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
  12 from nmutil.iocontrol import RecordObject
  13 from nmutil.extend import exts
  14
  15 from soc.decoder.power_regspec_map import regspec_decode_read
  16 from soc.decoder.power_regspec_map import regspec_decode_write
  17 from soc.decoder.power_decoder import create_pdecode
  18 from soc.decoder.power_enums import (InternalOp, CryIn, Function,
  19                                      CRInSel, CROutSel,
  20                                      LdstLen, In1Sel, In2Sel, In3Sel,
  21                                      OutSel, SPR, RC)
  22 from soc.decoder.decode2execute1 import Decode2ToExecute1Type, Data
  23
  24 from soc.regfile.regfiles import FastRegs
  25
  26 # see traptype (and trap main_stage.py)
  27
  28 TT_FP = 1<<0
  29 TT_PRIV = 1<<1
  30 TT_TRAP = 1<<2
  31 TT_ADDR = 1<<3
  32 TT_ILLEG = 1<<4
  33
  34 def decode_spr_num(spr):
  35     return Cat(spr[5:10], spr[0:5])
  36
  37
  38 def instr_is_priv(m, op, insn):
  39     """determines if the instruction is privileged or not
  40     """
  41     comb = m.d.comb
  42     Signal = is_priv_insn(reset_less=True)
  43     with m.Switch(op):
  44         with m.Case(InternalOp.OP_ATTN)  : comb += is_priv_insn.eq(1)
  45         with m.Case(InternalOp.OP_MFMSR) : comb += is_priv_insn.eq(1)
  46         with m.Case(InternalOp.OP_MTMSRD): comb += is_priv_insn.eq(1)
  47         with m.Case(InternalOp.OP_MTMSR): comb += is_priv_insn.eq(1)
  48         with m.Case(InternalOp.OP_RFID)  : comb += is_priv_insn.eq(1)
  49         with m.Case(InternalOp.OP_TLBIE) : comb += is_priv_insn.eq(1)
  50     with m.If(op == OP_MFSPR | op == OP_MTSPR):
  51         with m.If(insn[20]): # field XFX.spr[-1] i think
  52             comb += is_priv_insn.eq(1)
  53     return is_priv_insn
  54
  55
  56 class SPRMap(Elaboratable):
  57     """SPRMap: maps POWER9 SPR numbers to internal enum values
  58     """
  59     def __init__(self):
  60         self.spr_i = Signal(10, reset_less=True)
  61         self.spr_o = Signal(SPR, reset_less=True)
  62
  63     def elaborate(self, platform):
  64         m = Module()
  65         with m.Switch(self.spr_i):
  66             for i, x in enumerate(SPR):
  67                 with m.Case(x.value):
  68                     m.d.comb += self.spr_o.eq(i)
  69         return m
  70
  71
  72 class DecodeA(Elaboratable):
  73     """DecodeA from instruction
  74
  75     decodes register RA, whether immediate-zero, implicit and
  76     explicit CSRs
  77     """
  78
  79     def __init__(self, dec):
  80         self.dec = dec
  81         self.sel_in = Signal(In1Sel, reset_less=True)
  82         self.insn_in = Signal(32, reset_less=True)
  83         self.reg_out = Data(5, name="reg_a")
  84         self.immz_out = Signal(reset_less=True)
  85         self.spr_out = Data(SPR, "spr_a")
  86         self.fast_out = Data(3, "fast_a")
  87
  88     def elaborate(self, platform):
  89         m = Module()
  90         comb = m.d.comb
  91         m.submodules.sprmap = sprmap = SPRMap()
  92
  93         # select Register A field
  94         ra = Signal(5, reset_less=True)
  95         comb += ra.eq(self.dec.RA)
  96         with m.If((self.sel_in == In1Sel.RA) |
  97                   ((self.sel_in == In1Sel.RA_OR_ZERO) &
  98                    (ra != Const(0, 5)))):
  99             comb += self.reg_out.data.eq(ra)
 100             comb += self.reg_out.ok.eq(1)
 101
 102         # zero immediate requested
 103         with m.If((self.sel_in == In1Sel.RA_OR_ZERO) &
 104                   (self.reg_out.data == Const(0, 5))):
 105             comb += self.immz_out.eq(1)
 106
 107         # some Logic/ALU ops have RS as the 3rd arg, but no "RA".
 108         with m.If(self.sel_in == In1Sel.RS):
 109             comb += self.reg_out.data.eq(self.dec.RS)
 110             comb += self.reg_out.ok.eq(1)
 111
 112         # decode Fast-SPR based on instruction type
 113         op = self.dec.op
 114         # BC or BCREG: potential implicit register (CTR) NOTE: same in DecodeOut
 115         with m.If(op.internal_op == InternalOp.OP_BC):
 116             with m.If(~self.dec.BO[2]): # 3.0B p38 BO2=0, use CTR reg
 117                 comb += self.fast_out.data.eq(FastRegs.CTR) # constant: CTR
 118                 comb += self.fast_out.ok.eq(1)
 119         with m.Elif(op.internal_op == InternalOp.OP_BCREG):
 120             xo9 = self.dec.FormXL.XO[9] # 3.0B p38 top bit of XO
 121             xo5 = self.dec.FormXL.XO[5] # 3.0B p38
 122             with m.If(xo9 & ~xo5):
 123                 comb += self.fast_out.data.eq(FastRegs.CTR) # constant: CTR
 124                 comb += self.fast_out.ok.eq(1)
 125
 126         # MFSPR move from SPRs
 127         with m.If(op.internal_op == InternalOp.OP_MFSPR):
 128             spr = Signal(10, reset_less=True)
 129             comb += spr.eq(decode_spr_num(self.dec.SPR)) # from XFX
 130             with m.Switch(spr):
 131                 # fast SPRs
 132                 with m.Case(SPR.CTR.value):
 133                     comb += self.fast_out.data.eq(FastRegs.CTR)
 134                     comb += self.fast_out.ok.eq(1)
 135                 with m.Case(SPR.LR.value):
 136                     comb += self.fast_out.data.eq(FastRegs.LR)
 137                     comb += self.fast_out.ok.eq(1)
 138                 with m.Case(SPR.TAR.value):
 139                     comb += self.fast_out.data.eq(FastRegs.TAR)
 140                     comb += self.fast_out.ok.eq(1)
 141                 with m.Case(SPR.SRR0.value):
 142                     comb += self.fast_out.data.eq(FastRegs.SRR0)
 143                     comb += self.fast_out.ok.eq(1)
 144                 with m.Case(SPR.SRR1.value):
 145                     comb += self.fast_out.data.eq(FastRegs.SRR1)
 146                     comb += self.fast_out.ok.eq(1)
 147                 with m.Case(SPR.XER.value):
 148                     pass # do nothing
 149                 # XXX TODO: map to internal SPR numbers
 150                 # XXX TODO: dec and tb not to go through mapping.
 151                 with m.Default():
 152                     comb += sprmap.spr_i.eq(spr)
 153                     comb += self.spr_out.data.eq(sprmap.spr_o)
 154                     comb += self.spr_out.ok.eq(1)
 155
 156
 157         return m
 158
 159
 160 class DecodeB(Elaboratable):
 161     """DecodeB from instruction
 162
 163     decodes register RB, different forms of immediate (signed, unsigned),
 164     and implicit SPRs.  register B is basically "lane 2" into the CompUnits.
 165     by industry-standard convention, "lane 2" is where fully-decoded
 166     immediates are muxed in.
 167     """
 168
 169     def __init__(self, dec):
 170         self.dec = dec
 171         self.sel_in = Signal(In2Sel, reset_less=True)
 172         self.insn_in = Signal(32, reset_less=True)
 173         self.reg_out = Data(5, "reg_b")
 174         self.imm_out = Data(64, "imm_b")
 175         self.fast_out = Data(3, "fast_b")
 176
 177     def elaborate(self, platform):
 178         m = Module()
 179         comb = m.d.comb
 180
 181         # select Register B field
 182         with m.Switch(self.sel_in):
 183             with m.Case(In2Sel.RB):
 184                 comb += self.reg_out.data.eq(self.dec.RB)
 185                 comb += self.reg_out.ok.eq(1)
 186             with m.Case(In2Sel.RS):
 187                 comb += self.reg_out.data.eq(self.dec.RS) # for M-Form shiftrot
 188                 comb += self.reg_out.ok.eq(1)
 189             with m.Case(In2Sel.CONST_UI):
 190                 comb += self.imm_out.data.eq(self.dec.UI)
 191                 comb += self.imm_out.ok.eq(1)
 192             with m.Case(In2Sel.CONST_SI): # TODO: sign-extend here?
 193                 comb += self.imm_out.data.eq(
 194                     exts(self.dec.SI, 16, 64))
 195                 comb += self.imm_out.ok.eq(1)
 196             with m.Case(In2Sel.CONST_UI_HI):
 197                 comb += self.imm_out.data.eq(self.dec.UI<<16)
 198                 comb += self.imm_out.ok.eq(1)
 199             with m.Case(In2Sel.CONST_SI_HI): # TODO: sign-extend here?
 200                 comb += self.imm_out.data.eq(self.dec.SI<<16)
 201                 comb += self.imm_out.data.eq(
 202                     exts(self.dec.SI << 16, 32, 64))
 203                 comb += self.imm_out.ok.eq(1)
 204             with m.Case(In2Sel.CONST_LI):
 205                 comb += self.imm_out.data.eq(self.dec.LI<<2)
 206                 comb += self.imm_out.ok.eq(1)
 207             with m.Case(In2Sel.CONST_BD):
 208                 comb += self.imm_out.data.eq(self.dec.BD<<2)
 209                 comb += self.imm_out.ok.eq(1)
 210             with m.Case(In2Sel.CONST_DS):
 211                 comb += self.imm_out.data.eq(self.dec.DS<<2)
 212                 comb += self.imm_out.ok.eq(1)
 213             with m.Case(In2Sel.CONST_M1):
 214                 comb += self.imm_out.data.eq(~Const(0, 64)) # all 1s
 215                 comb += self.imm_out.ok.eq(1)
 216             with m.Case(In2Sel.CONST_SH):
 217                 comb += self.imm_out.data.eq(self.dec.sh)
 218                 comb += self.imm_out.ok.eq(1)
 219             with m.Case(In2Sel.CONST_SH32):
 220                 comb += self.imm_out.data.eq(self.dec.SH32)
 221                 comb += self.imm_out.ok.eq(1)
 222
 223         # decode SPR2 based on instruction type
 224         op = self.dec.op
 225         # BCREG implicitly uses LR or TAR for 2nd reg
 226         # CTR however is already in fast_spr1 *not* 2.
 227         with m.If(op.internal_op == InternalOp.OP_BCREG):
 228             xo9 = self.dec.FormXL.XO[9] # 3.0B p38 top bit of XO
 229             xo5 = self.dec.FormXL.XO[5] # 3.0B p38
 230             with m.If(~xo9):
 231                 comb += self.fast_out.data.eq(FastRegs.LR)
 232                 comb += self.fast_out.ok.eq(1)
 233             with m.Elif(xo5):
 234                 comb += self.fast_out.data.eq(FastRegs.TAR)
 235                 comb += self.fast_out.ok.eq(1)
 236
 237         return m
 238
 239
 240 class DecodeC(Elaboratable):
 241     """DecodeC from instruction
 242
 243     decodes register RC.  this is "lane 3" into some CompUnits (not many)
 244     """
 245
 246     def __init__(self, dec):
 247         self.dec = dec
 248         self.sel_in = Signal(In3Sel, reset_less=True)
 249         self.insn_in = Signal(32, reset_less=True)
 250         self.reg_out = Data(5, "reg_c")
 251
 252     def elaborate(self, platform):
 253         m = Module()
 254         comb = m.d.comb
 255
 256         # select Register C field
 257         with m.Switch(self.sel_in):
 258             with m.Case(In3Sel.RB):
 259                 comb += self.reg_out.data.eq(self.dec.RB) # for M-Form shiftrot
 260                 comb += self.reg_out.ok.eq(1)
 261             with m.Case(In3Sel.RS):
 262                 comb += self.reg_out.data.eq(self.dec.RS)
 263                 comb += self.reg_out.ok.eq(1)
 264
 265         return m
 266
 267
 268 class DecodeOut(Elaboratable):
 269     """DecodeOut from instruction
 270
 271     decodes output register RA, RT or SPR
 272     """
 273
 274     def __init__(self, dec):
 275         self.dec = dec
 276         self.sel_in = Signal(OutSel, reset_less=True)
 277         self.insn_in = Signal(32, reset_less=True)
 278         self.reg_out = Data(5, "reg_o")
 279         self.spr_out = Data(SPR, "spr_o")
 280         self.fast_out = Data(3, "fast_o")
 281
 282     def elaborate(self, platform):
 283         m = Module()
 284         comb = m.d.comb
 285         m.submodules.sprmap = sprmap = SPRMap()
 286         op = self.dec.op
 287
 288         # select Register out field
 289         with m.Switch(self.sel_in):
 290             with m.Case(OutSel.RT):
 291                 comb += self.reg_out.data.eq(self.dec.RT)
 292                 comb += self.reg_out.ok.eq(1)
 293             with m.Case(OutSel.RA):
 294                 comb += self.reg_out.data.eq(self.dec.RA)
 295                 comb += self.reg_out.ok.eq(1)
 296             with m.Case(OutSel.SPR):
 297                 spr = Signal(10, reset_less=True)
 298                 comb += spr.eq(decode_spr_num(self.dec.SPR)) # from XFX
 299                 # TODO MTSPR 1st spr (fast)
 300                 with m.If(op.internal_op == InternalOp.OP_MTSPR):
 301                     with m.Switch(spr):
 302                         # fast SPRs
 303                         with m.Case(SPR.CTR.value):
 304                             comb += self.fast_out.data.eq(FastRegs.CTR)
 305                             comb += self.fast_out.ok.eq(1)
 306                         with m.Case(SPR.LR.value):
 307                             comb += self.fast_out.data.eq(FastRegs.LR)
 308                             comb += self.fast_out.ok.eq(1)
 309                         with m.Case(SPR.TAR.value):
 310                             comb += self.fast_out.data.eq(FastRegs.TAR)
 311                             comb += self.fast_out.ok.eq(1)
 312                         with m.Case(SPR.SRR0.value):
 313                             comb += self.fast_out.data.eq(FastRegs.SRR0)
 314                             comb += self.fast_out.ok.eq(1)
 315                         with m.Case(SPR.SRR1.value):
 316                             comb += self.fast_out.data.eq(FastRegs.SRR1)
 317                             comb += self.fast_out.ok.eq(1)
 318                         with m.Case(SPR.XER.value):
 319                             pass # do nothing
 320                         # XXX TODO: map to internal SPR numbers
 321                         # XXX TODO: dec and tb not to go through mapping.
 322                         with m.Default():
 323                             comb += sprmap.spr_i.eq(spr)
 324                             comb += self.spr_out.data.eq(sprmap.spr_o)
 325                             comb += self.spr_out.ok.eq(1)
 326
 327         # BC or BCREG: potential implicit register (CTR) NOTE: same in DecodeA
 328         op = self.dec.op
 329         with m.If((op.internal_op == InternalOp.OP_BC) |
 330                   (op.internal_op == InternalOp.OP_BCREG)):
 331             with m.If(~self.dec.BO[2]): # 3.0B p38 BO2=0, use CTR reg
 332                 comb += self.fast_out.data.eq(FastRegs.CTR) # constant: CTR
 333                 comb += self.fast_out.ok.eq(1)
 334
 335         # RFID 1st spr (fast)
 336         with m.If(op.internal_op == InternalOp.OP_RFID):
 337             comb += self.fast_out.data.eq(FastRegs.SRR0) # constant: SRR0
 338             comb += self.fast_out.ok.eq(1)
 339
 340         return m
 341
 342
 343 class DecodeOut2(Elaboratable):
 344     """DecodeOut2 from instruction
 345
 346     decodes output registers
 347     """
 348
 349     def __init__(self, dec):
 350         self.dec = dec
 351         self.sel_in = Signal(OutSel, reset_less=True)
 352         self.lk = Signal(reset_less=True)
 353         self.insn_in = Signal(32, reset_less=True)
 354         self.reg_out = Data(5, "reg_o")
 355         self.fast_out = Data(3, "fast_o")
 356
 357     def elaborate(self, platform):
 358         m = Module()
 359         comb = m.d.comb
 360
 361         # update mode LD/ST uses read-reg A also as an output
 362         with m.If(self.dec.op.upd):
 363             comb += self.reg_out.eq(self.dec.RA)
 364             comb += self.reg_out.ok.eq(1)
 365
 366         # BC or BCREG: potential implicit register (LR) output
 367         op = self.dec.op
 368         with m.If((op.internal_op == InternalOp.OP_BC) |
 369                   (op.internal_op == InternalOp.OP_BCREG)):
 370             with m.If(self.lk): # "link" mode
 371                 comb += self.fast_out.data.eq(FastRegs.LR) # constant: LR
 372                 comb += self.fast_out.ok.eq(1)
 373
 374         # RFID 2nd spr (fast)
 375         with m.If(op.internal_op == InternalOp.OP_RFID):
 376                 comb += self.fast_out.data.eq(FastRegs.SRR1) # constant: SRR1
 377                 comb += self.fast_out.ok.eq(1)
 378
 379         return m
 380
 381
 382 class DecodeRC(Elaboratable):
 383     """DecodeRc from instruction
 384
 385     decodes Record bit Rc
 386     """
 387     def __init__(self, dec):
 388         self.dec = dec
 389         self.sel_in = Signal(RC, reset_less=True)
 390         self.insn_in = Signal(32, reset_less=True)
 391         self.rc_out = Data(1, "rc")
 392
 393     def elaborate(self, platform):
 394         m = Module()
 395         comb = m.d.comb
 396
 397         # select Record bit out field
 398         with m.Switch(self.sel_in):
 399             with m.Case(RC.RC):
 400                 comb += self.rc_out.data.eq(self.dec.Rc)
 401                 comb += self.rc_out.ok.eq(1)
 402             with m.Case(RC.ONE):
 403                 comb += self.rc_out.data.eq(1)
 404                 comb += self.rc_out.ok.eq(1)
 405             with m.Case(RC.NONE):
 406                 comb += self.rc_out.data.eq(0)
 407                 comb += self.rc_out.ok.eq(1)
 408
 409         return m
 410
 411
 412 class DecodeOE(Elaboratable):
 413     """DecodeOE from instruction
 414
 415     decodes OE field: uses RC decode detection which might not be good
 416
 417     -- For now, use "rc" in the decode table to decide whether oe exists.
 418     -- This is not entirely correct architecturally: For mulhd and
 419     -- mulhdu, the OE field is reserved. It remains to be seen what an
 420     -- actual POWER9 does if we set it on those instructions, for now we
 421     -- test that further down when assigning to the multiplier oe input.
 422     """
 423     def __init__(self, dec):
 424         self.dec = dec
 425         self.sel_in = Signal(RC, reset_less=True)
 426         self.insn_in = Signal(32, reset_less=True)
 427         self.oe_out = Data(1, "oe")
 428
 429     def elaborate(self, platform):
 430         m = Module()
 431         comb = m.d.comb
 432
 433         # select OE bit out field
 434         with m.Switch(self.sel_in):
 435             with m.Case(RC.RC):
 436                 comb += self.oe_out.data.eq(self.dec.OE)
 437                 comb += self.oe_out.ok.eq(1)
 438
 439         return m
 440
 441 class DecodeCRIn(Elaboratable):
 442     """Decodes input CR from instruction
 443
 444     CR indices - insn fields - (not the data *in* the CR) require only 3
 445     bits because they refer to CR0-CR7
 446     """
 447
 448     def __init__(self, dec):
 449         self.dec = dec
 450         self.sel_in = Signal(CRInSel, reset_less=True)
 451         self.insn_in = Signal(32, reset_less=True)
 452         self.cr_bitfield = Data(3, "cr_bitfield")
 453         self.cr_bitfield_b = Data(3, "cr_bitfield_b")
 454         self.cr_bitfield_o = Data(3, "cr_bitfield_o")
 455         self.whole_reg = Signal(reset_less=True)
 456
 457     def elaborate(self, platform):
 458         m = Module()
 459         comb = m.d.comb
 460
 461         comb += self.cr_bitfield.ok.eq(0)
 462         comb += self.cr_bitfield_b.ok.eq(0)
 463         comb += self.whole_reg.eq(0)
 464         with m.Switch(self.sel_in):
 465             with m.Case(CRInSel.NONE):
 466                 pass # No bitfield activated
 467             with m.Case(CRInSel.CR0):
 468                 comb += self.cr_bitfield.data.eq(0)
 469                 comb += self.cr_bitfield.ok.eq(1)
 470             with m.Case(CRInSel.BI):
 471                 comb += self.cr_bitfield.data.eq(self.dec.BI[2:5])
 472                 comb += self.cr_bitfield.ok.eq(1)
 473             with m.Case(CRInSel.BFA):
 474                 comb += self.cr_bitfield.data.eq(self.dec.FormX.BFA)
 475                 comb += self.cr_bitfield.ok.eq(1)
 476             with m.Case(CRInSel.BA_BB):
 477                 comb += self.cr_bitfield.data.eq(self.dec.BA[2:5])
 478                 comb += self.cr_bitfield.ok.eq(1)
 479                 comb += self.cr_bitfield_b.data.eq(self.dec.BB[2:5])
 480                 comb += self.cr_bitfield_b.ok.eq(1)
 481                 comb += self.cr_bitfield_o.data.eq(self.dec.BT[2:5])
 482                 comb += self.cr_bitfield_o.ok.eq(1)
 483             with m.Case(CRInSel.BC):
 484                 comb += self.cr_bitfield.data.eq(self.dec.BC[2:5])
 485                 comb += self.cr_bitfield.ok.eq(1)
 486             with m.Case(CRInSel.WHOLE_REG):
 487                 comb += self.whole_reg.eq(1)
 488
 489         return m
 490
 491
 492 class DecodeCROut(Elaboratable):
 493     """Decodes input CR from instruction
 494
 495     CR indices - insn fields - (not the data *in* the CR) require only 3
 496     bits because they refer to CR0-CR7
 497     """
 498
 499     def __init__(self, dec):
 500         self.dec = dec
 501         self.rc_in = Signal(reset_less=True)
 502         self.sel_in = Signal(CROutSel, reset_less=True)
 503         self.insn_in = Signal(32, reset_less=True)
 504         self.cr_bitfield = Data(3, "cr_bitfield")
 505         self.whole_reg = Signal(reset_less=True)
 506
 507     def elaborate(self, platform):
 508         m = Module()
 509         comb = m.d.comb
 510
 511         comb += self.cr_bitfield.ok.eq(0)
 512         comb += self.whole_reg.eq(0)
 513         with m.Switch(self.sel_in):
 514             with m.Case(CROutSel.NONE):
 515                 pass # No bitfield activated
 516             with m.Case(CROutSel.CR0):
 517                 comb += self.cr_bitfield.data.eq(0)
 518                 comb += self.cr_bitfield.ok.eq(self.rc_in) # only when RC=1
 519             with m.Case(CROutSel.BF):
 520                 comb += self.cr_bitfield.data.eq(self.dec.FormX.BF)
 521                 comb += self.cr_bitfield.ok.eq(1)
 522             with m.Case(CROutSel.BT):
 523                 comb += self.cr_bitfield.data.eq(self.dec.FormXL.BT[2:5])
 524                 comb += self.cr_bitfield.ok.eq(1)
 525             with m.Case(CROutSel.WHOLE_REG):
 526                 comb += self.whole_reg.eq(1)
 527
 528         return m
 529
 530
 531 class XerBits:
 532     def __init__(self):
 533         self.ca = Signal(2, reset_less=True)
 534         self.ov = Signal(2, reset_less=True)
 535         self.so = Signal(reset_less=True)
 536
 537     def ports(self):
 538         return [self.ca, self.ov, self.so]
 539
 540
 541 class PowerDecode2(Elaboratable):
 542
 543     def __init__(self, dec):
 544
 545         self.dec = dec
 546         self.e = Decode2ToExecute1Type()
 547         self.valid = Signal()
 548
 549     def ports(self):
 550         return self.dec.ports() + self.e.ports()
 551
 552     def elaborate(self, platform):
 553         m = Module()
 554         comb = m.d.comb
 555         e, op, do = self.e, self.dec.op, self.e.do
 556
 557         # set up submodule decoders
 558         m.submodules.dec = self.dec
 559         m.submodules.dec_a = dec_a = DecodeA(self.dec)
 560         m.submodules.dec_b = dec_b = DecodeB(self.dec)
 561         m.submodules.dec_c = dec_c = DecodeC(self.dec)
 562         m.submodules.dec_o = dec_o = DecodeOut(self.dec)
 563         m.submodules.dec_o2 = dec_o2 = DecodeOut2(self.dec)
 564         m.submodules.dec_rc = dec_rc = DecodeRC(self.dec)
 565         m.submodules.dec_oe = dec_oe = DecodeOE(self.dec)
 566         m.submodules.dec_cr_in = dec_cr_in = DecodeCRIn(self.dec)
 567         m.submodules.dec_cr_out = dec_cr_out = DecodeCROut(self.dec)
 568
 569         # copy instruction through...
 570         for i in [do.insn, dec_a.insn_in, dec_b.insn_in,
 571                   dec_c.insn_in, dec_o.insn_in, dec_o2.insn_in, dec_rc.insn_in,
 572                   dec_oe.insn_in, dec_cr_in.insn_in, dec_cr_out.insn_in]:
 573             comb += i.eq(self.dec.opcode_in)
 574
 575         # ...and subdecoders' input fields
 576         comb += dec_a.sel_in.eq(op.in1_sel)
 577         comb += dec_b.sel_in.eq(op.in2_sel)
 578         comb += dec_c.sel_in.eq(op.in3_sel)
 579         comb += dec_o.sel_in.eq(op.out_sel)
 580         comb += dec_o2.sel_in.eq(op.out_sel)
 581         comb += dec_o2.lk.eq(do.lk)
 582         comb += dec_rc.sel_in.eq(op.rc_sel)
 583         comb += dec_oe.sel_in.eq(op.rc_sel) # XXX should be OE sel
 584         comb += dec_cr_in.sel_in.eq(op.cr_in)
 585         comb += dec_cr_out.sel_in.eq(op.cr_out)
 586         comb += dec_cr_out.rc_in.eq(dec_rc.rc_out.data)
 587
 588         # set up instruction, pick fn unit
 589         comb += e.nia.eq(0)    # XXX TODO (or remove? not sure yet)
 590         fu = op.function_unit
 591         with m.If((fu == Function.NONE) &
 592                    (op.internal_op != InternalOp.OP_ATTN)):
 593             comb += do.insn_type.eq(InternalOp.OP_ILLEGAL)
 594         with m.Else():
 595             comb += do.insn_type.eq(op.internal_op)
 596         comb += do.fn_unit.eq(fu)
 597
 598         # registers a, b, c and out and out2 (LD/ST EA)
 599         comb += e.read_reg1.eq(dec_a.reg_out)
 600         comb += e.read_reg2.eq(dec_b.reg_out)
 601         comb += e.read_reg3.eq(dec_c.reg_out)
 602         comb += e.write_reg.eq(dec_o.reg_out)
 603         comb += e.write_ea.eq(dec_o2.reg_out)
 604         comb += do.imm_data.eq(dec_b.imm_out) # immediate in RB (usually)
 605         comb += do.zero_a.eq(dec_a.immz_out)  # RA==0 detected
 606
 607         # rc and oe out
 608         comb += do.rc.eq(dec_rc.rc_out)
 609         comb += do.oe.eq(dec_oe.oe_out)
 610
 611         # SPRs out
 612         comb += e.read_spr1.eq(dec_a.spr_out)
 613         comb += e.write_spr.eq(dec_o.spr_out)
 614
 615         # Fast regs out
 616         comb += e.read_fast1.eq(dec_a.fast_out)
 617         comb += e.read_fast2.eq(dec_b.fast_out)
 618         comb += e.write_fast1.eq(dec_o.fast_out)
 619         comb += e.write_fast2.eq(dec_o2.fast_out)
 620
 621         # condition registers (CR)
 622         comb += e.read_cr1.eq(dec_cr_in.cr_bitfield)
 623         comb += e.read_cr2.eq(dec_cr_in.cr_bitfield_b)
 624         comb += e.read_cr3.eq(dec_cr_in.cr_bitfield_o)
 625         comb += e.write_cr.eq(dec_cr_out.cr_bitfield)
 626
 627         comb += do.read_cr_whole.eq(dec_cr_in.whole_reg)
 628         comb += do.write_cr_whole.eq(dec_cr_out.whole_reg)
 629         comb += do.write_cr0.eq(dec_cr_out.cr_bitfield.ok)
 630
 631         # decoded/selected instruction flags
 632         comb += do.data_len.eq(op.ldst_len)
 633         comb += do.invert_a.eq(op.inv_a)
 634         comb += do.invert_out.eq(op.inv_out)
 635         comb += do.input_carry.eq(op.cry_in)   # carry comes in
 636         comb += do.output_carry.eq(op.cry_out) # carry goes out
 637         comb += do.is_32bit.eq(op.is_32b)
 638         comb += do.is_signed.eq(op.sgn)
 639         with m.If(op.lk):
 640             comb += do.lk.eq(self.dec.LK) # XXX TODO: accessor
 641
 642         comb += do.byte_reverse.eq(op.br)
 643         comb += do.sign_extend.eq(op.sgn_ext)
 644         comb += do.update.eq(op.upd) # LD/ST "update" mode.
 645
 646         # These should be removed eventually
 647         comb += do.input_cr.eq(op.cr_in)   # condition reg comes in
 648         comb += do.output_cr.eq(op.cr_out) # condition reg goes in
 649
 650         # sigh this is exactly the sort of thing for which the
 651         # decoder is designed to not need.  MTSPR, MFSPR and others need
 652         # access to the XER bits.  however setting e.oe is not appropriate
 653         with m.If(op.internal_op == InternalOp.OP_MFSPR):
 654             comb += e.xer_in.eq(1)
 655         with m.If(op.internal_op == InternalOp.OP_MTSPR):
 656             comb += e.xer_out.eq(1)
 657
 658         # set the trapaddr to 0x700 for a td/tw/tdi/twi operation
 659         with m.If(op.internal_op == InternalOp.OP_TRAP):
 660             comb += do.trapaddr.eq(0x70)    # addr=0x700 (strip first nibble)
 661
 662         # illegal instruction must redirect to trap. this is done by
 663         # *overwriting* the decoded instruction and starting again.
 664         # (note: the same goes for interrupts and for privileged operations,
 665         # just with different trapaddr and traptype)
 666         with m.If(op.internal_op == InternalOp.OP_ILLEGAL):
 667             # illegal instruction trap
 668             self.trap(m, TT_ILLEG, 0x700)
 669
 670         # trap: (note e.insn_type so this includes OP_ILLEGAL) set up fast regs
 671         # Note: OP_SC could actually be modified to just be a trap
 672         with m.If((do.insn_type == InternalOp.OP_TRAP) |
 673                   (do.insn_type == InternalOp.OP_SC)):
 674             # TRAP write fast1 = SRR0
 675             comb += e.write_fast1.data.eq(FastRegs.SRR0) # constant: SRR0
 676             comb += e.write_fast1.ok.eq(1)
 677             # TRAP write fast2 = SRR1
 678             comb += e.write_fast2.data.eq(FastRegs.SRR1) # constant: SRR1
 679             comb += e.write_fast2.ok.eq(1)
 680
 681         # RFID: needs to read SRR0/1
 682         with m.If(do.insn_type == InternalOp.OP_RFID):
 683             # TRAP read fast1 = SRR0
 684             comb += e.read_fast1.data.eq(FastRegs.SRR0) # constant: SRR0
 685             comb += e.read_fast1.ok.eq(1)
 686             # TRAP read fast2 = SRR1
 687             comb += e.read_fast2.data.eq(FastRegs.SRR1) # constant: SRR1
 688             comb += e.read_fast2.ok.eq(1)
 689
 690         return m
 691
 692         # TODO: get msr, then can do privileged instruction
 693         with m.If(instr_is_priv(m, op.internal_op, e.insn) & msr[MSR_PR]):
 694             # privileged instruction trap
 695             self.trap(m, TT_PRIV, 0x700)
 696         return m
 697
 698     def trap(self, m, traptype, trapaddr):
 699         """trap: this basically "rewrites" the decoded instruction as a trap
 700         """
 701         comb = m.d.comb
 702         e, op, do = self.e, self.dec.op, self.e.do
 703         comb += e.eq(0) # reset eeeeeverything
 704         # start again
 705         comb += do.insn.eq(self.dec.opcode_in)
 706         comb += do.insn_type.eq(InternalOp.OP_TRAP)
 707         comb += do.fn_unit.eq(Function.TRAP)
 708         comb += do.trapaddr.eq(trapaddr >> 4) # cut bottom 4 bits
 709         comb += do.traptype.eq(traptype) # request type
 710
 711     def regspecmap_read(self, regfile, regname):
 712         """regspecmap_read: provides PowerDecode2 with an encoding relationship
 713         to Function Unit port regfiles (read-enable, read regnum, write regnum)
 714         regfile and regname arguments are fields 1 and 2 from a given regspec.
 715         """
 716         return regspec_decode_read(self.e, regfile, regname)
 717
 718     def regspecmap_write(self, regfile, regname):
 719         """regspecmap_write: provides PowerDecode2 with an encoding relationship
 720         to Function Unit port regfiles (write port, write regnum)
 721         regfile and regname arguments are fields 1 and 2 from a given regspec.
 722         """
 723         return regspec_decode_write(self.e, regfile, regname)
 724
 725     def rdflags(self, cu):
 726         rdl = []
 727         for idx in range(cu.n_src):
 728             regfile, regname, _ = cu.get_in_spec(idx)
 729             rdflag, read = self.regspecmap_read(regfile, regname)
 730             rdl.append(rdflag)
 731         print ("rdflags", rdl)
 732         return Cat(*rdl)
 733
 734
 735 if __name__ == '__main__':
 736     pdecode = create_pdecode()
 737     dec2 = PowerDecode2(pdecode)
 738     vl = rtlil.convert(dec2, ports=dec2.ports() + pdecode.ports())
 739     with open("dec2.il", "w") as f:
 740         f.write(vl)
 741