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