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borin |
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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use work.riscompatible_package.all;
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entity Ula is
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port
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(
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Cy_I : in std_logic;
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Source1_I : in TRiscoWord;
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Source2_I : in TRiscoWord;
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Function_I : in std_logic_vector(4 downto 0);
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Output_O : out TRiscoWord;
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Cy_O : out std_logic;
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Ov_O : out std_logic;
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Zr_O : out std_logic;
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Ng_O : out std_logic
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);
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end Ula;
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architecture behavioral of ula is
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signal UlaTemp_W : std_logic_vector(32 downto 0);
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signal Carry_W : TRiscoWord;
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begin
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Carry_W(0) <= Cy_I;
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Carry_W(TRiscoWord'high downto 1) <= (others => '0');
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with Function_I select
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-- Fig. 5.8 of [1]
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-- Carry -> bit 32
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UlaTemp_W <=
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('0'&Source1_I) and ('0'&Source2_I) when C_AND,
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('0'&Source1_I) or ('0'&Source2_I) when C_OR,
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('0'&Source1_I) xor ('0'&Source2_I) when C_XOR,
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std_logic_vector(unsigned('0'¬(Source1_I)) + unsigned('0'&Source2_I) + unsigned(not(Carry_W))) when C_SUBRC,
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std_logic_vector(unsigned('0'¬(Source1_I)) + unsigned('0'&Source2_I) + unsigned(Carry_W) ) when C_SUBRCNOT,
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std_logic_vector(unsigned('0'¬(Source1_I)) + unsigned('0'&Source2_I) + 1 ) when C_SUBR,
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std_logic_vector(unsigned('0'¬(Source1_I)) + unsigned('0'&Source2_I) + 0 ) when C_SUBRNC,
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std_logic_vector(unsigned('0'&Source1_I) + unsigned('0'¬(Source2_I)) + unsigned(not(Carry_W))) when C_SUBC,
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std_logic_vector(unsigned('0'&Source1_I) + unsigned('0'¬(Source2_I)) + unsigned(Carry_W) ) when C_SUBCNOT,
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std_logic_vector(unsigned('0'&Source1_I) + unsigned('0'¬(Source2_I)) + 1 ) when C_SUB,
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std_logic_vector(unsigned('0'&Source1_I) + unsigned('0'¬(Source2_I)) + 0 ) when C_SUBNC,
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std_logic_vector(unsigned('0'&Source1_I) + unsigned('0'&Source2_I) + unsigned(not(Carry_W))) when C_ADDCNOT,
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std_logic_vector(unsigned('0'&Source1_I) + unsigned('0'&Source2_I) + unsigned(Carry_W) ) when C_ADDC,
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std_logic_vector(unsigned('0'&Source1_I) + unsigned('0'&Source2_I) + 1 ) when C_ADD1,
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std_logic_vector(unsigned('0'&Source1_I) + unsigned('0'&Source2_I) + 0 ) when C_ADD,
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(others => '0') when others;
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Output_O <= UlaTemp_W(Output_O'range);
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Cy_O <= UlaTemp_W(32);
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Ov_O <= UlaTemp_W(32);
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Zr_O <= IsZero_F(UlaTemp_W);
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Ng_O <= UlaTemp_W(31);
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end behavioral;
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