nmigen/back/pysim.py

   1 import os
   2 import tempfile
   3 import warnings
   4 import inspect
   5 from contextlib import contextmanager
   6 import itertools
   7 from vcd import VCDWriter
   8 from vcd.gtkw import GTKWSave
   9
  10 from .._utils import deprecated
  11 from ..hdl.ast import *
  12 from ..hdl.cd import *
  13 from ..hdl.ir import *
  14 from ..hdl.xfrm import ValueVisitor, StatementVisitor, LHSGroupFilter
  15
  16
  17 class Command:
  18     pass
  19
  20
  21 class Settle(Command):
  22     def __repr__(self):
  23         return "(settle)"
  24
  25
  26 class Delay(Command):
  27     def __init__(self, interval=None):
  28         self.interval = None if interval is None else float(interval)
  29
  30     def __repr__(self):
  31         if self.interval is None:
  32             return "(delay ε)"
  33         else:
  34             return "(delay {:.3}us)".format(self.interval * 1e6)
  35
  36
  37 class Tick(Command):
  38     def __init__(self, domain="sync"):
  39         if not isinstance(domain, (str, ClockDomain)):
  40             raise TypeError("Domain must be a string or a ClockDomain instance, not {!r}"
  41                             .format(domain))
  42         assert domain != "comb"
  43         self.domain = domain
  44
  45     def __repr__(self):
  46         return "(tick {})".format(self.domain)
  47
  48
  49 class Passive(Command):
  50     def __repr__(self):
  51         return "(passive)"
  52
  53
  54 class Active(Command):
  55     def __repr__(self):
  56         return "(active)"
  57
  58
  59 class _WaveformWriter:
  60     def update(self, timestamp, signal, value):
  61         raise NotImplementedError # :nocov:
  62
  63     def close(self, timestamp):
  64         raise NotImplementedError # :nocov:
  65
  66
  67 class _VCDWaveformWriter(_WaveformWriter):
  68     @staticmethod
  69     def timestamp_to_vcd(timestamp):
  70         return timestamp * (10 ** 10) # 1/(100 ps)
  71
  72     @staticmethod
  73     def decode_to_vcd(signal, value):
  74         return signal.decoder(value).expandtabs().replace(" ", "_")
  75
  76     def __init__(self, signal_names, *, vcd_file, gtkw_file=None, traces=()):
  77         if isinstance(vcd_file, str):
  78             vcd_file = open(vcd_file, "wt")
  79         if isinstance(gtkw_file, str):
  80             gtkw_file = open(gtkw_file, "wt")
  81
  82         self.vcd_vars = SignalDict()
  83         self.vcd_file = vcd_file
  84         self.vcd_writer = vcd_file and VCDWriter(self.vcd_file,
  85             timescale="100 ps", comment="Generated by nMigen")
  86
  87         self.gtkw_names = SignalDict()
  88         self.gtkw_file = gtkw_file
  89         self.gtkw_save = gtkw_file and GTKWSave(self.gtkw_file)
  90
  91         self.traces = []
  92
  93         trace_names = SignalDict()
  94         for trace in traces:
  95             if trace not in signal_names:
  96                 trace_names[trace] = {("top", trace.name)}
  97             self.traces.append(trace)
  98
  99         if self.vcd_writer is None:
 100             return
 101
 102         for signal, names in itertools.chain(signal_names.items(), trace_names.items()):
 103             if signal.decoder:
 104                 var_type = "string"
 105                 var_size = 1
 106                 var_init = self.decode_to_vcd(signal, signal.reset)
 107             else:
 108                 var_type = "wire"
 109                 var_size = signal.width
 110                 var_init = signal.reset
 111
 112             for (*var_scope, var_name) in names:
 113                 suffix = None
 114                 while True:
 115                     try:
 116                         if suffix is None:
 117                             var_name_suffix = var_name
 118                         else:
 119                             var_name_suffix = "{}${}".format(var_name, suffix)
 120                         vcd_var = self.vcd_writer.register_var(
 121                             scope=var_scope, name=var_name_suffix,
 122                             var_type=var_type, size=var_size, init=var_init)
 123                         break
 124                     except KeyError:
 125                         suffix = (suffix or 0) + 1
 126
 127                 if signal not in self.vcd_vars:
 128                     self.vcd_vars[signal] = set()
 129                 self.vcd_vars[signal].add(vcd_var)
 130
 131                 if signal not in self.gtkw_names:
 132                     self.gtkw_names[signal] = (*var_scope, var_name_suffix)
 133
 134     def update(self, timestamp, signal, value):
 135         vcd_vars = self.vcd_vars.get(signal)
 136         if vcd_vars is None:
 137             return
 138
 139         vcd_timestamp = self.timestamp_to_vcd(timestamp)
 140         if signal.decoder:
 141             var_value = self.decode_to_vcd(signal, value)
 142         else:
 143             var_value = value
 144         for vcd_var in vcd_vars:
 145             self.vcd_writer.change(vcd_var, vcd_timestamp, var_value)
 146
 147     def close(self, timestamp):
 148         if self.vcd_writer is not None:
 149             self.vcd_writer.close(self.timestamp_to_vcd(timestamp))
 150
 151         if self.gtkw_save is not None:
 152             self.gtkw_save.dumpfile(self.vcd_file.name)
 153             self.gtkw_save.dumpfile_size(self.vcd_file.tell())
 154
 155             self.gtkw_save.treeopen("top")
 156             for signal in self.traces:
 157                 if len(signal) > 1 and not signal.decoder:
 158                     suffix = "[{}:0]".format(len(signal) - 1)
 159                 else:
 160                     suffix = ""
 161                 self.gtkw_save.trace(".".join(self.gtkw_names[signal]) + suffix)
 162
 163         if self.vcd_file is not None:
 164             self.vcd_file.close()
 165         if self.gtkw_file is not None:
 166             self.gtkw_file.close()
 167
 168
 169 class _Process:
 170     __slots__ = ("runnable", "passive")
 171
 172     def reset(self):
 173         raise NotImplementedError # :nocov:
 174
 175     def run(self):
 176         raise NotImplementedError # :nocov:
 177
 178     @property
 179     def name(self):
 180         raise NotImplementedError # :nocov:
 181
 182
 183 class _SignalState:
 184     __slots__ = ("signal", "curr", "next", "waiters", "pending")
 185
 186     def __init__(self, signal, pending):
 187         self.signal = signal
 188         self.pending = pending
 189         self.waiters = dict()
 190         self.reset()
 191
 192     def reset(self):
 193         self.curr = self.next = self.signal.reset
 194
 195     def set(self, value):
 196         if self.next == value:
 197             return
 198         self.next = value
 199         self.pending.add(self)
 200
 201     def wait(self, task, *, trigger=None):
 202         assert task not in self.waiters
 203         self.waiters[task] = trigger
 204
 205     def commit(self):
 206         if self.curr == self.next:
 207             return False
 208         self.curr = self.next
 209         return True
 210
 211     def wakeup(self):
 212         awoken_any = False
 213         for process, trigger in self.waiters.items():
 214             if trigger is None or trigger == self.curr:
 215                 process.runnable = awoken_any = True
 216         return awoken_any
 217
 218
 219 class _SimulatorState:
 220     def __init__(self):
 221         self.signals = SignalDict()
 222         self.pending = set()
 223
 224         self.timestamp = 0.0
 225         self.deadlines = dict()
 226
 227         self.waveform_writer = None
 228
 229     def reset(self):
 230         for signal_state in self.signals.values():
 231             signal_state.reset()
 232         self.pending.clear()
 233
 234         self.timestamp = 0.0
 235         self.deadlines.clear()
 236
 237     def for_signal(self, signal):
 238         try:
 239             return self.signals[signal]
 240         except KeyError:
 241             signal_state = _SignalState(signal, self.pending)
 242             self.signals[signal] = signal_state
 243             return signal_state
 244
 245     def commit(self):
 246         awoken_any = False
 247         for signal_state in self.pending:
 248             if signal_state.commit():
 249                 if signal_state.wakeup():
 250                     awoken_any = True
 251                 if self.waveform_writer is not None:
 252                     self.waveform_writer.update(self.timestamp,
 253                         signal_state.signal, signal_state.curr)
 254         self.pending.clear()
 255         return awoken_any
 256
 257     def advance(self):
 258         nearest_processes = set()
 259         nearest_deadline = None
 260         for process, deadline in self.deadlines.items():
 261             if deadline is None:
 262                 if nearest_deadline is not None:
 263                     nearest_processes.clear()
 264                 nearest_processes.add(process)
 265                 nearest_deadline = self.timestamp
 266                 break
 267             elif nearest_deadline is None or deadline <= nearest_deadline:
 268                 assert deadline >= self.timestamp
 269                 if nearest_deadline is not None and deadline < nearest_deadline:
 270                     nearest_processes.clear()
 271                 nearest_processes.add(process)
 272                 nearest_deadline = deadline
 273
 274         if not nearest_processes:
 275             return False
 276
 277         for process in nearest_processes:
 278             process.runnable = True
 279             del self.deadlines[process]
 280         self.timestamp = nearest_deadline
 281
 282         return True
 283
 284     def start_waveform(self, waveform_writer):
 285         if self.timestamp != 0.0:
 286             raise ValueError("Cannot start writing waveforms after advancing simulation time")
 287         if self.waveform_writer is not None:
 288             raise ValueError("Already writing waveforms to {!r}"
 289                              .format(self.waveform_writer))
 290         self.waveform_writer = waveform_writer
 291
 292     def finish_waveform(self):
 293         if self.waveform_writer is None:
 294             return
 295         self.waveform_writer.close(self.timestamp)
 296         self.waveform_writer = None
 297
 298
 299 class _EvalContext:
 300     __slots__ = ("state", "indexes", "slots")
 301
 302     def __init__(self, state):
 303         self.state = state
 304         self.indexes = SignalDict()
 305         self.slots = []
 306
 307     def get_signal(self, signal):
 308         try:
 309             return self.indexes[signal]
 310         except KeyError:
 311             index = len(self.slots)
 312             self.slots.append(self.state.for_signal(signal))
 313             self.indexes[signal] = index
 314             return index
 315
 316     def get_in_signal(self, signal, *, trigger=None):
 317         index = self.get_signal(signal)
 318         self.slots[index].waiters[self] = trigger
 319         return index
 320
 321     def get_out_signal(self, signal):
 322         return self.get_signal(signal)
 323
 324
 325 class _Emitter:
 326     def __init__(self):
 327         self._buffer = []
 328         self._suffix = 0
 329         self._level  = 0
 330
 331     def append(self, code):
 332         self._buffer.append("    " * self._level)
 333         self._buffer.append(code)
 334         self._buffer.append("\n")
 335
 336     @contextmanager
 337     def indent(self):
 338         self._level += 1
 339         yield
 340         self._level -= 1
 341
 342     def flush(self, indent=""):
 343         code = "".join(self._buffer)
 344         self._buffer.clear()
 345         return code
 346
 347     def gen_var(self, prefix):
 348         name = f"{prefix}_{self._suffix}"
 349         self._suffix += 1
 350         return name
 351
 352     def def_var(self, prefix, value):
 353         name = self.gen_var(prefix)
 354         self.append(f"{name} = {value}")
 355         return name
 356
 357
 358 class _Compiler:
 359     def __init__(self, context, emitter):
 360         self.context = context
 361         self.emitter = emitter
 362
 363
 364 class _ValueCompiler(ValueVisitor, _Compiler):
 365     helpers = {
 366         "sign": lambda value, sign: value | sign if value & sign else value,
 367         "zdiv": lambda lhs, rhs: 0 if rhs == 0 else lhs // rhs,
 368         "zmod": lambda lhs, rhs: 0 if rhs == 0 else lhs % rhs,
 369     }
 370
 371     def on_ClockSignal(self, value):
 372         raise NotImplementedError # :nocov:
 373
 374     def on_ResetSignal(self, value):
 375         raise NotImplementedError # :nocov:
 376
 377     def on_AnyConst(self, value):
 378         raise NotImplementedError # :nocov:
 379
 380     def on_AnySeq(self, value):
 381         raise NotImplementedError # :nocov:
 382
 383     def on_Sample(self, value):
 384         raise NotImplementedError # :nocov:
 385
 386     def on_Initial(self, value):
 387         raise NotImplementedError # :nocov:
 388
 389
 390 class _RHSValueCompiler(_ValueCompiler):
 391     def __init__(self, context, emitter, *, mode, inputs=None):
 392         super().__init__(context, emitter)
 393         assert mode in ("curr", "next")
 394         self.mode = mode
 395         # If not None, `inputs` gets populated with RHS signals.
 396         self.inputs = inputs
 397
 398     def on_Const(self, value):
 399         return f"{value.value}"
 400
 401     def on_Signal(self, value):
 402         if self.inputs is not None:
 403             self.inputs.add(value)
 404
 405         if self.mode == "curr":
 406             return f"slots[{self.context.get_signal(value)}].{self.mode}"
 407         else:
 408             return f"next_{self.context.get_signal(value)}"
 409
 410     def on_Operator(self, value):
 411         def mask(value):
 412             value_mask = (1 << len(value)) - 1
 413             return f"({self(value)} & {value_mask})"
 414
 415         def sign(value):
 416             if value.shape().signed:
 417                 return f"sign({mask(value)}, {-1 << (len(value) - 1)})"
 418             else: # unsigned
 419                 return mask(value)
 420
 421         if len(value.operands) == 1:
 422             arg, = value.operands
 423             if value.operator == "~":
 424                 return f"(~{self(arg)})"
 425             if value.operator == "-":
 426                 return f"(-{self(arg)})"
 427             if value.operator == "b":
 428                 return f"bool({mask(arg)})"
 429             if value.operator == "r|":
 430                 return f"({mask(arg)} != 0)"
 431             if value.operator == "r&":
 432                 return f"({mask(arg)} == {(1 << len(arg)) - 1})"
 433             if value.operator == "r^":
 434                 # Believe it or not, this is the fastest way to compute a sideways XOR in Python.
 435                 return f"(format({mask(arg)}, 'b').count('1') % 2)"
 436             if value.operator in ("u", "s"):
 437                 # These operators don't change the bit pattern, only its interpretation.
 438                 return self(arg)
 439         elif len(value.operands) == 2:
 440             lhs, rhs = value.operands
 441             lhs_mask = (1 << len(lhs)) - 1
 442             rhs_mask = (1 << len(rhs)) - 1
 443             if value.operator == "+":
 444                 return f"({sign(lhs)} + {sign(rhs)})"
 445             if value.operator == "-":
 446                 return f"({sign(lhs)} - {sign(rhs)})"
 447             if value.operator == "*":
 448                 return f"({sign(lhs)} * {sign(rhs)})"
 449             if value.operator == "//":
 450                 return f"zdiv({sign(lhs)}, {sign(rhs)})"
 451             if value.operator == "%":
 452                 return f"zmod({sign(lhs)}, {sign(rhs)})"
 453             if value.operator == "&":
 454                 return f"({self(lhs)} & {self(rhs)})"
 455             if value.operator == "|":
 456                 return f"({self(lhs)} | {self(rhs)})"
 457             if value.operator == "^":
 458                 return f"({self(lhs)} ^ {self(rhs)})"
 459             if value.operator == "<<":
 460                 return f"({sign(lhs)} << {sign(rhs)})"
 461             if value.operator == ">>":
 462                 return f"({sign(lhs)} >> {sign(rhs)})"
 463             if value.operator == "==":
 464                 return f"({sign(lhs)} == {sign(rhs)})"
 465             if value.operator == "!=":
 466                 return f"({sign(lhs)} != {sign(rhs)})"
 467             if value.operator == "<":
 468                 return f"({sign(lhs)} < {sign(rhs)})"
 469             if value.operator == "<=":
 470                 return f"({sign(lhs)} <= {sign(rhs)})"
 471             if value.operator == ">":
 472                 return f"({sign(lhs)} > {sign(rhs)})"
 473             if value.operator == ">=":
 474                 return f"({sign(lhs)} >= {sign(rhs)})"
 475         elif len(value.operands) == 3:
 476             if value.operator == "m":
 477                 sel, val1, val0 = value.operands
 478                 return f"({self(val1)} if {self(sel)} else {self(val0)})"
 479         raise NotImplementedError("Operator '{}' not implemented".format(value.operator)) # :nocov:
 480
 481     def on_Slice(self, value):
 482         return f"(({self(value.value)} >> {value.start}) & {(1 << len(value)) - 1})"
 483
 484     def on_Part(self, value):
 485         offset_mask = (1 << len(value.offset)) - 1
 486         offset = f"(({self(value.offset)} & {offset_mask}) * {value.stride})"
 487         return f"({self(value.value)} >> {offset} & " \
 488                f"{(1 << value.width) - 1})"
 489
 490     def on_Cat(self, value):
 491         gen_parts = []
 492         offset = 0
 493         for part in value.parts:
 494             part_mask = (1 << len(part)) - 1
 495             gen_parts.append(f"(({self(part)} & {part_mask}) << {offset})")
 496             offset += len(part)
 497         if gen_parts:
 498             return f"({' | '.join(gen_parts)})"
 499         return f"0"
 500
 501     def on_Repl(self, value):
 502         part_mask = (1 << len(value.value)) - 1
 503         gen_part = self.emitter.def_var("repl", f"{self(value.value)} & {part_mask}")
 504         gen_parts = []
 505         offset = 0
 506         for _ in range(value.count):
 507             gen_parts.append(f"({gen_part} << {offset})")
 508             offset += len(value.value)
 509         if gen_parts:
 510             return f"({' | '.join(gen_parts)})"
 511         return f"0"
 512
 513     def on_ArrayProxy(self, value):
 514         index_mask = (1 << len(value.index)) - 1
 515         gen_index = self.emitter.def_var("rhs_index", f"{self(value.index)} & {index_mask}")
 516         gen_value = self.emitter.gen_var("rhs_proxy")
 517         if value.elems:
 518             gen_elems = []
 519             for index, elem in enumerate(value.elems):
 520                 if index == 0:
 521                     self.emitter.append(f"if {gen_index} == {index}:")
 522                 else:
 523                     self.emitter.append(f"elif {gen_index} == {index}:")
 524                 with self.emitter.indent():
 525                     self.emitter.append(f"{gen_value} = {self(elem)}")
 526             self.emitter.append(f"else:")
 527             with self.emitter.indent():
 528                 self.emitter.append(f"{gen_value} = {self(value.elems[-1])}")
 529             return gen_value
 530         else:
 531             return f"0"
 532
 533     @classmethod
 534     def compile(cls, context, value, *, mode, inputs=None):
 535         emitter = _Emitter()
 536         compiler = cls(context, emitter, mode=mode, inputs=inputs)
 537         emitter.append(f"result = {compiler(value)}")
 538         return emitter.flush()
 539
 540
 541 class _LHSValueCompiler(_ValueCompiler):
 542     def __init__(self, context, emitter, *, rhs, outputs=None):
 543         super().__init__(context, emitter)
 544         # `rrhs` is used to translate rvalues that are syntactically a part of an lvalue, e.g.
 545         # the offset of a Part.
 546         self.rrhs = rhs
 547         # `lrhs` is used to translate the read part of a read-modify-write cycle during partial
 548         # update of an lvalue.
 549         self.lrhs = _RHSValueCompiler(context, emitter, mode="next", inputs=None)
 550         # If not None, `outputs` gets populated with signals on LHS.
 551         self.outputs = outputs
 552
 553     def on_Const(self, value):
 554         raise TypeError # :nocov:
 555
 556     def on_Signal(self, value):
 557         if self.outputs is not None:
 558             self.outputs.add(value)
 559
 560         def gen(arg):
 561             value_mask = (1 << len(value)) - 1
 562             if value.shape().signed:
 563                 value_sign = f"sign({arg} & {value_mask}, {-1 << (len(value) - 1)})"
 564             else: # unsigned
 565                 value_sign = f"{arg} & {value_mask}"
 566             self.emitter.append(f"next_{self.context.get_out_signal(value)} = {value_sign}")
 567         return gen
 568
 569     def on_Operator(self, value):
 570         raise TypeError # :nocov:
 571
 572     def on_Slice(self, value):
 573         def gen(arg):
 574             width_mask = (1 << (value.stop - value.start)) - 1
 575             self(value.value)(f"({self.lrhs(value.value)} & " \
 576                 f"{~(width_mask << value.start)} | " \
 577                 f"(({arg} & {width_mask}) << {value.start}))")
 578         return gen
 579
 580     def on_Part(self, value):
 581         def gen(arg):
 582             width_mask = (1 << value.width) - 1
 583             offset_mask = (1 << len(value.offset)) - 1
 584             offset = f"(({self.rrhs(value.offset)} & {offset_mask}) * {value.stride})"
 585             self(value.value)(f"({self.lrhs(value.value)} & " \
 586                 f"~({width_mask} << {offset}) | " \
 587                 f"(({arg} & {width_mask}) << {offset}))")
 588         return gen
 589
 590     def on_Cat(self, value):
 591         def gen(arg):
 592             gen_arg = self.emitter.def_var("cat", arg)
 593             gen_parts = []
 594             offset = 0
 595             for part in value.parts:
 596                 part_mask = (1 << len(part)) - 1
 597                 self(part)(f"(({gen_arg} >> {offset}) & {part_mask})")
 598                 offset += len(part)
 599         return gen
 600
 601     def on_Repl(self, value):
 602         raise TypeError # :nocov:
 603
 604     def on_ArrayProxy(self, value):
 605         def gen(arg):
 606             index_mask = (1 << len(value.index)) - 1
 607             gen_index = self.emitter.def_var("index", f"{self.rrhs(value.index)} & {index_mask}")
 608             if value.elems:
 609                 gen_elems = []
 610                 for index, elem in enumerate(value.elems):
 611                     if index == 0:
 612                         self.emitter.append(f"if {gen_index} == {index}:")
 613                     else:
 614                         self.emitter.append(f"elif {gen_index} == {index}:")
 615                     with self.emitter.indent():
 616                         self(elem)(arg)
 617                 self.emitter.append(f"else:")
 618                 with self.emitter.indent():
 619                     self(value.elems[-1])(arg)
 620             else:
 621                 self.emitter.append(f"pass")
 622         return gen
 623
 624     @classmethod
 625     def compile(cls, context, stmt, *, inputs=None, outputs=None):
 626         emitter = _Emitter()
 627         compiler = cls(context, emitter, inputs=inputs, outputs=outputs)
 628         compiler(stmt)
 629         return emitter.flush()
 630
 631
 632 class _StatementCompiler(StatementVisitor, _Compiler):
 633     def __init__(self, context, emitter, *, inputs=None, outputs=None):
 634         super().__init__(context, emitter)
 635         self.rhs = _RHSValueCompiler(context, emitter, mode="curr", inputs=inputs)
 636         self.lhs = _LHSValueCompiler(context, emitter, rhs=self.rhs, outputs=outputs)
 637
 638     def on_statements(self, stmts):
 639         for stmt in stmts:
 640             self(stmt)
 641         if not stmts:
 642             self.emitter.append("pass")
 643
 644     def on_Assign(self, stmt):
 645         return self.lhs(stmt.lhs)(self.rhs(stmt.rhs))
 646
 647     def on_Switch(self, stmt):
 648         gen_test = self.emitter.def_var("test",
 649             f"{self.rhs(stmt.test)} & {(1 << len(stmt.test)) - 1}")
 650         for index, (patterns, stmts) in enumerate(stmt.cases.items()):
 651             gen_checks = []
 652             if not patterns:
 653                 gen_checks.append(f"True")
 654             else:
 655                 for pattern in patterns:
 656                     if "-" in pattern:
 657                         mask  = int("".join("0" if b == "-" else "1" for b in pattern), 2)
 658                         value = int("".join("0" if b == "-" else  b  for b in pattern), 2)
 659                         gen_checks.append(f"({gen_test} & {mask}) == {value}")
 660                     else:
 661                         value = int(pattern, 2)
 662                         gen_checks.append(f"{gen_test} == {value}")
 663             if index == 0:
 664                 self.emitter.append(f"if {' or '.join(gen_checks)}:")
 665             else:
 666                 self.emitter.append(f"elif {' or '.join(gen_checks)}:")
 667             with self.emitter.indent():
 668                 self(stmts)
 669
 670     def on_Assert(self, stmt):
 671         raise NotImplementedError # :nocov:
 672
 673     def on_Assume(self, stmt):
 674         raise NotImplementedError # :nocov:
 675
 676     def on_Cover(self, stmt):
 677         raise NotImplementedError # :nocov:
 678
 679     @classmethod
 680     def compile(cls, context, stmt, *, inputs=None, outputs=None):
 681         output_indexes = [context.get_signal(signal) for signal in stmt._lhs_signals()]
 682         emitter = _Emitter()
 683         for signal_index in output_indexes:
 684             emitter.append(f"next_{signal_index} = slots[{signal_index}].next")
 685         compiler = cls(context, emitter, inputs=inputs, outputs=outputs)
 686         compiler(stmt)
 687         for signal_index in output_indexes:
 688             emitter.append(f"slots[{signal_index}].set(next_{signal_index})")
 689         return emitter.flush()
 690
 691
 692 class _CompiledProcess(_Process):
 693     __slots__ = ("context", "comb", "name", "run")
 694
 695     def __init__(self, state, *, comb, name):
 696         self.context = _EvalContext(state)
 697         self.comb = comb
 698         self.name = name
 699         self.run = None # set by _FragmentCompiler
 700         self.reset()
 701
 702     def reset(self):
 703         self.runnable = self.comb
 704         self.passive = True
 705
 706
 707 class _FragmentCompiler:
 708     def __init__(self, state, signal_names):
 709         self.state = state
 710         self.signal_names = signal_names
 711
 712     def __call__(self, fragment, *, hierarchy=("top",)):
 713         processes = set()
 714
 715         def add_signal_name(signal):
 716             hierarchical_signal_name = (*hierarchy, signal.name)
 717             if signal not in self.signal_names:
 718                 self.signal_names[signal] = {hierarchical_signal_name}
 719             else:
 720                 self.signal_names[signal].add(hierarchical_signal_name)
 721
 722         for domain_name, domain_signals in fragment.drivers.items():
 723             domain_stmts = LHSGroupFilter(domain_signals)(fragment.statements)
 724             domain_process = _CompiledProcess(self.state, comb=domain_name is None,
 725                 name=".".join((*hierarchy, "<{}>".format(domain_name or "comb"))))
 726
 727             emitter = _Emitter()
 728             emitter.append(f"def run():")
 729             emitter._level += 1
 730
 731             if domain_name is None:
 732                 for signal in domain_signals:
 733                     signal_index = domain_process.context.get_signal(signal)
 734                     emitter.append(f"next_{signal_index} = {signal.reset}")
 735
 736                 inputs = SignalSet()
 737                 _StatementCompiler(domain_process.context, emitter, inputs=inputs)(domain_stmts)
 738
 739                 for input in inputs:
 740                     self.state.for_signal(input).wait(domain_process)
 741
 742             else:
 743                 domain = fragment.domains[domain_name]
 744                 add_signal_name(domain.clk)
 745                 if domain.rst is not None:
 746                     add_signal_name(domain.rst)
 747
 748                 clk_trigger = 1 if domain.clk_edge == "pos" else 0
 749                 self.state.for_signal(domain.clk).wait(domain_process, trigger=clk_trigger)
 750                 if domain.rst is not None and domain.async_reset:
 751                     rst_trigger = 1
 752                     self.state.for_signal(domain.rst).wait(domain_process, trigger=rst_trigger)
 753
 754                 gen_asserts = []
 755                 clk_index = domain_process.context.get_signal(domain.clk)
 756                 gen_asserts.append(f"slots[{clk_index}].curr == {clk_trigger}")
 757                 if domain.rst is not None and domain.async_reset:
 758                     rst_index = domain_process.context.get_signal(domain.rst)
 759                     gen_asserts.append(f"slots[{rst_index}].curr == {rst_trigger}")
 760                 emitter.append(f"assert {' or '.join(gen_asserts)}")
 761
 762                 for signal in domain_signals:
 763                     signal_index = domain_process.context.get_signal(signal)
 764                     emitter.append(f"next_{signal_index} = slots[{signal_index}].next")
 765
 766                 _StatementCompiler(domain_process.context, emitter)(domain_stmts)
 767
 768             for signal in domain_signals:
 769                 signal_index = domain_process.context.get_signal(signal)
 770                 emitter.append(f"slots[{signal_index}].set(next_{signal_index})")
 771
 772             # There shouldn't be any exceptions raised by the generated code, but if there are
 773             # (almost certainly due to a bug in the code generator), use this environment variable
 774             # to make backtraces useful.
 775             code = emitter.flush()
 776             if os.getenv("NMIGEN_pysim_dump"):
 777                 file = tempfile.NamedTemporaryFile("w", prefix="nmigen_pysim_", delete=False)
 778                 file.write(code)
 779                 filename = file.name
 780             else:
 781                 filename = "<string>"
 782
 783             exec_locals = {"slots": domain_process.context.slots, **_ValueCompiler.helpers}
 784             exec(compile(code, filename, "exec"), exec_locals)
 785             domain_process.run = exec_locals["run"]
 786
 787             processes.add(domain_process)
 788
 789             for used_signal in domain_process.context.indexes:
 790                 add_signal_name(used_signal)
 791
 792         for subfragment_index, (subfragment, subfragment_name) in enumerate(fragment.subfragments):
 793             if subfragment_name is None:
 794                 subfragment_name = "U${}".format(subfragment_index)
 795             processes.update(self(subfragment, hierarchy=(*hierarchy, subfragment_name)))
 796
 797         return processes
 798
 799
 800 class _CoroutineProcess(_Process):
 801     def __init__(self, state, domains, constructor, *, default_cmd=None):
 802         self.state = state
 803         self.domains = domains
 804         self.constructor = constructor
 805         self.default_cmd = default_cmd
 806         self.reset()
 807
 808     def reset(self):
 809         self.runnable = True
 810         self.passive = False
 811         self.coroutine = self.constructor()
 812         self.eval_context = _EvalContext(self.state)
 813         self.exec_locals = {
 814             "slots": self.eval_context.slots,
 815             "result": None,
 816             **_ValueCompiler.helpers
 817         }
 818         self.waits_on = set()
 819
 820     @property
 821     def name(self):
 822         coroutine = self.coroutine
 823         while coroutine.gi_yieldfrom is not None:
 824             coroutine = coroutine.gi_yieldfrom
 825         if inspect.isgenerator(coroutine):
 826             frame = coroutine.gi_frame
 827         if inspect.iscoroutine(coroutine):
 828             frame = coroutine.cr_frame
 829         return "{}:{}".format(inspect.getfile(frame), inspect.getlineno(frame))
 830
 831     def get_in_signal(self, signal, *, trigger=None):
 832         signal_state = self.state.for_signal(signal)
 833         assert self not in signal_state.waiters
 834         signal_state.waiters[self] = trigger
 835         self.waits_on.add(signal_state)
 836         return signal_state
 837
 838     def run(self):
 839         if self.coroutine is None:
 840             return
 841
 842         if self.waits_on:
 843             for signal_state in self.waits_on:
 844                 del signal_state.waiters[self]
 845             self.waits_on.clear()
 846
 847         response = None
 848         while True:
 849             try:
 850                 command = self.coroutine.send(response)
 851                 if command is None:
 852                     command = self.default_cmd
 853                 response = None
 854
 855                 if isinstance(command, Value):
 856                     exec(_RHSValueCompiler.compile(self.eval_context, command, mode="curr"),
 857                         self.exec_locals)
 858                     response = Const.normalize(self.exec_locals["result"], command.shape())
 859
 860                 elif isinstance(command, Statement):
 861                     exec(_StatementCompiler.compile(self.eval_context, command),
 862                         self.exec_locals)
 863
 864                 elif type(command) is Tick:
 865                     domain = command.domain
 866                     if isinstance(domain, ClockDomain):
 867                         pass
 868                     elif domain in self.domains:
 869                         domain = self.domains[domain]
 870                     else:
 871                         raise NameError("Received command {!r} that refers to a nonexistent "
 872                                         "domain {!r} from process {!r}"
 873                                         .format(command, command.domain, self.name))
 874                     self.get_in_signal(domain.clk, trigger=1 if domain.clk_edge == "pos" else 0)
 875                     if domain.rst is not None and domain.async_reset:
 876                         self.get_in_signal(domain.rst, trigger=1)
 877                     return
 878
 879                 elif type(command) is Settle:
 880                     self.state.deadlines[self] = None
 881                     return
 882
 883                 elif type(command) is Delay:
 884                     if command.interval is None:
 885                         self.state.deadlines[self] = None
 886                     else:
 887                         self.state.deadlines[self] = self.state.timestamp + command.interval
 888                     return
 889
 890                 elif type(command) is Passive:
 891                     self.passive = True
 892
 893                 elif type(command) is Active:
 894                     self.passive = False
 895
 896                 elif command is None: # only possible if self.default_cmd is None
 897                     raise TypeError("Received default command from process {!r} that was added "
 898                                     "with add_process(); did you mean to add this process with "
 899                                     "add_sync_process() instead?"
 900                                     .format(self.name))
 901
 902                 else:
 903                     raise TypeError("Received unsupported command {!r} from process {!r}"
 904                                     .format(command, self.name))
 905
 906             except StopIteration:
 907                 self.passive = True
 908                 self.coroutine = None
 909                 return
 910
 911             except Exception as exn:
 912                 self.coroutine.throw(exn)
 913
 914
 915 class _WaveformContextManager:
 916     def __init__(self, state, waveform_writer):
 917         self._state = state
 918         self._waveform_writer = waveform_writer
 919
 920     def __enter__(self):
 921         try:
 922             self._state.start_waveform(self._waveform_writer)
 923         except:
 924             self._waveform_writer.close(0)
 925             raise
 926
 927     def __exit__(self, *args):
 928         self._state.finish_waveform()
 929
 930
 931 class Simulator:
 932     def __init__(self, fragment, **kwargs):
 933         self._state = _SimulatorState()
 934         self._signal_names = SignalDict()
 935         self._fragment = Fragment.get(fragment, platform=None).prepare()
 936         self._processes = _FragmentCompiler(self._state, self._signal_names)(self._fragment)
 937         if kwargs: # :nocov:
 938             # TODO(nmigen-0.3): remove
 939             self._state.start_waveform(_VCDWaveformWriter(self._signal_names, **kwargs))
 940         self._clocked = set()
 941
 942     def _check_process(self, process):
 943         if not (inspect.isgeneratorfunction(process) or inspect.iscoroutinefunction(process)):
 944             if inspect.isgenerator(process) or inspect.iscoroutine(process):
 945                 warnings.warn("instead of generators, use generator functions as processes; "
 946                               "this allows the simulator to be repeatedly reset",
 947                               DeprecationWarning, stacklevel=3)
 948                 def wrapper():
 949                     yield from process
 950                 return wrapper
 951             else:
 952                 raise TypeError("Cannot add a process {!r} because it is not a generator function"
 953                                 .format(process))
 954         return process
 955
 956     def _add_coroutine_process(self, process, *, default_cmd):
 957         self._processes.add(_CoroutineProcess(self._state, self._fragment.domains, process,
 958                                               default_cmd=default_cmd))
 959
 960     def add_process(self, process):
 961         process = self._check_process(process)
 962         def wrapper():
 963             # Only start a bench process after comb settling, so that the reset values are correct.
 964             yield Settle()
 965             yield from process()
 966         self._add_coroutine_process(wrapper, default_cmd=None)
 967
 968     def add_sync_process(self, process, *, domain="sync"):
 969         process = self._check_process(process)
 970         def wrapper():
 971             # Only start a sync process after the first clock edge (or reset edge, if the domain
 972             # uses an asynchronous reset). This matches the behavior of synchronous FFs.
 973             yield Tick(domain)
 974             yield from process()
 975         return self._add_coroutine_process(wrapper, default_cmd=Tick(domain))
 976
 977     def add_clock(self, period, *, phase=None, domain="sync", if_exists=False):
 978         """Add a clock process.
 979
 980         Adds a process that drives the clock signal of ``domain`` at a 50% duty cycle.
 981
 982         Arguments
 983         ---------
 984         period : float
 985             Clock period. The process will toggle the ``domain`` clock signal every ``period / 2``
 986             seconds.
 987         phase : None or float
 988             Clock phase. The process will wait ``phase`` seconds before the first clock transition.
 989             If not specified, defaults to ``period / 2``.
 990         domain : str or ClockDomain
 991             Driven clock domain. If specified as a string, the domain with that name is looked up
 992             in the root fragment of the simulation.
 993         if_exists : bool
 994             If ``False`` (the default), raise an error if the driven domain is specified as
 995             a string and the root fragment does not have such a domain. If ``True``, do nothing
 996             in this case.
 997         """
 998         if isinstance(domain, ClockDomain):
 999             pass
1000         elif domain in self._fragment.domains:
1001             domain = self._fragment.domains[domain]
1002         elif if_exists:
1003             return
1004         else:
1005             raise ValueError("Domain {!r} is not present in simulation"
1006                              .format(domain))
1007         if domain in self._clocked:
1008             raise ValueError("Domain {!r} already has a clock driving it"
1009                              .format(domain.name))
1010
1011         half_period = period / 2
1012         if phase is None:
1013             # By default, delay the first edge by half period. This causes any synchronous activity
1014             # to happen at a non-zero time, distinguishing it from the reset values in the waveform
1015             # viewer.
1016             phase = half_period
1017         def clk_process():
1018             yield Passive()
1019             yield Delay(phase)
1020             # Behave correctly if the process is added after the clock signal is manipulated, or if
1021             # its reset state is high.
1022             initial = (yield domain.clk)
1023             steps = (
1024                 domain.clk.eq(~initial),
1025                 Delay(half_period),
1026                 domain.clk.eq(initial),
1027                 Delay(half_period),
1028             )
1029             while True:
1030                 yield from iter(steps)
1031         self._add_coroutine_process(clk_process, default_cmd=None)
1032         self._clocked.add(domain)
1033
1034     def reset(self):
1035         """Reset the simulation.
1036
1037         Assign the reset value to every signal in the simulation, and restart every user process.
1038         """
1039         self._state.reset()
1040         for process in self._processes:
1041             process.reset()
1042
1043     def _delta(self):
1044         """Perform a delta cycle.
1045
1046         Performs the two phases of a delta cycle:
1047             1. run and suspend every non-waiting process once, queueing signal changes;
1048             2. commit every queued signal change, waking up any waiting process.
1049         """
1050         for process in self._processes:
1051             if process.runnable:
1052                 process.runnable = False
1053                 process.run()
1054
1055         return self._state.commit()
1056
1057     def _settle(self):
1058         """Settle the simulation.
1059
1060         Run every process and commit changes until a fixed point is reached. If there is
1061         an unstable combinatorial loop, this function will never return.
1062         """
1063         while self._delta():
1064             pass
1065
1066     def step(self):
1067         """Step the simulation.
1068
1069         Run every process and commit changes until a fixed point is reached, then advance time
1070         to the closest deadline (if any). If there is an unstable combinatorial loop,
1071         this function will never return.
1072
1073         Returns ``True`` if there are any active processes, ``False`` otherwise.
1074         """
1075         self._settle()
1076         self._state.advance()
1077         return any(not process.passive for process in self._processes)
1078
1079     def run(self):
1080         """Run the simulation while any processes are active.
1081
1082         Processes added with :meth:`add_process` and :meth:`add_sync_process` are initially active,
1083         and may change their status using the ``yield Passive()`` and ``yield Active()`` commands.
1084         Processes compiled from HDL and added with :meth:`add_clock` are always passive.
1085         """
1086         while self.step():
1087             pass
1088
1089     def run_until(self, deadline, *, run_passive=False):
1090         """Run the simulation until it advances to ``deadline``.
1091
1092         If ``run_passive`` is ``False``, the simulation also stops when there are no active
1093         processes, similar to :meth:`run`. Otherwise, the simulation will stop only after it
1094         advances to or past ``deadline``.
1095
1096         If the simulation stops advancing, this function will never return.
1097         """
1098         assert self._state.timestamp <= deadline
1099         while (self.step() or run_passive) and self._state.timestamp < deadline:
1100             pass
1101
1102     def write_vcd(self, vcd_file, gtkw_file=None, *, traces=()):
1103         """Write waveforms to a Value Change Dump file, optionally populating a GTKWave save file.
1104
1105         This method returns a context manager. It can be used as: ::
1106
1107             sim = Simulator(frag)
1108             sim.add_clock(1e-6)
1109             with sim.write_vcd("dump.vcd", "dump.gtkw"):
1110                 sim.run_until(1e-3)
1111
1112         Arguments
1113         ---------
1114         vcd_file : str or file-like object
1115             Verilog Value Change Dump file or filename.
1116         gtkw_file : str or file-like object
1117             GTKWave save file or filename.
1118         traces : iterable of Signal
1119             Signals to display traces for.
1120         """
1121         waveform_writer = _VCDWaveformWriter(self._signal_names,
1122             vcd_file=vcd_file, gtkw_file=gtkw_file, traces=traces)
1123         return _WaveformContextManager(self._state, waveform_writer)
1124
1125     # TODO(nmigen-0.3): remove
1126     @deprecated("instead of `with Simulator(fragment, ...) as sim:`, use "
1127                 "`sim = Simulator(fragment); with sim.write_vcd(...):`")
1128     def __enter__(self): # :nocov:
1129         return self
1130
1131     # TODO(nmigen-0.3): remove
1132     def __exit__(self, *args): # :nocov:
1133         self._state.finish_waveform()