+= read registers from userland

[raggedstone] / dhwk / source / pci / io_rw_sel.vhd

-- J.STELZNER
-- INFORMATIK-3 LABOR
-- 23.08.2006
-- File: CONFIG_WR_SEL.VHD

library IEEE;
use IEEE.std_logic_1164.all;

entity IO_WR_SEL is
        port
        (
                IO_WR_COM :in std_logic;
                IRDY_REGn :in std_logic;
                TRDYn :in std_logic;
                ADDR_REG :in std_logic_vector(31 downto 0);
                CBE_REGn :in std_logic_vector( 3 downto 0);
                WRITE_XX1_0 :out std_logic;
                WRITE_XX3_2 :out std_logic;
                WRITE_XX5_4 :out std_logic;
                WRITE_XX7_6 :out std_logic
        );
end entity IO_WR_SEL;

--PCI Byte Enable
--C/BE[3..0] gueltige Datenbits
-------------------------------
-- 0000 AD 31..0
-- 1000 AD 23..0
-- 1100 AD 15..0
-- 1110 AD 7..0
-- 0011 AD 31..16

architecture IO_WR_SEL_DESIGN of IO_WR_SEL is

        signal WR_ENA :std_logic;
        signal ADDR :std_logic_vector( 5 downto 0);

begin

        WR_ENA <= '1' when
                  IO_WR_COM = '1' and
                  IRDY_REGn = '0' and
                  TRDYn = '0' else '0';

        ADDR <= ADDR_REG(3) & ADDR_REG(2) & CBE_REGn;

        WRITE_XX1_0 <= '1' when WR_ENA = '1' and ADDR = "001100" else '0';
        WRITE_XX3_2 <= '1' when WR_ENA = '1' and ADDR = "000011" else '0';
        WRITE_XX5_4 <= '1' when WR_ENA = '1' and ADDR = "011100" else '0';
        WRITE_XX7_6 <= '1' when WR_ENA = '1' and ADDR = "010011" else '0';

end architecture IO_WR_SEL_DESIGN;