--************************************************************************************************--  ALU(internal module) for AVR core--	Version 1.1--  Designed by Ruslan Lepetenok --	Modified 20.02.2002 (CPC/SBC/SBCI Z-flag bug found)--************************************************************************************************library IEEE;use IEEE.std_logic_1164.all;entity alu_avr is port(              alu_data_r_in   : in std_logic_vector(7 downto 0);              alu_data_d_in   : in std_logic_vector(7 downto 0);                            alu_c_flag_in   : in std_logic;              alu_z_flag_in   : in std_logic;-- OPERATION SIGNALS INPUTS              idc_add         :in std_logic;              idc_adc         :in std_logic;              idc_adiw        :in std_logic;              idc_sub         :in std_logic;              idc_subi        :in std_logic;              idc_sbc         :in std_logic;              idc_sbci        :in std_logic;              idc_sbiw        :in std_logic;              adiw_st         : in std_logic;              sbiw_st         : in std_logic;              idc_and         :in std_logic;              idc_andi        :in std_logic;              idc_or          :in std_logic;              idc_ori         :in std_logic;              idc_eor         :in std_logic;                            idc_com         :in std_logic;                            idc_neg         :in std_logic;              idc_inc         :in std_logic;              idc_dec         :in std_logic;              idc_cp          :in std_logic;                            idc_cpc         :in std_logic;              idc_cpi         :in std_logic;              idc_cpse        :in std_logic;                                          idc_lsr         :in std_logic;              idc_ror         :in std_logic;              idc_asr         :in std_logic;              idc_swap        :in std_logic;-- DATA OUTPUT              alu_data_out    : out std_logic_vector(7 downto 0);-- FLAGS OUTPUT              alu_c_flag_out  : out std_logic;              alu_z_flag_out  : out std_logic;              alu_n_flag_out  : out std_logic;              alu_v_flag_out  : out std_logic;              alu_s_flag_out  : out std_logic;              alu_h_flag_out  : out std_logic);end alu_avr;architecture rtl of alu_avr is-- ####################################################-- INTERNAL SIGNALS-- ####################################################signal alu_data_out_int		    : std_logic_vector (7 downto 0);	-- ALU FLAGS (INTERNAL)signal alu_z_flag_out_int       : std_logic;signal alu_c_flag_in_int        : std_logic;            -- INTERNAL CARRY FLAGsignal alu_n_flag_out_int       : std_logic;signal alu_v_flag_out_int       : std_logic;signal alu_c_flag_out_int       : std_logic;-- ADDER SIGNALS --signal adder_nadd_sub : std_logic;        -- 0 -> ADD ,1 -> SUBsignal adder_v_flag_out	: std_logic;signal adder_carry : std_logic_vector(8 downto 0);signal adder_d_in  : std_logic_vector(8 downto 0);signal adder_r_in  : std_logic_vector(8 downto 0);signal adder_out   : std_logic_vector(8 downto 0);-- NEG OPERATOR SIGNALS signal neg_op_in    : std_logic_vector(7 downto 0);	signal neg_op_carry : std_logic_vector(8 downto 0);signal neg_op_out   : std_logic_vector(8 downto 0);-- INC, DEC OPERATOR SIGNALS signal incdec_op_in    : std_logic_vector (7 downto 0);	signal incdec_op_carry : std_logic_vector(7 downto 0);signal incdec_op_out   : std_logic_vector(7 downto 0);signal com_op_out : std_logic_vector(7 downto 0);signal and_op_out : std_logic_vector(7 downto 0);signal or_op_out : std_logic_vector(7 downto 0);signal eor_op_out : std_logic_vector(7 downto 0);-- SHIFT SIGNALSsignal right_shift_out : std_logic_vector(7 downto 0);-- SWAP SIGNALSsignal swap_out : std_logic_vector(7 downto 0);begin	-- ########################################################################-- ###############              ALU-- ########################################################################adder_nadd_sub <=(idc_sub or idc_subi or idc_sbc or idc_sbci or idc_sbiw or sbiw_st or                  idc_cp or idc_cpc or idc_cpi or idc_cpse ); -- '0' -> '+'; '1' -> '-' -- SREG C FLAG (ALU INPUT)alu_c_flag_in_int <= alu_c_flag_in and (idc_adc or adiw_st or idc_sbc or idc_sbci or sbiw_st or idc_cpc oridc_ror);                                          -- SREG Z FLAG ()-- alu_z_flag_out <= (alu_z_flag_out_int and not(adiw_st or sbiw_st)) or --                   ((alu_z_flag_in and alu_z_flag_out_int) and (adiw_st or sbiw_st));alu_z_flag_out <= (alu_z_flag_out_int and not(adiw_st or sbiw_st or idc_cpc or idc_sbc or idc_sbci)) or                   ((alu_z_flag_in and alu_z_flag_out_int) and (adiw_st or sbiw_st))or				  (alu_z_flag_in and alu_z_flag_out_int and(idc_cpc or idc_sbc or idc_sbci));   -- Previous value (for CPC/SBC/SBCI instructions)-- SREG N FLAGalu_n_flag_out <= alu_n_flag_out_int;				  				  -- SREG V FLAGalu_v_flag_out <= alu_v_flag_out_int;				  alu_c_flag_out <= alu_c_flag_out_int;				  alu_data_out <= alu_data_out_int;-- #########################################################################################adder_d_in <= '0'&alu_data_d_in;adder_r_in <= '0'&alu_data_r_in;  --########################## ADDEER ###################################adder_out(0) <= adder_d_in(0) xor adder_r_in(0) xor alu_c_flag_in_int;adder_carry(0) <= ((adder_d_in(0) xor adder_nadd_sub) and adder_r_in(0)) or                (((adder_d_in(0) xor adder_nadd_sub) or adder_r_in(0)) and alu_c_flag_in_int);summator:for i in 1 to 8 generateadder_out(i) <= adder_d_in(i) xor adder_r_in(i) xor adder_carry(i-1);adder_carry(i) <= ((adder_d_in(i) xor adder_nadd_sub) and adder_r_in(i)) or                 (((adder_d_in(i) xor adder_nadd_sub) or adder_r_in(i)) and adder_carry(i-1));end generate;-- FLAGS  FOR ADDER INSTRUCTIONS: -- CARRY FLAG (C) -> adder_out(8)-- HALF CARRY FLAG (H) -> adder_carry(3)-- TOW'S COMPLEMENT OVERFLOW  (V) -> adder_v_flag_out <= (((adder_d_in(7) and adder_r_in(7) and not adder_out(7)) or                     (not adder_d_in(7) and not adder_r_in(7) and adder_out(7))) and not adder_nadd_sub) or -- ADD                    (((adder_d_in(7) and not adder_r_in(7) and not adder_out(7)) or					(not adder_d_in(7) and adder_r_in(7) and adder_out(7))) and adder_nadd_sub);																										   -- SUB--#####################################################################-- LOGICAL OPERATIONS FOR ONE OPERAND--########################## NEG OPERATION ####################neg_op_out(0)   <= not alu_data_d_in(0) xor '1';neg_op_carry(0) <= not alu_data_d_in(0) and '1';neg_op:for i in 1 to 7 generateneg_op_out(i)   <= not alu_data_d_in(i) xor neg_op_carry(i-1);neg_op_carry(i) <= not alu_data_d_in(i) and neg_op_carry(i-1);end generate;neg_op_out(8) <= neg_op_carry(7) xor '1';neg_op_carry(8) <= neg_op_carry(7);                            -- ??!!-- CARRY FLAGS  FOR NEG INSTRUCTION: -- CARRY FLAG -> neg_op_out(8)-- HALF CARRY FLAG -> neg_op_carry(3)-- TOW's COMPLEMENT OVERFLOW FLAG -> alu_data_d_in(7) and neg_op_carry(6) --############################################################################	--########################## INC, DEC OPERATIONS ####################incdec_op_out(0)      <=  alu_data_d_in(0) xor '1';incdec_op_carry(0)    <=  alu_data_d_in(0) xor idc_dec;inc_dec:for i in 1 to 7 generateincdec_op_out(i)   <= alu_data_d_in(i) xor incdec_op_carry(i-1);incdec_op_carry(i) <= (alu_data_d_in(i) xor idc_dec) and incdec_op_carry(i-1);end generate;-- TOW's COMPLEMENT OVERFLOW FLAG -> (alu_data_d_in(7) xor idc_dec) and incdec_op_carry(6) --####################################################################--########################## COM OPERATION ###################################com_op_out <= not alu_data_d_in;-- FLAGS -- TOW's COMPLEMENT OVERFLOW FLAG (V)  -> '0'-- CARRY FLAG (C) -> '1' --############################################################################-- LOGICAL OPERATIONS FOR TWO OPERANDS	--########################## AND OPERATION ###################################and_op_out <= alu_data_d_in and alu_data_r_in;-- FLAGS -- TOW's COMPLEMENT OVERFLOW FLAG (V)  -> '0'--############################################################################--########################## OR OPERATION ###################################or_op_out <= alu_data_d_in or alu_data_r_in;-- FLAGS -- TOW's COMPLEMENT OVERFLOW FLAG (V)  -> '0'--############################################################################--########################## EOR OPERATION ###################################eor_op_out <= alu_data_d_in xor alu_data_r_in;-- FLAGS -- TOW's COMPLEMENT OVERFLOW FLAG (V)  -> '0'--############################################################################-- SHIFT OPERATIONS -- ########################## RIGHT(LSR, ROR, ASR) #######################right_shift_out(7) <= (idc_ror and alu_c_flag_in_int) or (idc_asr and alu_data_d_in(7)); -- right_shift_out(7)shift_right:for i in 6 downto 0 generateright_shift_out(i) <= alu_data_d_in(i+1);end generate;	-- FLAGS -- CARRY FLAG (C)                      -> alu_data_d_in(0) -- NEGATIVE FLAG (N)                   -> right_shift_out(7)-- TOW's COMPLEMENT OVERFLOW FLAG (V)  -> N xor C  (left_shift_out(7) xor alu_data_d_in(0))-- #######################################################################-- ################################## SWAP ###############################swap_h:for i in 7 downto 4 generateswap_out(i) <= alu_data_d_in(i-4);end generate;swap_l:for i in 3 downto 0 generateswap_out(i) <= alu_data_d_in(i+4);end generate;-- #######################################################################-- ALU OUTPUT MUXalu_data_out_mux:for i in alu_data_out_int'range generatealu_data_out_int(i) <= (adder_out(i) and (idc_add or idc_adc or (idc_adiw or adiw_st) or    -- !!!!!                                     idc_sub or idc_subi or idc_sbc or idc_sbci or                                     (idc_sbiw or sbiw_st) or    -- !!!!!                                     idc_cpse or idc_cp or idc_cpc or idc_cpi)) or                                      (neg_op_out(i) and idc_neg) or                               -- NEG                                     (incdec_op_out(i) and (idc_inc or idc_dec)) or               -- INC/DEC                                     (com_op_out(i) and idc_com) or                               -- COM                                     (and_op_out(i) and (idc_and or idc_andi)) or                 -- AND/ANDI                                                                        (or_op_out(i)  and (idc_or or idc_ori)) or                   -- OR/ORI                                                                        (eor_op_out(i) and idc_eor) or                               -- EOR                                     (right_shift_out(i) and (idc_lsr or idc_ror or idc_asr)) or  -- LSR/ROR/ASR                                     (swap_out(i) and idc_swap);                                  -- SWAP                                     end generate;--@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ ALU FLAGS OUTPUTS @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@alu_h_flag_out <= (adder_carry(3) and                                                      -- ADDER INSTRUCTIONS             (idc_add or idc_adc or idc_sub or idc_subi or idc_sbc or idc_sbci or idc_cp or idc_cpc or idc_cpi)) or                (neg_op_carry(3) and idc_neg);                                          -- NEG                          alu_s_flag_out <= alu_n_flag_out_int xor alu_v_flag_out_int;alu_v_flag_out_int <= (adder_v_flag_out and	                            (idc_add or idc_adc or idc_sub or idc_subi or idc_sbc or idc_sbci or adiw_st or sbiw_st or idc_cp or idc_cpi or idc_cpc)) or             ((alu_data_d_in(7) and neg_op_carry(6)) and idc_neg) or                                       -- NEG		     (not alu_data_d_in(7) and incdec_op_carry(6) and idc_inc) or -- INC		     (alu_data_d_in(7) and incdec_op_carry(6) and idc_dec) or	  -- DEC			 ((alu_n_flag_out_int xor alu_c_flag_out_int) and (idc_lsr or idc_ror or idc_asr));            -- LSR,ROR,ASRalu_n_flag_out_int <= alu_data_out_int(7);alu_z_flag_out_int <= '1' when alu_data_out_int="00000000" else '0';alu_c_flag_out_int <= (adder_out(8) and                        (idc_add or idc_adc or (idc_adiw or adiw_st) or idc_sub or idc_subi or idc_sbc or idc_sbci or (idc_sbiw or sbiw_st) or idc_cp or idc_cpc or idc_cpi)) or -- ADDER					   (not alu_z_flag_out_int and idc_neg) or    -- NEG					   (alu_data_d_in(0) and (idc_lsr or idc_ror or idc_asr)) or idc_com;-- @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@end rtl;