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87 lines
2.6 KiB
VHDL
87 lines
2.6 KiB
VHDL
library ieee;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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use ieee.math_real.all;
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entity cache_ram is
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generic(
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ROW_BITS : integer := 16;
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WIDTH : integer := 64;
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BYTEWID : integer := 8;
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TRACE : boolean := false;
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ADD_BUF : boolean := false
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);
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port(
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clk : in std_logic;
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rd_en : in std_logic;
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rd_addr : in std_logic_vector(ROW_BITS - 1 downto 0);
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rd_data : out std_logic_vector(WIDTH - 1 downto 0);
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wr_sel : in std_logic_vector(WIDTH/BYTEWID - 1 downto 0);
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wr_addr : in std_logic_vector(ROW_BITS - 1 downto 0);
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wr_data : in std_logic_vector(WIDTH - 1 downto 0)
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);
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end cache_ram;
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architecture rtl of cache_ram is
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constant SIZE : integer := 2**ROW_BITS;
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type ram_type is array (0 to SIZE - 1) of std_logic_vector(WIDTH - 1 downto 0);
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signal ram : ram_type;
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attribute ram_style : string;
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attribute ram_style of ram : signal is "block";
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signal rd_data0 : std_logic_vector(WIDTH - 1 downto 0);
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begin
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process(clk)
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variable lbit : integer range 0 to WIDTH - 1;
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variable mbit : integer range 0 to WIDTH - 1;
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variable widx : integer range 0 to SIZE - 1;
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constant sel0 : std_logic_vector(WIDTH/BYTEWID - 1 downto 0)
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:= (others => '0');
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begin
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if rising_edge(clk) then
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if TRACE then
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if wr_sel /= sel0 then
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report "write a:" & to_hstring(wr_addr) &
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" sel:" & to_hstring(wr_sel) &
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" dat:" & to_hstring(wr_data);
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end if;
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end if;
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for i in 0 to WIDTH/BYTEWID-1 loop
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lbit := i * BYTEWID;
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mbit := lbit + BYTEWID - 1;
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widx := to_integer(unsigned(wr_addr));
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if wr_sel(i) = '1' then
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ram(widx)(mbit downto lbit) <= wr_data(mbit downto lbit);
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end if;
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end loop;
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if rd_en = '1' then
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rd_data0 <= ram(to_integer(unsigned(rd_addr)));
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if TRACE then
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report "read a:" & to_hstring(rd_addr) &
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" dat:" & to_hstring(ram(to_integer(unsigned(rd_addr))));
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end if;
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end if;
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end if;
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end process;
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buf: if ADD_BUF generate
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begin
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process(clk)
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begin
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if rising_edge(clk) then
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rd_data <= rd_data0;
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end if;
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end process;
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end generate;
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nobuf: if not ADD_BUF generate
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begin
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rd_data <= rd_data0;
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end generate;
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end;
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