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.insn_helpers.all; entity decode2 is generic ( EX1_BYPASS : boolean := true; HAS_FPU : boolean := true; -- Non-zero to enable log data collection LOG_LENGTH : natural := 0 ); port ( clk : in std_ulogic; rst : in std_ulogic; complete_in : in instr_tag_t; busy_in : in std_ulogic; stall_out : out std_ulogic; stopped_out : out std_ulogic; flush_in: in std_ulogic; d_in : in Decode1ToDecode2Type; e_out : out Decode2ToExecute1Type; r_in : in RegisterFileToDecode2Type; r_out : out Decode2ToRegisterFileType; c_in : in CrFileToDecode2Type; c_out : out Decode2ToCrFileType; execute_bypass : in bypass_data_t; execute_cr_bypass : in cr_bypass_data_t; execute2_bypass : in bypass_data_t; execute2_cr_bypass : in cr_bypass_data_t; writeback_bypass : in bypass_data_t; -- Access to SPRs from core_debug module dbg_spr_req : in std_ulogic; dbg_spr_addr : in std_ulogic_vector(7 downto 0); log_out : out std_ulogic_vector(9 downto 0) ); end entity decode2; architecture behaviour of decode2 is type reg_type is record e : Decode2ToExecute1Type; repeat : repeat_t; busy : std_ulogic; sgl_pipe : std_ulogic; prev_sgl : std_ulogic; reg_a_valid : std_ulogic; reg_b_valid : std_ulogic; reg_c_valid : std_ulogic; reg_o_valid : std_ulogic; input_ov : std_ulogic; output_ov : std_ulogic; read_rspr : std_ulogic; end record; constant reg_type_init : reg_type := (e => Decode2ToExecute1Init, repeat => NONE, others => '0'); signal dc2, dc2in : reg_type; signal deferred : std_ulogic; type decode_input_reg_t is record reg_valid : std_ulogic; reg : gspr_index_t; data : std_ulogic_vector(63 downto 0); end record; constant decode_input_reg_init : decode_input_reg_t := ('0', (others => '0'), (others => '0')); type decode_output_reg_t is record reg_valid : std_ulogic; reg : gspr_index_t; end record; constant decode_output_reg_init : decode_output_reg_t := ('0', (others => '0')); function decode_input_reg_a (t : input_reg_a_t; insn_in : std_ulogic_vector(31 downto 0); instr_addr : std_ulogic_vector(63 downto 0)) return decode_input_reg_t is begin if t = RA or (t = RA_OR_ZERO and insn_ra(insn_in) /= "00000") then return ('1', gpr_to_gspr(insn_ra(insn_in)), (others => '0')); elsif t = CIA then return ('0', (others => '0'), instr_addr); elsif HAS_FPU and t = FRA then return ('1', fpr_to_gspr(insn_fra(insn_in)), (others => '0')); else return ('0', (others => '0'), (others => '0')); end if; end; function decode_input_reg_b (t : input_reg_b_t; insn_in : std_ulogic_vector(31 downto 0)) return decode_input_reg_t is variable ret : decode_input_reg_t; begin case t is when RB => ret := ('1', gpr_to_gspr(insn_rb(insn_in)), (others => '0')); when FRB => if HAS_FPU then ret := ('1', fpr_to_gspr(insn_frb(insn_in)), (others => '0')); else ret := ('0', (others => '0'), (others => '0')); end if; when CONST_UI => ret := ('0', (others => '0'), std_ulogic_vector(resize(unsigned(insn_ui(insn_in)), 64))); when CONST_SI => ret := ('0', (others => '0'), std_ulogic_vector(resize(signed(insn_si(insn_in)), 64))); when CONST_SI_HI => ret := ('0', (others => '0'), std_ulogic_vector(resize(signed(insn_si(insn_in)) & x"0000", 64))); when CONST_UI_HI => ret := ('0', (others => '0'), std_ulogic_vector(resize(unsigned(insn_si(insn_in)) & x"0000", 64))); when CONST_LI => ret := ('0', (others => '0'), std_ulogic_vector(resize(signed(insn_li(insn_in)) & "00", 64))); when CONST_BD => ret := ('0', (others => '0'), std_ulogic_vector(resize(signed(insn_bd(insn_in)) & "00", 64))); when CONST_DS => ret := ('0', (others => '0'), std_ulogic_vector(resize(signed(insn_ds(insn_in)) & "00", 64))); when CONST_DQ => ret := ('0', (others => '0'), std_ulogic_vector(resize(signed(insn_dq(insn_in)) & "0000", 64))); when CONST_DXHI4 => ret := ('0', (others => '0'), std_ulogic_vector(resize(signed(insn_dx(insn_in)) & x"0004", 64))); when CONST_M1 => ret := ('0', (others => '0'), x"FFFFFFFFFFFFFFFF"); when CONST_SH => ret := ('0', (others => '0'), x"00000000000000" & "00" & insn_in(1) & insn_in(15 downto 11)); when CONST_SH32 => ret := ('0', (others => '0'), x"00000000000000" & "000" & insn_in(15 downto 11)); when NONE => ret := ('0', (others => '0'), (others => '0')); end case; return ret; end; function decode_input_reg_c (t : input_reg_c_t; insn_in : std_ulogic_vector(31 downto 0)) return decode_input_reg_t is begin case t is when RS => return ('1', gpr_to_gspr(insn_rs(insn_in)), (others => '0')); when RCR => return ('1', gpr_to_gspr(insn_rcreg(insn_in)), (others => '0')); when FRS => if HAS_FPU then return ('1', fpr_to_gspr(insn_frt(insn_in)), (others => '0')); else return ('0', (others => '0'), (others => '0')); end if; when FRC => if HAS_FPU then return ('1', fpr_to_gspr(insn_frc(insn_in)), (others => '0')); else return ('0', (others => '0'), (others => '0')); end if; when NONE => return ('0', (others => '0'), (others => '0')); end case; end; function decode_output_reg (t : output_reg_a_t; insn_in : std_ulogic_vector(31 downto 0)) return decode_output_reg_t is begin case t is when RT => return ('1', gpr_to_gspr(insn_rt(insn_in))); when RA => return ('1', gpr_to_gspr(insn_ra(insn_in))); when FRT => if HAS_FPU then return ('1', fpr_to_gspr(insn_frt(insn_in))); else return ('0', "000000"); end if; when NONE => return ('0', "000000"); end case; end; function decode_rc (t : rc_t; insn_in : std_ulogic_vector(31 downto 0)) return std_ulogic is begin case t is when RC => return insn_rc(insn_in); when ONE => return '1'; when NONE => return '0'; end case; end; -- control signals that are derived from insn_type type mux_select_array_t is array(insn_type_t) of std_ulogic_vector(2 downto 0); constant result_select : mux_select_array_t := ( OP_AND => "001", -- logical_result OP_OR => "001", OP_XOR => "001", OP_PRTY => "001", OP_CMPB => "001", OP_EXTS => "001", OP_BPERM => "001", OP_BCD => "001", OP_MTSPR => "001", OP_RLC => "010", -- rotator_result OP_RLCL => "010", OP_RLCR => "010", OP_SHL => "010", OP_SHR => "010", OP_EXTSWSLI => "010", OP_MUL_L64 => "011", -- muldiv_result OP_B => "110", -- next_nia OP_BC => "110", OP_BCREG => "110", OP_ADDG6S => "111", -- misc_result OP_ISEL => "111", OP_DARN => "111", OP_MFMSR => "111", OP_MFCR => "111", OP_SETB => "111", others => "000" -- default to adder_result ); constant subresult_select : mux_select_array_t := ( OP_MUL_L64 => "000", -- muldiv_result OP_MUL_H64 => "001", OP_MUL_H32 => "010", OP_DIV => "011", OP_DIVE => "011", OP_MOD => "011", OP_ADDG6S => "001", -- misc_result OP_ISEL => "010", OP_DARN => "011", OP_MFMSR => "100", OP_MFCR => "101", OP_SETB => "110", OP_CMP => "000", -- cr_result OP_CMPRB => "001", OP_CMPEQB => "010", OP_CROP => "011", OP_MCRXRX => "100", OP_MTCRF => "101", others => "000" ); signal decoded_reg_a : decode_input_reg_t; signal decoded_reg_b : decode_input_reg_t; signal decoded_reg_c : decode_input_reg_t; signal decoded_reg_o : decode_output_reg_t; -- issue control signals signal control_valid_in : std_ulogic; signal control_valid_out : std_ulogic; signal control_serialize : std_logic; signal gpr_write_valid : std_ulogic; signal gpr_write : gspr_index_t; signal gpr_a_read_valid : std_ulogic; signal gpr_a_read : gspr_index_t; signal gpr_a_bypass : std_ulogic_vector(1 downto 0); signal gpr_b_read_valid : std_ulogic; signal gpr_b_read : gspr_index_t; signal gpr_b_bypass : std_ulogic_vector(1 downto 0); signal gpr_c_read_valid : std_ulogic; signal gpr_c_read : gspr_index_t; signal gpr_c_bypass : std_ulogic_vector(1 downto 0); signal cr_read_valid : std_ulogic; signal cr_write_valid : std_ulogic; signal cr_bypass : std_ulogic_vector(1 downto 0); signal ov_read_valid : std_ulogic; signal ov_write_valid : std_ulogic; signal instr_tag : instr_tag_t; begin control_0: entity work.control generic map ( EX1_BYPASS => EX1_BYPASS ) port map ( clk => clk, rst => rst, complete_in => complete_in, valid_in => control_valid_in, deferred => deferred, flush_in => flush_in, serialize => control_serialize, stop_mark_in => d_in.stop_mark, gpr_write_valid_in => gpr_write_valid, gpr_write_in => gpr_write, gpr_a_read_valid_in => gpr_a_read_valid, gpr_a_read_in => gpr_a_read, gpr_b_read_valid_in => gpr_b_read_valid, gpr_b_read_in => gpr_b_read, gpr_c_read_valid_in => gpr_c_read_valid, gpr_c_read_in => gpr_c_read, execute_next_tag => execute_bypass.tag, execute_next_cr_tag => execute_cr_bypass.tag, execute2_next_tag => execute2_bypass.tag, execute2_next_cr_tag => execute2_cr_bypass.tag, cr_read_in => cr_read_valid, cr_write_in => cr_write_valid, cr_bypass => cr_bypass, ov_read_in => ov_read_valid, ov_write_in => ov_write_valid, valid_out => control_valid_out, stopped_out => stopped_out, gpr_bypass_a => gpr_a_bypass, gpr_bypass_b => gpr_b_bypass, gpr_bypass_c => gpr_c_bypass, instr_tag_out => instr_tag ); deferred <= dc2.e.valid and busy_in; decode2_0: process(clk) begin if rising_edge(clk) then if rst = '1' or flush_in = '1' then dc2 <= reg_type_init; elsif deferred = '0' then if dc2in.e.valid = '1' then report "execute " & to_hstring(dc2in.e.nia) & " tag=" & integer'image(dc2in.e.instr_tag.tag) & std_ulogic'image(dc2in.e.instr_tag.valid); end if; dc2 <= dc2in; elsif dc2.read_rspr = '0' then -- Update debug SPR access signals even when stalled -- if the instruction in dc2.e doesn't read any SPRs. dc2.e.dbg_spr_access <= dc2in.e.dbg_spr_access; dc2.e.ramspr_even_rdaddr <= dc2in.e.ramspr_even_rdaddr; dc2.e.ramspr_odd_rdaddr <= dc2in.e.ramspr_odd_rdaddr; dc2.e.ramspr_rd_odd <= dc2in.e.ramspr_rd_odd; end if; if d_in.valid = '1' then assert decoded_reg_a.reg_valid = '0' or decoded_reg_a.reg = d_in.reg_a severity failure; assert decoded_reg_b.reg_valid = '0' or decoded_reg_b.reg = d_in.reg_b severity failure; assert decoded_reg_c.reg_valid = '0' or decoded_reg_c.reg = d_in.reg_c severity failure; end if; end if; end process; c_out.read <= d_in.decode.input_cr; decode2_addrs: process(all) begin decoded_reg_a <= decode_input_reg_init; decoded_reg_b <= decode_input_reg_init; decoded_reg_c <= decode_input_reg_init; decoded_reg_o <= decode_output_reg_init; if d_in.valid = '1' then decoded_reg_a <= decode_input_reg_a (d_in.decode.input_reg_a, d_in.insn, d_in.nia); decoded_reg_b <= decode_input_reg_b (d_in.decode.input_reg_b, d_in.insn); decoded_reg_c <= decode_input_reg_c (d_in.decode.input_reg_c, d_in.insn); decoded_reg_o <= decode_output_reg (d_in.decode.output_reg_a, d_in.insn); end if; r_out.read1_enable <= decoded_reg_a.reg_valid; r_out.read2_enable <= decoded_reg_b.reg_valid; r_out.read3_enable <= decoded_reg_c.reg_valid; end process; decode2_1: process(all) variable v : reg_type; variable length : std_ulogic_vector(3 downto 0); variable op : insn_type_t; variable valid_in : std_ulogic; variable decctr : std_ulogic; variable sprs_busy : std_ulogic; begin v := dc2; valid_in := d_in.valid or dc2.busy; if dc2.busy = '0' then v.e := Decode2ToExecute1Init; sprs_busy := '0'; if d_in.valid = '1' then v.prev_sgl := dc2.sgl_pipe; v.sgl_pipe := d_in.decode.sgl_pipe; end if; v.e.input_cr := d_in.decode.input_cr; v.e.output_cr := d_in.decode.output_cr; -- Work out whether XER SO/OV/OV32 bits are set -- or used by this instruction v.e.rc := decode_rc(d_in.decode.rc, d_in.insn); v.e.output_xer := d_in.decode.output_carry; v.input_ov := d_in.decode.output_carry; v.output_ov := '0'; if d_in.decode.input_carry = OV then v.input_ov := '1'; v.output_ov := '1'; end if; if v.e.rc = '1' and d_in.decode.facility /= FPU then v.input_ov := '1'; end if; case d_in.decode.insn_type is when OP_ADD | OP_MUL_L64 | OP_DIV | OP_DIVE => -- OE field is valid in OP_ADD/OP_MUL_L64 with major opcode 31 only if d_in.insn(31 downto 26) = "011111" and insn_oe(d_in.insn) = '1' then v.e.oe := '1'; v.e.output_xer := '1'; v.output_ov := '1'; v.input_ov := '1'; -- need SO state if setting OV to 0 end if; when OP_MFSPR => if decode_spr_num(d_in.insn) = SPR_XER then v.input_ov := '1'; end if; when OP_MTSPR => if decode_spr_num(d_in.insn) = SPR_XER then v.e.output_xer := '1'; v.output_ov := '1'; end if; when OP_CMP | OP_MCRXRX => v.input_ov := '1'; when others => end case; v.reg_a_valid := decoded_reg_a.reg_valid; v.reg_b_valid := decoded_reg_b.reg_valid; v.reg_c_valid := decoded_reg_c.reg_valid; v.reg_o_valid := decoded_reg_o.reg_valid; if d_in.decode.lr = '1' then v.e.lr := insn_lk(d_in.insn); -- b and bc have even major opcodes; bcreg is considered absolute v.e.br_abs := insn_aa(d_in.insn) or d_in.insn(26); end if; op := d_in.decode.insn_type; -- Does this instruction decrement CTR? -- bc, bclr, bctar with BO(2) = 0 do, but not bcctr. decctr := '0'; if d_in.insn(23) = '0' and (op = OP_BC or (op = OP_BCREG and not (d_in.insn(10) = '1' and d_in.insn(6) = '0'))) then decctr := '1'; end if; v.e.dec_ctr := decctr; v.repeat := d_in.decode.repeat; if d_in.decode.repeat /= NONE then v.e.repeat := '1'; end if; v.e.spr_select := d_in.spr_info; if decctr = '1' then -- read and write CTR v.e.ramspr_odd_rdaddr := RAMSPR_CTR; v.e.ramspr_wraddr := RAMSPR_CTR; v.e.ramspr_write_odd := '1'; sprs_busy := '1'; end if; if v.e.lr = '1' then -- write LR v.e.ramspr_wraddr := RAMSPR_LR; v.e.ramspr_write_even := '1'; end if; case op is when OP_BCREG => if d_in.insn(10) = '0' then v.e.ramspr_even_rdaddr := RAMSPR_LR; elsif d_in.insn(6) = '0' then v.e.ramspr_odd_rdaddr := RAMSPR_CTR; v.e.ramspr_rd_odd := '1'; else v.e.ramspr_even_rdaddr := RAMSPR_TAR; end if; sprs_busy := '1'; when OP_MFSPR => v.e.ramspr_even_rdaddr := d_in.ram_spr.index; v.e.ramspr_odd_rdaddr := d_in.ram_spr.index; v.e.ramspr_rd_odd := d_in.ram_spr.isodd; v.e.spr_is_ram := d_in.ram_spr.valid; sprs_busy := d_in.ram_spr.valid; when OP_MTSPR => v.e.ramspr_wraddr := d_in.ram_spr.index; v.e.ramspr_write_even := d_in.ram_spr.valid and not d_in.ram_spr.isodd; v.e.ramspr_write_odd := d_in.ram_spr.valid and d_in.ram_spr.isodd; v.e.spr_is_ram := d_in.ram_spr.valid; when OP_RFID => v.e.ramspr_even_rdaddr := RAMSPR_SRR0; v.e.ramspr_odd_rdaddr := RAMSPR_SRR1; sprs_busy := '1'; when others => end case; v.read_rspr := sprs_busy and d_in.valid; case d_in.decode.length is when is1B => length := "0001"; when is2B => length := "0010"; when is4B => length := "0100"; when is8B => length := "1000"; when NONE => length := "0000"; end case; -- execute unit v.e.nia := d_in.nia; v.e.unit := d_in.decode.unit; v.e.fac := d_in.decode.facility; v.e.read_reg1 := d_in.reg_a; v.e.read_reg2 := d_in.reg_b; v.e.read_reg3 := d_in.reg_c; v.e.write_reg := decoded_reg_o.reg; v.e.write_reg_enable := decoded_reg_o.reg_valid; v.e.invert_a := d_in.decode.invert_a; v.e.insn_type := op; v.e.invert_out := d_in.decode.invert_out; v.e.input_carry := d_in.decode.input_carry; v.e.output_carry := d_in.decode.output_carry; v.e.is_32bit := d_in.decode.is_32bit; v.e.is_signed := d_in.decode.is_signed; v.e.insn := d_in.insn; v.e.data_len := length; v.e.byte_reverse := d_in.decode.byte_reverse; v.e.sign_extend := d_in.decode.sign_extend; v.e.update := d_in.decode.update; v.e.reserve := d_in.decode.reserve; v.e.br_pred := d_in.br_pred; v.e.result_sel := result_select(op); v.e.sub_select := subresult_select(op); if op = OP_MFSPR then if d_in.ram_spr.valid = '1' then v.e.result_sel := "101"; -- ramspr_result elsif d_in.spr_info.valid = '0' then -- Privileged mfspr to invalid/unimplemented SPR numbers -- writes the contents of RT back to RT (i.e. it's a no-op) v.e.result_sel := "001"; -- logical_result end if; end if; elsif dc2.e.valid = '1' then -- dc2.busy = 1 and dc2.e.valid = 1, thus this must be a repeated instruction. -- Set up for the second iteration (if deferred = 1 this will all be ignored) v.e.second := '1'; -- DUPD is the only possibility here: -- update-form loads, 2nd instruction writes RA v.e.write_reg := dc2.e.read_reg1; end if; -- issue control control_valid_in <= valid_in; control_serialize <= v.sgl_pipe or v.prev_sgl; gpr_write_valid <= v.reg_o_valid; gpr_write <= v.e.write_reg; gpr_a_read_valid <= v.reg_a_valid; gpr_a_read <= v.e.read_reg1; gpr_b_read_valid <= v.reg_b_valid; gpr_b_read <= v.e.read_reg2; gpr_c_read_valid <= v.reg_c_valid; gpr_c_read <= v.e.read_reg3; cr_write_valid <= v.e.output_cr or v.e.rc; -- Since ops that write CR only write some of the fields, -- any op that writes CR effectively also reads it. cr_read_valid <= cr_write_valid or v.e.input_cr; ov_read_valid <= v.input_ov; ov_write_valid <= v.output_ov; -- See if any of the operands can get their value via the bypass path. if dc2.busy = '0' or gpr_a_bypass /= "00" then case gpr_a_bypass is when "01" => v.e.read_data1 := execute_bypass.data; when "10" => v.e.read_data1 := execute2_bypass.data; when "11" => v.e.read_data1 := writeback_bypass.data; when others => if decoded_reg_a.reg_valid = '1' then v.e.read_data1 := r_in.read1_data; else v.e.read_data1 := decoded_reg_a.data; end if; end case; end if; if dc2.busy = '0' or gpr_b_bypass /= "00" then case gpr_b_bypass is when "01" => v.e.read_data2 := execute_bypass.data; when "10" => v.e.read_data2 := execute2_bypass.data; when "11" => v.e.read_data2 := writeback_bypass.data; when others => if decoded_reg_b.reg_valid = '1' then v.e.read_data2 := r_in.read2_data; else v.e.read_data2 := decoded_reg_b.data; end if; end case; end if; if dc2.busy = '0' or gpr_c_bypass /= "00" then case gpr_c_bypass is when "01" => v.e.read_data3 := execute_bypass.data; when "10" => v.e.read_data3 := execute2_bypass.data; when "11" => v.e.read_data3 := writeback_bypass.data; when others => if decoded_reg_c.reg_valid = '1' then v.e.read_data3 := r_in.read3_data; else v.e.read_data3 := decoded_reg_c.data; end if; end case; end if; case cr_bypass is when "10" => v.e.cr := execute_cr_bypass.data; when "11" => v.e.cr := execute2_cr_bypass.data; when others => v.e.cr := c_in.read_cr_data; end case; v.e.xerc := c_in.read_xerc_data; v.e.valid := control_valid_out; v.e.instr_tag := instr_tag; v.busy := valid_in and (not control_valid_out or (v.e.repeat and not v.e.second)); stall_out <= dc2.busy or deferred; v.e.dbg_spr_access := dbg_spr_req and not v.read_rspr; if v.e.dbg_spr_access = '1' then v.e.ramspr_even_rdaddr := unsigned(dbg_spr_addr(3 downto 1)); v.e.ramspr_odd_rdaddr := unsigned(dbg_spr_addr(3 downto 1)); v.e.ramspr_rd_odd := dbg_spr_addr(0); end if; -- Update registers dc2in <= v; -- Update outputs e_out <= dc2.e; end process; d2_log: if LOG_LENGTH > 0 generate signal log_data : std_ulogic_vector(9 downto 0); begin dec2_log : process(clk) begin if rising_edge(clk) then log_data <= dc2.e.nia(5 downto 2) & dc2.e.valid & stopped_out & stall_out & (gpr_a_bypass(1) xor gpr_a_bypass(0)) & (gpr_b_bypass(1) xor gpr_b_bypass(0)) & (gpr_c_bypass(1) xor gpr_c_bypass(0)); end if; end process; log_out <= log_data; end generate; end architecture behaviour;