src/nmutil/sim_tmp_alternative.py

   1 """Run-time selection of simulator engine
   2
   3 Usage::
   4
   5     from nmutil.sim_tmp_alternative import Simulator
   6
   7 Then, use :py:class:`Simulator` as usual.
   8
   9 This should be backwards compatible to old developer versions of nMigen.
  10
  11 To use cxxsim, export ``NMIGEN_SIM_MODE=cxxsim`` from the shell.
  12 Be sure to check out the ``cxxsim`` branch of nMigen, and update yosys
  13 to the latest commit as well.
  14
  15 To use pysim, just keep ``NMIGEN_SIM_MODE`` unset.
  16 Alternatively, export ``NMIGEN_SIM_MODE=pysim``.
  17
  18 Example::
  19
  20     $ export NMIGEN_SIM_MODE=...  # pysim or cxxsim, default is pysim
  21     $ python ...
  22
  23 or, even::
  24
  25     $ NMIGEN_SIM_MODE=...  python ...
  26 """
  27
  28 import os
  29
  30 try:
  31     from nmigen.sim import (Simulator as RealSimulator, Delay, Settle, Tick,
  32                             Passive)
  33     detected_new_api = True
  34 except ImportError:
  35     detected_new_api = False
  36     try:
  37         from nmigen.sim.pysim import (Simulator as RealSimulator,
  38                                       Delay, Settle, Tick, Passive)
  39     except ImportError:
  40         from nmigen.back.pysim import (Simulator as RealSimulator,
  41                                        Delay, Settle, Tick, Passive)
  42
  43 nmigen_sim_environ_variable = os.environ.get("NMIGEN_SIM_MODE") \
  44     or "pysim"
  45 """Detected run-time engine from environment"""
  46
  47
  48 def Simulator(*args, **kwargs):
  49     """Wrapper that allows run-time selection of simulator engine"""
  50     if detected_new_api and 'engine' not in kwargs:
  51         kwargs['engine'] = nmigen_sim_environ_variable
  52     return RealSimulator(*args, **kwargs)
  53
  54
  55 def is_engine_cxxsim():
  56     """Returns ``True`` if the selected engine is cxxsim"""
  57     return detected_new_api and nmigen_sim_environ_variable == "cxxsim"
  58
  59
  60 def is_engine_pysim():
  61     """Returns ``True`` if the selected engine is pysim"""
  62     return not detected_new_api or nmigen_sim_environ_variable == "pysim"
  63
  64
  65 nmigen_sim_top_module = "top." if is_engine_pysim() else ""
  66 """Work-around for cxxsim not defining the top-level module"""