr[0] ? lsrh_rddata_s1[15:8] : lsrh_rddata_s1[7:0];
+                               lsrh_rddata = {{24{lsrh_rddata_s2[7]}}, lsrh_rddata_s2};
+                       end
+                       2'b11: begin /* signed half */
+                               wr_data = {2{op2[15:0]}};
+                               lsrh_rddata = raddr[1] ? {{16{rd_data[31]}}, rd_data[31:16]} : {{16{rd_data[15]}}, rd_data[15:0]};
+                       end
+                       endcase
+
+                       case(lsrh_state)
+                       2'b01: begin
+                               rd_req = insn[20];
+                               wr_req = ~insn[20];
+                               next_write_num = insn[15:12];
+                               next_write_data = lsrh_rddata;
+                               if(insn[20]) begin
+                                       next_write_reg = 1'b1;
+                               end
+                               if(insn[21] | !insn[24]) begin
+                                       outstall = 1'b1;
+                                       if(!rw_wait)
+                                               next_lsrh_state = 2'b10;
+                               end
+                       end
+                       2'b10: begin
+                               next_write_reg = 1'b1;
+                               next_write_num = insn[19:16];
+                               next_write_data = addr;
+                               next_lsrh_state = 2'b10;
+                       end
+                       default: begin end
+                       endcase
+               end