ticks.py revision 4167:ce5d0f62f13b 
1# Copyright (c) 2007 The Regents of The University of Michigan
2# All rights reserved.
3#
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5# modification, are permitted provided that the following conditions are
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8# redistributions in binary form must reproduce the above copyright
9# notice, this list of conditions and the following disclaimer in the
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13# this software without specific prior written permission.
14#
15# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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21# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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26#
27# Authors: Nathan Binkert
28
29import sys
30
31import convert
32import internal
33
34tps = 1.0e12         # default to 1 THz (1 Tick == 1 ps)
35tps_fixed = False    # once set to true, can't be changed
36
37# fix the global frequency and tell C++ about it
38def fixGlobalFrequency():
39    global tps, tps_fixed
40    if not tps_fixed:
41        tps_fixed = True
42        internal.core.setClockFrequency(int(tps))
43        print "Global frequency set at %d ticks per second" % int(tps)
44
45def setGlobalFrequency(ticksPerSecond):
46    global tps, tps_fixed
47
48    if tps_fixed:
49        raise AttributeError, \
50              "Global frequency already fixed at %f ticks/s." % tps
51
52    if isinstance(ticksPerSecond, (int, long)):
53        tps = ticksPerSecond
54    elif isinstance(ticksPerSecond, float):
55        tps = ticksPerSecond
56    elif isinstance(ticksPerSecond, str):
57        tps = round(convert.anyToFrequency(ticksPerSecond))
58    else:
59        raise TypeError, \
60              "wrong type '%s' for ticksPerSecond" % type(ticksPerSecond)
61
62# how big does a rounding error need to be before we warn about it?
63frequency_tolerance = 0.001  # 0.1%
64
65def fromSeconds(value):
66    if not isinstance(value, float):
67        raise TypeError, "can't convert '%s' to type tick" % type(value)
68
69    # once someone needs to convert to seconds, the global frequency
70    # had better be fixed
71    if not tps_fixed:
72        raise AttributeError, \
73              "In order to do conversions, the global frequency must be fixed"
74
75    if value == 0:
76        return 0
77
78    # convert the value from time to ticks
79    value *= tps
80
81    int_value = int(round(value))
82    err = (value - int_value) / value
83    if err > frequency_tolerance:
84        print >>sys.stderr, "Warning: rounding error > tolerance"
85        print >>sys.stderr, "    %f rounded to %d" % (value, int_value)
86    return int_value
87
88__all__ = [ 'setGlobalFrequency', 'fixGlobalFrequency', 'fromSeconds',
89            'frequency_tolerance' ]
90