litex/build/sim/config.py

   1 # This file is Copyright (c) 2017 Pierre-Olivier Vauboin <po@lambdaconcept>
   2 # This file is Copyright (c) 2018 Florent Kermarrec <florent@enjoy-digital.fr>
   3 # License: BSD
   4
   5 import json
   6 import math
   7
   8 class SimConfig():
   9     def __init__(self, timebase_ps=None):
  10         self.modules = []
  11         self.timebase_ps = timebase_ps
  12
  13     def _format_interfaces(self, interfaces):
  14         if not isinstance(interfaces, list):
  15             interfaces = [interfaces]
  16         new = []
  17         for it in interfaces:
  18             obj = it
  19             if isinstance(it, tuple):
  20                 name, index = it
  21                 obj = {"name": name, "index": index}
  22             new.append(obj)
  23         return new
  24
  25     def _format_timebase(self):
  26         timebase_ps = self.timebase_ps
  27         if timebase_ps is None:
  28             timebase_ps = self._get_timebase_ps()
  29         return {"timebase": int(timebase_ps)}
  30
  31     def _get_timebase_ps(self):
  32         clockers = [m for m in self.modules if m["module"] == "clocker"]
  33         periods_ps = [1e12 / m["args"]["freq_hz"] for m in clockers]
  34         # timebase is half of the shortest period
  35         for p in periods_ps:
  36             assert round(p/2) == int(p//2), "Period cannot be represented: {}".format(p)
  37         half_period = [int(p//2) for p in periods_ps]
  38         # find greatest common denominator
  39         gcd = half_period[0]
  40         for p in half_period[1:]:
  41             gcd = math.gcd(gcd, p)
  42         assert gcd >= 1
  43         return gcd
  44
  45     def add_clocker(self, clk, freq_hz, phase_deg=0):
  46         args = {"freq_hz": freq_hz, "phase_deg": phase_deg}
  47         self.add_module("clocker", [], clocks=clk, tickfirst=True, args=args)
  48
  49     def add_module(self, name, interfaces, clocks="sys_clk", args=None, tickfirst=False):
  50         interfaces = self._format_interfaces(interfaces)
  51         interfaces += self._format_interfaces(clocks)
  52         newmod = {
  53             "module": name,
  54             "interface": interfaces,
  55         }
  56         if args:
  57             newmod.update({"args": args})
  58         if tickfirst:
  59             newmod.update({"tickfirst": tickfirst})
  60         self.modules.append(newmod)
  61
  62     def has_module(self, name):
  63         for module in self.modules:
  64             if module["module"] == name:
  65                 return True
  66         return False
  67
  68     def get_json(self):
  69         assert "clocker" in (m["module"] for m in self.modules), \
  70             "No simulation clocker found! Use sim_config.add_clocker() to define one or more clockers."
  71         config = self.modules + [self._format_timebase()]
  72         return json.dumps(config, indent=4)