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For multiply and divide operations, execute1 now records the destination GPR number, RC and OE from the instruction, and the XER value. This means that the multiply and divide units don't need to record those values and then send them back to execute1. This makes the interface to those units a bit simpler. They simply report an overflow signal along with the result value, and execute1 takes care of updating XER if necessary. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
711 lines
22 KiB
VHDL
711 lines
22 KiB
VHDL
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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library work;
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use work.decode_types.all;
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use work.common.all;
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use work.helpers.all;
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use work.crhelpers.all;
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use work.insn_helpers.all;
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use work.ppc_fx_insns.all;
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entity execute1 is
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port (
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clk : in std_ulogic;
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rst : in std_ulogic;
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-- asynchronous
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flush_out : out std_ulogic;
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stall_out : out std_ulogic;
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e_in : in Decode2ToExecute1Type;
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-- asynchronous
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f_out : out Execute1ToFetch1Type;
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e_out : out Execute1ToWritebackType;
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icache_inval : out std_ulogic;
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terminate_out : out std_ulogic
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);
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end entity execute1;
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architecture behaviour of execute1 is
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type reg_type is record
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e : Execute1ToWritebackType;
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lr_update : std_ulogic;
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next_lr : std_ulogic_vector(63 downto 0);
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mul_in_progress : std_ulogic;
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div_in_progress : std_ulogic;
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slow_op_dest : gpr_index_t;
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slow_op_rc : std_ulogic;
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slow_op_oe : std_ulogic;
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slow_op_xerc : xer_common_t;
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end record;
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signal r, rin : reg_type;
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signal ctrl: ctrl_t := (others => (others => '0'));
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signal ctrl_tmp: ctrl_t := (others => (others => '0'));
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signal right_shift, rot_clear_left, rot_clear_right: std_ulogic;
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signal rotator_result: std_ulogic_vector(63 downto 0);
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signal rotator_carry: std_ulogic;
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signal logical_result: std_ulogic_vector(63 downto 0);
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signal countzero_result: std_ulogic_vector(63 downto 0);
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-- multiply signals
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signal x_to_multiply: Execute1ToMultiplyType;
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signal multiply_to_x: MultiplyToExecute1Type;
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-- divider signals
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signal x_to_divider: Execute1ToDividerType;
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signal divider_to_x: DividerToExecute1Type;
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procedure set_carry(e: inout Execute1ToWritebackType;
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carry32 : in std_ulogic;
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carry : in std_ulogic) is
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begin
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e.xerc.ca32 := carry32;
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e.xerc.ca := carry;
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e.write_xerc_enable := '1';
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end;
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procedure set_ov(e: inout Execute1ToWritebackType;
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ov : in std_ulogic;
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ov32 : in std_ulogic) is
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begin
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e.xerc.ov32 := ov32;
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e.xerc.ov := ov;
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if ov = '1' then
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e.xerc.so := '1';
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end if;
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e.write_xerc_enable := '1';
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end;
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function calc_ov(msb_a : std_ulogic; msb_b: std_ulogic;
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ca: std_ulogic; msb_r: std_ulogic) return std_ulogic is
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begin
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return (ca xor msb_r) and not (msb_a xor msb_b);
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end;
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function decode_input_carry(ic : carry_in_t;
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xerc : xer_common_t) return std_ulogic is
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begin
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case ic is
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when ZERO =>
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return '0';
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when CA =>
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return xerc.ca;
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when ONE =>
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return '1';
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end case;
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end;
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begin
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rotator_0: entity work.rotator
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port map (
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rs => e_in.read_data3,
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ra => e_in.read_data1,
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shift => e_in.read_data2(6 downto 0),
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insn => e_in.insn,
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is_32bit => e_in.is_32bit,
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right_shift => right_shift,
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arith => e_in.is_signed,
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clear_left => rot_clear_left,
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clear_right => rot_clear_right,
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result => rotator_result,
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carry_out => rotator_carry
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);
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logical_0: entity work.logical
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port map (
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rs => e_in.read_data3,
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rb => e_in.read_data2,
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op => e_in.insn_type,
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invert_in => e_in.invert_a,
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invert_out => e_in.invert_out,
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result => logical_result
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);
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countzero_0: entity work.zero_counter
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port map (
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rs => e_in.read_data3,
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count_right => e_in.insn(10),
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is_32bit => e_in.is_32bit,
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result => countzero_result
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);
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multiply_0: entity work.multiply
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port map (
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clk => clk,
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m_in => x_to_multiply,
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m_out => multiply_to_x
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);
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divider_0: entity work.divider
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port map (
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clk => clk,
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rst => rst,
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d_in => x_to_divider,
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d_out => divider_to_x
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);
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execute1_0: process(clk)
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begin
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if rising_edge(clk) then
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r <= rin;
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ctrl <= ctrl_tmp;
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assert not (r.lr_update = '1' and e_in.valid = '1')
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report "LR update collision with valid in EX1"
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severity failure;
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if r.lr_update = '1' then
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report "LR update to " & to_hstring(r.next_lr);
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end if;
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end if;
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end process;
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execute1_1: process(all)
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variable v : reg_type;
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variable a_inv : std_ulogic_vector(63 downto 0);
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variable result : std_ulogic_vector(63 downto 0);
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variable newcrf : std_ulogic_vector(3 downto 0);
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variable result_with_carry : std_ulogic_vector(64 downto 0);
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variable result_en : std_ulogic;
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variable crnum : crnum_t;
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variable crbit : integer range 0 to 31;
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variable scrnum : crnum_t;
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variable lo, hi : integer;
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variable sh, mb, me : std_ulogic_vector(5 downto 0);
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variable sh32, mb32, me32 : std_ulogic_vector(4 downto 0);
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variable bo, bi : std_ulogic_vector(4 downto 0);
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variable bf, bfa : std_ulogic_vector(2 downto 0);
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variable cr_op : std_ulogic_vector(9 downto 0);
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variable bt, ba, bb : std_ulogic_vector(4 downto 0);
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variable btnum, banum, bbnum : integer range 0 to 31;
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variable crresult : std_ulogic;
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variable l : std_ulogic;
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variable next_nia : std_ulogic_vector(63 downto 0);
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variable carry_32, carry_64 : std_ulogic;
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variable sign1, sign2 : std_ulogic;
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variable abs1, abs2 : signed(63 downto 0);
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variable overflow : std_ulogic;
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begin
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result := (others => '0');
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result_with_carry := (others => '0');
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result_en := '0';
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newcrf := (others => '0');
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v := r;
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v.e := Execute1ToWritebackInit;
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-- XER forwarding. To avoid having to track XER hazards, we
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-- use the previously latched value.
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--
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-- If the XER was modified by a multiply or a divide, those are
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-- single issue, we'll get the up to date value from decode2 from
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-- the register file.
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--
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-- If it was modified by an instruction older than the previous
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-- one in EX1, it will have also hit writeback and will be up
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-- to date in decode2.
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--
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-- That leaves us with the case where it was updated by the previous
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-- instruction in EX1. In that case, we can forward it back here.
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--
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-- This will break if we allow pipelining of multiply and divide,
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-- but ideally, those should go via EX1 anyway and run as a state
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-- machine from here.
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--
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-- One additional hazard to beware of is an XER:SO modifying instruction
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-- in EX1 followed immediately by a store conditional. Due to our
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-- writeback latency, the store will go down the LSU with the previous
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-- XER value, thus the stcx. will set CR0:SO using an obsolete SO value.
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--
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-- We will need to handle that if we ever make stcx. not single issue
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--
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-- We always pass a valid XER value downto writeback even when
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-- we aren't updating it, in order for XER:SO -> CR0:SO transfer
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-- to work for RC instructions.
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--
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if r.e.write_xerc_enable = '1' then
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v.e.xerc := r.e.xerc;
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else
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v.e.xerc := e_in.xerc;
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end if;
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v.lr_update := '0';
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v.mul_in_progress := '0';
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v.div_in_progress := '0';
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-- signals to multiply unit
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x_to_multiply <= Execute1ToMultiplyInit;
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x_to_multiply.insn_type <= e_in.insn_type;
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x_to_multiply.is_32bit <= e_in.is_32bit;
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if e_in.is_32bit = '1' then
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if e_in.is_signed = '1' then
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x_to_multiply.data1 <= (others => e_in.read_data1(31));
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x_to_multiply.data1(31 downto 0) <= e_in.read_data1(31 downto 0);
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x_to_multiply.data2 <= (others => e_in.read_data2(31));
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x_to_multiply.data2(31 downto 0) <= e_in.read_data2(31 downto 0);
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else
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x_to_multiply.data1 <= '0' & x"00000000" & e_in.read_data1(31 downto 0);
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x_to_multiply.data2 <= '0' & x"00000000" & e_in.read_data2(31 downto 0);
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end if;
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else
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if e_in.is_signed = '1' then
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x_to_multiply.data1 <= e_in.read_data1(63) & e_in.read_data1;
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x_to_multiply.data2 <= e_in.read_data2(63) & e_in.read_data2;
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else
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x_to_multiply.data1 <= '0' & e_in.read_data1;
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x_to_multiply.data2 <= '0' & e_in.read_data2;
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end if;
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end if;
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-- signals to divide unit
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sign1 := '0';
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sign2 := '0';
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if e_in.is_signed = '1' then
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if e_in.is_32bit = '1' then
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sign1 := e_in.read_data1(31);
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sign2 := e_in.read_data2(31);
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else
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sign1 := e_in.read_data1(63);
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sign2 := e_in.read_data2(63);
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end if;
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end if;
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-- take absolute values
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if sign1 = '0' then
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abs1 := signed(e_in.read_data1);
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else
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abs1 := - signed(e_in.read_data1);
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end if;
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if sign2 = '0' then
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abs2 := signed(e_in.read_data2);
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else
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abs2 := - signed(e_in.read_data2);
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end if;
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x_to_divider <= Execute1ToDividerInit;
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x_to_divider.is_signed <= e_in.is_signed;
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x_to_divider.is_32bit <= e_in.is_32bit;
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if e_in.insn_type = OP_MOD then
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x_to_divider.is_modulus <= '1';
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end if;
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x_to_divider.neg_result <= sign1 xor (sign2 and not x_to_divider.is_modulus);
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if e_in.is_32bit = '0' then
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-- 64-bit forms
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if e_in.insn_type = OP_DIVE then
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x_to_divider.is_extended <= '1';
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end if;
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x_to_divider.dividend <= std_ulogic_vector(abs1);
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x_to_divider.divisor <= std_ulogic_vector(abs2);
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else
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-- 32-bit forms
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x_to_divider.is_extended <= '0';
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if e_in.insn_type = OP_DIVE then -- extended forms
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x_to_divider.dividend <= std_ulogic_vector(abs1(31 downto 0)) & x"00000000";
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else
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x_to_divider.dividend <= x"00000000" & std_ulogic_vector(abs1(31 downto 0));
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end if;
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x_to_divider.divisor <= x"00000000" & std_ulogic_vector(abs2(31 downto 0));
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end if;
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ctrl_tmp <= ctrl;
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-- FIXME: run at 512MHz not core freq
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ctrl_tmp.tb <= std_ulogic_vector(unsigned(ctrl.tb) + 1);
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terminate_out <= '0';
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icache_inval <= '0';
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stall_out <= '0';
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f_out <= Execute1ToFetch1TypeInit;
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-- Next insn adder used in a couple of places
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next_nia := std_ulogic_vector(unsigned(e_in.nia) + 4);
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-- rotator control signals
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right_shift <= '1' when e_in.insn_type = OP_SHR else '0';
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rot_clear_left <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCL else '0';
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rot_clear_right <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCR else '0';
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if e_in.valid = '1' then
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v.e.valid := '1';
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v.e.write_reg := e_in.write_reg;
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v.e.write_len := x"8";
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v.e.sign_extend := '0';
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v.slow_op_dest := gspr_to_gpr(e_in.write_reg);
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v.slow_op_rc := e_in.rc;
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v.slow_op_oe := e_in.oe;
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v.slow_op_xerc := v.e.xerc;
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case_0: case e_in.insn_type is
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when OP_ILLEGAL =>
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terminate_out <= '1';
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report "illegal";
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when OP_NOP =>
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-- Do nothing
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when OP_ADD =>
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if e_in.invert_a = '0' then
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a_inv := e_in.read_data1;
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else
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a_inv := not e_in.read_data1;
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end if;
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result_with_carry := ppc_adde(a_inv, e_in.read_data2,
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decode_input_carry(e_in.input_carry, v.e.xerc));
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result := result_with_carry(63 downto 0);
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carry_32 := result(32) xor a_inv(32) xor e_in.read_data2(32);
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carry_64 := result_with_carry(64);
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if e_in.output_carry = '1' then
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set_carry(v.e, carry_32, carry_64);
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end if;
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if e_in.oe = '1' then
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set_ov(v.e,
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calc_ov(a_inv(63), e_in.read_data2(63), carry_64, result_with_carry(63)),
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calc_ov(a_inv(31), e_in.read_data2(31), carry_32, result_with_carry(31)));
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end if;
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result_en := '1';
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when OP_AND | OP_OR | OP_XOR =>
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result := logical_result;
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result_en := '1';
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when OP_B =>
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f_out.redirect <= '1';
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if (insn_aa(e_in.insn)) then
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f_out.redirect_nia <= std_ulogic_vector(signed(e_in.read_data2));
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else
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f_out.redirect_nia <= std_ulogic_vector(signed(e_in.nia) + signed(e_in.read_data2));
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end if;
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when OP_BC =>
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-- read_data1 is CTR
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bo := insn_bo(e_in.insn);
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bi := insn_bi(e_in.insn);
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if bo(4-2) = '0' then
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result := std_ulogic_vector(unsigned(e_in.read_data1) - 1);
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result_en := '1';
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v.e.write_reg := fast_spr_num(SPR_CTR);
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end if;
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if ppc_bc_taken(bo, bi, e_in.cr, e_in.read_data1) = 1 then
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f_out.redirect <= '1';
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if (insn_aa(e_in.insn)) then
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f_out.redirect_nia <= std_ulogic_vector(signed(e_in.read_data2));
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else
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f_out.redirect_nia <= std_ulogic_vector(signed(e_in.nia) + signed(e_in.read_data2));
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end if;
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end if;
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when OP_BCREG =>
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-- read_data1 is CTR
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-- read_data2 is target register (CTR, LR or TAR)
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bo := insn_bo(e_in.insn);
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bi := insn_bi(e_in.insn);
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if bo(4-2) = '0' and e_in.insn(10) = '0' then
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result := std_ulogic_vector(unsigned(e_in.read_data1) - 1);
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result_en := '1';
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v.e.write_reg := fast_spr_num(SPR_CTR);
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end if;
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if ppc_bc_taken(bo, bi, e_in.cr, e_in.read_data1) = 1 then
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f_out.redirect <= '1';
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f_out.redirect_nia <= e_in.read_data2(63 downto 2) & "00";
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end if;
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when OP_CMPB =>
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result := ppc_cmpb(e_in.read_data3, e_in.read_data2);
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result_en := '1';
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when OP_CMP =>
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bf := insn_bf(e_in.insn);
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l := insn_l(e_in.insn);
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v.e.write_cr_enable := '1';
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crnum := to_integer(unsigned(bf));
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v.e.write_cr_mask := num_to_fxm(crnum);
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for i in 0 to 7 loop
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lo := i*4;
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hi := lo + 3;
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v.e.write_cr_data(hi downto lo) := ppc_cmp(l, e_in.read_data1, e_in.read_data2, v.e.xerc.so);
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end loop;
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when OP_CMPL =>
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bf := insn_bf(e_in.insn);
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l := insn_l(e_in.insn);
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v.e.write_cr_enable := '1';
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crnum := to_integer(unsigned(bf));
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v.e.write_cr_mask := num_to_fxm(crnum);
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for i in 0 to 7 loop
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lo := i*4;
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hi := lo + 3;
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v.e.write_cr_data(hi downto lo) := ppc_cmpl(l, e_in.read_data1, e_in.read_data2, v.e.xerc.so);
|
|
end loop;
|
|
when OP_CNTZ =>
|
|
result := countzero_result;
|
|
result_en := '1';
|
|
when OP_EXTS =>
|
|
v.e.write_len := e_in.data_len;
|
|
v.e.sign_extend := '1';
|
|
result := e_in.read_data3;
|
|
result_en := '1';
|
|
when OP_ISEL =>
|
|
crbit := to_integer(unsigned(insn_bc(e_in.insn)));
|
|
if e_in.cr(31-crbit) = '1' then
|
|
result := e_in.read_data1;
|
|
else
|
|
result := e_in.read_data2;
|
|
end if;
|
|
result_en := '1';
|
|
when OP_MCRF =>
|
|
cr_op := insn_cr(e_in.insn);
|
|
report "CR OP " & to_hstring(cr_op);
|
|
if cr_op(0) = '0' then -- 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;
|
|
else
|
|
v.e.write_cr_enable := '1';
|
|
bt := insn_bt(e_in.insn);
|
|
ba := insn_ba(e_in.insn);
|
|
bb := insn_bb(e_in.insn);
|
|
btnum := 31 - to_integer(unsigned(bt));
|
|
banum := 31 - to_integer(unsigned(ba));
|
|
bbnum := 31 - to_integer(unsigned(bb));
|
|
case cr_op(8 downto 5) is
|
|
when "1001" => -- CREQV
|
|
crresult := not(e_in.cr(banum) xor e_in.cr(bbnum));
|
|
when "0111" => -- CRNAND
|
|
crresult := not(e_in.cr(banum) and e_in.cr(bbnum));
|
|
when "0100" => -- CRANDC
|
|
crresult := (e_in.cr(banum) and not e_in.cr(bbnum));
|
|
when "1000" => -- CRAND
|
|
crresult := (e_in.cr(banum) and e_in.cr(bbnum));
|
|
when "0001" => -- CRNOR
|
|
crresult := not(e_in.cr(banum) or e_in.cr(bbnum));
|
|
when "1101" => -- CRORC
|
|
crresult := (e_in.cr(banum) or not e_in.cr(bbnum));
|
|
when "0110" => -- CRXOR
|
|
crresult := (e_in.cr(banum) xor e_in.cr(bbnum));
|
|
when "1110" => -- CROR
|
|
crresult := (e_in.cr(banum) or e_in.cr(bbnum));
|
|
when others =>
|
|
crresult := '0';
|
|
report "BAD CR?";
|
|
end case;
|
|
v.e.write_cr_mask := num_to_fxm((31-btnum) / 4);
|
|
for i in 0 to 31 loop
|
|
if i = btnum then
|
|
v.e.write_cr_data(i) := crresult;
|
|
else
|
|
v.e.write_cr_data(i) := e_in.cr(i);
|
|
end if;
|
|
end loop;
|
|
end if;
|
|
when OP_MFSPR =>
|
|
if is_fast_spr(e_in.read_reg1) then
|
|
result := e_in.read_data1;
|
|
if decode_spr_num(e_in.insn) = SPR_XER then
|
|
-- bits 0:31 and 35:43 are treated as reserved and return 0s when read using mfxer
|
|
result(63 downto 32) := (others => '0');
|
|
result(63-32) := v.e.xerc.so;
|
|
result(63-33) := v.e.xerc.ov;
|
|
result(63-34) := v.e.xerc.ca;
|
|
result(63-35 downto 63-43) := "000000000";
|
|
result(63-44) := v.e.xerc.ov32;
|
|
result(63-45) := v.e.xerc.ca32;
|
|
end if;
|
|
else
|
|
case decode_spr_num(e_in.insn) is
|
|
when SPR_TB =>
|
|
result := ctrl.tb;
|
|
when others =>
|
|
result := (others => '0');
|
|
end case;
|
|
end if;
|
|
result_en := '1';
|
|
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 =>
|
|
report "MTSPR to SPR " & integer'image(decode_spr_num(e_in.insn)) &
|
|
"=" & to_hstring(e_in.read_data3);
|
|
if is_fast_spr(e_in.write_reg) then
|
|
result := e_in.read_data3;
|
|
result_en := '1';
|
|
if decode_spr_num(e_in.insn) = SPR_XER then
|
|
v.e.xerc.so := e_in.read_data3(63-32);
|
|
v.e.xerc.ov := e_in.read_data3(63-33);
|
|
v.e.xerc.ca := e_in.read_data3(63-34);
|
|
v.e.xerc.ov32 := e_in.read_data3(63-44);
|
|
v.e.xerc.ca32 := e_in.read_data3(63-45);
|
|
v.e.write_xerc_enable := '1';
|
|
end if;
|
|
else
|
|
-- TODO: Implement slow SPRs
|
|
-- case decode_spr_num(e_in.insn) is
|
|
-- when others =>
|
|
-- end case;
|
|
end if;
|
|
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
|
|
set_carry(v.e, rotator_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.
|
|
result := x"0000000000000000";
|
|
result_en := '1';
|
|
|
|
when OP_TDI =>
|
|
-- Keep our test cases happy for now, ignore trap instructions
|
|
report "OP_TDI FIXME";
|
|
|
|
when OP_ISYNC =>
|
|
f_out.redirect <= '1';
|
|
f_out.redirect_nia <= next_nia;
|
|
|
|
when OP_ICBI =>
|
|
icache_inval <= '1';
|
|
|
|
when OP_MUL_L64 | OP_MUL_H64 | OP_MUL_H32 =>
|
|
v.e.valid := '0';
|
|
v.mul_in_progress := '1';
|
|
stall_out <= '1';
|
|
x_to_multiply.valid <= '1';
|
|
|
|
when OP_DIV | OP_DIVE | OP_MOD =>
|
|
v.e.valid := '0';
|
|
v.div_in_progress := '1';
|
|
stall_out <= '1';
|
|
x_to_divider.valid <= '1';
|
|
|
|
when others =>
|
|
terminate_out <= '1';
|
|
report "illegal";
|
|
end case;
|
|
|
|
v.e.rc := e_in.rc and e_in.valid;
|
|
|
|
-- Update LR on the next cycle after a branch link
|
|
--
|
|
-- WARNING: The LR update isn't tracked by our hazard tracker. This
|
|
-- will work (well I hope) because it only happens on branches
|
|
-- which will flush all decoded instructions. By the time
|
|
-- fetch catches up, we'll have the new LR. This will
|
|
-- *not* work properly however if we have a branch predictor,
|
|
-- in which case the solution would probably be to keep a
|
|
-- local cache of the updated LR in execute1 (flushed on
|
|
-- exceptions) that is used instead of the value from
|
|
-- decode when its content is valid.
|
|
if e_in.lr = '1' then
|
|
v.lr_update := '1';
|
|
v.next_lr := next_nia;
|
|
v.e.valid := '0';
|
|
report "Delayed LR update to " & to_hstring(next_nia);
|
|
stall_out <= '1';
|
|
end if;
|
|
elsif r.lr_update = '1' then
|
|
result_en := '1';
|
|
result := r.next_lr;
|
|
v.e.write_reg := fast_spr_num(SPR_LR);
|
|
v.e.write_len := x"8";
|
|
v.e.sign_extend := '0';
|
|
v.e.valid := '1';
|
|
elsif r.mul_in_progress = '1' or r.div_in_progress = '1' then
|
|
if (r.mul_in_progress = '1' and multiply_to_x.valid = '1') or
|
|
(r.div_in_progress = '1' and divider_to_x.valid = '1') then
|
|
if r.mul_in_progress = '1' then
|
|
result := multiply_to_x.write_reg_data;
|
|
overflow := multiply_to_x.overflow;
|
|
else
|
|
result := divider_to_x.write_reg_data;
|
|
overflow := divider_to_x.overflow;
|
|
end if;
|
|
result_en := '1';
|
|
v.e.write_reg := gpr_to_gspr(v.slow_op_dest);
|
|
v.e.rc := v.slow_op_rc;
|
|
v.e.xerc := v.slow_op_xerc;
|
|
v.e.write_xerc_enable := v.slow_op_oe;
|
|
-- We must test oe because the RC update code in writeback
|
|
-- will use the xerc value to set CR0:SO so we must not clobber
|
|
-- xerc if OE wasn't set.
|
|
if v.slow_op_oe = '1' then
|
|
v.e.xerc.ov := overflow;
|
|
v.e.xerc.ov32 := overflow;
|
|
v.e.xerc.so := v.slow_op_xerc.so or overflow;
|
|
end if;
|
|
v.e.valid := '1';
|
|
v.e.write_len := x"8";
|
|
v.e.sign_extend := '0';
|
|
else
|
|
stall_out <= '1';
|
|
v.mul_in_progress := r.mul_in_progress;
|
|
v.div_in_progress := r.div_in_progress;
|
|
end if;
|
|
end if;
|
|
|
|
v.e.write_data := result;
|
|
v.e.write_enable := result_en;
|
|
|
|
-- Update registers
|
|
rin <= v;
|
|
|
|
-- update outputs
|
|
--f_out <= r.f;
|
|
e_out <= r.e;
|
|
flush_out <= f_out.redirect;
|
|
end process;
|
|
end architecture behaviour;
|