litex/gen/sim/vcd.py

   1 from itertools import count
   2 import tempfile
   3 import os
   4 from collections import OrderedDict
   5 import shutil
   6
   7 from litex.gen.fhdl.namer import build_namespace
   8
   9
  10 def vcd_codes():
  11     codechars = [chr(i) for i in range(33, 127)]
  12     for n in count():
  13         q, r = divmod(n, len(codechars))
  14         code = codechars[r]
  15         while q > 0:
  16             q, r = divmod(q, len(codechars))
  17             code = codechars[r] + code
  18         yield code
  19
  20
  21 class VCDWriter:
  22     def __init__(self, filename):
  23         self.filename = filename
  24         self.out_file = open(self.filename, "w")
  25         self.codegen = vcd_codes()
  26         self.codes = OrderedDict()
  27         self.signal_values = dict()
  28         self.t = 0
  29
  30     def _write_value(self, f, signal, value):
  31         l = len(signal)
  32         if value < 0:
  33             value += 2**l
  34         if l > 1:
  35             fmtstr = "b{:0" + str(l) + "b} {}\n"
  36         else:
  37             fmtstr = "{}{}\n"
  38         code = self.codes[signal]
  39         f.write(fmtstr.format(value, code))
  40
  41     def init(self, signals):
  42         # generate codes
  43         for signal in signals:
  44             try:
  45                 code = self.codes[signal]
  46             except KeyError:
  47                 code = next(self.codegen)
  48                 self.codes[signal] = code
  49
  50         # write vcd header
  51         out = self.out_file
  52         ns = build_namespace(self.codes.keys())
  53         for signal, code in self.codes.items():
  54             name = ns.get_name(signal)
  55             out.write("$var wire {len} {code} {name} $end\n"
  56                       .format(name=name, code=code, len=len(signal)))
  57         out.write("$dumpvars\n")
  58         for signal in self.codes.keys():
  59             self._write_value(out, signal, signal.reset.value)
  60         out.write("$end\n")
  61         out.write("#0\n")
  62
  63     def set(self, signal, value):
  64         if (signal not in self.signal_values
  65                 or self.signal_values[signal] != value):
  66             self._write_value(self.out_file, signal, value)
  67             self.signal_values[signal] = value
  68
  69     def delay(self, delay):
  70         self.t += delay
  71         self.out_file.write("#{}\n".format(self.t))
  72
  73     def close(self):
  74         self.out_file.close()
  75
  76
  77 class DummyVCDWriter:
  78     def init(self):
  79         pass
  80
  81     def set(self, signal, value):
  82         pass
  83
  84     def delay(self, delay):
  85         pass
  86
  87     def close(self):
  88         pass