library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

library work;
use work.decode_types.all;
use work.common.all;
use work.helpers.all;
use work.crhelpers.all;
use work.insn_helpers.all;
use work.ppc_fx_insns.all;

entity execute1 is
	generic (
		SIM   : boolean := false
	);
	port (
		clk   : in std_logic;

		-- asynchronous
		flush_out : out std_ulogic;

		e_in  : in Decode2ToExecute1Type;

		-- asynchronous
		f_out : out Execute1ToFetch1Type;

		e_out : out Execute1ToExecute2Type;

		terminate_out : out std_ulogic
	);
end entity execute1;

architecture behaviour of execute1 is
	type reg_type is record
		--f : Execute1ToFetch1Type;
		e : Execute1ToExecute2Type;
	end record;

	signal r, rin : reg_type;

	signal ctrl: ctrl_t := (carry => '0', others => (others => '0'));
	signal ctrl_tmp: ctrl_t := (carry => '0', others => (others => '0'));

	signal right_shift, rot_clear_left, rot_clear_right: std_ulogic;
	signal rotator_result: std_ulogic_vector(63 downto 0);
	signal rotator_carry: std_ulogic;
	signal logical_result: std_ulogic_vector(63 downto 0);

        function decode_input_carry (carry_sel : carry_in_t; ca_in : std_ulogic) return std_ulogic is
        begin
                case carry_sel is
                when ZERO =>
                        return '0';
                when CA =>
                        return ca_in;
                when ONE =>
                        return '1';
                end case;
        end;
begin

	rotator_0: entity work.rotator
		port map (
			rs => e_in.read_data3,
			ra => e_in.read_data1,
			shift => e_in.read_data2(6 downto 0),
			insn => e_in.insn,
			is_32bit => e_in.is_32bit,
			right_shift => right_shift,
			arith => e_in.is_signed,
			clear_left => rot_clear_left,
			clear_right => rot_clear_right,
			result => rotator_result,
			carry_out => rotator_carry
		);

	logical_0: entity work.logical
		port map (
			rs => e_in.read_data3,
			rb => e_in.read_data2,
			op => e_in.insn_type,
			invert_in => e_in.invert_a,
			invert_out => e_in.invert_out,
			result => logical_result
		);

	execute1_0: process(clk)
	begin
		if rising_edge(clk) then
			r <= rin;
			ctrl <= ctrl_tmp;
		end if;
	end process;

	execute1_1: process(all)
		variable v : reg_type;
                variable a_inv : std_ulogic_vector(63 downto 0);
		variable result : std_ulogic_vector(63 downto 0);
		variable newcrf : std_ulogic_vector(3 downto 0);
		variable result_with_carry : std_ulogic_vector(64 downto 0);
		variable result_en : integer;
		variable crnum : integer;
		variable scrnum : integer;
		variable lo, hi : integer;
                variable sh, mb, me : std_ulogic_vector(5 downto 0);
                variable sh32, mb32, me32 : std_ulogic_vector(4 downto 0);
                variable bo, bi : std_ulogic_vector(4 downto 0);
                variable bf, bfa : std_ulogic_vector(2 downto 0);
                variable l : std_ulogic;
	begin
		result := (others => '0');
		result_with_carry := (others => '0');
		result_en := 0;

		v := r;
		v.e := Execute1ToExecute2Init;
		--v.f := Execute1ToFetch1TypeInit;

		ctrl_tmp <= ctrl;
		-- FIXME: run at 512MHz not core freq
		ctrl_tmp.tb <= std_ulogic_vector(unsigned(ctrl.tb) + 1);

		terminate_out <= '0';
		f_out <= Execute1ToFetch1TypeInit;

		-- rotator control signals
		right_shift <= '1' when e_in.insn_type = OP_SHR else '0';
		rot_clear_left <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCL else '0';
		rot_clear_right <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCR else '0';

		if e_in.valid = '1' then

			v.e.valid := '1';
			v.e.write_reg := e_in.write_reg;

			case_0: case e_in.insn_type is

				when OP_ILLEGAL =>
					terminate_out <= '1';
					report "illegal";
				when OP_NOP =>
					-- Do nothing
				when OP_ADD =>
                                        if e_in.invert_a = '0' then
                                                a_inv := e_in.read_data1;
                                        else
                                                a_inv := not e_in.read_data1;
                                        end if;
					result_with_carry := ppc_adde(a_inv, e_in.read_data2, decode_input_carry(e_in.input_carry, ctrl.carry));
					result := result_with_carry(63 downto 0);
                                        if e_in.output_carry then
                                                ctrl_tmp.carry <= result_with_carry(64);
                                        end if;
					result_en := 1;
				when OP_AND | OP_OR | OP_XOR =>
                                        result := logical_result;
                                        result_en := 1;
				when OP_B =>
					f_out.redirect <= '1';
					if (insn_aa(e_in.insn)) then
					    f_out.redirect_nia <= std_ulogic_vector(signed(e_in.read_data2));
					else
					    f_out.redirect_nia <= std_ulogic_vector(signed(e_in.nia) + signed(e_in.read_data2));
					end if;
				when OP_BC =>
                                        bo := insn_bo(e_in.insn);
                                        bi := insn_bi(e_in.insn);
					if bo(4-2) = '0' then
						ctrl_tmp.ctr <= std_ulogic_vector(unsigned(ctrl.ctr) - 1);
					end if;
					if ppc_bc_taken(bo, bi, e_in.cr, ctrl.ctr) = 1 then
						f_out.redirect <= '1';
						if (insn_aa(e_in.insn)) then
						    f_out.redirect_nia <= std_ulogic_vector(signed(e_in.read_data2));
						else
						    f_out.redirect_nia <= std_ulogic_vector(signed(e_in.nia) + signed(e_in.read_data2));
						end if;
					end if;
				when OP_BCREG =>
                                        -- bits 10 and 6 distinguish between bclr, bcctr and bctar
                                        bo := insn_bo(e_in.insn);
                                        bi := insn_bi(e_in.insn);
					if bo(4-2) = '0' and e_in.insn(10) = '0' then
						ctrl_tmp.ctr <= std_ulogic_vector(unsigned(ctrl.ctr) - 1);
					end if;
					if ppc_bc_taken(bo, bi, e_in.cr, ctrl.ctr) = 1 then
						f_out.redirect <= '1';
                                                if e_in.insn(10) = '0' then
                                                        f_out.redirect_nia <= ctrl.lr(63 downto 2) & "00";
                                                else
                                                        f_out.redirect_nia <= ctrl.ctr(63 downto 2) & "00";
                                                end if;
					end if;
				when OP_CMPB =>
					result := ppc_cmpb(e_in.read_data3, e_in.read_data2);
					result_en := 1;
				when OP_CMP =>
                                        bf := insn_bf(e_in.insn);
                                        l := insn_l(e_in.insn);
					v.e.write_cr_enable := '1';
					crnum := to_integer(unsigned(bf));
					v.e.write_cr_mask := num_to_fxm(crnum);
					for i in 0 to 7 loop
						lo := i*4;
						hi := lo + 3;
						v.e.write_cr_data(hi downto lo) := ppc_cmp(l, e_in.read_data1, e_in.read_data2);
					end loop;
				when OP_CMPL =>
                                        bf := insn_bf(e_in.insn);
                                        l := insn_l(e_in.insn);
					v.e.write_cr_enable := '1';
					crnum := to_integer(unsigned(bf));
					v.e.write_cr_mask := num_to_fxm(crnum);
					for i in 0 to 7 loop
						lo := i*4;
						hi := lo + 3;
						v.e.write_cr_data(hi downto lo) := ppc_cmpl(l, e_in.read_data1, e_in.read_data2);
					end loop;
				when OP_CNTLZW =>
					result := ppc_cntlzw(e_in.read_data3);
					result_en := 1;
				when OP_CNTTZW =>
					result := ppc_cnttzw(e_in.read_data3);
					result_en := 1;
				when OP_CNTLZD =>
					result := ppc_cntlzd(e_in.read_data3);
					result_en := 1;
				when OP_CNTTZD =>
					result := ppc_cnttzd(e_in.read_data3);
					result_en := 1;
				when OP_EXTSB =>
					result := ppc_extsb(e_in.read_data3);
					result_en := 1;
				when OP_EXTSH =>
					result := ppc_extsh(e_in.read_data3);
					result_en := 1;
				when OP_EXTSW =>
					result := ppc_extsw(e_in.read_data3);
					result_en := 1;
				when OP_ISEL =>
					crnum := to_integer(unsigned(insn_bc(e_in.insn)));
					if e_in.cr(31-crnum) = '1' then
						result := e_in.read_data1;
					else
						result := e_in.read_data2;
					end if;
					result_en := 1;
				when OP_MCRF =>
                                        bf := insn_bf(e_in.insn);
                                        bfa := insn_bfa(e_in.insn);
					v.e.write_cr_enable := '1';
					crnum := to_integer(unsigned(bf));
					scrnum := to_integer(unsigned(bfa));
					v.e.write_cr_mask := num_to_fxm(crnum);
					for i in 0 to 7 loop
					    lo := (7-i)*4;
					    hi := lo + 3;
					    if i = scrnum then
						newcrf := e_in.cr(hi downto lo);
					    end if;
					end loop;
					for i in 0 to 7 loop
						lo := i*4;
						hi := lo + 3;
						v.e.write_cr_data(hi downto lo) := newcrf;
					end loop;
                                when OP_MFSPR =>
                                        if std_match(e_in.insn(20 downto 11), "0100100000") then
                                                result := ctrl.ctr;
                                                result_en := 1;
                                        elsif std_match(e_in.insn(20 downto 11), "0100000000") then
                                                result := ctrl.lr;
                                                result_en := 1;
                                        elsif std_match(e_in.insn(20 downto 11), "0110001000") then
                                                result := ctrl.tb;
                                                result_en := 1;
                                        end if;
				when OP_MFCR =>
                                        if e_in.insn(20) = '0' then
                                                -- mfcr
                                                result := x"00000000" & e_in.cr;
                                        else
                                                -- mfocrf
                                                crnum := fxm_to_num(insn_fxm(e_in.insn));
                                                result := (others => '0');
                                                for i in 0 to 7 loop
                                                        lo := (7-i)*4;
                                                        hi := lo + 3;
                                                        if crnum = i then
                                                                result(hi downto lo) := e_in.cr(hi downto lo);
                                                        end if;
                                                end loop;
                                        end if;
					result_en := 1;
				when OP_MTCRF =>
					v.e.write_cr_enable := '1';
                                        if e_in.insn(20) = '0' then
                                                -- mtcrf
                                                v.e.write_cr_mask := insn_fxm(e_in.insn);
                                        else
                                                -- mtocrf: We require one hot priority encoding here
                                                crnum := fxm_to_num(insn_fxm(e_in.insn));
                                                v.e.write_cr_mask := num_to_fxm(crnum);
                                        end if;
					v.e.write_cr_data := e_in.read_data3(31 downto 0);
				when OP_MTSPR =>
                                        if std_match(e_in.insn(20 downto 11), "0100100000") then
                                                ctrl_tmp.ctr <= e_in.read_data3;
                                        elsif std_match(e_in.insn(20 downto 11), "0100000000") then
                                                ctrl_tmp.lr <= e_in.read_data3;
                                        end if;
				when OP_NEG =>
					result := ppc_neg(e_in.read_data1);
					result_en := 1;
				when OP_POPCNTB =>
					result := ppc_popcntb(e_in.read_data3);
					result_en := 1;
				when OP_POPCNTW =>
					result := ppc_popcntw(e_in.read_data3);
					result_en := 1;
				when OP_POPCNTD =>
					result := ppc_popcntd(e_in.read_data3);
					result_en := 1;
				when OP_PRTYD =>
					result := ppc_prtyd(e_in.read_data3);
					result_en := 1;
				when OP_PRTYW =>
					result := ppc_prtyw(e_in.read_data3);
					result_en := 1;
				when OP_RLC | OP_RLCL | OP_RLCR | OP_SHL | OP_SHR =>
					result := rotator_result;
					if e_in.output_carry = '1' then
						ctrl_tmp.carry <= rotator_carry;
					end if;
					result_en := 1;
				when OP_SIM_CONFIG =>
					-- bit 0 was used to select the microwatt console, which
					-- we no longer support.
					if SIM = true then
						result := x"0000000000000000";
					else
						result := x"0000000000000000";
					end if;
					result_en := 1;

				when OP_TDI =>
					-- Keep our test cases happy for now, ignore trap instructions
					report "OP_TDI FIXME";

				when others =>
					terminate_out <= '1';
					report "illegal";
			end case;

			if e_in.lr = '1' then
				ctrl_tmp.lr <= std_ulogic_vector(unsigned(e_in.nia) + 4);
			end if;

			if result_en = 1 then
				v.e.write_data := result;
				v.e.write_enable := '1';
				v.e.rc := e_in.rc;
			end if;
		end if;

                -- Update registers
                rin <= v;

		-- update outputs
		--f_out <= r.f;
		e_out <= r.e;
		flush_out <= f_out.redirect;
	end process;
end architecture behaviour;