1 /* Microsoft Reference Implementation for TPM 2.0
2  *
3  *  The copyright in this software is being made available under the BSD License,
4  *  included below. This software may be subject to other third party and
5  *  contributor rights, including patent rights, and no such rights are granted
6  *  under this license.
7  *
8  *  Copyright (c) Microsoft Corporation
9  *
10  *  All rights reserved.
11  *
12  *  BSD License
13  *
14  *  Redistribution and use in source and binary forms, with or without modification,
15  *  are permitted provided that the following conditions are met:
16  *
17  *  Redistributions of source code must retain the above copyright notice, this list
18  *  of conditions and the following disclaimer.
19  *
20  *  Redistributions in binary form must reproduce the above copyright notice, this
21  *  list of conditions and the following disclaimer in the documentation and/or
22  *  other materials provided with the distribution.
23  *
24  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ""AS IS""
25  *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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33  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34  */
35 // This file contains the instance data for the Platform module. It is collected
36 // in this file so that the state of the module is easier to manage.
37 
38 #ifndef _PLATFORM_CLOCK_H_
39 #define _PLATFORM_CLOCK_H_
40 
41 #ifdef _MSC_VER
42 #include <sys/types.h>
43 #include <sys/timeb.h>
44 #else
45 #include <sys/time.h>
46 #include <time.h>
47 #endif
48 
49 // CLOCK_NOMINAL is the number of hardware ticks per mS. A value of 300000 means
50 // that the nominal clock rate used to drive the hardware clock is 30 MHz. The
51 // adjustment rates are used to determine the conversion of the hardware ticks to
52 // internal hardware clock value. In practice, we would expect that there would be
53 // a hardware register will accumulated mS. It would be incremented by the output
54 // of a pre-scaler. The pre-scaler would divide the ticks from the clock by some
55 // value that would compensate for the difference between clock time and real time.
56 // The code in Clock does the emulation of this function.
57 #define     CLOCK_NOMINAL           30000
58 // A 1% change in rate is 300 counts
59 #define     CLOCK_ADJUST_COARSE     300
60 // A 0.1% change in rate is 30 counts
61 #define     CLOCK_ADJUST_MEDIUM     30
62 // A minimum change in rate is 1 count
63 #define     CLOCK_ADJUST_FINE       1
64 // The clock tolerance is +/-15% (4500 counts)
65 // Allow some guard band (16.7%)
66 #define     CLOCK_ADJUST_LIMIT      5000
67 
68 #endif // _PLATFORM_CLOCK_H_
69