common.vhdl

   1 library ieee;
   2 use ieee.std_logic_1164.all;
   3 use ieee.numeric_std.all;
   4
   5 library work;
   6 use work.utils.all;
   7 use work.decode_types.all;
   8
   9 package common is
  10     -- Processor Version Number
  11     constant PVR_MICROWATT  : std_ulogic_vector(31 downto 0) := x"00630000";
  12
  13     -- MSR bit numbers
  14     constant MSR_SF  : integer := (63 - 0);     -- Sixty-Four bit mode
  15     constant MSR_EE  : integer := (63 - 48);    -- External interrupt Enable
  16     constant MSR_PR  : integer := (63 - 49);    -- PRoblem state
  17     constant MSR_FP  : integer := (63 - 50);    -- Floating Point available
  18     constant MSR_FE0 : integer := (63 - 52);    -- Floating Exception mode
  19     constant MSR_SE  : integer := (63 - 53);    -- Single-step bit of TE field
  20     constant MSR_BE  : integer := (63 - 54);    -- Branch trace bit of TE field
  21     constant MSR_FE1 : integer := (63 - 55);    -- Floating Exception mode
  22     constant MSR_IR  : integer := (63 - 58);    -- Instruction Relocation
  23     constant MSR_DR  : integer := (63 - 59);    -- Data Relocation
  24     constant MSR_RI  : integer := (63 - 62);    -- Recoverable Interrupt
  25     constant MSR_LE  : integer := (63 - 63);    -- Little Endian
  26
  27     -- SPR numbers
  28     subtype spr_num_t is integer range 0 to 1023;
  29
  30     function decode_spr_num(insn: std_ulogic_vector(31 downto 0)) return spr_num_t;
  31
  32     constant SPR_XER    : spr_num_t := 1;
  33     constant SPR_LR     : spr_num_t := 8;
  34     constant SPR_CTR    : spr_num_t := 9;
  35     constant SPR_TAR    : spr_num_t := 815;
  36     constant SPR_DSISR  : spr_num_t := 18;
  37     constant SPR_DAR    : spr_num_t := 19;
  38     constant SPR_TB     : spr_num_t := 268;
  39     constant SPR_TBU    : spr_num_t := 269;
  40     constant SPR_DEC    : spr_num_t := 22;
  41     constant SPR_SRR0   : spr_num_t := 26;
  42     constant SPR_SRR1   : spr_num_t := 27;
  43     constant SPR_CFAR   : spr_num_t := 28;
  44     constant SPR_HSRR0  : spr_num_t := 314;
  45     constant SPR_HSRR1  : spr_num_t := 315;
  46     constant SPR_SPRG0  : spr_num_t := 272;
  47     constant SPR_SPRG1  : spr_num_t := 273;
  48     constant SPR_SPRG2  : spr_num_t := 274;
  49     constant SPR_SPRG3  : spr_num_t := 275;
  50     constant SPR_SPRG3U : spr_num_t := 259;
  51     constant SPR_HSPRG0 : spr_num_t := 304;
  52     constant SPR_HSPRG1 : spr_num_t := 305;
  53     constant SPR_PID    : spr_num_t := 48;
  54     constant SPR_PTCR   : spr_num_t := 464;
  55     constant SPR_PVR    : spr_num_t := 287;
  56
  57     -- GPR indices in the register file (GPR only)
  58     subtype gpr_index_t is std_ulogic_vector(4 downto 0);
  59
  60     -- Extended GPR index (can hold an SPR or a FPR)
  61     subtype gspr_index_t is std_ulogic_vector(6 downto 0);
  62
  63     -- FPR indices
  64     subtype fpr_index_t is std_ulogic_vector(4 downto 0);
  65
  66     -- Some SPRs are stored in the register file, they use the magic
  67     -- GPR numbers above 31.
  68     --
  69     -- The function fast_spr_num() returns the corresponding fast
  70     -- pseudo-GPR number for a given SPR number. The result MSB
  71     -- indicates if this is indeed a fast SPR. If clear, then
  72     -- the SPR is not stored in the GPR file.
  73     --
  74     -- FPRs are also stored in the register file, using GSPR
  75     -- numbers from 64 to 95.
  76     --
  77     function fast_spr_num(spr: spr_num_t) return gspr_index_t;
  78
  79     -- Indices conversion functions
  80     function gspr_to_gpr(i: gspr_index_t) return gpr_index_t;
  81     function gpr_to_gspr(i: gpr_index_t) return gspr_index_t;
  82     function gpr_or_spr_to_gspr(g: gpr_index_t; s: gspr_index_t) return gspr_index_t;
  83     function is_fast_spr(s: gspr_index_t) return std_ulogic;
  84     function fpr_to_gspr(f: fpr_index_t) return gspr_index_t;
  85
  86     -- The XER is split: the common bits (CA, OV, SO, OV32 and CA32) are
  87     -- in the CR file as a kind of CR extension (with a separate write
  88     -- control). The rest is stored as a fast SPR.
  89     type xer_common_t is record
  90         ca : std_ulogic;
  91         ca32 : std_ulogic;
  92         ov : std_ulogic;
  93         ov32 : std_ulogic;
  94         so : std_ulogic;
  95     end record;
  96     constant xerc_init : xer_common_t := (others => '0');
  97
  98     -- FPSCR bit numbers
  99     constant FPSCR_FX     : integer := 63 - 32;
 100     constant FPSCR_FEX    : integer := 63 - 33;
 101     constant FPSCR_VX     : integer := 63 - 34;
 102     constant FPSCR_OX     : integer := 63 - 35;
 103     constant FPSCR_UX     : integer := 63 - 36;
 104     constant FPSCR_ZX     : integer := 63 - 37;
 105     constant FPSCR_XX     : integer := 63 - 38;
 106     constant FPSCR_VXSNAN : integer := 63 - 39;
 107     constant FPSCR_VXISI  : integer := 63 - 40;
 108     constant FPSCR_VXIDI  : integer := 63 - 41;
 109     constant FPSCR_VXZDZ  : integer := 63 - 42;
 110     constant FPSCR_VXIMZ  : integer := 63 - 43;
 111     constant FPSCR_VXVC   : integer := 63 - 44;
 112     constant FPSCR_FR     : integer := 63 - 45;
 113     constant FPSCR_FI     : integer := 63 - 46;
 114     constant FPSCR_C      : integer := 63 - 47;
 115     constant FPSCR_FL     : integer := 63 - 48;
 116     constant FPSCR_FG     : integer := 63 - 49;
 117     constant FPSCR_FE     : integer := 63 - 50;
 118     constant FPSCR_FU     : integer := 63 - 51;
 119     constant FPSCR_VXSOFT : integer := 63 - 53;
 120     constant FPSCR_VXSQRT : integer := 63 - 54;
 121     constant FPSCR_VXCVI  : integer := 63 - 55;
 122     constant FPSCR_VE     : integer := 63 - 56;
 123     constant FPSCR_OE     : integer := 63 - 57;
 124     constant FPSCR_UE     : integer := 63 - 58;
 125     constant FPSCR_ZE     : integer := 63 - 59;
 126     constant FPSCR_XE     : integer := 63 - 60;
 127     constant FPSCR_NI     : integer := 63 - 61;
 128     constant FPSCR_RN     : integer := 63 - 63;
 129
 130     -- Used for tracking instruction completion and pending register writes
 131     constant TAG_COUNT : positive := 4;
 132     constant TAG_NUMBER_BITS : natural := log2(TAG_COUNT);
 133     subtype tag_number_t is integer range 0 to TAG_COUNT - 1;
 134     subtype tag_index_t is unsigned(TAG_NUMBER_BITS - 1 downto 0);
 135     type instr_tag_t is record
 136         tag   : tag_number_t;
 137         valid : std_ulogic;
 138     end record;
 139     constant instr_tag_init : instr_tag_t := (tag => 0, valid => '0');
 140     function tag_match(tag1 : instr_tag_t; tag2 : instr_tag_t) return boolean;
 141
 142     subtype intr_vector_t is integer range 0 to 16#fff#;
 143
 144     -- For now, fixed 16 sources, make this either a parametric
 145     -- package of some sort or an unconstrainted array.
 146     type ics_to_icp_t is record
 147         -- Level interrupts only, ICS just keeps prsenting the
 148         -- highest priority interrupt. Once handling edge, something
 149         -- smarter involving handshake & reject support will be needed
 150         src : std_ulogic_vector(3 downto 0);
 151         pri : std_ulogic_vector(7 downto 0);
 152     end record;
 153
 154     -- This needs to die...
 155     type ctrl_t is record
 156         tb: std_ulogic_vector(63 downto 0);
 157         dec: std_ulogic_vector(63 downto 0);
 158         msr: std_ulogic_vector(63 downto 0);
 159         cfar: std_ulogic_vector(63 downto 0);
 160     end record;
 161
 162     type Fetch1ToIcacheType is record
 163         req: std_ulogic;
 164         virt_mode : std_ulogic;
 165         priv_mode : std_ulogic;
 166         big_endian : std_ulogic;
 167         stop_mark: std_ulogic;
 168         sequential: std_ulogic;
 169         predicted : std_ulogic;
 170         nia: std_ulogic_vector(63 downto 0);
 171     end record;
 172
 173     type IcacheToDecode1Type is record
 174         valid: std_ulogic;
 175         stop_mark: std_ulogic;
 176         fetch_failed: std_ulogic;
 177         nia: std_ulogic_vector(63 downto 0);
 178         insn: std_ulogic_vector(31 downto 0);
 179         big_endian: std_ulogic;
 180         next_predicted: std_ulogic;
 181     end record;
 182
 183     type Decode1ToDecode2Type is record
 184         valid: std_ulogic;
 185         stop_mark : std_ulogic;
 186         nia: std_ulogic_vector(63 downto 0);
 187         insn: std_ulogic_vector(31 downto 0);
 188         ispr1: gspr_index_t; -- (G)SPR used for branch condition (CTR) or mfspr
 189         ispr2: gspr_index_t; -- (G)SPR used for branch target (CTR, LR, TAR)
 190         ispro: gspr_index_t; -- (G)SPR written with LR or CTR
 191         decode: decode_rom_t;
 192         br_pred: std_ulogic; -- Branch was predicted to be taken
 193         big_endian: std_ulogic;
 194     end record;
 195     constant Decode1ToDecode2Init : Decode1ToDecode2Type :=
 196         (valid => '0', stop_mark => '0', nia => (others => '0'), insn => (others => '0'),
 197          ispr1 => (others => '0'), ispr2 => (others => '0'), ispro => (others => '0'),
 198          decode => decode_rom_init, br_pred => '0', big_endian => '0');
 199
 200     type Decode1ToFetch1Type is record
 201         redirect     : std_ulogic;
 202         redirect_nia : std_ulogic_vector(63 downto 0);
 203     end record;
 204
 205     type bypass_data_t is record
 206         tag  : instr_tag_t;
 207         data : std_ulogic_vector(63 downto 0);
 208     end record;
 209     constant bypass_data_init : bypass_data_t := (tag => instr_tag_init, data => (others => '0'));
 210
 211     type cr_bypass_data_t is record
 212         tag  : instr_tag_t;
 213         data : std_ulogic_vector(31 downto 0);
 214     end record;
 215     constant cr_bypass_data_init : cr_bypass_data_t := (tag => instr_tag_init, data => (others => '0'));
 216
 217     type Decode2ToExecute1Type is record
 218         valid: std_ulogic;
 219         unit : unit_t;
 220         fac : facility_t;
 221         insn_type: insn_type_t;
 222         nia: std_ulogic_vector(63 downto 0);
 223         instr_tag : instr_tag_t;
 224         write_reg: gspr_index_t;
 225         write_reg_enable: std_ulogic;
 226         read_reg1: gspr_index_t;
 227         read_reg2: gspr_index_t;
 228         read_data1: std_ulogic_vector(63 downto 0);
 229         read_data2: std_ulogic_vector(63 downto 0);
 230         read_data3: std_ulogic_vector(63 downto 0);
 231         cr: std_ulogic_vector(31 downto 0);
 232         xerc: xer_common_t;
 233         lr: std_ulogic;
 234         br_abs: std_ulogic;
 235         rc: std_ulogic;
 236         oe: std_ulogic;
 237         invert_a: std_ulogic;
 238         addm1 : std_ulogic;
 239         invert_out: std_ulogic;
 240         input_carry: carry_in_t;
 241         output_carry: std_ulogic;
 242         input_cr: std_ulogic;
 243         output_cr: std_ulogic;
 244         output_xer: std_ulogic;
 245         is_32bit: std_ulogic;
 246         is_signed: std_ulogic;
 247         insn: std_ulogic_vector(31 downto 0);
 248         data_len: std_ulogic_vector(3 downto 0);
 249         byte_reverse : std_ulogic;
 250         sign_extend : std_ulogic;                       -- do we need to sign extend?
 251         update : std_ulogic;                            -- is this an update instruction?
 252         reserve : std_ulogic;                           -- set for larx/stcx
 253         br_pred : std_ulogic;
 254         result_sel : std_ulogic_vector(2 downto 0);     -- select source of result
 255         sub_select : std_ulogic_vector(2 downto 0);     -- sub-result selection
 256         repeat : std_ulogic;                            -- set if instruction is cracked into two ops
 257         second : std_ulogic;                            -- set if this is the second op
 258     end record;
 259     constant Decode2ToExecute1Init : Decode2ToExecute1Type :=
 260         (valid => '0', unit => NONE, fac => NONE, insn_type => OP_ILLEGAL, instr_tag => instr_tag_init,
 261          write_reg_enable => '0',
 262          lr => '0', br_abs => '0', rc => '0', oe => '0', invert_a => '0', addm1 => '0',
 263          invert_out => '0', input_carry => ZERO, output_carry => '0', input_cr => '0',
 264          output_cr => '0', output_xer => '0',
 265          is_32bit => '0', is_signed => '0', xerc => xerc_init, reserve => '0', br_pred => '0',
 266          byte_reverse => '0', sign_extend => '0', update => '0', nia => (others => '0'),
 267          read_data1 => (others => '0'), read_data2 => (others => '0'), read_data3 => (others => '0'),
 268          cr => (others => '0'), insn => (others => '0'), data_len => (others => '0'),
 269          result_sel => "000", sub_select => "000",
 270          repeat => '0', second => '0', others => (others => '0'));
 271
 272     type MultiplyInputType is record
 273         valid: std_ulogic;
 274         data1: std_ulogic_vector(63 downto 0);
 275         data2: std_ulogic_vector(63 downto 0);
 276         addend: std_ulogic_vector(127 downto 0);
 277         is_32bit: std_ulogic;
 278         not_result: std_ulogic;
 279     end record;
 280     constant MultiplyInputInit : MultiplyInputType := (valid => '0',
 281                                                        is_32bit => '0', not_result => '0',
 282                                                        others => (others => '0'));
 283
 284     type MultiplyOutputType is record
 285         valid: std_ulogic;
 286         result: std_ulogic_vector(127 downto 0);
 287         overflow : std_ulogic;
 288     end record;
 289     constant MultiplyOutputInit : MultiplyOutputType := (valid => '0', overflow => '0',
 290                                                          others => (others => '0'));
 291
 292     type Execute1ToDividerType is record
 293         valid: std_ulogic;
 294         dividend: std_ulogic_vector(63 downto 0);
 295         divisor: std_ulogic_vector(63 downto 0);
 296         is_signed: std_ulogic;
 297         is_32bit: std_ulogic;
 298         is_extended: std_ulogic;
 299         is_modulus: std_ulogic;
 300         neg_result: std_ulogic;
 301     end record;
 302     constant Execute1ToDividerInit: Execute1ToDividerType := (valid => '0', is_signed => '0', is_32bit => '0',
 303                                                               is_extended => '0', is_modulus => '0',
 304                                                               neg_result => '0', others => (others => '0'));
 305
 306     type Decode2ToRegisterFileType is record
 307         read1_enable : std_ulogic;
 308         read1_reg : gspr_index_t;
 309         read2_enable : std_ulogic;
 310         read2_reg : gspr_index_t;
 311         read3_enable : std_ulogic;
 312         read3_reg : gspr_index_t;
 313     end record;
 314
 315     type RegisterFileToDecode2Type is record
 316         read1_data : std_ulogic_vector(63 downto 0);
 317         read2_data : std_ulogic_vector(63 downto 0);
 318         read3_data : std_ulogic_vector(63 downto 0);
 319     end record;
 320
 321     type Decode2ToCrFileType is record
 322         read : std_ulogic;
 323     end record;
 324
 325     type CrFileToDecode2Type is record
 326         read_cr_data   : std_ulogic_vector(31 downto 0);
 327         read_xerc_data : xer_common_t;
 328     end record;
 329
 330     type Execute1ToLoadstore1Type is record
 331         valid : std_ulogic;
 332         op : insn_type_t;                               -- what ld/st or m[tf]spr or TLB op to do
 333         nia : std_ulogic_vector(63 downto 0);
 334         insn : std_ulogic_vector(31 downto 0);
 335         instr_tag : instr_tag_t;
 336         addr1 : std_ulogic_vector(63 downto 0);
 337         addr2 : std_ulogic_vector(63 downto 0);
 338         data : std_ulogic_vector(63 downto 0);          -- data to write, unused for read
 339         write_reg : gspr_index_t;
 340         length : std_ulogic_vector(3 downto 0);
 341         ci : std_ulogic;                                -- cache-inhibited load/store
 342         byte_reverse : std_ulogic;
 343         sign_extend : std_ulogic;                       -- do we need to sign extend?
 344         update : std_ulogic;                            -- is this an update instruction?
 345         xerc : xer_common_t;
 346         reserve : std_ulogic;                           -- set for larx/stcx.
 347         rc : std_ulogic;                                -- set for stcx.
 348         virt_mode : std_ulogic;                         -- do translation through TLB
 349         priv_mode : std_ulogic;                         -- privileged mode (MSR[PR] = 0)
 350         mode_32bit : std_ulogic;                        -- trim addresses to 32 bits
 351         is_32bit : std_ulogic;
 352         repeat : std_ulogic;
 353         second : std_ulogic;
 354         msr : std_ulogic_vector(63 downto 0);
 355     end record;
 356     constant Execute1ToLoadstore1Init : Execute1ToLoadstore1Type :=
 357         (valid => '0', op => OP_ILLEGAL, ci => '0', byte_reverse => '0',
 358          sign_extend => '0', update => '0', xerc => xerc_init,
 359          reserve => '0', rc => '0', virt_mode => '0', priv_mode => '0',
 360          nia => (others => '0'), insn => (others => '0'),
 361          instr_tag => instr_tag_init,
 362          addr1 => (others => '0'), addr2 => (others => '0'), data => (others => '0'),
 363          write_reg => (others => '0'),
 364          length => (others => '0'),
 365          mode_32bit => '0', is_32bit => '0',
 366          repeat => '0', second => '0',
 367          msr => (others => '0'));
 368
 369     type Loadstore1ToExecute1Type is record
 370         busy : std_ulogic;
 371         in_progress : std_ulogic;
 372         interrupt : std_ulogic;
 373     end record;
 374
 375     type Loadstore1ToDcacheType is record
 376         valid : std_ulogic;
 377         hold : std_ulogic;
 378         load : std_ulogic;                              -- is this a load
 379         dcbz : std_ulogic;
 380         nc : std_ulogic;
 381         reserve : std_ulogic;
 382         atomic : std_ulogic;                            -- part of a multi-transfer atomic op
 383         atomic_last : std_ulogic;
 384         virt_mode : std_ulogic;
 385         priv_mode : std_ulogic;
 386         addr : std_ulogic_vector(63 downto 0);
 387         data : std_ulogic_vector(63 downto 0);          -- valid the cycle after .valid = 1
 388         byte_sel : std_ulogic_vector(7 downto 0);
 389     end record;
 390
 391     type DcacheToLoadstore1Type is record
 392         valid : std_ulogic;
 393         data : std_ulogic_vector(63 downto 0);
 394         store_done : std_ulogic;
 395         error : std_ulogic;
 396         cache_paradox : std_ulogic;
 397     end record;
 398
 399     type Loadstore1ToMmuType is record
 400         valid : std_ulogic;
 401         tlbie : std_ulogic;
 402         slbia : std_ulogic;
 403         mtspr : std_ulogic;
 404         iside : std_ulogic;
 405         load  : std_ulogic;
 406         priv  : std_ulogic;
 407         sprn  : std_ulogic_vector(9 downto 0);
 408         addr  : std_ulogic_vector(63 downto 0);
 409         rs    : std_ulogic_vector(63 downto 0);
 410     end record;
 411
 412     type MmuToLoadstore1Type is record
 413         done       : std_ulogic;
 414         err        : std_ulogic;
 415         invalid    : std_ulogic;
 416         badtree    : std_ulogic;
 417         segerr     : std_ulogic;
 418         perm_error : std_ulogic;
 419         rc_error   : std_ulogic;
 420         sprval     : std_ulogic_vector(63 downto 0);
 421     end record;
 422
 423     type MmuToDcacheType is record
 424         valid : std_ulogic;
 425         tlbie : std_ulogic;
 426         doall : std_ulogic;
 427         tlbld : std_ulogic;
 428         addr  : std_ulogic_vector(63 downto 0);
 429         pte   : std_ulogic_vector(63 downto 0);
 430     end record;
 431
 432     type DcacheToMmuType is record
 433         stall : std_ulogic;
 434         done  : std_ulogic;
 435         err   : std_ulogic;
 436         data  : std_ulogic_vector(63 downto 0);
 437     end record;
 438
 439     type MmuToIcacheType is record
 440         tlbld : std_ulogic;
 441         tlbie : std_ulogic;
 442         doall : std_ulogic;
 443         addr  : std_ulogic_vector(63 downto 0);
 444         pte   : std_ulogic_vector(63 downto 0);
 445     end record;
 446
 447     type Loadstore1ToWritebackType is record
 448         valid : std_ulogic;
 449         instr_tag : instr_tag_t;
 450         write_enable: std_ulogic;
 451         write_reg : gspr_index_t;
 452         write_data : std_ulogic_vector(63 downto 0);
 453         xerc : xer_common_t;
 454         rc : std_ulogic;
 455         store_done : std_ulogic;
 456         interrupt : std_ulogic;
 457         intr_vec : intr_vector_t;
 458         srr0: std_ulogic_vector(63 downto 0);
 459         srr1: std_ulogic_vector(15 downto 0);
 460     end record;
 461     constant Loadstore1ToWritebackInit : Loadstore1ToWritebackType :=
 462         (valid => '0', instr_tag => instr_tag_init, write_enable => '0',
 463          write_reg => (others => '0'), write_data => (others => '0'),
 464          xerc => xerc_init, rc => '0', store_done => '0',
 465          interrupt => '0', intr_vec => 0,
 466          srr0 => (others => '0'), srr1 => (others => '0'));
 467
 468     type Execute1ToWritebackType is record
 469         valid: std_ulogic;
 470         instr_tag : instr_tag_t;
 471         rc : std_ulogic;
 472         mode_32bit : std_ulogic;
 473         write_enable : std_ulogic;
 474         write_reg: gspr_index_t;
 475         write_data: std_ulogic_vector(63 downto 0);
 476         write_cr_enable : std_ulogic;
 477         write_cr_mask : std_ulogic_vector(7 downto 0);
 478         write_cr_data : std_ulogic_vector(31 downto 0);
 479         write_xerc_enable : std_ulogic;
 480         xerc : xer_common_t;
 481         interrupt : std_ulogic;
 482         intr_vec : intr_vector_t;
 483         redirect: std_ulogic;
 484         redir_mode: std_ulogic_vector(3 downto 0);
 485         last_nia: std_ulogic_vector(63 downto 0);
 486         br_offset: std_ulogic_vector(63 downto 0);
 487         br_last: std_ulogic;
 488         br_taken: std_ulogic;
 489         abs_br: std_ulogic;
 490         srr1: std_ulogic_vector(15 downto 0);
 491         msr: std_ulogic_vector(63 downto 0);
 492     end record;
 493     constant Execute1ToWritebackInit : Execute1ToWritebackType :=
 494         (valid => '0', instr_tag => instr_tag_init, rc => '0', mode_32bit => '0',
 495          write_enable => '0', write_cr_enable => '0',
 496          write_xerc_enable => '0', xerc => xerc_init,
 497          write_data => (others => '0'), write_cr_mask => (others => '0'),
 498          write_cr_data => (others => '0'), write_reg => (others => '0'),
 499          interrupt => '0', intr_vec => 0, redirect => '0', redir_mode => "0000",
 500          last_nia => (others => '0'), br_offset => (others => '0'),
 501          br_last => '0', br_taken => '0', abs_br => '0',
 502          srr1 => (others => '0'), msr => (others => '0'));
 503
 504     type Execute1ToFPUType is record
 505         valid   : std_ulogic;
 506         op      : insn_type_t;
 507         nia     : std_ulogic_vector(63 downto 0);
 508         itag    : instr_tag_t;
 509         insn    : std_ulogic_vector(31 downto 0);
 510         single  : std_ulogic;
 511         fe_mode : std_ulogic_vector(1 downto 0);
 512         fra     : std_ulogic_vector(63 downto 0);
 513         frb     : std_ulogic_vector(63 downto 0);
 514         frc     : std_ulogic_vector(63 downto 0);
 515         frt     : gspr_index_t;
 516         rc      : std_ulogic;
 517         out_cr  : std_ulogic;
 518     end record;
 519     constant Execute1ToFPUInit : Execute1ToFPUType := (valid => '0', op => OP_ILLEGAL, nia => (others => '0'),
 520                                                        itag => instr_tag_init,
 521                                                        insn  => (others => '0'), fe_mode => "00", rc => '0',
 522                                                        fra => (others => '0'), frb => (others => '0'),
 523                                                        frc => (others => '0'), frt => (others => '0'),
 524                                                        single => '0', out_cr => '0');
 525
 526     type FPUToExecute1Type is record
 527         busy      : std_ulogic;
 528         exception : std_ulogic;
 529     end record;
 530     constant FPUToExecute1Init : FPUToExecute1Type := (others => '0');
 531
 532     type FPUToWritebackType is record
 533         valid           : std_ulogic;
 534         interrupt       : std_ulogic;
 535         instr_tag       : instr_tag_t;
 536         write_enable    : std_ulogic;
 537         write_reg       : gspr_index_t;
 538         write_data      : std_ulogic_vector(63 downto 0);
 539         write_cr_enable : std_ulogic;
 540         write_cr_mask   : std_ulogic_vector(7 downto 0);
 541         write_cr_data   : std_ulogic_vector(31 downto 0);
 542         intr_vec        : intr_vector_t;
 543         srr0            : std_ulogic_vector(63 downto 0);
 544         srr1            : std_ulogic_vector(15 downto 0);
 545     end record;
 546     constant FPUToWritebackInit : FPUToWritebackType :=
 547         (valid => '0', interrupt => '0', instr_tag => instr_tag_init,
 548          write_enable => '0', write_reg => (others => '0'),
 549          write_cr_enable => '0', write_cr_mask => (others => '0'),
 550          write_cr_data => (others => '0'),
 551          intr_vec => 0, srr1 => (others => '0'),
 552          others => (others => '0'));
 553
 554     type DividerToExecute1Type is record
 555         valid: std_ulogic;
 556         write_reg_data: std_ulogic_vector(63 downto 0);
 557         overflow : std_ulogic;
 558     end record;
 559     constant DividerToExecute1Init : DividerToExecute1Type := (valid => '0', overflow => '0',
 560                                                                others => (others => '0'));
 561
 562     type WritebackToFetch1Type is record
 563         redirect: std_ulogic;
 564         virt_mode: std_ulogic;
 565         priv_mode: std_ulogic;
 566         big_endian: std_ulogic;
 567         mode_32bit: std_ulogic;
 568         redirect_nia: std_ulogic_vector(63 downto 0);
 569         br_nia : std_ulogic_vector(63 downto 0);
 570         br_last : std_ulogic;
 571         br_taken : std_ulogic;
 572     end record;
 573     constant WritebackToFetch1Init : WritebackToFetch1Type :=
 574         (redirect => '0', virt_mode => '0', priv_mode => '0', big_endian => '0',
 575          mode_32bit => '0', redirect_nia => (others => '0'),
 576          br_last => '0', br_taken => '0', br_nia => (others => '0'));
 577
 578     type WritebackToRegisterFileType is record
 579         write_reg : gspr_index_t;
 580         write_data : std_ulogic_vector(63 downto 0);
 581         write_enable : std_ulogic;
 582     end record;
 583     constant WritebackToRegisterFileInit : WritebackToRegisterFileType :=
 584         (write_enable => '0', write_data => (others => '0'), others => (others => '0'));
 585
 586     type WritebackToCrFileType is record
 587         write_cr_enable : std_ulogic;
 588         write_cr_mask : std_ulogic_vector(7 downto 0);
 589         write_cr_data : std_ulogic_vector(31 downto 0);
 590         write_xerc_enable : std_ulogic;
 591         write_xerc_data : xer_common_t;
 592     end record;
 593     constant WritebackToCrFileInit : WritebackToCrFileType := (write_cr_enable => '0', write_xerc_enable => '0',
 594                                                                write_xerc_data => xerc_init,
 595                                                                write_cr_mask => (others => '0'),
 596                                                                write_cr_data => (others => '0'));
 597
 598 end common;
 599
 600 package body common is
 601     function decode_spr_num(insn: std_ulogic_vector(31 downto 0)) return spr_num_t is
 602     begin
 603         return to_integer(unsigned(insn(15 downto 11) & insn(20 downto 16)));
 604     end;
 605     function fast_spr_num(spr: spr_num_t) return gspr_index_t is
 606        variable n : integer range 0 to 31;
 607        -- tmp variable introduced as workaround for VCS compilation
 608        -- simulation was failing with subtype constraint mismatch error
 609        -- see GitHub PR #173
 610        variable tmp : std_ulogic_vector(4 downto 0);
 611     begin
 612        case spr is
 613        when SPR_LR =>
 614            n := 0;              -- N.B. decode2 relies on this specific value
 615        when SPR_CTR =>
 616            n := 1;              -- N.B. decode2 relies on this specific value
 617        when SPR_SRR0 =>
 618            n := 2;
 619        when SPR_SRR1 =>
 620            n := 3;
 621        when SPR_HSRR0 =>
 622            n := 4;
 623        when SPR_HSRR1 =>
 624            n := 5;
 625        when SPR_SPRG0 =>
 626            n := 6;
 627        when SPR_SPRG1 =>
 628            n := 7;
 629        when SPR_SPRG2 =>
 630            n := 8;
 631        when SPR_SPRG3 | SPR_SPRG3U =>
 632            n := 9;
 633        when SPR_HSPRG0 =>
 634            n := 10;
 635        when SPR_HSPRG1 =>
 636            n := 11;
 637        when SPR_XER =>
 638            n := 12;
 639        when SPR_TAR =>
 640            n := 13;
 641        when others =>
 642            n := 0;
 643            return "0000000";
 644        end case;
 645        tmp := std_ulogic_vector(to_unsigned(n, 5));
 646        return "01" & tmp;
 647     end;
 648
 649     function gspr_to_gpr(i: gspr_index_t) return gpr_index_t is
 650     begin
 651         return i(4 downto 0);
 652     end;
 653
 654     function gpr_to_gspr(i: gpr_index_t) return gspr_index_t is
 655     begin
 656         return "00" & i;
 657     end;
 658
 659     function gpr_or_spr_to_gspr(g: gpr_index_t; s: gspr_index_t) return gspr_index_t is
 660     begin
 661         if s(5) = '1' then
 662             return s;
 663         else
 664             return gpr_to_gspr(g);
 665         end if;
 666     end;
 667
 668     function is_fast_spr(s: gspr_index_t) return std_ulogic is
 669     begin
 670         return s(5);
 671     end;
 672
 673     function fpr_to_gspr(f: fpr_index_t) return gspr_index_t is
 674     begin
 675         return "10" & f;
 676     end;
 677
 678     function tag_match(tag1 : instr_tag_t; tag2 : instr_tag_t) return boolean is
 679     begin
 680         return tag1.valid = '1' and tag2.valid = '1' and tag1.tag = tag2.tag;
 681     end;
 682 end common;