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-- Author : Timo Alho
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-- e-mail : timo.a.alho@tut.fi
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-- Date : 14.06.2004 14:36:26
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-- File : Rom_dct_sub.vhd
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-- Design :
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------------------------------------------------------------------------------
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-- Description : Pre-calculated DCT-coefficients for subtraction -terms
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------------------------------------------------------------------------------
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LIBRARY ieee;
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USE ieee.std_logic_1164.ALL;
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USE ieee.std_logic_arith.ALL;
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ENTITY Rom_dct_sub IS
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GENERIC(
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coeffw_g : integer := 14
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);
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PORT(
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addr_in : IN std_logic_vector (3 DOWNTO 0);
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clk : IN std_logic;
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data_out : OUT std_logic_vector (4*coeffw_g-1 DOWNTO 0)
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);
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-- Declarations
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END Rom_dct_sub ;
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--
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ARCHITECTURE rtl OF Rom_dct_sub IS
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TYPE Rom16x4x15 IS ARRAY (0 TO 15) OF signed(15*4-1 DOWNTO 0);
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CONSTANT ROM_SUB : Rom16x4x15 := (
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conv_signed(0, 15) & conv_signed(0, 15) & conv_signed(0, 15) & conv_signed(0, 15),
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conv_signed(5681, 15) & conv_signed(4816, 15) & conv_signed(3218, 15) & conv_signed(1130, 15),
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conv_signed(4816, 15) & conv_signed(-1130, 15) & conv_signed(-5681, 15) & conv_signed(-3218, 15),
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conv_signed(10498, 15) & conv_signed(3686, 15) & conv_signed(-2463, 15) & conv_signed(-2088, 15),
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conv_signed(3218, 15) & conv_signed(-5681, 15) & conv_signed(1130, 15) & conv_signed(4816, 15),
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conv_signed(8900, 15) & conv_signed(-865, 15) & conv_signed(4348, 15) & conv_signed(5946, 15),
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conv_signed(8035, 15) & conv_signed(-6811, 15) & conv_signed(-4551, 15) & conv_signed(1598, 15),
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conv_signed(13716, 15) & conv_signed(-1995, 15) & conv_signed(-1333, 15) & conv_signed(2728, 15),
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conv_signed(1130, 15) & conv_signed(-3218, 15) & conv_signed(4816, 15) & conv_signed(-5681, 15),
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conv_signed(6811, 15) & conv_signed(1598, 15) & conv_signed(8035, 15) & conv_signed(-4551, 15),
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conv_signed(5946, 15) & conv_signed(-4348, 15) & conv_signed(-865, 15) & conv_signed(-8900, 15),
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conv_signed(11628, 15) & conv_signed(468, 15) & conv_signed(2353, 15) & conv_signed(-7769, 15),
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conv_signed(4348, 15) & conv_signed(-8900, 15) & conv_signed(5946, 15) & conv_signed(-865, 15),
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conv_signed(10030, 15) & conv_signed(-4083, 15) & conv_signed(9165, 15) & conv_signed(265, 15),
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conv_signed(9165, 15) & conv_signed(-10030, 15) & conv_signed(265, 15) & conv_signed(-4083, 15),
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conv_signed(14846, 15) & conv_signed(-5213, 15) & conv_signed(3483, 15) & conv_signed(-2953, 15));
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SIGNAL addr_r : std_logic_vector(3 DOWNTO 0);
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BEGIN
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clocked : PROCESS (clk)
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BEGIN -- PROCESS clocked
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IF clk'event AND clk = '1' THEN -- rising clock edge
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addr_r <= addr_in;
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END IF;
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END PROCESS clocked;
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access_rom : PROCESS (addr_r)
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VARIABLE address : integer;
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BEGIN
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address := conv_integer(unsigned(addr_r));
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data_out <= conv_std_logic_vector(ROM_SUB(address), 4*coeffw_g);
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END PROCESS access_rom;
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END rtl;
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