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--This library is free software; you can redistribute it and/or
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--modify it under the terms of the GNU Lesser General Public
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--License as published by the Free Software Foundation; either
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--version 2.1 of the License, or (at your option) any later version.
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--This library is distributed in the hope that it will be useful,
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--but WITHOUT ANY WARRANTY; without even the implied warranty of
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--MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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--Lesser General Public License for more details.
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--You should have received a copy of the GNU Lesser General Public
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--License along with this library; if not, write to the Free Software
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--Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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-- e_mail : j.l.nunez-yanez@byacom.co.uk
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----------------------------------
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-- ENTITY = LC_ASSEMBLER --
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-- version = 1.0 --
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-- last update = 16/06/99 --
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-- author = Jose Nunez --
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----------------------------------
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-- FUNCTION
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-- assembles literal characters into a left aligned format.
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-- input match type determines which bytes are valid.
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-- PIN LIST
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-- MASK = valid bytes
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-- MATCH_TYPE = input match type (active low), i.e a low indicates that the corresponding
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-- byte in LITERAL_DATA is valid.
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-- LITERAL_DATA = input literal data characters
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-- CODE = output bytes assembled in left justified format adding miss type if needed
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-- LENGTH = length of output code in bits
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library ieee,dzx;
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use ieee.std_logic_1164.all;
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entity LC_ASSEMBLER is
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port
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(
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MASK : in bit_vector(4 downto 0);
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MATCH_TYPE : in bit_vector(3 downto 0);
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LITERAL_DATA : in bit_vector(31 downto 0);
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CODE : out bit_vector(33 downto 0);
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MISS : out bit;
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LENGTH : out bit_vector(5 downto 0)
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);
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end LC_ASSEMBLER;
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architecture FIRST of LC_ASSEMBLER is
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signal MISS_TYPE_CODE : bit_vector(33 downto 0);
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signal MISS_TYPE_LENGTH : bit_vector(5 downto 0);
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signal CODE_AUX : bit_vector(33 downto 0);
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signal LENGTH_AUX : bit_vector(5 downto 0);
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signal MISS_AUX : bit;
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component MISS_TYPE_CODER
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port
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(
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MASK : in bit_vector(4 downto 0);
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LITERAL_DATA :in bit_vector(31 downto 0);
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CODE : out bit_vector(33 downto 0);
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LENGTH : out bit_vector(5 downto 0)
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);
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end component;
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begin
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MSS_CODER : MISS_TYPE_CODER
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port map
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(
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MASK => MASK,
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LITERAL_DATA => LITERAL_DATA,
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CODE => MISS_TYPE_CODE,
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LENGTH => MISS_TYPE_LENGTH
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);
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ASSEMBLE : process(MATCH_TYPE, LITERAL_DATA, MISS_TYPE_CODE, MISS_TYPE_LENGTH)
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variable BYTE3 : bit_vector(7 downto 0);
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variable BYTE2 : bit_vector(7 downto 0);
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variable BYTE1 : bit_vector(7 downto 0);
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variable BYTE0 : bit_vector(7 downto 0);
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begin
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BYTE3 := LITERAL_DATA(31 downto 24);
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BYTE2 := LITERAL_DATA(23 downto 16);
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BYTE1 := LITERAL_DATA(15 downto 8);
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BYTE0 := LITERAL_DATA(7 downto 0);
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case MATCH_TYPE is
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when "1111" => CODE_AUX <= MISS_TYPE_CODE;LENGTH_AUX <= MISS_TYPE_LENGTH;MISS_AUX <= '1';
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when "1110" => CODE_AUX <= MISS_TYPE_CODE;LENGTH_AUX <= MISS_TYPE_LENGTH;MISS_AUX <= '1';
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when "1101" => CODE_AUX <= MISS_TYPE_CODE;LENGTH_AUX <= MISS_TYPE_LENGTH;MISS_AUX <= '1';
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when "1100" => CODE_AUX <= BYTE3 & BYTE2 & "000000000000000000"; LENGTH_AUX <= "010000";MISS_AUX <= '0';
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when "1011" => CODE_AUX <= MISS_TYPE_CODE;LENGTH_AUX <= MISS_TYPE_LENGTH;MISS_AUX <= '1';
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when "1010" => CODE_AUX <= MISS_TYPE_CODE;LENGTH_AUX <= MISS_TYPE_LENGTH;MISS_AUX <= '1';
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when "1001" => CODE_AUX <= BYTE3 & BYTE0 & "000000000000000000"; LENGTH_AUX <= "010000";MISS_AUX <= '0';
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when "1000" => CODE_AUX <= BYTE3 & "00000000000000000000000000"; LENGTH_AUX <= "001000";MISS_AUX <= '0';
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when "0111" => CODE_AUX <= MISS_TYPE_CODE;LENGTH_AUX <= MISS_TYPE_LENGTH;MISS_AUX <= '1';
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when "0110" => CODE_AUX <= BYTE2 & BYTE1 & "000000000000000000"; LENGTH_AUX <= "010000";MISS_AUX <= '0';
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when "0101" => CODE_AUX <= MISS_TYPE_CODE;LENGTH_AUX <= MISS_TYPE_LENGTH;MISS_AUX <= '1';
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when "0100" => CODE_AUX <= BYTE2 & "00000000000000000000000000"; LENGTH_AUX <= "001000";MISS_AUX <= '0';
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when "0011" => CODE_AUX <= BYTE1 & BYTE0 & "000000000000000000"; LENGTH_AUX <= "010000";MISS_AUX <= '0';
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when "0010" => CODE_AUX <= BYTE1 & "00000000000000000000000000"; LENGTH_AUX <= "001000";MISS_AUX <= '0';
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when "0001" => CODE_AUX <= BYTE0 & "00000000000000000000000000"; LENGTH_AUX <= "001000";MISS_AUX <= '0';
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when "0000" => CODE_AUX <= "0000000000000000000000000000000000"; LENGTH_AUX <= "000000";MISS_AUX <= '0';
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end case;
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end process ASSEMBLE;
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DECIDE : process ( CODE_AUX, LENGTH_AUX, MASK, MATCH_TYPE, MISS_AUX, MISS_TYPE_CODE, MISS_TYPE_LENGTH)
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begin
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if (MASK(1) = '1') then -- full word
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CODE <= CODE_AUX;
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LENGTH <= LENGTH_AUX;
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MISS <= MISS_AUX;
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elsif (MATCH_TYPE = "0000") then -- partial word but full match
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CODE <= CODE_AUX;
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LENGTH <= LENGTH_AUX;
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MISS <= MISS_AUX;
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else -- partial word and partial match
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CODE <= MISS_TYPE_CODE;
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LENGTH <= MISS_TYPE_LENGTH;
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MISS <= '1';
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end if;
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end process DECIDE;
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end FIRST; -- end of architecture
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