Coverage for MC6809/components/mc6809_speedlimited.py: 21%

1#!/usr/bin/env python 

2 

3""" 

4 MC6809 - 6809 CPU emulator in Python 

5 ======================================= 

6 

7 6809 is Big-Endian 

8 

9 Links: 

10 http://dragondata.worldofdragon.org/Publications/inside-dragon.htm 

11 http://www.burgins.com/m6809.html 

12 http://koti.mbnet.fi/~atjs/mc6809/ 

13 

14 :copyleft: 2013-2015 by the MC6809 team, see AUTHORS for more details. 

15 :license: GNU GPL v3 or above, see LICENSE for more details. 

16 

17 Based on: 

18 * ApplyPy by James Tauber (MIT license) 

19 * XRoar emulator by Ciaran Anscomb (GPL license) 

20 more info, see README 

21""" 

22 

23 

24import time 

25 

26 

27class CPUSpeedLimitMixin: 

28 max_delay = 0.01 # maximum time.sleep() value per burst run 

29 delay = 0 # the current time.sleep() value per burst run 

30 

31 def delayed_burst_run(self, target_cycles_per_sec): 

32 """ Run CPU not faster than given speedlimit """ 

33 old_cycles = self.cycles 

34 start_time = time.time() 

35 

36 self.burst_run() 

37 

38 is_duration = time.time() - start_time 

39 new_cycles = self.cycles - old_cycles 

40 try: 

41 is_cycles_per_sec = new_cycles / is_duration 

42 except ZeroDivisionError: 

43 pass 

44 else: 

45 should_burst_duration = is_cycles_per_sec / target_cycles_per_sec 

46 target_duration = should_burst_duration * is_duration 

47 delay = target_duration - is_duration 

48 if delay > 0: 

49 if delay > self.max_delay: 

50 self.delay = self.max_delay 

51 else: 

52 self.delay = delay 

53 time.sleep(self.delay) 

54 

55 self.call_sync_callbacks()