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2051e520
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Arnaud Dieumegard
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library ieee;
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use ieee.std_logic_1164.all;
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library ieee;
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use ieee.numeric_std.all;
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entity sub_125 is
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port (
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le : out std_logic;
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sign : in std_logic;
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result : out std_logic_vector(31 downto 0);
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in_a : in std_logic_vector(31 downto 0);
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in_b : in std_logic_vector(31 downto 0)
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);
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end sub_125;
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architecture augh of sub_125 is
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signal carry_inA : std_logic_vector(33 downto 0);
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signal carry_inB : std_logic_vector(33 downto 0);
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signal carry_res : std_logic_vector(33 downto 0);
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-- Signals to generate the comparison outputs
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signal msb_abr : std_logic_vector(2 downto 0);
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signal tmp_sign : std_logic;
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signal tmp_eq : std_logic;
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signal tmp_le : std_logic;
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signal tmp_ge : std_logic;
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begin
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-- To handle the CI input, the operation is '0' - CI
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-- If CI is not present, the operation is '0' - '0'
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carry_inA <= '0' & in_a & '0';
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carry_inB <= '0' & in_b & '0';
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-- Compute the result
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carry_res <= std_logic_vector(unsigned(carry_inA) - unsigned(carry_inB));
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-- Set the outputs
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result <= carry_res(32 downto 1);
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-- Other comparison outputs
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-- Temporary signals
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msb_abr <= carry_inA(32) & carry_inB(32) & carry_res(32);
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tmp_sign <= sign;
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tmp_eq <= '1' when in_a = in_b else '0';
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tmp_le <=
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tmp_eq when msb_abr = "000" or msb_abr = "110" else
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'1' when msb_abr = "001" or msb_abr = "111" else
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'1' when tmp_sign = '0' and (msb_abr = "010" or msb_abr = "011") else
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'1' when tmp_sign = '1' and (msb_abr = "100" or msb_abr = "101") else
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'0';
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tmp_ge <=
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'1' when msb_abr = "000" or msb_abr = "110" else
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'1' when tmp_sign = '0' and (msb_abr = "100" or msb_abr = "101") else
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'1' when tmp_sign = '1' and (msb_abr = "010" or msb_abr = "011") else
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'0';
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le <= tmp_le;
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end architecture;
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