src/add/nmigen_add_experiment.py

   1 # IEEE Floating Point Adder (Single Precision)
   2 # Copyright (C) Jonathan P Dawson 2013
   3 # 2013-12-12
   4
   5 from nmigen import Module, Signal, Cat
   6 from nmigen.cli import main, verilog
   7
   8 from fpbase import FPNumIn, FPNumOut, FPOp, Overflow, FPBase, FPNumBase
   9
  10
  11 class FPState(FPBase):
  12     def __init__(self, state_from):
  13         self.state_from = state_from
  14
  15     def set_inputs(self, inputs):
  16         self.inputs = inputs
  17         for k,v in inputs.items():
  18             setattr(self, k, v)
  19
  20     def set_outputs(self, outputs):
  21         self.outputs = outputs
  22         for k,v in outputs.items():
  23             setattr(self, k, v)
  24
  25
  26 class FPGetOpA(FPState):
  27     """ gets operand a
  28     """
  29
  30     def __init__(self, in_a, width):
  31         FPState.__init__(self, "get_a")
  32         self.in_a = in_a
  33         self.a = FPNumIn(in_a, width)
  34
  35     def action(self, m):
  36         self.get_op(m, self.in_a, self.a, "get_b")
  37
  38
  39 class FPGetOpB(FPState):
  40     """ gets operand b
  41     """
  42
  43     def __init__(self, in_b, width):
  44         FPState.__init__(self, "get_b")
  45         self.in_b = in_b
  46         self.b = FPNumIn(self.in_b, width)
  47
  48     def action(self, m):
  49         self.get_op(m, self.in_b, self.b, "special_cases")
  50
  51
  52 class FPAddSpecialCasesMod:
  53     """ special cases: NaNs, infs, zeros, denormalised
  54         NOTE: some of these are unique to add.  see "Special Operations"
  55         https://steve.hollasch.net/cgindex/coding/ieeefloat.html
  56     """
  57
  58     def __init__(self, width):
  59         self.in_a = FPNumBase(width)
  60         self.in_b = FPNumBase(width)
  61         self.out_z = FPNumOut(width, False)
  62         self.out_do_z = Signal(reset_less=True)
  63
  64     def setup(self, m, in_a, in_b, out_z, out_do_z):
  65         """ links module to inputs and outputs
  66         """
  67         m.d.comb += self.in_a.copy(in_a)
  68         m.d.comb += self.in_b.copy(in_b)
  69         m.d.comb += out_z.v.eq(self.out_z.v)
  70         m.d.comb += out_do_z.eq(self.out_do_z)
  71
  72     def elaborate(self, platform):
  73         m = Module()
  74
  75         m.submodules.sc_in_a = self.in_a
  76         m.submodules.sc_in_b = self.in_b
  77         m.submodules.sc_out_z = self.out_z
  78
  79         s_nomatch = Signal()
  80         m.d.comb += s_nomatch.eq(self.in_a.s != self.in_b.s)
  81
  82         m_match = Signal()
  83         m.d.comb += m_match.eq(self.in_a.m == self.in_b.m)
  84
  85         # if a is NaN or b is NaN return NaN
  86         with m.If(self.in_a.is_nan | self.in_b.is_nan):
  87             m.d.comb += self.out_do_z.eq(1)
  88             m.d.comb += self.out_z.nan(0)
  89
  90         # XXX WEIRDNESS for FP16 non-canonical NaN handling
  91         # under review
  92
  93         ## if a is zero and b is NaN return -b
  94         #with m.If(a.is_zero & (a.s==0) & b.is_nan):
  95         #    m.d.comb += self.out_do_z.eq(1)
  96         #    m.d.comb += z.create(b.s, b.e, Cat(b.m[3:-2], ~b.m[0]))
  97
  98         ## if b is zero and a is NaN return -a
  99         #with m.Elif(b.is_zero & (b.s==0) & a.is_nan):
 100         #    m.d.comb += self.out_do_z.eq(1)
 101         #    m.d.comb += z.create(a.s, a.e, Cat(a.m[3:-2], ~a.m[0]))
 102
 103         ## if a is -zero and b is NaN return -b
 104         #with m.Elif(a.is_zero & (a.s==1) & b.is_nan):
 105         #    m.d.comb += self.out_do_z.eq(1)
 106         #    m.d.comb += z.create(a.s & b.s, b.e, Cat(b.m[3:-2], 1))
 107
 108         ## if b is -zero and a is NaN return -a
 109         #with m.Elif(b.is_zero & (b.s==1) & a.is_nan):
 110         #    m.d.comb += self.out_do_z.eq(1)
 111         #    m.d.comb += z.create(a.s & b.s, a.e, Cat(a.m[3:-2], 1))
 112
 113         # if a is inf return inf (or NaN)
 114         with m.Elif(self.in_a.is_inf):
 115             m.d.comb += self.out_do_z.eq(1)
 116             m.d.comb += self.out_z.inf(self.in_a.s)
 117             # if a is inf and signs don't match return NaN
 118             with m.If(self.in_b.exp_128 & s_nomatch):
 119                 m.d.comb += self.out_z.nan(0)
 120
 121         # if b is inf return inf
 122         with m.Elif(self.in_b.is_inf):
 123             m.d.comb += self.out_do_z.eq(1)
 124             m.d.comb += self.out_z.inf(self.in_b.s)
 125
 126         # if a is zero and b zero return signed-a/b
 127         with m.Elif(self.in_a.is_zero & self.in_b.is_zero):
 128             m.d.comb += self.out_do_z.eq(1)
 129             m.d.comb += self.out_z.create(self.in_a.s & self.in_b.s,
 130                                           self.in_b.e,
 131                                           self.in_b.m[3:-1])
 132
 133         # if a is zero return b
 134         with m.Elif(self.in_a.is_zero):
 135             m.d.comb += self.out_do_z.eq(1)
 136             m.d.comb += self.out_z.create(self.in_b.s, self.in_b.e,
 137                                       self.in_b.m[3:-1])
 138
 139         # if b is zero return a
 140         with m.Elif(self.in_b.is_zero):
 141             m.d.comb += self.out_do_z.eq(1)
 142             m.d.comb += self.out_z.create(self.in_a.s, self.in_a.e,
 143                                       self.in_a.m[3:-1])
 144
 145         # if a equal to -b return zero (+ve zero)
 146         with m.Elif(s_nomatch & m_match & (self.in_a.e == self.in_b.e)):
 147             m.d.comb += self.out_do_z.eq(1)
 148             m.d.comb += self.out_z.zero(0)
 149
 150         # Denormalised Number checks
 151         with m.Else():
 152             m.d.comb += self.out_do_z.eq(0)
 153
 154         return m
 155
 156
 157 class FPAddSpecialCases(FPState):
 158     """ special cases: NaNs, infs, zeros, denormalised
 159         NOTE: some of these are unique to add.  see "Special Operations"
 160         https://steve.hollasch.net/cgindex/coding/ieeefloat.html
 161     """
 162
 163     def __init__(self, width):
 164         FPState.__init__(self, "special_cases")
 165         self.mod = FPAddSpecialCasesMod(width)
 166         self.out_z = FPNumOut(width, False)
 167         self.out_do_z = Signal(reset_less=True)
 168
 169     def action(self, m):
 170         with m.If(self.out_do_z):
 171             m.d.sync += self.z.v.eq(self.out_z.v) # only take the output
 172             m.next = "put_z"
 173         with m.Else():
 174             m.next = "denormalise"
 175
 176
 177 class FPAddDeNormMod(FPState):
 178
 179     def __init__(self, width):
 180         self.in_a = FPNumBase(width)
 181         self.in_b = FPNumBase(width)
 182         self.out_a = FPNumBase(width)
 183         self.out_b = FPNumBase(width)
 184
 185     def setup(self, m, in_a, in_b, out_a, out_b):
 186         """ links module to inputs and outputs
 187         """
 188         m.d.comb += self.in_a.copy(in_a)
 189         m.d.comb += self.in_b.copy(in_b)
 190         m.d.comb += out_a.copy(self.out_a)
 191         m.d.comb += out_b.copy(self.out_b)
 192
 193     def elaborate(self, platform):
 194         m = Module()
 195         m.submodules.denorm_in_a = self.in_a
 196         m.submodules.denorm_in_b = self.in_b
 197         m.submodules.denorm_out_a = self.out_a
 198         m.submodules.denorm_out_b = self.out_b
 199         # hmmm, don't like repeating identical code
 200         m.d.comb += self.out_a.copy(self.in_a)
 201         with m.If(self.in_a.exp_n127):
 202             m.d.comb += self.out_a.e.eq(self.in_a.N126) # limit a exponent
 203         with m.Else():
 204             m.d.comb += self.out_a.m[-1].eq(1) # set top mantissa bit
 205
 206         m.d.comb += self.out_b.copy(self.in_b)
 207         with m.If(self.in_b.exp_n127):
 208             m.d.comb += self.out_b.e.eq(self.in_b.N126) # limit a exponent
 209         with m.Else():
 210             m.d.comb += self.out_b.m[-1].eq(1) # set top mantissa bit
 211
 212         return m
 213
 214
 215 class FPAddDeNorm(FPState):
 216
 217     def __init__(self, width):
 218         FPState.__init__(self, "denormalise")
 219         self.mod = FPAddDeNormMod(width)
 220         self.out_a = FPNumBase(width)
 221         self.out_b = FPNumBase(width)
 222
 223     def action(self, m):
 224         # Denormalised Number checks
 225         m.next = "align"
 226         m.d.sync += self.a.copy(self.out_a)
 227         m.d.sync += self.b.copy(self.out_b)
 228
 229
 230 class FPAddAlignMultiMod(FPState):
 231
 232     def __init__(self, width):
 233         self.in_a = FPNumBase(width)
 234         self.in_b = FPNumBase(width)
 235         self.out_a = FPNumIn(None, width)
 236         self.out_b = FPNumIn(None, width)
 237         self.exp_eq = Signal(reset_less=True)
 238
 239     def setup(self, m, in_a, in_b, out_a, out_b, exp_eq):
 240         """ links module to inputs and outputs
 241         """
 242         m.d.comb += self.in_a.copy(in_a)
 243         m.d.comb += self.in_b.copy(in_b)
 244         m.d.comb += out_a.copy(self.out_a)
 245         m.d.comb += out_b.copy(self.out_b)
 246         m.d.comb += exp_eq.eq(self.exp_eq)
 247
 248     def elaborate(self, platform):
 249         # This one however (single-cycle) will do the shift
 250         # in one go.
 251
 252         m = Module()
 253
 254         #m.submodules.align_in_a = self.in_a
 255         #m.submodules.align_in_b = self.in_b
 256         m.submodules.align_out_a = self.out_a
 257         m.submodules.align_out_b = self.out_b
 258
 259         # NOTE: this does *not* do single-cycle multi-shifting,
 260         #       it *STAYS* in the align state until exponents match
 261
 262         # exponent of a greater than b: shift b down
 263         m.d.comb += self.exp_eq.eq(0)
 264         m.d.comb += self.out_a.copy(self.in_a)
 265         m.d.comb += self.out_b.copy(self.in_b)
 266         agtb = Signal(reset_less=True)
 267         altb = Signal(reset_less=True)
 268         m.d.comb += agtb.eq(self.in_a.e > self.in_b.e)
 269         m.d.comb += altb.eq(self.in_a.e < self.in_b.e)
 270         with m.If(agtb):
 271             m.d.comb += self.out_b.shift_down(self.in_b)
 272         # exponent of b greater than a: shift a down
 273         with m.Elif(altb):
 274             m.d.comb += self.out_a.shift_down(self.in_a)
 275         # exponents equal: move to next stage.
 276         with m.Else():
 277             m.d.comb += self.exp_eq.eq(1)
 278         return m
 279
 280
 281 class FPAddAlignMulti(FPState):
 282
 283     def __init__(self, width):
 284         FPState.__init__(self, "align")
 285         self.mod = FPAddAlignMultiMod(width)
 286         self.out_a = FPNumIn(None, width)
 287         self.out_b = FPNumIn(None, width)
 288         self.exp_eq = Signal(reset_less=True)
 289
 290     def action(self, m):
 291         m.d.sync += self.a.copy(self.out_a)
 292         m.d.sync += self.b.copy(self.out_b)
 293         with m.If(self.exp_eq):
 294             m.next = "add_0"
 295
 296
 297 class FPAddAlignSingleMod:
 298
 299     def __init__(self, width):
 300         self.in_a = FPNumBase(width)
 301         self.in_b = FPNumBase(width)
 302         self.out_a = FPNumIn(None, width)
 303         self.out_b = FPNumIn(None, width)
 304         #self.out_a = FPNumBase(width)
 305         #self.out_b = FPNumBase(width)
 306
 307     def setup(self, m, in_a, in_b, out_a, out_b):
 308         """ links module to inputs and outputs
 309         """
 310         m.d.comb += self.in_a.copy(in_a)
 311         m.d.comb += self.in_b.copy(in_b)
 312         m.d.comb += out_a.copy(self.out_a)
 313         m.d.comb += out_b.copy(self.out_b)
 314
 315     def elaborate(self, platform):
 316         # This one however (single-cycle) will do the shift
 317         # in one go.
 318
 319         m = Module()
 320
 321         #m.submodules.align_in_a = self.in_a
 322         #m.submodules.align_in_b = self.in_b
 323         m.submodules.align_out_a = self.out_a
 324         m.submodules.align_out_b = self.out_b
 325
 326         # XXX TODO: the shifter used here is quite expensive
 327         # having only one would be better
 328
 329         ediff = Signal((len(self.in_a.e), True), reset_less=True)
 330         ediffr = Signal((len(self.in_a.e), True), reset_less=True)
 331         m.d.comb += ediff.eq(self.in_a.e - self.in_b.e)
 332         m.d.comb += ediffr.eq(self.in_b.e - self.in_a.e)
 333         m.d.comb += self.out_a.copy(self.in_a)
 334         m.d.comb += self.out_b.copy(self.in_b)
 335         with m.If(ediff > 0):
 336             m.d.comb += self.out_b.shift_down_multi(ediff)
 337         # exponent of b greater than a: shift a down
 338         with m.Elif(ediff < 0):
 339             m.d.comb += self.out_a.shift_down_multi(ediffr)
 340         return m
 341
 342
 343 class FPAddAlignSingle(FPState):
 344
 345     def __init__(self, width):
 346         FPState.__init__(self, "align")
 347         self.mod = FPAddAlignSingleMod(width)
 348         self.out_a = FPNumIn(None, width)
 349         self.out_b = FPNumIn(None, width)
 350
 351     def action(self, m):
 352         m.d.sync += self.a.copy(self.out_a)
 353         m.d.sync += self.b.copy(self.out_b)
 354         m.next = "add_0"
 355
 356
 357 class FPAddStage0Mod:
 358
 359     def __init__(self, width):
 360         self.in_a = FPNumBase(width)
 361         self.in_b = FPNumBase(width)
 362         self.in_z = FPNumBase(width, False)
 363         self.out_z = FPNumBase(width, False)
 364         self.out_tot = Signal(self.out_z.m_width + 4, reset_less=True)
 365
 366     def setup(self, m, in_a, in_b, in_z, out_z, out_tot):
 367         """ links module to inputs and outputs
 368         """
 369         m.d.comb += self.in_a.copy(in_a)
 370         m.d.comb += self.in_b.copy(in_b)
 371         m.d.comb += self.in_z.copy(in_z)
 372         m.d.comb += out_z.copy(self.out_z)
 373         m.d.comb += out_tot.eq(self.out_tot)
 374
 375     def elaborate(self, platform):
 376         m = Module()
 377         #m.submodules.add0_in_a = self.in_a
 378         #m.submodules.add0_in_b = self.in_b
 379         #m.submodules.add0_in_z = self.in_z
 380         #m.submodules.add0_out_z = self.out_z
 381
 382         m.d.comb += self.out_z.e.eq(self.in_a.e)
 383         # same-sign (both negative or both positive) add mantissas
 384         with m.If(self.in_a.s == self.in_b.s):
 385             m.d.comb += [
 386                 self.out_tot.eq(Cat(self.in_a.m, 0) + Cat(self.in_b.m, 0)),
 387                 self.out_z.s.eq(self.in_a.s)
 388             ]
 389         # a mantissa greater than b, use a
 390         with m.Elif(self.in_a.m >= self.in_b.m):
 391             m.d.comb += [
 392                 self.out_tot.eq(Cat(self.in_a.m, 0) - Cat(self.in_b.m, 0)),
 393                 self.out_z.s.eq(self.in_a.s)
 394             ]
 395         # b mantissa greater than a, use b
 396         with m.Else():
 397             m.d.comb += [
 398                 self.out_tot.eq(Cat(self.in_b.m, 0) - Cat(self.in_a.m, 0)),
 399                 self.out_z.s.eq(self.in_b.s)
 400         ]
 401         return m
 402
 403
 404 class FPAddStage0(FPState):
 405     """ First stage of add.  covers same-sign (add) and subtract
 406         special-casing when mantissas are greater or equal, to
 407         give greatest accuracy.
 408     """
 409
 410     def __init__(self, width):
 411         FPState.__init__(self, "add_0")
 412         self.mod = FPAddStage0Mod(width)
 413         self.out_z = FPNumBase(width, False)
 414         self.out_tot = Signal(self.out_z.m_width + 4, reset_less=True)
 415
 416     def action(self, m):
 417         m.next = "add_1"
 418         m.d.sync += self.z.copy(self.out_z)
 419
 420
 421 class FPAddStage1Mod(FPState):
 422     """ Second stage of add: preparation for normalisation.
 423         detects when tot sum is too big (tot[27] is kinda a carry bit)
 424     """
 425
 426     def __init__(self, width):
 427         self.out_norm = Signal(reset_less=True)
 428         self.in_z = FPNumBase(width, False)
 429         self.in_tot = Signal(self.in_z.m_width + 4, reset_less=True)
 430         self.out_z = FPNumBase(width, False)
 431         self.out_of = Overflow()
 432
 433     def setup(self, m, in_tot, in_z, out_z, out_of):
 434         """ links module to inputs and outputs
 435         """
 436         m.d.comb += self.in_z.copy(in_z)
 437         m.d.comb += self.in_tot.eq(in_tot)
 438         m.d.comb += out_z.copy(self.out_z)
 439         m.d.comb += out_of.copy(self.out_of)
 440
 441     def elaborate(self, platform):
 442         m = Module()
 443         #m.submodules.norm1_in_overflow = self.in_of
 444         #m.submodules.norm1_out_overflow = self.out_of
 445         #m.submodules.norm1_in_z = self.in_z
 446         #m.submodules.norm1_out_z = self.out_z
 447         m.d.comb += self.out_z.copy(self.in_z)
 448         # tot[27] gets set when the sum overflows. shift result down
 449         with m.If(self.in_tot[-1]):
 450             m.d.comb += [
 451                 self.out_z.m.eq(self.in_tot[4:]),
 452                 self.out_of.m0.eq(self.in_tot[4]),
 453                 self.out_of.guard.eq(self.in_tot[3]),
 454                 self.out_of.round_bit.eq(self.in_tot[2]),
 455                 self.out_of.sticky.eq(self.in_tot[1] | self.in_tot[0]),
 456                 self.out_z.e.eq(self.in_z.e + 1)
 457         ]
 458         # tot[27] zero case
 459         with m.Else():
 460             m.d.comb += [
 461                 self.out_z.m.eq(self.in_tot[3:]),
 462                 self.out_of.m0.eq(self.in_tot[3]),
 463                 self.out_of.guard.eq(self.in_tot[2]),
 464                 self.out_of.round_bit.eq(self.in_tot[1]),
 465                 self.out_of.sticky.eq(self.in_tot[0])
 466         ]
 467         return m
 468
 469
 470 class FPAddStage1(FPState):
 471
 472     def __init__(self, width):
 473         FPState.__init__(self, "add_1")
 474         self.mod = FPAddStage1Mod(width)
 475         self.out_z = FPNumBase(width, False)
 476         self.out_of = Overflow()
 477
 478     def action(self, m):
 479         m.d.sync += self.of.copy(self.out_of)
 480         m.d.sync += self.z.copy(self.out_z)
 481         m.next = "normalise_1"
 482
 483
 484 class FPNorm1Mod:
 485
 486     def __init__(self, width):
 487         self.out_norm = Signal(reset_less=True)
 488         self.in_z = FPNumBase(width, False)
 489         self.out_z = FPNumBase(width, False)
 490         self.in_of = Overflow()
 491         self.out_of = Overflow()
 492
 493     def setup(self, m, in_z, out_z, in_of, out_of, out_norm):
 494         """ links module to inputs and outputs
 495         """
 496         m.d.comb += self.in_z.copy(in_z)
 497         m.d.comb += out_z.copy(self.out_z)
 498         m.d.comb += self.in_of.copy(in_of)
 499         m.d.comb += out_of.copy(self.out_of)
 500         m.d.comb += out_norm.eq(self.out_norm)
 501
 502     def elaborate(self, platform):
 503         m = Module()
 504         m.submodules.norm1_in_overflow = self.in_of
 505         m.submodules.norm1_out_overflow = self.out_of
 506         m.submodules.norm1_in_z = self.in_z
 507         m.submodules.norm1_out_z = self.out_z
 508         m.d.comb += self.out_z.copy(self.in_z)
 509         m.d.comb += self.out_of.copy(self.in_of)
 510         m.d.comb += self.out_norm.eq((self.in_z.m_msbzero) & \
 511                                      (self.in_z.exp_gt_n126))
 512         with m.If(self.out_norm):
 513             m.d.comb += [
 514                 self.out_z.e.eq(self.in_z.e - 1),  # DECREASE exponent
 515                 self.out_z.m.eq(self.in_z.m << 1), # shift mantissa UP
 516                 self.out_z.m[0].eq(self.in_of.guard), # steal guard (was tot[2])
 517                 self.out_of.guard.eq(self.in_of.round_bit), # round (was tot[1])
 518                 self.out_of.round_bit.eq(0),        # reset round bit
 519                 self.out_of.m0.eq(self.in_of.guard),
 520             ]
 521
 522         return m
 523
 524
 525 class FPNorm1(FPState):
 526
 527     def __init__(self, width):
 528         FPState.__init__(self, "normalise_1")
 529         self.mod = FPNorm1Mod(width)
 530         self.out_norm = Signal(reset_less=True)
 531         self.out_z = FPNumBase(width)
 532         self.out_of = Overflow()
 533
 534     def action(self, m):
 535         m.d.sync += self.of.copy(self.out_of)
 536         m.d.sync += self.z.copy(self.out_z)
 537         with m.If(~self.out_norm):
 538             m.next = "normalise_2"
 539
 540
 541 class FPNorm2Mod:
 542
 543     def __init__(self, width):
 544         self.out_norm = Signal(reset_less=True)
 545         self.in_z = FPNumBase(width, False)
 546         self.out_z = FPNumBase(width, False)
 547         self.in_of = Overflow()
 548         self.out_of = Overflow()
 549
 550     def setup(self, m, in_z, out_z, in_of, out_of, out_norm):
 551         """ links module to inputs and outputs
 552         """
 553         m.d.comb += self.in_z.copy(in_z)
 554         m.d.comb += out_z.copy(self.out_z)
 555         m.d.comb += self.in_of.copy(in_of)
 556         m.d.comb += out_of.copy(self.out_of)
 557         m.d.comb += out_norm.eq(self.out_norm)
 558
 559     def elaborate(self, platform):
 560         m = Module()
 561         m.submodules.norm2_in_overflow = self.in_of
 562         m.submodules.norm2_out_overflow = self.out_of
 563         m.submodules.norm2_in_z = self.in_z
 564         m.submodules.norm2_out_z = self.out_z
 565         m.d.comb += self.out_z.copy(self.in_z)
 566         m.d.comb += self.out_of.copy(self.in_of)
 567         m.d.comb += self.out_norm.eq(self.in_z.exp_lt_n126)
 568         with m.If(self.out_norm):
 569             m.d.comb += [
 570                 self.out_z.e.eq(self.in_z.e + 1),  # INCREASE exponent
 571                 self.out_z.m.eq(self.in_z.m >> 1), # shift mantissa DOWN
 572                 self.out_of.guard.eq(self.in_z.m[0]),
 573                 self.out_of.m0.eq(self.in_z.m[1]),
 574                 self.out_of.round_bit.eq(self.in_of.guard),
 575                 self.out_of.sticky.eq(self.in_of.sticky | self.in_of.round_bit)
 576             ]
 577
 578         return m
 579
 580
 581 class FPNorm2(FPState):
 582
 583     def __init__(self, width):
 584         FPState.__init__(self, "normalise_2")
 585         self.mod = FPNorm2Mod(width)
 586         self.out_norm = Signal(reset_less=True)
 587         self.out_z = FPNumBase(width)
 588         self.out_of = Overflow()
 589
 590     def action(self, m):
 591         #m.d.sync += self.of.copy(self.out_of)
 592         m.d.sync += self.z.copy(self.out_z)
 593         with m.If(~self.out_norm):
 594             m.next = "round"
 595
 596
 597 class FPRoundMod:
 598
 599     def __init__(self, width):
 600         self.in_roundz = Signal(reset_less=True)
 601         self.in_z = FPNumBase(width, False)
 602         self.out_z = FPNumBase(width, False)
 603
 604     def setup(self, m, in_z, out_z, in_of):
 605         """ links module to inputs and outputs
 606         """
 607         m.d.comb += self.in_z.copy(in_z)
 608         m.d.comb += out_z.copy(self.out_z)
 609         m.d.comb += self.in_roundz.eq(in_of.roundz)
 610
 611     def elaborate(self, platform):
 612         m = Module()
 613         m.d.comb += self.out_z.copy(self.in_z)
 614         with m.If(self.in_roundz):
 615             m.d.comb += self.out_z.m.eq(self.in_z.m + 1) # mantissa rounds up
 616             with m.If(self.in_z.m == self.in_z.m1s): # all 1s
 617                 m.d.comb += self.out_z.e.eq(self.in_z.e + 1) # exponent up
 618         return m
 619
 620
 621 class FPRound(FPState):
 622
 623     def __init__(self, width):
 624         FPState.__init__(self, "round")
 625         self.mod = FPRoundMod(width)
 626         self.out_z = FPNumBase(width)
 627
 628     def action(self, m):
 629         m.d.sync += self.z.copy(self.out_z)
 630         m.next = "corrections"
 631
 632
 633 class FPCorrectionsMod:
 634
 635     def __init__(self, width):
 636         self.in_z = FPNumOut(width, False)
 637         self.out_z = FPNumOut(width, False)
 638
 639     def setup(self, m, in_z, out_z):
 640         """ links module to inputs and outputs
 641         """
 642         m.d.comb += self.in_z.copy(in_z)
 643         m.d.comb += out_z.copy(self.out_z)
 644
 645     def elaborate(self, platform):
 646         m = Module()
 647         m.submodules.corr_in_z = self.in_z
 648         m.submodules.corr_out_z = self.out_z
 649         m.d.comb += self.out_z.copy(self.in_z)
 650         with m.If(self.in_z.is_denormalised):
 651             m.d.comb += self.out_z.e.eq(self.in_z.N127)
 652
 653         #        with m.If(self.in_z.is_overflowed):
 654         #            m.d.comb += self.out_z.inf(self.in_z.s)
 655         #        with m.Else():
 656         #            m.d.comb += self.out_z.create(self.in_z.s, self.in_z.e, self.in_z.m)
 657         return m
 658
 659
 660 class FPCorrections(FPState):
 661
 662     def __init__(self, width):
 663         FPState.__init__(self, "corrections")
 664         self.mod = FPCorrectionsMod(width)
 665         self.out_z = FPNumBase(width)
 666
 667     def action(self, m):
 668         m.d.sync += self.z.copy(self.out_z)
 669         m.next = "pack"
 670
 671
 672 class FPPackMod:
 673
 674     def __init__(self, width):
 675         self.in_z = FPNumOut(width, False)
 676         self.out_z = FPNumOut(width, False)
 677
 678     def setup(self, m, in_z, out_z):
 679         """ links module to inputs and outputs
 680         """
 681         m.d.comb += self.in_z.copy(in_z)
 682         m.d.comb += out_z.v.eq(self.out_z.v)
 683
 684     def elaborate(self, platform):
 685         m = Module()
 686         m.submodules.pack_in_z = self.in_z
 687         with m.If(self.in_z.is_overflowed):
 688             m.d.comb += self.out_z.inf(self.in_z.s)
 689         with m.Else():
 690             m.d.comb += self.out_z.create(self.in_z.s, self.in_z.e, self.in_z.m)
 691         return m
 692
 693
 694 class FPPack(FPState):
 695
 696     def __init__(self, width):
 697         FPState.__init__(self, "pack")
 698         self.mod = FPPackMod(width)
 699         self.out_z = FPNumOut(width, False)
 700
 701     def action(self, m):
 702         m.d.sync += self.z.v.eq(self.out_z.v)
 703         m.next = "put_z"
 704
 705
 706 class FPPutZ(FPState):
 707
 708     def action(self, m):
 709         self.put_z(m, self.z, self.out_z, "get_a")
 710
 711
 712 class FPADD:
 713
 714     def __init__(self, width, single_cycle=False):
 715         self.width = width
 716         self.single_cycle = single_cycle
 717
 718         self.in_a  = FPOp(width)
 719         self.in_b  = FPOp(width)
 720         self.out_z = FPOp(width)
 721
 722         self.states = []
 723
 724     def add_state(self, state):
 725         self.states.append(state)
 726         return state
 727
 728     def get_fragment(self, platform=None):
 729         """ creates the HDL code-fragment for FPAdd
 730         """
 731         m = Module()
 732
 733         # Latches
 734         #a = FPNumIn(self.in_a, self.width)
 735         #b = FPNumIn(self.in_b, self.width)
 736         z = FPNumOut(self.width, False)
 737
 738         #m.submodules.fpnum_b = b
 739         m.submodules.fpnum_z = z
 740
 741         w = z.m_width + 4
 742
 743         of = Overflow()
 744         m.submodules.overflow = of
 745
 746         geta = self.add_state(FPGetOpA(self.in_a, self.width))
 747         #geta.set_inputs({"in_a": self.in_a})
 748         #geta.set_outputs({"a": a})
 749         a = geta.a
 750         # XXX m.d.comb += a.v.eq(self.in_a.v) # links in_a to a
 751         m.submodules.fpnum_a = a
 752
 753         getb = self.add_state(FPGetOpB(self.in_b, self.width))
 754         #getb.set_inputs({"in_b": self.in_b})
 755         #getb.set_outputs({"b": b})
 756         b = getb.b
 757         # XXX m.d.comb += b.v.eq(self.in_b.v) # links in_b to b
 758         m.submodules.fpnum_b = b
 759
 760         sc = self.add_state(FPAddSpecialCases(self.width))
 761         sc.set_inputs({"a": a, "b": b})
 762         sc.set_outputs({"z": z})
 763         sc.mod.setup(m, a, b, sc.out_z, sc.out_do_z)
 764         m.submodules.specialcases = sc.mod
 765
 766         dn = self.add_state(FPAddDeNorm(self.width))
 767         dn.set_inputs({"a": a, "b": b})
 768         dn.set_outputs({"a": a, "b": b}) # XXX outputs same as inputs
 769         dn.mod.setup(m, a, b, dn.out_a, dn.out_b)
 770         m.submodules.denormalise = dn.mod
 771
 772         if self.single_cycle:
 773             alm = self.add_state(FPAddAlignSingle(self.width))
 774             alm.set_inputs({"a": a, "b": b})
 775             alm.set_outputs({"a": a, "b": b}) # XXX outputs same as inputs
 776             alm.mod.setup(m, a, b, alm.out_a, alm.out_b)
 777         else:
 778             alm = self.add_state(FPAddAlignMulti(self.width))
 779             alm.set_inputs({"a": a, "b": b})
 780             alm.set_outputs({"a": a, "b": b}) # XXX outputs same as inputs
 781             alm.mod.setup(m, a, b, alm.out_a, alm.out_b, alm.exp_eq)
 782         m.submodules.align = alm.mod
 783
 784         add0 = self.add_state(FPAddStage0(self.width))
 785         add0.set_inputs({"a": a, "b": b})
 786         add0.set_outputs({"z": z})
 787         add0.mod.setup(m, a, b, z, add0.out_z, add0.out_tot)
 788         m.submodules.add0 = add0.mod
 789
 790         add1 = self.add_state(FPAddStage1(self.width))
 791         add1.set_inputs({"tot": add0.out_tot, "z": add0.out_z})
 792         add1.set_outputs({"z": z, "of": of})  # XXX Z as output
 793         add1.mod.setup(m, add0.out_tot, z, add1.out_z, add1.out_of)
 794         m.submodules.add1 = add1.mod
 795
 796         n1 = self.add_state(FPNorm1(self.width))
 797         n1.set_inputs({"z": z, "of": of})  # XXX Z as output
 798         n1.set_outputs({"z": z})  # XXX Z as output
 799         n1.mod.setup(m, z, n1.out_z, of, n1.out_of, n1.out_norm)
 800         m.submodules.normalise_1 = n1.mod
 801
 802         n2 = self.add_state(FPNorm2(self.width))
 803         n2.set_inputs({"z": n1.out_z, "of": n1.out_of})
 804         n2.set_outputs({"z": z})
 805         n2.mod.setup(m, n1.out_z, n2.out_z, of, n2.out_of, n2.out_norm)
 806         m.submodules.normalise_2 = n2.mod
 807
 808         rn = self.add_state(FPRound(self.width))
 809         rn.set_inputs({"z": n2.out_z, "of": n2.out_of})
 810         rn.set_outputs({"z": z})
 811         rn.mod.setup(m, n2.out_z, rn.out_z, of)
 812         m.submodules.roundz = rn.mod
 813
 814         cor = self.add_state(FPCorrections(self.width))
 815         cor.set_inputs({"z": z})  # XXX Z as output
 816         cor.set_outputs({"z": z})  # XXX Z as output
 817         cor.mod.setup(m, z, cor.out_z)
 818         m.submodules.corrections = cor.mod
 819
 820         pa = self.add_state(FPPack(self.width))
 821         pa.set_inputs({"z": z})  # XXX Z as output
 822         pa.set_outputs({"z": z})  # XXX Z as output
 823         pa.mod.setup(m, z, pa.out_z)
 824         m.submodules.pack = pa.mod
 825
 826         pz = self.add_state(FPPutZ("put_z"))
 827         pz.set_inputs({"z": z})
 828         pz.set_outputs({"out_z": self.out_z})
 829
 830         with m.FSM() as fsm:
 831
 832             for state in self.states:
 833                 with m.State(state.state_from):
 834                     state.action(m)
 835
 836         return m
 837
 838
 839 if __name__ == "__main__":
 840     alu = FPADD(width=32)
 841     main(alu, ports=alu.in_a.ports() + alu.in_b.ports() + alu.out_z.ports())
 842
 843
 844     # works... but don't use, just do "python fname.py convert -t v"
 845     #print (verilog.convert(alu, ports=[
 846     #                        ports=alu.in_a.ports() + \
 847     #                              alu.in_b.ports() + \
 848     #                              alu.out_z.ports())