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library ieee;
use ieee.std_logic_1164.all;
library ieee;
use ieee.numeric_std.all;
entity sub_144 is
port (
output : out std_logic_vector(63 downto 0);
le : out std_logic;
sign : in std_logic;
ge : out std_logic;
in_a : in std_logic_vector(63 downto 0);
in_b : in std_logic_vector(63 downto 0)
);
end sub_144;
architecture augh of sub_144 is
signal carry_inA : std_logic_vector(65 downto 0);
signal carry_inB : std_logic_vector(65 downto 0);
signal carry_res : std_logic_vector(65 downto 0);
-- Signals to generate the comparison outputs
signal msb_abr : std_logic_vector(2 downto 0);
signal tmp_sign : std_logic;
signal tmp_eq : std_logic;
signal tmp_le : std_logic;
signal tmp_ge : std_logic;
begin
-- To handle the CI input, the operation is '0' - CI
-- If CI is not present, the operation is '0' - '0'
carry_inA <= '0' & in_a & '0';
carry_inB <= '0' & in_b & '0';
-- Compute the result
carry_res <= std_logic_vector(unsigned(carry_inA) - unsigned(carry_inB));
-- Set the outputs
output <= carry_res(64 downto 1);
-- Other comparison outputs
-- Temporary signals
msb_abr <= in_a(63) & in_b(63) & carry_res(64);
tmp_sign <= sign;
tmp_eq <= '1' when in_a = in_b else '0';
tmp_le <=
tmp_eq when msb_abr = "000" or msb_abr = "110" else
'1' when msb_abr = "001" else
'1' when tmp_sign = '0' and (msb_abr = "010" or msb_abr = "001" or msb_abr = "111") else
'1' when tmp_sign = '1' and (msb_abr = "100" or msb_abr = "101") else
'0';
tmp_ge <=
'1' when msb_abr = "000" or msb_abr = "110" else
'1' when tmp_sign = '0' and (msb_abr = "100" or msb_abr = "101") else
'1' when tmp_sign = '1' and (msb_abr = "010" or msb_abr = "011" or msb_abr = "111") else
'0';
ge <= tmp_ge;
le <= tmp_le;
end architecture;
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