src/soc/decoder/power_decoder2.py

   1 """Power ISA Decoder second stage
   2
   3 based on Anton Blanchard microwatt decode2.vhdl
   4
   5 Note: OP_TRAP is used for exceptions and interrupts (micro-code style) by
   6 over-riding the internal opcode when an exception is needed.
   7 """
   8
   9 from nmigen import Module, Elaboratable, Signal, Mux, Const, Cat, Repl, Record
  10 from nmigen.cli import rtlil
  11 from nmutil.util import sel
  12
  13 from soc.regfile.regfiles import XERRegs
  14
  15 from nmutil.picker import PriorityPicker
  16 from nmutil.iocontrol import RecordObject
  17 from nmutil.extend import exts
  18
  19 from soc.experiment.mem_types import LDSTException
  20
  21 from soc.decoder.power_svp64_prefix import SVP64PrefixDecoder
  22 from soc.decoder.power_svp64_extra import SVP64CRExtra, SVP64RegExtra
  23 from soc.decoder.power_regspec_map import regspec_decode_read
  24 from soc.decoder.power_regspec_map import regspec_decode_write
  25 from soc.decoder.power_decoder import create_pdecode
  26 from soc.decoder.power_enums import (MicrOp, CryIn, Function,
  27                                      CRInSel, CROutSel,
  28                                      LdstLen, In1Sel, In2Sel, In3Sel,
  29                                      OutSel, SPR, RC, LDSTMode,
  30                                      SVEXTRA, SVEtype)
  31 from soc.decoder.decode2execute1 import (Decode2ToExecute1Type, Data,
  32                                          Decode2ToOperand)
  33 from soc.sv.svp64 import SVP64Rec
  34 from soc.consts import (MSR, SPEC, EXTRA2, EXTRA3, SVP64P, field,
  35                         SPEC_SIZE, SPECb, SPEC_AUG_SIZE, SVP64CROffs)
  36
  37 from soc.regfile.regfiles import FastRegs
  38 from soc.consts import TT
  39 from soc.config.state import CoreState
  40 from soc.regfile.util import spr_to_fast
  41
  42
  43 def decode_spr_num(spr):
  44     return Cat(spr[5:10], spr[0:5])
  45
  46
  47 def instr_is_priv(m, op, insn):
  48     """determines if the instruction is privileged or not
  49     """
  50     comb = m.d.comb
  51     is_priv_insn = Signal(reset_less=True)
  52     with m.Switch(op):
  53         with m.Case(MicrOp.OP_ATTN, MicrOp.OP_MFMSR, MicrOp.OP_MTMSRD,
  54                     MicrOp.OP_MTMSR, MicrOp.OP_RFID):
  55             comb += is_priv_insn.eq(1)
  56         with m.Case(MicrOp.OP_TLBIE) : comb += is_priv_insn.eq(1)
  57         with m.Case(MicrOp.OP_MFSPR, MicrOp.OP_MTSPR):
  58             with m.If(insn[20]):  # field XFX.spr[-1] i think
  59                 comb += is_priv_insn.eq(1)
  60     return is_priv_insn
  61
  62
  63 class SPRMap(Elaboratable):
  64     """SPRMap: maps POWER9 SPR numbers to internal enum values, fast and slow
  65     """
  66
  67     def __init__(self):
  68         self.spr_i = Signal(10, reset_less=True)
  69         self.spr_o = Data(SPR, name="spr_o")
  70         self.fast_o = Data(3, name="fast_o")
  71
  72     def elaborate(self, platform):
  73         m = Module()
  74         with m.Switch(self.spr_i):
  75             for i, x in enumerate(SPR):
  76                 with m.Case(x.value):
  77                     m.d.comb += self.spr_o.data.eq(i)
  78                     m.d.comb += self.spr_o.ok.eq(1)
  79             for x, v in spr_to_fast.items():
  80                 with m.Case(x.value):
  81                     m.d.comb += self.fast_o.data.eq(v)
  82                     m.d.comb += self.fast_o.ok.eq(1)
  83         return m
  84
  85
  86 class DecodeA(Elaboratable):
  87     """DecodeA from instruction
  88
  89     decodes register RA, implicit and explicit CSRs
  90     """
  91
  92     def __init__(self, dec):
  93         self.dec = dec
  94         self.sel_in = Signal(In1Sel, reset_less=True)
  95         self.insn_in = Signal(32, reset_less=True)
  96         self.reg_out = Data(5, name="reg_a")
  97         self.spr_out = Data(SPR, "spr_a")
  98         self.fast_out = Data(3, "fast_a")
  99
 100     def elaborate(self, platform):
 101         m = Module()
 102         comb = m.d.comb
 103         op = self.dec.op
 104         reg = self.reg_out
 105         m.submodules.sprmap = sprmap = SPRMap()
 106
 107         # select Register A field
 108         ra = Signal(5, reset_less=True)
 109         comb += ra.eq(self.dec.RA)
 110         with m.If((self.sel_in == In1Sel.RA) |
 111                   ((self.sel_in == In1Sel.RA_OR_ZERO) &
 112                    (ra != Const(0, 5)))):
 113             comb += reg.data.eq(ra)
 114             comb += reg.ok.eq(1)
 115
 116         # some Logic/ALU ops have RS as the 3rd arg, but no "RA".
 117         # moved it to 1st position (in1_sel)... because
 118         rs = Signal(5, reset_less=True)
 119         comb += rs.eq(self.dec.RS)
 120         with m.If(self.sel_in == In1Sel.RS):
 121             comb += reg.data.eq(rs)
 122             comb += reg.ok.eq(1)
 123
 124         # decode Fast-SPR based on instruction type
 125         with m.Switch(op.internal_op):
 126
 127             # BC or BCREG: implicit register (CTR) NOTE: same in DecodeOut
 128             with m.Case(MicrOp.OP_BC):
 129                 with m.If(~self.dec.BO[2]):  # 3.0B p38 BO2=0, use CTR reg
 130                     # constant: CTR
 131                     comb += self.fast_out.data.eq(FastRegs.CTR)
 132                     comb += self.fast_out.ok.eq(1)
 133             with m.Case(MicrOp.OP_BCREG):
 134                 xo9 = self.dec.FormXL.XO[9]  # 3.0B p38 top bit of XO
 135                 xo5 = self.dec.FormXL.XO[5]  # 3.0B p38
 136                 with m.If(xo9 & ~xo5):
 137                     # constant: CTR
 138                     comb += self.fast_out.data.eq(FastRegs.CTR)
 139                     comb += self.fast_out.ok.eq(1)
 140
 141             # MFSPR move from SPRs
 142             with m.Case(MicrOp.OP_MFSPR):
 143                 spr = Signal(10, reset_less=True)
 144                 comb += spr.eq(decode_spr_num(self.dec.SPR))  # from XFX
 145                 comb += sprmap.spr_i.eq(spr)
 146                 comb += self.spr_out.eq(sprmap.spr_o)
 147                 comb += self.fast_out.eq(sprmap.fast_o)
 148
 149         return m
 150
 151
 152 class DecodeAImm(Elaboratable):
 153     """DecodeA immediate from instruction
 154
 155     decodes register RA, whether immediate-zero, implicit and
 156     explicit CSRs
 157     """
 158
 159     def __init__(self, dec):
 160         self.dec = dec
 161         self.sel_in = Signal(In1Sel, reset_less=True)
 162         self.immz_out = Signal(reset_less=True)
 163
 164     def elaborate(self, platform):
 165         m = Module()
 166         comb = m.d.comb
 167
 168         # zero immediate requested
 169         ra = Signal(5, reset_less=True)
 170         comb += ra.eq(self.dec.RA)
 171         with m.If((self.sel_in == In1Sel.RA_OR_ZERO) & (ra == Const(0, 5))):
 172             comb += self.immz_out.eq(1)
 173
 174         return m
 175
 176
 177 class DecodeB(Elaboratable):
 178     """DecodeB from instruction
 179
 180     decodes register RB, different forms of immediate (signed, unsigned),
 181     and implicit SPRs.  register B is basically "lane 2" into the CompUnits.
 182     by industry-standard convention, "lane 2" is where fully-decoded
 183     immediates are muxed in.
 184     """
 185
 186     def __init__(self, dec):
 187         self.dec = dec
 188         self.sel_in = Signal(In2Sel, reset_less=True)
 189         self.insn_in = Signal(32, reset_less=True)
 190         self.reg_out = Data(7, "reg_b")
 191         self.reg_isvec = Signal(1, name="reg_b_isvec") # TODO: in reg_out
 192         self.fast_out = Data(3, "fast_b")
 193
 194     def elaborate(self, platform):
 195         m = Module()
 196         comb = m.d.comb
 197         op = self.dec.op
 198         reg = self.reg_out
 199
 200         # select Register B field
 201         with m.Switch(self.sel_in):
 202             with m.Case(In2Sel.RB):
 203                 comb += reg.data.eq(self.dec.RB)
 204                 comb += reg.ok.eq(1)
 205             with m.Case(In2Sel.RS):
 206                 # for M-Form shiftrot
 207                 comb += reg.data.eq(self.dec.RS)
 208                 comb += reg.ok.eq(1)
 209
 210         # decode SPR2 based on instruction type
 211         # BCREG implicitly uses LR or TAR for 2nd reg
 212         # CTR however is already in fast_spr1 *not* 2.
 213         with m.If(op.internal_op == MicrOp.OP_BCREG):
 214             xo9 = self.dec.FormXL.XO[9]  # 3.0B p38 top bit of XO
 215             xo5 = self.dec.FormXL.XO[5]  # 3.0B p38
 216             with m.If(~xo9):
 217                 comb += self.fast_out.data.eq(FastRegs.LR)
 218                 comb += self.fast_out.ok.eq(1)
 219             with m.Elif(xo5):
 220                 comb += self.fast_out.data.eq(FastRegs.TAR)
 221                 comb += self.fast_out.ok.eq(1)
 222
 223         return m
 224
 225
 226 class DecodeBImm(Elaboratable):
 227     """DecodeB immediate from instruction
 228     """
 229     def __init__(self, dec):
 230         self.dec = dec
 231         self.sel_in = Signal(In2Sel, reset_less=True)
 232         self.imm_out = Data(64, "imm_b")
 233
 234     def elaborate(self, platform):
 235         m = Module()
 236         comb = m.d.comb
 237
 238         # select Register B Immediate
 239         with m.Switch(self.sel_in):
 240             with m.Case(In2Sel.CONST_UI): # unsigned
 241                 comb += self.imm_out.data.eq(self.dec.UI)
 242                 comb += self.imm_out.ok.eq(1)
 243             with m.Case(In2Sel.CONST_SI):  # sign-extended 16-bit
 244                 si = Signal(16, reset_less=True)
 245                 comb += si.eq(self.dec.SI)
 246                 comb += self.imm_out.data.eq(exts(si, 16, 64))
 247                 comb += self.imm_out.ok.eq(1)
 248             with m.Case(In2Sel.CONST_SI_HI):  # sign-extended 16+16=32 bit
 249                 si_hi = Signal(32, reset_less=True)
 250                 comb += si_hi.eq(self.dec.SI << 16)
 251                 comb += self.imm_out.data.eq(exts(si_hi, 32, 64))
 252                 comb += self.imm_out.ok.eq(1)
 253             with m.Case(In2Sel.CONST_UI_HI): # unsigned
 254                 ui = Signal(16, reset_less=True)
 255                 comb += ui.eq(self.dec.UI)
 256                 comb += self.imm_out.data.eq(ui << 16)
 257                 comb += self.imm_out.ok.eq(1)
 258             with m.Case(In2Sel.CONST_LI): # sign-extend 24+2=26 bit
 259                 li = Signal(26, reset_less=True)
 260                 comb += li.eq(self.dec.LI << 2)
 261                 comb += self.imm_out.data.eq(exts(li, 26, 64))
 262                 comb += self.imm_out.ok.eq(1)
 263             with m.Case(In2Sel.CONST_BD): # sign-extend (14+2)=16 bit
 264                 bd = Signal(16, reset_less=True)
 265                 comb += bd.eq(self.dec.BD << 2)
 266                 comb += self.imm_out.data.eq(exts(bd, 16, 64))
 267                 comb += self.imm_out.ok.eq(1)
 268             with m.Case(In2Sel.CONST_DS): # sign-extended (14+2=16) bit
 269                 ds = Signal(16, reset_less=True)
 270                 comb += ds.eq(self.dec.DS << 2)
 271                 comb += self.imm_out.data.eq(exts(ds, 16, 64))
 272                 comb += self.imm_out.ok.eq(1)
 273             with m.Case(In2Sel.CONST_M1): # signed (-1)
 274                 comb += self.imm_out.data.eq(~Const(0, 64))  # all 1s
 275                 comb += self.imm_out.ok.eq(1)
 276             with m.Case(In2Sel.CONST_SH): # unsigned - for shift
 277                 comb += self.imm_out.data.eq(self.dec.sh)
 278                 comb += self.imm_out.ok.eq(1)
 279             with m.Case(In2Sel.CONST_SH32): # unsigned - for shift
 280                 comb += self.imm_out.data.eq(self.dec.SH32)
 281                 comb += self.imm_out.ok.eq(1)
 282
 283         return m
 284
 285
 286 class DecodeC(Elaboratable):
 287     """DecodeC from instruction
 288
 289     decodes register RC.  this is "lane 3" into some CompUnits (not many)
 290     """
 291
 292     def __init__(self, dec):
 293         self.dec = dec
 294         self.sel_in = Signal(In3Sel, reset_less=True)
 295         self.insn_in = Signal(32, reset_less=True)
 296         self.reg_out = Data(5, "reg_c")
 297
 298     def elaborate(self, platform):
 299         m = Module()
 300         comb = m.d.comb
 301         op = self.dec.op
 302         reg = self.reg_out
 303
 304         # select Register C field
 305         with m.Switch(self.sel_in):
 306             with m.Case(In3Sel.RB):
 307                 # for M-Form shiftrot
 308                 comb += reg.data.eq(self.dec.RB)
 309                 comb += reg.ok.eq(1)
 310             with m.Case(In3Sel.RS):
 311                 comb += reg.data.eq(self.dec.RS)
 312                 comb += reg.ok.eq(1)
 313
 314         return m
 315
 316
 317 class DecodeOut(Elaboratable):
 318     """DecodeOut from instruction
 319
 320     decodes output register RA, RT or SPR
 321     """
 322
 323     def __init__(self, dec):
 324         self.dec = dec
 325         self.sel_in = Signal(OutSel, reset_less=True)
 326         self.insn_in = Signal(32, reset_less=True)
 327         self.reg_out = Data(5, "reg_o")
 328         self.spr_out = Data(SPR, "spr_o")
 329         self.fast_out = Data(3, "fast_o")
 330
 331     def elaborate(self, platform):
 332         m = Module()
 333         comb = m.d.comb
 334         m.submodules.sprmap = sprmap = SPRMap()
 335         op = self.dec.op
 336         reg = self.reg_out
 337
 338         # select Register out field
 339         with m.Switch(self.sel_in):
 340             with m.Case(OutSel.RT):
 341                 comb += reg.data.eq(self.dec.RT)
 342                 comb += reg.ok.eq(1)
 343             with m.Case(OutSel.RA):
 344                 comb += reg.data.eq(self.dec.RA)
 345                 comb += reg.ok.eq(1)
 346             with m.Case(OutSel.SPR):
 347                 spr = Signal(10, reset_less=True)
 348                 comb += spr.eq(decode_spr_num(self.dec.SPR))  # from XFX
 349                 # MFSPR move to SPRs - needs mapping
 350                 with m.If(op.internal_op == MicrOp.OP_MTSPR):
 351                     comb += sprmap.spr_i.eq(spr)
 352                     comb += self.spr_out.eq(sprmap.spr_o)
 353                     comb += self.fast_out.eq(sprmap.fast_o)
 354
 355         # determine Fast Reg
 356         with m.Switch(op.internal_op):
 357
 358             # BC or BCREG: implicit register (CTR) NOTE: same in DecodeA
 359             with m.Case(MicrOp.OP_BC, MicrOp.OP_BCREG):
 360                 with m.If(~self.dec.BO[2]):  # 3.0B p38 BO2=0, use CTR reg
 361                     # constant: CTR
 362                     comb += self.fast_out.data.eq(FastRegs.CTR)
 363                     comb += self.fast_out.ok.eq(1)
 364
 365             # RFID 1st spr (fast)
 366             with m.Case(MicrOp.OP_RFID):
 367                 comb += self.fast_out.data.eq(FastRegs.SRR0)  # constant: SRR0
 368                 comb += self.fast_out.ok.eq(1)
 369
 370         return m
 371
 372
 373 class DecodeOut2(Elaboratable):
 374     """DecodeOut2 from instruction
 375
 376     decodes output registers (2nd one).  note that RA is *implicit* below,
 377     which now causes problems with SVP64
 378
 379     TODO: SVP64 is a little more complex, here.  svp64 allows extending
 380     by one more destination by having one more EXTRA field.  RA-as-src
 381     is not the same as RA-as-dest.  limited in that it's the same first
 382     5 bits (from the v3.0B opcode), but still kinda cool.  mostly used
 383     for operations that have src-as-dest: mostly this is LD/ST-with-update
 384     but there are others.
 385     """
 386
 387     def __init__(self, dec):
 388         self.dec = dec
 389         self.sel_in = Signal(OutSel, reset_less=True)
 390         self.lk = Signal(reset_less=True)
 391         self.insn_in = Signal(32, reset_less=True)
 392         self.reg_out = Data(5, "reg_o2")
 393         self.fast_out = Data(3, "fast_o2")
 394
 395     def elaborate(self, platform):
 396         m = Module()
 397         comb = m.d.comb
 398         op = self.dec.op
 399         #m.submodules.svdec = svdec = SVP64RegExtra()
 400
 401         # get the 5-bit reg data before svp64-munging it into 7-bit plus isvec
 402         #reg = Signal(5, reset_less=True)
 403
 404         if hasattr(self.dec.op, "upd"):
 405             # update mode LD/ST uses read-reg A also as an output
 406             with m.If(self.dec.op.upd == LDSTMode.update):
 407                 comb += self.reg_out.data.eq(self.dec.RA)
 408                 comb += self.reg_out.ok.eq(1)
 409
 410         # B, BC or BCREG: potential implicit register (LR) output
 411         # these give bl, bcl, bclrl, etc.
 412         with m.Switch(op.internal_op):
 413
 414             # BC* implicit register (LR)
 415             with m.Case(MicrOp.OP_BC, MicrOp.OP_B, MicrOp.OP_BCREG):
 416                 with m.If(self.lk):  # "link" mode
 417                     comb += self.fast_out.data.eq(FastRegs.LR)  # constant: LR
 418                     comb += self.fast_out.ok.eq(1)
 419
 420             # RFID 2nd spr (fast)
 421             with m.Case(MicrOp.OP_RFID):
 422                 comb += self.fast_out.data.eq(FastRegs.SRR1)  # constant: SRR1
 423                 comb += self.fast_out.ok.eq(1)
 424
 425         return m
 426
 427
 428 class DecodeRC(Elaboratable):
 429     """DecodeRc from instruction
 430
 431     decodes Record bit Rc
 432     """
 433
 434     def __init__(self, dec):
 435         self.dec = dec
 436         self.sel_in = Signal(RC, reset_less=True)
 437         self.insn_in = Signal(32, reset_less=True)
 438         self.rc_out = Data(1, "rc")
 439
 440     def elaborate(self, platform):
 441         m = Module()
 442         comb = m.d.comb
 443
 444         # select Record bit out field
 445         with m.Switch(self.sel_in):
 446             with m.Case(RC.RC):
 447                 comb += self.rc_out.data.eq(self.dec.Rc)
 448                 comb += self.rc_out.ok.eq(1)
 449             with m.Case(RC.ONE):
 450                 comb += self.rc_out.data.eq(1)
 451                 comb += self.rc_out.ok.eq(1)
 452             with m.Case(RC.NONE):
 453                 comb += self.rc_out.data.eq(0)
 454                 comb += self.rc_out.ok.eq(1)
 455
 456         return m
 457
 458
 459 class DecodeOE(Elaboratable):
 460     """DecodeOE from instruction
 461
 462     decodes OE field: uses RC decode detection which might not be good
 463
 464     -- For now, use "rc" in the decode table to decide whether oe exists.
 465     -- This is not entirely correct architecturally: For mulhd and
 466     -- mulhdu, the OE field is reserved. It remains to be seen what an
 467     -- actual POWER9 does if we set it on those instructions, for now we
 468     -- test that further down when assigning to the multiplier oe input.
 469     """
 470
 471     def __init__(self, dec):
 472         self.dec = dec
 473         self.sel_in = Signal(RC, reset_less=True)
 474         self.insn_in = Signal(32, reset_less=True)
 475         self.oe_out = Data(1, "oe")
 476
 477     def elaborate(self, platform):
 478         m = Module()
 479         comb = m.d.comb
 480         op = self.dec.op
 481
 482         with m.Switch(op.internal_op):
 483
 484             # mulhw, mulhwu, mulhd, mulhdu - these *ignore* OE
 485             # also rotate
 486             # XXX ARGH! ignoring OE causes incompatibility with microwatt
 487             # http://lists.libre-soc.org/pipermail/libre-soc-dev/2020-August/000302.html
 488             with m.Case(MicrOp.OP_MUL_H64, MicrOp.OP_MUL_H32,
 489                         MicrOp.OP_EXTS, MicrOp.OP_CNTZ,
 490                         MicrOp.OP_SHL, MicrOp.OP_SHR, MicrOp.OP_RLC,
 491                         MicrOp.OP_LOAD, MicrOp.OP_STORE,
 492                         MicrOp.OP_RLCL, MicrOp.OP_RLCR,
 493                         MicrOp.OP_EXTSWSLI):
 494                 pass
 495
 496             # all other ops decode OE field
 497             with m.Default():
 498                 # select OE bit out field
 499                 with m.Switch(self.sel_in):
 500                     with m.Case(RC.RC):
 501                         comb += self.oe_out.data.eq(self.dec.OE)
 502                         comb += self.oe_out.ok.eq(1)
 503
 504         return m
 505
 506
 507 class DecodeCRIn(Elaboratable):
 508     """Decodes input CR from instruction
 509
 510     CR indices - insn fields - (not the data *in* the CR) require only 3
 511     bits because they refer to CR0-CR7
 512     """
 513
 514     def __init__(self, dec):
 515         self.dec = dec
 516         self.sel_in = Signal(CRInSel, reset_less=True)
 517         self.insn_in = Signal(32, reset_less=True)
 518         self.cr_bitfield = Data(3, "cr_bitfield")
 519         self.cr_bitfield_b = Data(3, "cr_bitfield_b")
 520         self.cr_bitfield_o = Data(3, "cr_bitfield_o")
 521         self.whole_reg = Data(8,  "cr_fxm")
 522         self.sv_override = Signal(2, reset_less=True) # do not do EXTRA spec
 523
 524     def elaborate(self, platform):
 525         m = Module()
 526         comb = m.d.comb
 527         op = self.dec.op
 528         m.submodules.ppick = ppick = PriorityPicker(8, reverse_i=True,
 529                                                        reverse_o=True)
 530
 531         # zero-initialisation
 532         comb += self.cr_bitfield.ok.eq(0)
 533         comb += self.cr_bitfield_b.ok.eq(0)
 534         comb += self.cr_bitfield_o.ok.eq(0)
 535         comb += self.whole_reg.ok.eq(0)
 536         comb += self.sv_override.eq(0)
 537
 538         # select the relevant CR bitfields
 539         with m.Switch(self.sel_in):
 540             with m.Case(CRInSel.NONE):
 541                 pass  # No bitfield activated
 542             with m.Case(CRInSel.CR0):
 543                 comb += self.cr_bitfield.data.eq(0) # CR0 (MSB0 numbering)
 544                 comb += self.cr_bitfield.ok.eq(1)
 545                 comb += self.sv_override.eq(1)
 546             with m.Case(CRInSel.CR1):
 547                 comb += self.cr_bitfield.data.eq(1) # CR1 (MSB0 numbering)
 548                 comb += self.cr_bitfield.ok.eq(1)
 549                 comb += self.sv_override.eq(2)
 550             with m.Case(CRInSel.BI):
 551                 comb += self.cr_bitfield.data.eq(self.dec.BI[2:5])
 552                 comb += self.cr_bitfield.ok.eq(1)
 553             with m.Case(CRInSel.BFA):
 554                 comb += self.cr_bitfield.data.eq(self.dec.FormX.BFA)
 555                 comb += self.cr_bitfield.ok.eq(1)
 556             with m.Case(CRInSel.BA_BB):
 557                 comb += self.cr_bitfield.data.eq(self.dec.BA[2:5])
 558                 comb += self.cr_bitfield.ok.eq(1)
 559                 comb += self.cr_bitfield_b.data.eq(self.dec.BB[2:5])
 560                 comb += self.cr_bitfield_b.ok.eq(1)
 561                 comb += self.cr_bitfield_o.data.eq(self.dec.BT[2:5])
 562                 comb += self.cr_bitfield_o.ok.eq(1)
 563             with m.Case(CRInSel.BC):
 564                 comb += self.cr_bitfield.data.eq(self.dec.BC[2:5])
 565                 comb += self.cr_bitfield.ok.eq(1)
 566             with m.Case(CRInSel.WHOLE_REG):
 567                 comb += self.whole_reg.ok.eq(1)
 568                 move_one = Signal(reset_less=True)
 569                 comb += move_one.eq(self.insn_in[20]) # MSB0 bit 11
 570                 with m.If((op.internal_op == MicrOp.OP_MFCR) & move_one):
 571                     # must one-hot the FXM field
 572                     comb += ppick.i.eq(self.dec.FXM)
 573                     comb += self.whole_reg.data.eq(ppick.o)
 574                 with m.Else():
 575                     # otherwise use all of it
 576                     comb += self.whole_reg.data.eq(0xff)
 577
 578         return m
 579
 580
 581 class DecodeCROut(Elaboratable):
 582     """Decodes input CR from instruction
 583
 584     CR indices - insn fields - (not the data *in* the CR) require only 3
 585     bits because they refer to CR0-CR7
 586     """
 587
 588     def __init__(self, dec):
 589         self.dec = dec
 590         self.rc_in = Signal(reset_less=True)
 591         self.sel_in = Signal(CROutSel, reset_less=True)
 592         self.insn_in = Signal(32, reset_less=True)
 593         self.cr_bitfield = Data(3, "cr_bitfield")
 594         self.whole_reg = Data(8,  "cr_fxm")
 595         self.sv_override = Signal(2, reset_less=True) # do not do EXTRA spec
 596
 597     def elaborate(self, platform):
 598         m = Module()
 599         comb = m.d.comb
 600         op = self.dec.op
 601         m.submodules.ppick = ppick = PriorityPicker(8, reverse_i=True,
 602                                                        reverse_o=True)
 603
 604         comb += self.cr_bitfield.ok.eq(0)
 605         comb += self.whole_reg.ok.eq(0)
 606         comb += self.sv_override.eq(0)
 607
 608         # please note these MUST match (setting of cr_bitfield.ok) exactly
 609         # with write_cr0 below in PowerDecoder2.  the reason it's separated
 610         # is to avoid having duplicate copies of DecodeCROut in multiple
 611         # PowerDecoderSubsets.  register decoding should be a one-off in
 612         # PowerDecoder2.  see https://bugs.libre-soc.org/show_bug.cgi?id=606
 613
 614         with m.Switch(self.sel_in):
 615             with m.Case(CROutSel.NONE):
 616                 pass  # No bitfield activated
 617             with m.Case(CROutSel.CR0):
 618                 comb += self.cr_bitfield.data.eq(0) # CR0 (MSB0 numbering)
 619                 comb += self.cr_bitfield.ok.eq(self.rc_in)  # only when RC=1
 620                 comb += self.sv_override.eq(1)
 621             with m.Case(CROutSel.CR1):
 622                 comb += self.cr_bitfield.data.eq(1) # CR1 (MSB0 numbering)
 623                 comb += self.cr_bitfield.ok.eq(self.rc_in)  # only when RC=1
 624                 comb += self.sv_override.eq(2)
 625             with m.Case(CROutSel.BF):
 626                 comb += self.cr_bitfield.data.eq(self.dec.FormX.BF)
 627                 comb += self.cr_bitfield.ok.eq(1)
 628             with m.Case(CROutSel.BT):
 629                 comb += self.cr_bitfield.data.eq(self.dec.FormXL.BT[2:5])
 630                 comb += self.cr_bitfield.ok.eq(1)
 631             with m.Case(CROutSel.WHOLE_REG):
 632                 comb += self.whole_reg.ok.eq(1)
 633                 move_one = Signal(reset_less=True)
 634                 comb += move_one.eq(self.insn_in[20])
 635                 with m.If((op.internal_op == MicrOp.OP_MTCRF)):
 636                     with m.If(move_one):
 637                         # must one-hot the FXM field
 638                         comb += ppick.i.eq(self.dec.FXM)
 639                         with m.If(ppick.en_o):
 640                             comb += self.whole_reg.data.eq(ppick.o)
 641                         with m.Else():
 642                             comb += self.whole_reg.data.eq(0b00000001) # CR7
 643                     with m.Else():
 644                         comb += self.whole_reg.data.eq(self.dec.FXM)
 645                 with m.Else():
 646                     # otherwise use all of it
 647                     comb += self.whole_reg.data.eq(0xff)
 648
 649         return m
 650
 651 # dictionary of Input Record field names that, if they exist,
 652 # will need a corresponding CSV Decoder file column (actually, PowerOp)
 653 # to be decoded (this includes the single bit names)
 654 record_names = {'insn_type': 'internal_op',
 655                 'fn_unit': 'function_unit',
 656                 'rc': 'rc_sel',
 657                 'oe': 'rc_sel',
 658                 'zero_a': 'in1_sel',
 659                 'imm_data': 'in2_sel',
 660                 'invert_in': 'inv_a',
 661                 'invert_out': 'inv_out',
 662                 'rc': 'cr_out',
 663                 'oe': 'cr_in',
 664                 'output_carry': 'cry_out',
 665                 'input_carry': 'cry_in',
 666                 'is_32bit': 'is_32b',
 667                 'is_signed': 'sgn',
 668                 'lk': 'lk',
 669                 'data_len': 'ldst_len',
 670                 'byte_reverse': 'br',
 671                 'sign_extend': 'sgn_ext',
 672                 'ldst_mode': 'upd',
 673                 }
 674
 675
 676 class PowerDecodeSubset(Elaboratable):
 677     """PowerDecodeSubset: dynamic subset decoder
 678
 679     only fields actually requested are copied over. hence, "subset" (duh).
 680     """
 681     def __init__(self, dec, opkls=None, fn_name=None, final=False, state=None):
 682
 683         self.sv_rm = SVP64Rec(name="dec_svp64") # SVP64 RM field
 684         self.final = final
 685         self.opkls = opkls
 686         self.fn_name = fn_name
 687         if opkls is None:
 688             opkls = Decode2ToOperand
 689         self.do = opkls(fn_name)
 690         col_subset = self.get_col_subset(self.do)
 691
 692         # only needed for "main" PowerDecode2
 693         if not self.final:
 694             self.e = Decode2ToExecute1Type(name=self.fn_name, do=self.do)
 695
 696         # create decoder if one not already given
 697         if dec is None:
 698             dec = create_pdecode(name=fn_name, col_subset=col_subset,
 699                                       row_subset=self.rowsubsetfn)
 700         self.dec = dec
 701
 702         # state information needed by the Decoder
 703         if state is None:
 704             state = CoreState("dec2")
 705         self.state = state
 706
 707     def get_col_subset(self, do):
 708         subset = { 'cr_in', 'cr_out', 'rc_sel'} # needed, non-optional
 709         for k, v in record_names.items():
 710             if hasattr(do, k):
 711                 subset.add(v)
 712         print ("get_col_subset", self.fn_name, do.fields, subset)
 713         return subset
 714
 715     def rowsubsetfn(self, opcode, row):
 716         return row['unit'] == self.fn_name
 717
 718     def ports(self):
 719         return self.dec.ports() + self.e.ports() + self.sv_rm.ports()
 720
 721     def needs_field(self, field, op_field):
 722         if self.final:
 723             do = self.do
 724         else:
 725             do = self.e_tmp.do
 726         return hasattr(do, field) and self.op_get(op_field) is not None
 727
 728     def do_copy(self, field, val, final=False):
 729         if final or self.final:
 730             do = self.do
 731         else:
 732             do = self.e_tmp.do
 733         if hasattr(do, field) and val is not None:
 734             return getattr(do, field).eq(val)
 735         return []
 736
 737     def op_get(self, op_field):
 738         return getattr(self.dec.op, op_field, None)
 739
 740     def elaborate(self, platform):
 741         m = Module()
 742         comb = m.d.comb
 743         state = self.state
 744         op, do = self.dec.op, self.do
 745         msr, cia = state.msr, state.pc
 746         # fill in for a normal instruction (not an exception)
 747         # copy over if non-exception, non-privileged etc. is detected
 748         if not self.final:
 749             if self.fn_name is None:
 750                 name = "tmp"
 751             else:
 752                 name = self.fn_name + "tmp"
 753             self.e_tmp = Decode2ToExecute1Type(name=name, opkls=self.opkls)
 754
 755         # set up submodule decoders
 756         m.submodules.dec = self.dec
 757         m.submodules.dec_rc = self.dec_rc = dec_rc = DecodeRC(self.dec)
 758         m.submodules.dec_oe = dec_oe = DecodeOE(self.dec)
 759
 760         # copy instruction through...
 761         for i in [do.insn, dec_rc.insn_in, dec_oe.insn_in, ]:
 762             comb += i.eq(self.dec.opcode_in)
 763
 764         # ...and subdecoders' input fields
 765         comb += dec_rc.sel_in.eq(op.rc_sel)
 766         comb += dec_oe.sel_in.eq(op.rc_sel)  # XXX should be OE sel
 767
 768         # copy "state" over
 769         comb += self.do_copy("msr", msr)
 770         comb += self.do_copy("cia", cia)
 771
 772         # set up instruction type
 773         # no op: defaults to OP_ILLEGAL
 774         # FIX https://bugs.libre-soc.org/show_bug.cgi?id=607
 775         comb += self.do_copy("insn_type", self.op_get("internal_op"))
 776
 777         # function unit for decoded instruction: requires minor redirect
 778         # for SPR set/get
 779         fn = self.op_get("function_unit")
 780         spr = Signal(10, reset_less=True)
 781         comb += spr.eq(decode_spr_num(self.dec.SPR)) # from XFX
 782
 783         # Microwatt doesn't implement the partition table
 784         # instead has PRTBL(SVSRR0) register (SPR) to point to process table
 785         with m.If(((self.dec.op.internal_op == MicrOp.OP_MTSPR) |
 786                    (self.dec.op.internal_op == MicrOp.OP_MFSPR)) &
 787                    ((spr == SPR.DSISR.value) | (spr == SPR.DAR.value) |
 788                      (spr==SPR.SVSRR0.value) | (spr==SPR.PIDR.value))):
 789             comb += self.do_copy("fn_unit", Function.MMU)
 790         with m.Else():
 791             comb += self.do_copy("fn_unit",fn)
 792
 793         # immediates
 794         if self.needs_field("zero_a", "in1_sel"):
 795             m.submodules.dec_ai = dec_ai = DecodeAImm(self.dec)
 796             comb += dec_ai.sel_in.eq(op.in1_sel)
 797             comb += self.do_copy("zero_a", dec_ai.immz_out)  # RA==0 detected
 798         if self.needs_field("imm_data", "in2_sel"):
 799             m.submodules.dec_bi = dec_bi = DecodeBImm(self.dec)
 800             comb += dec_bi.sel_in.eq(op.in2_sel)
 801             comb += self.do_copy("imm_data", dec_bi.imm_out) # imm in RB
 802
 803         # rc and oe out
 804         comb += self.do_copy("rc", dec_rc.rc_out)
 805         comb += self.do_copy("oe", dec_oe.oe_out)
 806
 807         # CR in/out - note: these MUST match with what happens in
 808         # DecodeCROut!
 809         rc_out = self.dec_rc.rc_out.data
 810         with m.Switch(op.cr_out):
 811             with m.Case(CROutSel.CR0, CROutSel.CR1):
 812                 comb += self.do_copy("write_cr0", rc_out) # only when RC=1
 813             with m.Case(CROutSel.BF, CROutSel.BT):
 814                 comb += self.do_copy("write_cr0", 1)
 815
 816         comb += self.do_copy("input_cr", self.op_get("cr_in"))   # CR in
 817         comb += self.do_copy("output_cr", self.op_get("cr_out"))  # CR out
 818
 819         # decoded/selected instruction flags
 820         comb += self.do_copy("data_len", self.op_get("ldst_len"))
 821         comb += self.do_copy("invert_in", self.op_get("inv_a"))
 822         comb += self.do_copy("invert_out", self.op_get("inv_out"))
 823         comb += self.do_copy("input_carry", self.op_get("cry_in"))
 824         comb += self.do_copy("output_carry", self.op_get("cry_out"))
 825         comb += self.do_copy("is_32bit", self.op_get("is_32b"))
 826         comb += self.do_copy("is_signed", self.op_get("sgn"))
 827         lk = self.op_get("lk")
 828         if lk is not None:
 829             with m.If(lk):
 830                 comb += self.do_copy("lk", self.dec.LK)  # XXX TODO: accessor
 831
 832         comb += self.do_copy("byte_reverse", self.op_get("br"))
 833         comb += self.do_copy("sign_extend", self.op_get("sgn_ext"))
 834         comb += self.do_copy("ldst_mode", self.op_get("upd"))  # LD/ST mode
 835
 836         return m
 837
 838
 839 class PowerDecode2(PowerDecodeSubset):
 840     """PowerDecode2: the main instruction decoder.
 841
 842     whilst PowerDecode is responsible for decoding the actual opcode, this
 843     module encapsulates further specialist, sparse information and
 844     expansion of fields that is inconvenient to have in the CSV files.
 845     for example: the encoding of the immediates, which are detected
 846     and expanded out to their full value from an annotated (enum)
 847     representation.
 848
 849     implicit register usage is also set up, here.  for example: OP_BC
 850     requires implicitly reading CTR, OP_RFID requires implicitly writing
 851     to SRR1 and so on.
 852
 853     in addition, PowerDecoder2 is responsible for detecting whether
 854     instructions are illegal (or privileged) or not, and instead of
 855     just leaving at that, *replacing* the instruction to execute with
 856     a suitable alternative (trap).
 857
 858     LDSTExceptions are done the cycle _after_ they're detected (after
 859     they come out of LDSTCompUnit).  basically despite the instruction
 860     being decoded, the results of the decode are completely ignored
 861     and "exception.happened" used to set the "actual" instruction to
 862     "OP_TRAP".  the LDSTException data structure gets filled in,
 863     in the CompTrapOpSubset and that's what it fills in SRR.
 864
 865     to make this work, TestIssuer must notice "exception.happened"
 866     after the (failed) LD/ST and copies the LDSTException info from
 867     the output, into here (PowerDecoder2).  without incrementing PC.
 868     """
 869
 870     def __init__(self, dec, opkls=None, fn_name=None, final=False, state=None):
 871         super().__init__(dec, opkls, fn_name, final, state)
 872         self.exc = LDSTException("dec2_exc")
 873
 874         self.cr_out_isvec = Signal(1, name="cr_out_isvec")
 875         self.cr_in_isvec = Signal(1, name="cr_in_isvec")
 876         self.cr_in_b_isvec = Signal(1, name="cr_in_b_isvec")
 877         self.cr_in_o_isvec = Signal(1, name="cr_in_o_isvec")
 878         self.in1_isvec = Signal(1, name="reg_a_isvec")
 879         self.in2_isvec = Signal(1, name="reg_b_isvec")
 880         self.in3_isvec = Signal(1, name="reg_c_isvec")
 881         self.o_isvec = Signal(1, name="reg_o_isvec")
 882         self.o2_isvec = Signal(1, name="reg_o2_isvec")
 883         self.no_in_vec = Signal(1, name="no_in_vec") # no inputs are vectors
 884         self.no_out_vec = Signal(1, name="no_out_vec") # no outputs are vectors
 885
 886     def get_col_subset(self, opkls):
 887         subset = super().get_col_subset(opkls)
 888         subset.add("asmcode")
 889         subset.add("in1_sel")
 890         subset.add("in2_sel")
 891         subset.add("in3_sel")
 892         subset.add("out_sel")
 893         subset.add("sv_in1")
 894         subset.add("sv_in2")
 895         subset.add("sv_in3")
 896         subset.add("sv_out")
 897         subset.add("sv_cr_in")
 898         subset.add("sv_cr_out")
 899         subset.add("SV_Etype")
 900         subset.add("SV_Ptype")
 901         subset.add("lk")
 902         subset.add("internal_op")
 903         subset.add("form")
 904         return subset
 905
 906     def elaborate(self, platform):
 907         m = super().elaborate(platform)
 908         comb = m.d.comb
 909         state = self.state
 910         e_out, op, do_out = self.e, self.dec.op, self.e.do
 911         dec_spr, msr, cia, ext_irq = state.dec, state.msr, state.pc, state.eint
 912         rc_out = self.dec_rc.rc_out.data
 913         e = self.e_tmp
 914         do = e.do
 915
 916         # fill in for a normal instruction (not an exception)
 917         # copy over if non-exception, non-privileged etc. is detected
 918
 919         # set up submodule decoders
 920         m.submodules.dec_a = dec_a = DecodeA(self.dec)
 921         m.submodules.dec_b = dec_b = DecodeB(self.dec)
 922         m.submodules.dec_c = dec_c = DecodeC(self.dec)
 923         m.submodules.dec_o = dec_o = DecodeOut(self.dec)
 924         m.submodules.dec_o2 = dec_o2 = DecodeOut2(self.dec)
 925         m.submodules.dec_cr_in = self.dec_cr_in = DecodeCRIn(self.dec)
 926         m.submodules.dec_cr_out = self.dec_cr_out = DecodeCROut(self.dec)
 927
 928         # and SVP64 Extra decoders
 929         m.submodules.crout_svdec = crout_svdec = SVP64CRExtra()
 930         m.submodules.crin_svdec = crin_svdec = SVP64CRExtra()
 931         m.submodules.crin_svdec_b = crin_svdec_b = SVP64CRExtra()
 932         m.submodules.crin_svdec_o = crin_svdec_o = SVP64CRExtra()
 933         m.submodules.in1_svdec = in1_svdec = SVP64RegExtra()
 934         m.submodules.in2_svdec = in2_svdec = SVP64RegExtra()
 935         m.submodules.in3_svdec = in3_svdec = SVP64RegExtra()
 936         m.submodules.o_svdec = o_svdec = SVP64RegExtra()
 937         m.submodules.o2_svdec = o2_svdec = SVP64RegExtra()
 938
 939         # debug access to crout_svdec (used in get_pdecode_cr_out)
 940         self.crout_svdec = crout_svdec
 941
 942         # get the 5-bit reg data before svp64-munging it into 7-bit plus isvec
 943         reg = Signal(5, reset_less=True)
 944
 945         # copy instruction through...
 946         for i in [do.insn, dec_a.insn_in, dec_b.insn_in,
 947                   self.dec_cr_in.insn_in, self.dec_cr_out.insn_in,
 948                   dec_c.insn_in, dec_o.insn_in, dec_o2.insn_in]:
 949             comb += i.eq(self.dec.opcode_in)
 950
 951         # CR setup
 952         comb += self.dec_cr_in.sel_in.eq(op.cr_in)
 953         comb += self.dec_cr_out.sel_in.eq(op.cr_out)
 954         comb += self.dec_cr_out.rc_in.eq(rc_out)
 955
 956         # CR register info
 957         comb += self.do_copy("read_cr_whole", self.dec_cr_in.whole_reg)
 958         comb += self.do_copy("write_cr_whole", self.dec_cr_out.whole_reg)
 959
 960         # now do the SVP64 munging.  op.SV_Etype and op.sv_in1 comes from
 961         # PowerDecoder which in turn comes from LDST-RM*.csv and RM-*.csv
 962         # which in turn were auto-generated by sv_analysis.py
 963         extra = self.sv_rm.extra            # SVP64 extra bits 10:18
 964
 965         #######
 966         # CR out
 967         comb += crout_svdec.idx.eq(op.sv_cr_out)  # SVP64 CR out
 968         comb += self.cr_out_isvec.eq(crout_svdec.isvec)
 969
 970         #######
 971         # CR in - index selection slightly different due to shared CR field sigh
 972         cr_a_idx = Signal(SVEXTRA)
 973         cr_b_idx = Signal(SVEXTRA)
 974
 975         # these change slightly, when decoding BA/BB.  really should have
 976         # their own separate CSV column: sv_cr_in1 and sv_cr_in2, but hey
 977         comb += cr_a_idx.eq(op.sv_cr_in)
 978         comb += cr_b_idx.eq(SVEXTRA.NONE)
 979         with m.If(op.sv_cr_in == SVEXTRA.Idx_1_2.value):
 980             comb += cr_a_idx.eq(SVEXTRA.Idx1)
 981             comb += cr_b_idx.eq(SVEXTRA.Idx2)
 982
 983         comb += self.cr_in_isvec.eq(crin_svdec.isvec)
 984         comb += self.cr_in_b_isvec.eq(crin_svdec_b.isvec)
 985         comb += self.cr_in_o_isvec.eq(crin_svdec_o.isvec)
 986
 987         # indices are slightly different, BA/BB mess sorted above
 988         comb += crin_svdec.idx.eq(cr_a_idx)       # SVP64 CR in A
 989         comb += crin_svdec_b.idx.eq(cr_b_idx)     # SVP64 CR in B
 990         comb += crin_svdec_o.idx.eq(op.sv_cr_out) # SVP64 CR out
 991
 992         # ...and subdecoders' input fields
 993         comb += dec_a.sel_in.eq(op.in1_sel)
 994         comb += dec_b.sel_in.eq(op.in2_sel)
 995         comb += dec_c.sel_in.eq(op.in3_sel)
 996         comb += dec_o.sel_in.eq(op.out_sel)
 997         comb += dec_o2.sel_in.eq(op.out_sel)
 998         if hasattr(do, "lk"):
 999             comb += dec_o2.lk.eq(do.lk)
1000
1001         # get SVSTATE srcstep (TODO: elwidth, dststep etc.) needed below
1002         srcstep = Signal.like(self.state.svstate.srcstep)
1003         comb += srcstep.eq(self.state.svstate.srcstep)
1004
1005         # registers a, b, c and out and out2 (LD/ST EA)
1006         for to_reg, fromreg, svdec in (
1007             (e.read_reg1, dec_a.reg_out, in1_svdec),
1008             (e.read_reg2, dec_b.reg_out, in2_svdec),
1009             (e.read_reg3, dec_c.reg_out, in3_svdec),
1010             (e.write_reg, dec_o.reg_out, o_svdec),
1011             (e.write_ea, dec_o2.reg_out, o2_svdec)):
1012             comb += svdec.extra.eq(extra)        # EXTRA field of SVP64 RM
1013             comb += svdec.etype.eq(op.SV_Etype)  # EXTRA2/3 for this insn
1014             comb += svdec.reg_in.eq(fromreg.data) # 3-bit (CR0/BC/BFA)
1015             comb += to_reg.ok.eq(fromreg.ok)
1016             # detect if Vectorised: add srcstep if yes.  TODO: a LOT.
1017             # this trick only holds when elwidth=default and in single-pred
1018             with m.If(svdec.isvec):
1019                 comb += to_reg.data.eq(srcstep+svdec.reg_out) # 7-bit output
1020             with m.Else():
1021                 comb += to_reg.data.eq(svdec.reg_out) # 7-bit output
1022
1023         comb += in1_svdec.idx.eq(op.sv_in1)  # SVP64 reg #1 (matches in1_sel)
1024         comb += in2_svdec.idx.eq(op.sv_in2)  # SVP64 reg #2 (matches in2_sel)
1025         comb += in3_svdec.idx.eq(op.sv_in3)  # SVP64 reg #3 (matches in3_sel)
1026         comb += o_svdec.idx.eq(op.sv_out)    # SVP64 output (matches out_sel)
1027         # XXX TODO - work out where this should come from.  the problem is
1028         # that LD-with-update is implied (computed from "is instruction in
1029         # "update mode" rather than specified cleanly as its own CSV column
1030         #comb += o2_svdec.idx.eq(op.sv_out)    # SVP64 output (implicit)
1031
1032         # output reg-is-vectorised (and when no input or output is vectorised)
1033         comb += self.in1_isvec.eq(in1_svdec.isvec)
1034         comb += self.in2_isvec.eq(in2_svdec.isvec)
1035         comb += self.in3_isvec.eq(in3_svdec.isvec)
1036         comb += self.o_isvec.eq(o_svdec.isvec)
1037         comb += self.o2_isvec.eq(o2_svdec.isvec)
1038         # TODO add SPRs here.  must be True when *all* are scalar
1039         l = map(lambda svdec: svdec.isvec, [in1_svdec, in2_svdec, in3_svdec,
1040                                     crin_svdec, crin_svdec_b, crin_svdec_o])
1041         comb += self.no_in_vec.eq(~Cat(*l).bool()) # all input scalar
1042         l = map(lambda svdec: svdec.isvec, [o2_svdec, o_svdec, crout_svdec])
1043         comb += self.no_out_vec.eq(~Cat(*l).bool()) # all output scalar
1044
1045         # SPRs out
1046         comb += e.read_spr1.eq(dec_a.spr_out)
1047         comb += e.write_spr.eq(dec_o.spr_out)
1048
1049         # Fast regs out
1050         comb += e.read_fast1.eq(dec_a.fast_out)
1051         comb += e.read_fast2.eq(dec_b.fast_out)
1052         comb += e.write_fast1.eq(dec_o.fast_out)
1053         comb += e.write_fast2.eq(dec_o2.fast_out)
1054
1055         # condition registers (CR)
1056         for to_reg, cr, name, svdec in (
1057             (e.read_cr1, self.dec_cr_in, "cr_bitfield", crin_svdec),
1058             (e.read_cr2, self.dec_cr_in, "cr_bitfield_b", crin_svdec_b),
1059             (e.read_cr3, self.dec_cr_in, "cr_bitfield_o", crin_svdec_o),
1060             (e.write_cr, self.dec_cr_out, "cr_bitfield", crout_svdec)):
1061             fromreg = getattr(cr, name)
1062             comb += svdec.extra.eq(extra)        # EXTRA field of SVP64 RM
1063             comb += svdec.etype.eq(op.SV_Etype)  # EXTRA2/3 for this insn
1064             comb += svdec.cr_in.eq(fromreg.data) # 3-bit (CR0/BC/BFA)
1065             with m.If(svdec.isvec):
1066                 # check if this is CR0 or CR1: treated differently
1067                 # (does not "listen" to EXTRA2/3 spec for a start)
1068                 # also: the CRs start from completely different locations
1069                 with m.If(cr.sv_override == 1): # CR0
1070                     offs = SVP64CROffs.CR0
1071                     comb += to_reg.data.eq(srcstep+offs)
1072                 with m.Elif(cr.sv_override == 2): # CR1
1073                     offs = SVP64CROffs.CR1
1074                     comb += to_reg.data.eq(srcstep+1)
1075                 with m.Else():
1076                     comb += to_reg.data.eq(srcstep+svdec.cr_out) # 7-bit output
1077             with m.Else():
1078                 comb += to_reg.data.eq(svdec.cr_out) # 7-bit output
1079             comb += to_reg.ok.eq(fromreg.ok)
1080
1081         # sigh this is exactly the sort of thing for which the
1082         # decoder is designed to not need.  MTSPR, MFSPR and others need
1083         # access to the XER bits.  however setting e.oe is not appropriate
1084         with m.If(op.internal_op == MicrOp.OP_MFSPR):
1085             comb += e.xer_in.eq(0b111) # SO, CA, OV
1086         with m.If(op.internal_op == MicrOp.OP_CMP):
1087             comb += e.xer_in.eq(1<<XERRegs.SO) # SO
1088         with m.If(op.internal_op == MicrOp.OP_MTSPR):
1089             comb += e.xer_out.eq(1)
1090
1091         # set the trapaddr to 0x700 for a td/tw/tdi/twi operation
1092         with m.If(op.internal_op == MicrOp.OP_TRAP):
1093             # *DO NOT* call self.trap here.  that would reset absolutely
1094             # everything including destroying read of RA and RB.
1095             comb += self.do_copy("trapaddr", 0x70) # strip first nibble
1096
1097         ####################
1098         # ok so the instruction's been decoded, blah blah, however
1099         # now we need to determine if it's actually going to go ahead...
1100         # *or* if in fact it's a privileged operation, whether there's
1101         # an external interrupt, etc. etc.  this is a simple priority
1102         # if-elif-elif sequence.  decrement takes highest priority,
1103         # EINT next highest, privileged operation third.
1104
1105         # check if instruction is privileged
1106         is_priv_insn = instr_is_priv(m, op.internal_op, e.do.insn)
1107
1108         # different IRQ conditions
1109         ext_irq_ok = Signal()
1110         dec_irq_ok = Signal()
1111         priv_ok = Signal()
1112         illeg_ok = Signal()
1113         exc = self.exc
1114
1115         comb += ext_irq_ok.eq(ext_irq & msr[MSR.EE]) # v3.0B p944 (MSR.EE)
1116         comb += dec_irq_ok.eq(dec_spr[63] & msr[MSR.EE]) # 6.5.11 p1076
1117         comb += priv_ok.eq(is_priv_insn & msr[MSR.PR])
1118         comb += illeg_ok.eq(op.internal_op == MicrOp.OP_ILLEGAL)
1119
1120         # LD/ST exceptions.  TestIssuer copies the exception info at us
1121         # after a failed LD/ST.
1122         with m.If(exc.happened):
1123             with m.If(exc.alignment):
1124                 self.trap(m, TT.PRIV, 0x600)
1125             with m.Elif(exc.instr_fault):
1126                 with m.If(exc.segment_fault):
1127                     self.trap(m, TT.PRIV, 0x480)
1128                 with m.Else():
1129                     # pass exception info to trap to create SRR1
1130                     self.trap(m, TT.MEMEXC, 0x400, exc)
1131             with m.Else():
1132                 with m.If(exc.segment_fault):
1133                     self.trap(m, TT.PRIV, 0x380)
1134                 with m.Else():
1135                     self.trap(m, TT.PRIV, 0x300)
1136
1137         # decrement counter (v3.0B p1099): TODO 32-bit version (MSR.LPCR)
1138         with m.Elif(dec_irq_ok):
1139             self.trap(m, TT.DEC, 0x900)   # v3.0B 6.5 p1065
1140
1141         # external interrupt? only if MSR.EE set
1142         with m.Elif(ext_irq_ok):
1143             self.trap(m, TT.EINT, 0x500)
1144
1145         # privileged instruction trap
1146         with m.Elif(priv_ok):
1147             self.trap(m, TT.PRIV, 0x700)
1148
1149         # illegal instruction must redirect to trap. this is done by
1150         # *overwriting* the decoded instruction and starting again.
1151         # (note: the same goes for interrupts and for privileged operations,
1152         # just with different trapaddr and traptype)
1153         with m.Elif(illeg_ok):
1154             # illegal instruction trap
1155             self.trap(m, TT.ILLEG, 0x700)
1156
1157         # no exception, just copy things to the output
1158         with m.Else():
1159             comb += e_out.eq(e)
1160
1161         ####################
1162         # follow-up after trap/irq to set up SRR0/1
1163
1164         # trap: (note e.insn_type so this includes OP_ILLEGAL) set up fast regs
1165         # Note: OP_SC could actually be modified to just be a trap
1166         with m.If((do_out.insn_type == MicrOp.OP_TRAP) |
1167                   (do_out.insn_type == MicrOp.OP_SC)):
1168             # TRAP write fast1 = SRR0
1169             comb += e_out.write_fast1.data.eq(FastRegs.SRR0)  # constant: SRR0
1170             comb += e_out.write_fast1.ok.eq(1)
1171             # TRAP write fast2 = SRR1
1172             comb += e_out.write_fast2.data.eq(FastRegs.SRR1)  # constant: SRR1
1173             comb += e_out.write_fast2.ok.eq(1)
1174
1175         # RFID: needs to read SRR0/1
1176         with m.If(do_out.insn_type == MicrOp.OP_RFID):
1177             # TRAP read fast1 = SRR0
1178             comb += e_out.read_fast1.data.eq(FastRegs.SRR0)  # constant: SRR0
1179             comb += e_out.read_fast1.ok.eq(1)
1180             # TRAP read fast2 = SRR1
1181             comb += e_out.read_fast2.data.eq(FastRegs.SRR1)  # constant: SRR1
1182             comb += e_out.read_fast2.ok.eq(1)
1183
1184         # annoying simulator bug
1185         if hasattr(e_out, "asmcode") and hasattr(self.dec.op, "asmcode"):
1186             comb += e_out.asmcode.eq(self.dec.op.asmcode)
1187
1188         return m
1189
1190     def trap(self, m, traptype, trapaddr, exc=None):
1191         """trap: this basically "rewrites" the decoded instruction as a trap
1192         """
1193         comb = m.d.comb
1194         op, e = self.dec.op, self.e
1195         comb += e.eq(0)  # reset eeeeeverything
1196
1197         # start again
1198         comb += self.do_copy("insn", self.dec.opcode_in, True)
1199         comb += self.do_copy("insn_type", MicrOp.OP_TRAP, True)
1200         comb += self.do_copy("fn_unit", Function.TRAP, True)
1201         comb += self.do_copy("trapaddr", trapaddr >> 4, True) # bottom 4 bits
1202         comb += self.do_copy("traptype", traptype, True)  # request type
1203         comb += self.do_copy("ldst_exc", exc, True)  # request type
1204         comb += self.do_copy("msr", self.state.msr, True) # copy of MSR "state"
1205         comb += self.do_copy("cia", self.state.pc, True)  # copy of PC "state"
1206
1207
1208
1209 def get_rdflags(e, cu):
1210     rdl = []
1211     for idx in range(cu.n_src):
1212         regfile, regname, _ = cu.get_in_spec(idx)
1213         rdflag, read = regspec_decode_read(e, regfile, regname)
1214         rdl.append(rdflag)
1215     print("rdflags", rdl)
1216     return Cat(*rdl)
1217
1218
1219 if __name__ == '__main__':
1220     pdecode = create_pdecode()
1221     dec2 = PowerDecode2(pdecode)
1222     vl = rtlil.convert(dec2, ports=dec2.ports() + pdecode.ports())
1223     with open("dec2.il", "w") as f:
1224         f.write(vl)