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---------------------------------------------------------------------- ---- tdpram_asym ---- ---- ---- ---- This file is part of the ---- ---- Modular Simultaneous Exponentiation Core project ---- ---- http://www.opencores.org/cores/mod_sim_exp/ ---- ---- ---- ---- Description ---- ---- behavorial description of an asymmetric true dual port ---- ---- ram with one (widthA)-bit read/write port and one 32-bit ---- ---- read/write port. Made using the templates of xilinx and ---- ---- altera for asymmetric ram. ---- ---- ---- ---- Dependencies: none ---- ---- ---- ---- Authors: ---- ---- - Geoffrey Ottoy, DraMCo research group ---- ---- - Jonas De Craene, JonasDC@opencores.org ---- ---- ---- ---------------------------------------------------------------------- ---- ---- ---- Copyright (C) 2011 DraMCo research group and OPENCORES.ORG ---- ---- ---- ---- This source file may be used and distributed without ---- ---- restriction provided that this copyright statement is not ---- ---- removed from the file and that any derivative work contains ---- ---- the original copyright notice and the associated disclaimer. ---- ---- ---- ---- This source file is free software; you can redistribute it ---- ---- and/or modify it under the terms of the GNU Lesser General ---- ---- Public License as published by the Free Software Foundation; ---- ---- either version 2.1 of the License, or (at your option) any ---- ---- later version. ---- ---- ---- ---- This source is distributed in the hope that it will be ---- ---- useful, but WITHOUT ANY WARRANTY; without even the implied ---- ---- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ---- ---- PURPOSE. See the GNU Lesser General Public License for more ---- ---- details. ---- ---- ---- ---- You should have received a copy of the GNU Lesser General ---- ---- Public License along with this source; if not, download it ---- ---- from http://www.opencores.org/lgpl.shtml ---- ---- ---- ---------------------------------------------------------------------- library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; use ieee.std_logic_arith.all; library mod_sim_exp; use mod_sim_exp.std_functions.all; -- altera infers ramblocks from a depth of 9 (or 2 with any ram size recognition -- option on or contstraint below on) and widthA 1,2,4,8,16 -- xilinx infers ramblocks from a depth of 2 and widthA 1,2,4,8,16,32 entity tdpram_asym is generic ( depthB : integer := 4; -- nr of 32-bit words widthA : integer := 2; -- port A width, must be smaller than or equal to 32 device : string := "xilinx" ); port ( -- port A (widthA)-bit clkA : in std_logic; addrA : in std_logic_vector(log2((depthB*32)/widthA)-1 downto 0); weA : in std_logic; dinA : in std_logic_vector(widthA-1 downto 0); doutA : out std_logic_vector(widthA-1 downto 0); -- port B 32-bit clkB : in std_logic; addrB : in std_logic_vector(log2(depthB)-1 downto 0); weB : in std_logic; dinB : in std_logic_vector(31 downto 0); doutB : out std_logic_vector(31 downto 0) ); end tdpram_asym; architecture behavorial of tdpram_asym is -- constants constant R : natural := 32/widthA; -- ratio begin xilinx_device : if device="xilinx" generate -- An asymmetric RAM is modelled in a similar way as a symmetric RAM, with an -- array of array object. Its aspect ratio corresponds to the port with the -- lower data width (larger depth) type ramType is array (0 to ((depthB*32)/widthA)-1) of std_logic_vector(widthA-1 downto 0); -- You need to declare ram as a shared variable when : -- - the RAM has two write ports, -- - the RAM has only one write port whose data width is maxWIDTH -- In all other cases, ram can be a signal. shared variable ram : ramType := (others => (others => '0')); begin process (clkA) begin if rising_edge(clkA) then if weA = '1' then ram(conv_integer(addrA)) := dinA; end if; doutA <= ram(conv_integer(addrA)); end if; end process; process (clkB) begin if rising_edge(clkB) then for i in 0 to R-1 loop if weB = '1' then ram(conv_integer(addrB & conv_std_logic_vector(i,log2(R)))) := dinB((i+1)*widthA-1 downto i*widthA); end if; doutB((i+1)*widthA-1 downto i*widthA) <= ram(conv_integer(addrB & conv_std_logic_vector(i,log2(R)))); end loop; end if; end process; end generate; altera_device : if device="altera" generate -- Use a multidimensional array to model mixed-width type word_t is array(R-1 downto 0) of std_logic_vector(widthA-1 downto 0); type ram_t is array (0 to depthB-1) of word_t; -- altera constraints: -- for smal depths: -- if the synthesis option "allow any size of RAM to be inferred" is on, these lines -- may be left commented. -- uncomment this attribute if that option is off and you know wich primitives should be used. --attribute ramstyle : string; --attribute ramstyle of RAM : signal is "M9K, no_rw_check"; -- delcare the RAM signal ram : ram_t; signal wB_local : word_t; signal qB_local : word_t; begin -- rtl -- Re-organize the write data to match the RAM word type unpack: for i in 0 to R-1 generate wB_local(i) <= dinB(widthA*(i+1)-1 downto widthA*i); doutB(widthA*(i+1)-1 downto widthA*i) <= qB_local(i); end generate unpack; --port B process(clkB) begin if(rising_edge(clkB)) then if(weB = '1') then ram(conv_integer(addrB)) <= wB_local; end if; qB_local <= ram(conv_integer(addrB)); end if; end process; -- port A process(clkA) begin if(rising_edge(clkA)) then doutA <= ram(conv_integer(addrA) / R )(conv_integer(addrA) mod R); if(weA ='1') then ram(conv_integer(addrA) / R)(conv_integer(addrA) mod R) <= dinA; end if; end if; end process; end generate; end behavorial;
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