vme_local_switch.vhd

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LIBRARY ieee ;
USE ieee.std_logic_1164.all;
USE ieee.numeric_std.all;


use work.CMXpackage.all;
--use work.CMX_VME_defs.all;

entity vme_local_switch is
  port(
    data_vme_up : out  std_logic_vector (15 downto 0);
    data_vme_from_below : in arr_16;

    bus_drive_up : out std_logic;

    bus_drive_from_below : in std_logic_vector
    
    );

-- Declarations

end vme_local_switch ;

ARCHITECTURE rtl OF vme_local_switch IS

  constant num_regs_below : integer := bus_drive_from_below'length;

  signal data_vme_up_sig : std_logic_vector(15 downto 0);
  signal bus_drive_up_sig : std_logic;

  signal or_all_data_vme_from_below_tmp  : arr_16(num_regs_below-1 downto 0);
  signal or_all_bus_drive_from_below_tmp : std_logic_vector(num_regs_below-1 downto 0);
  

BEGIN

  assert (bus_drive_from_below'length = data_vme_from_below'length) report "in vme_local_switch number of bus drive requests not equal to the number of vme busses" severity failure;

  or_all_data_vme_from_below_tmp(0)<=data_vme_from_below(0);
  or_all_bus_drive_from_below_tmp(0)<=bus_drive_from_below(0);

  or_gen: for reg_i in 1 to (num_regs_below-1) generate
    or_all_data_vme_from_below_tmp(reg_i)<=data_vme_from_below(reg_i) or or_all_data_vme_from_below_tmp(reg_i-1);
    or_all_bus_drive_from_below_tmp(reg_i)<=bus_drive_from_below(reg_i) or or_all_bus_drive_from_below_tmp(reg_i-1);
  end generate or_gen;

  bus_drive_up_sig<=or_all_bus_drive_from_below_tmp(num_regs_below-1);

  --data_vme_up_sig<= bus_drive_up_sig and or_all_data_vme_from_below_tmp(num_regs_below-1);

  data_vme_up_sig<=  or_all_data_vme_from_below_tmp(num_regs_below-1) when bus_drive_up_sig='1' else (others=>'0');
  
  bus_drive_up<=bus_drive_up_sig;
  data_vme_up<=data_vme_up_sig;

END rtl;