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library ieee;
use ieee.std_logic_1164.all;
library ieee;
use ieee.numeric_std.all;
entity output_split4 is
port (
wa0_data : in std_logic_vector(7 downto 0);
wa0_addr : in std_logic_vector(2 downto 0);
ra0_data : out std_logic_vector(7 downto 0);
ra0_addr : in std_logic_vector(2 downto 0);
wa0_en : in std_logic;
clk : in std_logic
);
end output_split4;
architecture augh of output_split4 is
-- Embedded RAM
type ram_type is array (0 to 7) of std_logic_vector(7 downto 0);
signal ram : ram_type := (others => (others => '0'));
-- Little utility functions to make VHDL syntactically correct
-- with the syntax to_integer(unsigned(vector)) when 'vector' is a std_logic.
-- This happens when accessing arrays with <= 2 cells, for example.
function to_integer(B: std_logic) return integer is
variable V: std_logic_vector(0 to 0);
begin
V(0) := B;
return to_integer(unsigned(V));
end;
function to_integer(V: std_logic_vector) return integer is
begin
return to_integer(unsigned(V));
end;
begin
-- Sequential process
-- It handles the Writes
process (clk)
begin
if rising_edge(clk) then
-- Write to the RAM
-- Note: there should be only one port.
if wa0_en = '1' then
ram( to_integer(wa0_addr) ) <= wa0_data;
end if;
end if;
end process;
-- The Read side (the outputs)
ra0_data <= ram( to_integer(ra0_addr) );
end architecture;
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