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[/] [potato/] [trunk/] [soc/] [pp_soc_memory.vhd] - Rev 36
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-- The Potato Processor - A simple processor for FPGAs -- (c) Kristian Klomsten Skordal 2014 - 2015 <kristian.skordal@wafflemail.net> -- Report bugs and issues on <http://opencores.org/project,potato,bugtracker> library ieee; use ieee.std_logic_1164.all; use ieee.numeric_std.all; use ieee.std_logic_textio.all; use std.textio.all; use work.pp_utilities.all; --! @brief Simple memory module for use in Wishbone-based systems. entity pp_soc_memory is generic( MEMORY_SIZE : natural := 4096 --! Memory size in bytes. ); port( clk : in std_logic; reset : in std_logic; -- Wishbone interface: wb_adr_in : in std_logic_vector(log2(MEMORY_SIZE) - 1 downto 0); wb_dat_in : in std_logic_vector(31 downto 0); wb_dat_out : out std_logic_vector(31 downto 0); wb_cyc_in : in std_logic; wb_stb_in : in std_logic; wb_sel_in : in std_logic_vector( 3 downto 0); wb_we_in : in std_logic; wb_ack_out : out std_logic ); end entity pp_soc_memory; architecture behaviour of pp_soc_memory is type memory_array is array(0 to (MEMORY_SIZE / 4) - 1) of std_logic_vector(31 downto 0); signal memory : memory_array := (others => (others => '0')); attribute ram_style : string; attribute ram_style of memory : signal is "block"; type state_type is (IDLE, ACK); signal state : state_type; signal read_ack : std_logic; begin wb_ack_out <= read_ack and wb_stb_in; process(clk) begin if rising_edge(clk) then if reset = '1' then read_ack <= '0'; state <= IDLE; else if wb_cyc_in = '1' then case state is when IDLE => if wb_stb_in = '1' and wb_we_in = '1' then for i in 0 to 3 loop if wb_sel_in(i) = '1' then memory(to_integer(unsigned(wb_adr_in(wb_adr_in'left downto 2))))(((i + 1) * 8) - 1 downto i * 8) <= wb_dat_in(((i + 1) * 8) - 1 downto i * 8); end if; end loop; read_ack <= '1'; state <= ACK; elsif wb_stb_in = '1' then wb_dat_out <= memory(to_integer(unsigned(wb_adr_in(wb_adr_in'left downto 2)))); read_ack <= '1'; state <= ACK; end if; when ACK => if wb_stb_in = '0' then read_ack <= '0'; state <= IDLE; end if; end case; else state <= IDLE; read_ack <= '0'; end if; end if; end if; end process clk; end architecture behaviour;
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