alumux.vhd

Standard 8051 IP Core

       when DIV_ACC_RAM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= acc_i;
         dvsor_o     <= ram_data_i;
         addsub_o    <= '0';
         addsub_cy_o <= '0';
         opa_o       <= ( others => '0' );
         opb_o       <= ( others => '0' );
       when MUL_ACC_RAM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= acc_i;
         mltplctr_o  <= ram_data_i;
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '0';
         addsub_cy_o <= '0';
         opa_o       <= ( others => '0' );
         opb_o       <= ( others => '0' );
       when INC_ACC =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '1';
         addsub_cy_o <= '0';
         opa_o       <= acc_i;
         opb_o       <= std_logic_vector(conv_unsigned(1, DWIDTH));
       when INC_RAM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '1';
         addsub_cy_o <= '0';
         opa_o       <= ram_data_i;
         opb_o       <= std_logic_vector(conv_unsigned(1, DWIDTH));
       when DEC_ACC =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '0';
         addsub_cy_o <= '0';
         opa_o       <= acc_i;
         opb_o       <= std_logic_vector(conv_unsigned(1, DWIDTH));
       when DEC_RAM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '0';
         addsub_cy_o <= '0';
         opa_o       <= ram_data_i;
         opb_o       <= std_logic_vector(conv_unsigned(1, DWIDTH));
       when SUB_ACC_RAM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '0';
         addsub_cy_o <= cy_i((DWIDTH-1)/4);
         opa_o       <= acc_i;
         opb_o       <= ram_data_i;
       when SUB_ACC_ROM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '0';
         addsub_cy_o <= cy_i((DWIDTH-1)/4);
         opa_o       <= acc_i;
         opb_o       <= rom_data_i;
       when ADD_ACC_RAM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '1';
         addsub_cy_o <= '0';
         opa_o       <= acc_i;
         opb_o       <= ram_data_i;
       when ADD_ACC_ROM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '1';
         addsub_cy_o <= '0';
         opa_o       <= acc_i;
         opb_o       <= rom_data_i;
       when ADDC_ACC_RAM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '1';
         addsub_cy_o <= cy_i((DWIDTH-1)/4);
         opa_o       <= acc_i;
         opb_o       <= ram_data_i;
       when ADDC_ACC_ROM =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '1';
         addsub_cy_o <= cy_i((DWIDTH-1)/4);
         opa_o       <= acc_i;
         opb_o       <= rom_data_i;
       when others =>
         dcml_data_o <= ( others => '0' );
         mltplcnd_o  <= ( others => '0' );
         mltplctr_o  <= ( others => '0' );
         dvdnd_o     <= ( others => '0' );
         dvsor_o     <= ( others => '0' );
         addsub_o    <= '0';
         addsub_cy_o <= '0';
         opa_o       <= ( others => '0' );
         opb_o       <= ( others => '0' );
    end case;
  end process p_ext_mux;

  -- Multiplex the results for all the units contributing to the ALU.
  p_rslt_mux : process (ram_data_i,
                        cy_i,
                        ov_i,
                        product_i,
                        qutnt_i,
                        rmndr_i,
                        result_i,
                        new_cy_i,
			addsub_rslt_i,
			addsub_cy_i,
			addsub_ov_i,
                        dcml_data_i,
                        dcml_cy_i,
                        cmd_i)
  begin
    case cmd_i is
       when DA          =>
	 if (C_IMPL_DA /= 0) then
           result_a_o         <= dcml_data_i;
           result_b_o         <= ( others => '0' );
           cy_o               <= cy_i;
           cy_o((DWIDTH-1)/4) <= dcml_cy_i;
           ov_o               <= ov_i;
	 else  
           result_a_o         <= ( others => '0' );
           result_b_o         <= ( others => '0' );
           cy_o               <= conv_std_logic_vector(0,(DWIDTH-1)/4+1);
           ov_o               <= '0';
	 end if;
       when DIV_ACC_RAM =>
	 if (C_IMPL_DIV /= 0) then
           result_a_o         <= qutnt_i;
           result_b_o         <= rmndr_i;
           cy_o               <= conv_std_logic_vector(0,(DWIDTH-1)/4+1);
           if ram_data_i = conv_std_logic_vector(0,DWIDTH) then
             ov_o             <= '1';
           else
             ov_o             <= '0';
           end if;
	 else
           result_a_o         <= ( others => '0' );
           result_b_o         <= ( others => '0' );
           cy_o               <= conv_std_logic_vector(0,(DWIDTH-1)/4+1);
	   ov_o               <= '0';
	 end if;
       when MUL_ACC_RAM =>
	 if (C_IMPL_MUL /= 0) then
           result_a_o         <= product_i(DWIDTH-1 downto 0);
           result_b_o         <= product_i(DWIDTH*2-1 downto DWIDTH);
           cy_o               <= conv_std_logic_vector(0,(DWIDTH-1)/4+1);
           if product_i(DWIDTH*2-1 downto DWIDTH)
               = conv_std_logic_vector(0, DWIDTH) then
             ov_o             <= '0';
           else
             ov_o             <= '1';
           end if;
	 else
           result_a_o         <= ( others => '0' );
           result_b_o         <= ( others => '0' );
           cy_o               <= conv_std_logic_vector(0,(DWIDTH-1)/4+1);
           ov_o               <= '0';
	 end if;
       when SUB_ACC_RAM | SUB_ACC_ROM | ADD_ACC_RAM | ADD_ACC_ROM |
	    ADDC_ACC_RAM | ADDC_ACC_ROM  =>
         result_a_o         <= addsub_rslt_i;
         result_b_o         <= ( others => '0' );
         cy_o               <= addsub_cy_i;
         ov_o               <= addsub_ov_i;
       when INC_ACC | INC_RAM | DEC_ACC | DEC_RAM =>
         result_a_o         <= addsub_rslt_i;
         result_b_o         <= ( others => '0' );
         cy_o               <= cy_i;
         ov_o               <= addsub_ov_i;	 
       when others      =>
         result_a_o         <= result_i;
         result_b_o         <= ( others => '0' );
         cy_o               <= new_cy_i;
         ov_o               <= ov_i;
    end case;
  end process p_rslt_mux;

end rtl;
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