ticks.py revision 11802:be62996c95d1 
1# Copyright (c) 2007 The Regents of The University of Michigan
2# All rights reserved.
3#
4# Redistribution and use in source and binary forms, with or without
5# modification, are permitted provided that the following conditions are
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7# notice, this list of conditions and the following disclaimer;
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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11# neither the name of the copyright holders nor the names of its
12# contributors may be used to endorse or promote products derived from
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
17# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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21# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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25# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26#
27# Authors: Nathan Binkert
28
29import sys
30from m5.util import warn
31
32tps = 1.0e12         # default to 1 THz (1 Tick == 1 ps)
33tps_fixed = False    # once set to true, can't be changed
34
35# fix the global frequency and tell C++ about it
36def fixGlobalFrequency():
37    import _m5.core
38    global tps, tps_fixed
39    if not tps_fixed:
40        tps_fixed = True
41        _m5.core.setClockFrequency(int(tps))
42        print "Global frequency set at %d ticks per second" % int(tps)
43
44def setGlobalFrequency(ticksPerSecond):
45    from m5.util import convert
46
47    global tps, tps_fixed
48
49    if tps_fixed:
50        raise AttributeError, \
51              "Global frequency already fixed at %f ticks/s." % tps
52
53    if isinstance(ticksPerSecond, (int, long)):
54        tps = ticksPerSecond
55    elif isinstance(ticksPerSecond, float):
56        tps = ticksPerSecond
57    elif isinstance(ticksPerSecond, str):
58        tps = round(convert.anyToFrequency(ticksPerSecond))
59    else:
60        raise TypeError, \
61              "wrong type '%s' for ticksPerSecond" % type(ticksPerSecond)
62
63# how big does a rounding error need to be before we warn about it?
64frequency_tolerance = 0.001  # 0.1%
65
66def fromSeconds(value):
67    if not isinstance(value, float):
68        raise TypeError, "can't convert '%s' to type tick" % type(value)
69
70    # once someone needs to convert to seconds, the global frequency
71    # had better be fixed
72    if not tps_fixed:
73        raise AttributeError, \
74              "In order to do conversions, the global frequency must be fixed"
75
76    if value == 0:
77        return 0
78
79    # convert the value from time to ticks
80    value *= tps
81
82    int_value = int(round(value))
83    err = (value - int_value) / value
84    if err > frequency_tolerance:
85        warn("rounding error > tolerance\n    %f rounded to %d", value,
86            int_value)
87    return int_value
88
89__all__ = [ 'setGlobalFrequency', 'fixGlobalFrequency', 'fromSeconds',
90            'frequency_tolerance' ]
91