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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 = ENCODE16_4 --
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-- version = 2.0 --
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-- last update = 16/06/98 --
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-- author = Jose Nunez --
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---------------------------------
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-- FUNCTION
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-- 16 to 4 encoder to convert active low 16 bit maatch bus input
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-- to a 4 bit wide binary code.
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-- PIN LIST
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-- MATCH_LOC_IN = 16 bit match location input bus (active low)
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-- MATCH_LOC_OUT = 4 bit binary output match location bus
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-- MISS = active low signal to indicate that a miss has occurred
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library ieee,dzx;
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use ieee.std_logic_1164.all;
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entity ENCODE16_4 is
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port
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(
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MATCH_LOC_IN : in bit_vector(15 downto 0);
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MATCH_LOC_OUT : out bit_vector(3 downto 0)
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);
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end ENCODE16_4;
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architecture ENC2 of ENCODE16_4 is
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begin
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ENCODER : process (MATCH_LOC_IN)
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begin
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case MATCH_LOC_IN is
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when x"FFFE" => MATCH_LOC_OUT <= "0000";
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when x"FFFD" => MATCH_LOC_OUT <= "0001";
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when x"FFFB" => MATCH_LOC_OUT <= "0010";
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when x"FFF7" => MATCH_LOC_OUT <= "0011";
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when x"FFEF" => MATCH_LOC_OUT <= "0100";
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when x"FFDF" => MATCH_LOC_OUT <= "0101";
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when x"FFBF" => MATCH_LOC_OUT <= "0110";
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when x"FF7F" => MATCH_LOC_OUT <= "0111";
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when x"FEFF" => MATCH_LOC_OUT <= "1000";
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when x"FDFF" => MATCH_LOC_OUT <= "1001";
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when x"FBFF" => MATCH_LOC_OUT <= "1010";
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when x"F7FF" => MATCH_LOC_OUT <= "1011";
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when x"EFFF" => MATCH_LOC_OUT <= "1100";
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when x"DFFF" => MATCH_LOC_OUT <= "1101";
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when x"BFFF" => MATCH_LOC_OUT <= "1110";
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when x"7FFF" => MATCH_LOC_OUT <= "1111";
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when x"FFFF" => MATCH_LOC_OUT <= "1111";
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when others => MATCH_LOC_OUT <= "1111";
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-- when others => null;
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end case;
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end process ENCODER;
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end ENC2; -- end of architecture
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