gram/compat.py

   1 # This file is Copyright (c) 2020 LambdaConcept <contact@lambdaconcept.com>
   2
   3 import unittest
   4
   5 from nmigen import *
   6 from nmigen import tracer
   7 from nmigen.compat import Case
   8 from nmigen.back.pysim import *
   9
  10 __ALL__ = ["delayed_enter", "Timeline", "CSRPrefixProxy"]
  11
  12
  13 def delayed_enter(m, src, dst, delay):
  14     assert delay > 0
  15
  16     for i in range(delay):
  17         if i == 0:
  18             statename = src
  19         else:
  20             statename = "{}-{}".format(src, i)
  21
  22         if i == delay-1:
  23             deststate = dst
  24         else:
  25             deststate = "{}-{}".format(src, i+1)
  26
  27         with m.State(statename):
  28             m.next = deststate
  29
  30
  31 class Timeline(Elaboratable):
  32     def __init__(self, events):
  33         self.trigger = Signal()
  34         self._events = events
  35
  36     def elaborate(self, platform):
  37         m = Module()
  38
  39         lastevent = max([e[0] for e in self._events])
  40         counter = Signal(range(lastevent+1))
  41
  42         # Counter incrementation
  43         # (with overflow handling)
  44         if (lastevent & (lastevent + 1)) != 0:
  45             with m.If(counter == lastevent):
  46                 m.d.sync += counter.eq(0)
  47             with m.Else():
  48                 with m.If(counter != 0):
  49                     m.d.sync += counter.eq(counter+1)
  50                 with m.Elif(self.trigger):
  51                     m.d.sync += counter.eq(1)
  52         else:
  53             with m.If(counter != 0):
  54                 m.d.sync += counter.eq(counter+1)
  55             with m.Elif(self.trigger):
  56                 m.d.sync += counter.eq(1)
  57
  58         for e in self._events:
  59             if e[0] == 0:
  60                 with m.If(self.trigger & (counter == 0)):
  61                     m.d.sync += e[1]
  62             else:
  63                 with m.If(counter == e[0]):
  64                     m.d.sync += e[1]
  65
  66         return m
  67
  68
  69 class CSRPrefixProxy:
  70     def __init__(self, bank, prefix):
  71         self._bank = bank
  72         self._prefix = prefix
  73
  74     def csr(self, width, access, *, addr=None, alignment=None, name=None,
  75             src_loc_at=0):
  76         if name is not None and not isinstance(name, str):
  77             raise TypeError("Name must be a string, not {!r}".format(name))
  78         name = name or tracer.get_var_name(depth=2 + src_loc_at).lstrip("_")
  79
  80         prefixed_name = "{}_{}".format(self._prefix, name)
  81         return self._bank.csr(width=width, access=access, addr=addr,
  82                               alignment=alignment, name=prefixed_name)