/src/ibmswtpm2/src/Clock.c

Source (jump to first uncovered line)
/********************************************************************************/
/*                    */
/*     Used by the simulator to mimic a hardware clock      */
/*           Written by Ken Goldman       */
/*           IBM Thomas J. Watson Research Center     */
/*            $Id: Clock.c 1311 2018-08-23 21:39:29Z kgoldman $     */
/*                    */
/*  Licenses and Notices              */
/*                    */
/*  1. Copyright Licenses:              */
/*                    */
/*  - Trusted Computing Group (TCG) grants to the user of the source code in  */
/*    this specification (the "Source Code") a worldwide, irrevocable,    */
/*    nonexclusive, royalty free, copyright license to reproduce, create  */
/*    derivative works, distribute, display and perform the Source Code and */
/*    derivative works thereof, and to grant others the rights granted herein.  */
/*                    */
/*  - The TCG grants to the user of the other parts of the specification  */
/*    (other than the Source Code) the rights to reproduce, distribute,   */
/*    display, and perform the specification solely for the purpose of    */
/*    developing products based on such documents.        */
/*                    */
/*  2. Source Code Distribution Conditions:         */
/*                    */
/*  - Redistributions of Source Code must retain the above copyright licenses,  */
/*    this list of conditions and the following disclaimers.      */
/*                    */
/*  - Redistributions in binary form must reproduce the above copyright   */
/*    licenses, this list of conditions and the following disclaimers in the  */
/*    documentation and/or other materials provided with the distribution.  */
/*                    */
/*  3. Disclaimers:               */
/*                    */
/*  - THE COPYRIGHT LICENSES SET FORTH ABOVE DO NOT REPRESENT ANY FORM OF */
/*  LICENSE OR WAIVER, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, WITH */
/*  RESPECT TO PATENT RIGHTS HELD BY TCG MEMBERS (OR OTHER THIRD PARTIES) */
/*  THAT MAY BE NECESSARY TO IMPLEMENT THIS SPECIFICATION OR OTHERWISE.   */
/*  Contact TCG Administration (admin@trustedcomputinggroup.org) for    */
/*  information on specification licensing rights available through TCG   */
/*  membership agreements.              */
/*                    */
/*  - THIS SPECIFICATION IS PROVIDED "AS IS" WITH NO EXPRESS OR IMPLIED   */
/*    WARRANTIES WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR   */
/*    FITNESS FOR A PARTICULAR PURPOSE, ACCURACY, COMPLETENESS, OR    */
/*    NONINFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS, OR ANY WARRANTY    */
/*    OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION OR SAMPLE.   */
/*                    */
/*  - Without limitation, TCG and its members and licensors disclaim all  */
/*    liability, including liability for infringement of any proprietary  */
/*    rights, relating to use of information in this specification and to the */
/*    implementation of this specification, and TCG disclaims all liability for */
/*    cost of procurement of substitute goods or services, lost profits, loss   */
/*    of use, loss of data or any incidental, consequential, direct, indirect,  */
/*    or special damages, whether under contract, tort, warranty or otherwise,  */
/*    arising in any way out of use or reliance upon this specification or any  */
/*    information herein.             */
/*                    */
/*  (c) Copyright IBM Corp. and others, 2016 - 2018       */
/*                    */
/********************************************************************************/

/* added for portability because Linux clock is 32 bits */

#include <stdint.h>
#include <stdio.h>
#include <time.h>

/* C.3 Clock.c */
/* C.3.1. Description */
/* This file contains the routines that are used by the simulator to mimic a hardware clock on a
   TPM. In this implementation, all the time values are measured in millisecond. However, the
   precision of the clock functions may be implementation dependent. */
/* C.3.2. Includes and Data Definitions */
#include "PlatformData.h"
#include "Platform_fp.h"
#include "TpmFail_fp.h"
#include <assert.h>
/* C.3.3. Simulator Functions */
/* C.3.3.1. Introduction */
/* This set of functions is intended to be called by the simulator environment in order to simulate
   hardware events. */
/* C.3.3.2. _plat__TimerReset() */
/* This function sets current system clock time as t0 for counting TPM time. This function is called
   at a power on event to reset the clock.  When the clock is reset, the indication that the clock
   was stopped is also set. */
LIB_EXPORT void
_plat__TimerReset(
      void
      )
{
    s_lastSystemTime = 0;
    s_tpmTime = 0;
    s_adjustRate = CLOCK_NOMINAL;
    s_timerReset = TRUE;
    s_timerStopped = TRUE;
    return;
}
/* C.3.3.3. _plat__TimerRestart() */
/* This function should be called in order to simulate the restart of the timer should it be stopped
   while power is still applied. */
LIB_EXPORT void
_plat__TimerRestart(
        void
        )
{
    s_timerStopped = TRUE;
    return;
}

/* C.3.4. Functions Used by TPM */
/* C.3.4.1. Introduction */
/* These functions are called by the TPM code. They should be replaced by appropriated hardware
   functions. */

clock_t     debugTime;
/* C.3.4.2. _plat__Time() */
/* This is another, probably futile, attempt to define a portable function that will return a 64-bit
   clock value that has mSec resolution. */
uint64_t
_plat__RealTime(
    void
    )
{
    clock64_t           time;
    //#ifdef _MSC_VER kgold
#ifdef TPM_WINDOWS
    #include <SYS/Timeb.h>
    struct _timeb       sysTime;
    //
    _ftime(&sysTime); /* kgold, mingw doesn't have _ftime_s */
    time = (clock64_t)(sysTime.time) * 1000 + sysTime.millitm;
    // set the time back by one hour if daylight savings
    if(sysTime.dstflag)
  time -= 1000 * 60 * 60;  // mSec/sec * sec/min * min/hour = ms/hour
#else
    // hopefully, this will work with most UNIX systems
    struct timespec     systime;
    //
    clock_gettime(CLOCK_MONOTONIC, &systime);
    time = (clock64_t)systime.tv_sec * 1000 + (systime.tv_nsec / 1000000);
#endif
    return time;
}



/* C.3.4.3. _plat__TimerRead() */
/* This function provides access to the tick timer of the platform. The TPM code uses this value to
   drive the TPM Clock. */
/* The tick timer is supposed to run when power is applied to the device. This timer should not be
   reset by time events including _TPM_Init(). It should only be reset when TPM power is
   re-applied. */
/* If the TPM is run in a protected environment, that environment may provide the tick time to the
   TPM as long as the time provided by the environment is not allowed to go backwards. If the time
   provided by the system can go backwards during a power discontinuity, then the
   _plat__Signal_PowerOn() should call _plat__TimerReset(). */
LIB_EXPORT uint64_t
_plat__TimerRead(
     void
     )
{
#ifdef HARDWARE_CLOCK
#error      "need a defintion for reading the hardware clock"
    return HARDWARE_CLOCK
#else
    clock64_t         timeDiff;
    clock64_t         adjustedTimeDiff;
    clock64_t         timeNow;
    clock64_t         readjustedTimeDiff;
    // This produces a timeNow that is basically locked to the system clock.
    timeNow = _plat__RealTime();
    // if this hasn't been initialized, initialize it
    if(s_lastSystemTime == 0)
  {
      s_lastSystemTime = timeNow;
      debugTime = clock();
      s_lastReportedTime = 0;
      s_realTimePrevious = 0;
  }
    // The system time can bounce around and that's OK as long as we don't allow
    // time to go backwards. When the time does appear to go backwards, set
    // lastSystemTime to be the new value and then update the reported time.
    if(timeNow < s_lastReportedTime)
  s_lastSystemTime = timeNow;
    s_lastReportedTime = s_lastReportedTime + timeNow - s_lastSystemTime;
    s_lastSystemTime = timeNow;
    timeNow = s_lastReportedTime;
    // The code above produces a timeNow that is similar to the value returned
    // by Clock(). The difference is that timeNow does not max out, and it is
    // at a ms. rate rather than at a CLOCKS_PER_SEC rate. The code below
    // uses that value and does the rate adjustment on the time value.
    // If there is no difference in time, then skip all the computations
    if(s_realTimePrevious >= timeNow)
  return s_tpmTime;
    // Compute the amount of time since the last update of the system clock
    timeDiff = timeNow - s_realTimePrevious;
    // Do the time rate adjustment and conversion from CLOCKS_PER_SEC to mSec
    adjustedTimeDiff = (timeDiff * CLOCK_NOMINAL) / ((uint64_t)s_adjustRate);
    // update the TPM time with the adjusted timeDiff
    s_tpmTime += (clock64_t)adjustedTimeDiff;
    // Might have some rounding error that would loose CLOCKS. See what is not
    // being used. As mentioned above, this could result in putting back more than
    // is taken out. Here, we are trying to recreate timeDiff.
    readjustedTimeDiff = (adjustedTimeDiff * (uint64_t)s_adjustRate )
       / CLOCK_NOMINAL;
    // adjusted is now converted back to being the amount we should advance the
    // previous sampled time. It should always be less than or equal to timeDiff.
    // That is, we could not have use more time than we started with.
    s_realTimePrevious = s_realTimePrevious + readjustedTimeDiff;
#ifdef  DEBUGGING_TIME
    // Put this in so that TPM time will pass much faster than real time when
    // doing debug.
    // A value of 1000 for DEBUG_TIME_MULTIPLER will make each ms into a second
    // A good value might be 100
    return (s_tpmTime * DEBUG_TIME_MULTIPLIER);
#endif
    return s_tpmTime;
#endif
}


/* C.3.4.3. _plat__TimerWasReset() */
/* This function is used to interrogate the flag indicating if the tick timer has been reset. */
/* If the resetFlag parameter is SET, then the flag will be CLEAR before the function returns. */
LIB_EXPORT BOOL
_plat__TimerWasReset(
         void
         )
{
    BOOL         retVal = s_timerReset;
    s_timerReset = FALSE;
    return retVal;
}
/* C.3.4.4. _plat__TimerWasStopped() */
/* This function is used to interrogate the flag indicating if the tick timer has been stopped. If
   so, this is typically a reason to roll the nonce. */
/* This function will CLEAR the s_timerStopped flag before returning. This provides functionality
   that is similar to status register that is cleared when read. This is the model used here because
   it is the one that has the most impact on the TPM code as the flag can only be accessed by one
   entity in the TPM. Any other implementation of the hardware can be made to look like a read-once
   register. */
LIB_EXPORT BOOL
_plat__TimerWasStopped(
           void
           )
{
    BOOL         retVal = s_timerStopped;
    s_timerStopped = FALSE;
    return retVal;
}
/* C.3.4.5. _plat__ClockAdjustRate() */
/* Adjust the clock rate */
LIB_EXPORT void
_plat__ClockAdjustRate(
           int  adjust         // IN: the adjust number.  It could be positive
           //     or negative
           )
{
    // We expect the caller should only use a fixed set of constant values to
    // adjust the rate
    switch(adjust)
  {
    case CLOCK_ADJUST_COARSE:
      s_adjustRate += CLOCK_ADJUST_COARSE;
      break;
    case -CLOCK_ADJUST_COARSE:
      s_adjustRate -= CLOCK_ADJUST_COARSE;
      break;
    case CLOCK_ADJUST_MEDIUM:
      s_adjustRate += CLOCK_ADJUST_MEDIUM;
      break;
    case -CLOCK_ADJUST_MEDIUM:
      s_adjustRate -= CLOCK_ADJUST_MEDIUM;
      break;
    case CLOCK_ADJUST_FINE:
      s_adjustRate += CLOCK_ADJUST_FINE;
      break;
    case -CLOCK_ADJUST_FINE:
      s_adjustRate -= CLOCK_ADJUST_FINE;
      break;
    default:
      // ignore any other values;
      break;
  }
    if(s_adjustRate > (CLOCK_NOMINAL + CLOCK_ADJUST_LIMIT))
  s_adjustRate = CLOCK_NOMINAL + CLOCK_ADJUST_LIMIT;
    if(s_adjustRate < (CLOCK_NOMINAL - CLOCK_ADJUST_LIMIT))
  s_adjustRate = CLOCK_NOMINAL - CLOCK_ADJUST_LIMIT;
    return;
}

Coverage Report

Created: 2025-07-18 06:07

Line	Count	Source (jump to first uncovered line)
1		/********************************************************************************/
2		/* */
3		/* Used by the simulator to mimic a hardware clock */
4		/* Written by Ken Goldman */
5		/* IBM Thomas J. Watson Research Center */
6		/* $Id: Clock.c 1311 2018-08-23 21:39:29Z kgoldman $ */
7		/* */
8		/* Licenses and Notices */
9		/* */
10		/* 1. Copyright Licenses: */
11		/* */
12		/* - Trusted Computing Group (TCG) grants to the user of the source code in */
13		/* this specification (the "Source Code") a worldwide, irrevocable, */
14		/* nonexclusive, royalty free, copyright license to reproduce, create */
15		/* derivative works, distribute, display and perform the Source Code and */
16		/* derivative works thereof, and to grant others the rights granted herein. */
17		/* */
18		/* - The TCG grants to the user of the other parts of the specification */
19		/* (other than the Source Code) the rights to reproduce, distribute, */
20		/* display, and perform the specification solely for the purpose of */
21		/* developing products based on such documents. */
22		/* */
23		/* 2. Source Code Distribution Conditions: */
24		/* */
25		/* - Redistributions of Source Code must retain the above copyright licenses, */
26		/* this list of conditions and the following disclaimers. */
27		/* */
28		/* - Redistributions in binary form must reproduce the above copyright */
29		/* licenses, this list of conditions and the following disclaimers in the */
30		/* documentation and/or other materials provided with the distribution. */
31		/* */
32		/* 3. Disclaimers: */
33		/* */
34		/* - THE COPYRIGHT LICENSES SET FORTH ABOVE DO NOT REPRESENT ANY FORM OF */
35		/* LICENSE OR WAIVER, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, WITH */
36		/* RESPECT TO PATENT RIGHTS HELD BY TCG MEMBERS (OR OTHER THIRD PARTIES) */
37		/* THAT MAY BE NECESSARY TO IMPLEMENT THIS SPECIFICATION OR OTHERWISE. */
38		/* Contact TCG Administration (admin@trustedcomputinggroup.org) for */
39		/* information on specification licensing rights available through TCG */
40		/* membership agreements. */
41		/* */
42		/* - THIS SPECIFICATION IS PROVIDED "AS IS" WITH NO EXPRESS OR IMPLIED */
43		/* WARRANTIES WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR */
44		/* FITNESS FOR A PARTICULAR PURPOSE, ACCURACY, COMPLETENESS, OR */
45		/* NONINFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS, OR ANY WARRANTY */
46		/* OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION OR SAMPLE. */
47		/* */
48		/* - Without limitation, TCG and its members and licensors disclaim all */
49		/* liability, including liability for infringement of any proprietary */
50		/* rights, relating to use of information in this specification and to the */
51		/* implementation of this specification, and TCG disclaims all liability for */
52		/* cost of procurement of substitute goods or services, lost profits, loss */
53		/* of use, loss of data or any incidental, consequential, direct, indirect, */
54		/* or special damages, whether under contract, tort, warranty or otherwise, */
55		/* arising in any way out of use or reliance upon this specification or any */
56		/* information herein. */
57		/* */
58		/* (c) Copyright IBM Corp. and others, 2016 - 2018 */
59		/* */
60		/********************************************************************************/
61
62		/* added for portability because Linux clock is 32 bits */
63
64		#include <stdint.h>
65		#include <stdio.h>
66		#include <time.h>
67
68		/* C.3 Clock.c */
69		/* C.3.1. Description */
70		/* This file contains the routines that are used by the simulator to mimic a hardware clock on a
71		TPM. In this implementation, all the time values are measured in millisecond. However, the
72		precision of the clock functions may be implementation dependent. */
73		/* C.3.2. Includes and Data Definitions */
74		#include "PlatformData.h"
75		#include "Platform_fp.h"
76		#include "TpmFail_fp.h"
77		#include <assert.h>
78		/* C.3.3. Simulator Functions */
79		/* C.3.3.1. Introduction */
80		/* This set of functions is intended to be called by the simulator environment in order to simulate
81		hardware events. */
82		/* C.3.3.2. _plat__TimerReset() */
83		/* This function sets current system clock time as t0 for counting TPM time. This function is called
84		at a power on event to reset the clock. When the clock is reset, the indication that the clock
85		was stopped is also set. */
86		LIB_EXPORT void
87		_plat__TimerReset(
88		void
89		)
90	1	{
91	1	s_lastSystemTime = 0;
92	1	s_tpmTime = 0;
93	1	s_adjustRate = CLOCK_NOMINAL;
94	1	s_timerReset = TRUE;
95	1	s_timerStopped = TRUE;
96	1	return;
97	1	}
98		/* C.3.3.3. _plat__TimerRestart() */
99		/* This function should be called in order to simulate the restart of the timer should it be stopped
100		while power is still applied. */
101		LIB_EXPORT void
102		_plat__TimerRestart(
103		void
104		)
105	0	{
106	0	s_timerStopped = TRUE;
107	0	return;
108	0	}
109
110		/* C.3.4. Functions Used by TPM */
111		/* C.3.4.1. Introduction */
112		/* These functions are called by the TPM code. They should be replaced by appropriated hardware
113		functions. */
114
115		clock_t debugTime;
116		/* C.3.4.2. _plat__Time() */
117		/* This is another, probably futile, attempt to define a portable function that will return a 64-bit
118		clock value that has mSec resolution. */
119		uint64_t
120		_plat__RealTime(
121		void
122		)
123	6.47k	{
124	6.47k	clock64_t time;
125		//#ifdef _MSC_VER kgold
126		#ifdef TPM_WINDOWS
127		#include <SYS/Timeb.h>
128		struct _timeb sysTime;
129		//
130		_ftime(&sysTime); /* kgold, mingw doesn't have _ftime_s */
131		time = (clock64_t)(sysTime.time) * 1000 + sysTime.millitm;
132		// set the time back by one hour if daylight savings
133		if(sysTime.dstflag)
134		time -= 1000 * 60 * 60; // mSec/sec * sec/min * min/hour = ms/hour
135		#else
136		// hopefully, this will work with most UNIX systems
137	6.47k	struct timespec systime;
138		//
139	6.47k	clock_gettime(CLOCK_MONOTONIC, &systime);
140	6.47k	time = (clock64_t)systime.tv_sec * 1000 + (systime.tv_nsec / 1000000);
141	6.47k	#endif
142	6.47k	return time;
143	6.47k	}
144
145
146
147		/* C.3.4.3. _plat__TimerRead() */
148		/* This function provides access to the tick timer of the platform. The TPM code uses this value to
149		drive the TPM Clock. */
150		/* The tick timer is supposed to run when power is applied to the device. This timer should not be
151		reset by time events including _TPM_Init(). It should only be reset when TPM power is
152		re-applied. */
153		/* If the TPM is run in a protected environment, that environment may provide the tick time to the
154		TPM as long as the time provided by the environment is not allowed to go backwards. If the time
155		provided by the system can go backwards during a power discontinuity, then the
156		_plat__Signal_PowerOn() should call _plat__TimerReset(). */
157		LIB_EXPORT uint64_t
158		_plat__TimerRead(
159		void
160		)
161	1	{
162		#ifdef HARDWARE_CLOCK
163		#error "need a defintion for reading the hardware clock"
164		return HARDWARE_CLOCK
165		#else
166	1	clock64_t timeDiff;
167	1	clock64_t adjustedTimeDiff;
168	1	clock64_t timeNow;
169	1	clock64_t readjustedTimeDiff;
170		// This produces a timeNow that is basically locked to the system clock.
171	1	timeNow = _plat__RealTime();
172		// if this hasn't been initialized, initialize it
173	1	if(s_lastSystemTime == 0)
174	1	{
175	1	s_lastSystemTime = timeNow;
176	1	debugTime = clock();
177	1	s_lastReportedTime = 0;
178	1	s_realTimePrevious = 0;
179	1	}
180		// The system time can bounce around and that's OK as long as we don't allow
181		// time to go backwards. When the time does appear to go backwards, set
182		// lastSystemTime to be the new value and then update the reported time.
183	1	if(timeNow < s_lastReportedTime)
184	0	s_lastSystemTime = timeNow;
185	1	s_lastReportedTime = s_lastReportedTime + timeNow - s_lastSystemTime;
186	1	s_lastSystemTime = timeNow;
187	1	timeNow = s_lastReportedTime;
188		// The code above produces a timeNow that is similar to the value returned
189		// by Clock(). The difference is that timeNow does not max out, and it is
190		// at a ms. rate rather than at a CLOCKS_PER_SEC rate. The code below
191		// uses that value and does the rate adjustment on the time value.
192		// If there is no difference in time, then skip all the computations
193	1	if(s_realTimePrevious >= timeNow)
194	1	return s_tpmTime;
195		// Compute the amount of time since the last update of the system clock
196	0	timeDiff = timeNow - s_realTimePrevious;
197		// Do the time rate adjustment and conversion from CLOCKS_PER_SEC to mSec
198	0	adjustedTimeDiff = (timeDiff * CLOCK_NOMINAL) / ((uint64_t)s_adjustRate);
199		// update the TPM time with the adjusted timeDiff
200	0	s_tpmTime += (clock64_t)adjustedTimeDiff;
201		// Might have some rounding error that would loose CLOCKS. See what is not
202		// being used. As mentioned above, this could result in putting back more than
203		// is taken out. Here, we are trying to recreate timeDiff.
204	0	readjustedTimeDiff = (adjustedTimeDiff * (uint64_t)s_adjustRate )
205	0	/ CLOCK_NOMINAL;
206		// adjusted is now converted back to being the amount we should advance the
207		// previous sampled time. It should always be less than or equal to timeDiff.
208		// That is, we could not have use more time than we started with.
209	0	s_realTimePrevious = s_realTimePrevious + readjustedTimeDiff;
210		#ifdef DEBUGGING_TIME
211		// Put this in so that TPM time will pass much faster than real time when
212		// doing debug.
213		// A value of 1000 for DEBUG_TIME_MULTIPLER will make each ms into a second
214		// A good value might be 100
215		return (s_tpmTime * DEBUG_TIME_MULTIPLIER);
216		#endif
217	0	return s_tpmTime;
218	1	#endif
219	1	}
220
221
222		/* C.3.4.3. _plat__TimerWasReset() */
223		/* This function is used to interrogate the flag indicating if the tick timer has been reset. */
224		/* If the resetFlag parameter is SET, then the flag will be CLEAR before the function returns. */
225		LIB_EXPORT BOOL
226		_plat__TimerWasReset(
227		void
228		)
229	0	{
230	0	BOOL retVal = s_timerReset;
231	0	s_timerReset = FALSE;
232	0	return retVal;
233	0	}
234		/* C.3.4.4. _plat__TimerWasStopped() */
235		/* This function is used to interrogate the flag indicating if the tick timer has been stopped. If
236		so, this is typically a reason to roll the nonce. */
237		/* This function will CLEAR the s_timerStopped flag before returning. This provides functionality
238		that is similar to status register that is cleared when read. This is the model used here because
239		it is the one that has the most impact on the TPM code as the flag can only be accessed by one
240		entity in the TPM. Any other implementation of the hardware can be made to look like a read-once
241		register. */
242		LIB_EXPORT BOOL
243		_plat__TimerWasStopped(
244		void
245		)
246	0	{
247	0	BOOL retVal = s_timerStopped;
248	0	s_timerStopped = FALSE;
249	0	return retVal;
250	0	}
251		/* C.3.4.5. _plat__ClockAdjustRate() */
252		/* Adjust the clock rate */
253		LIB_EXPORT void
254		_plat__ClockAdjustRate(
255		int adjust // IN: the adjust number. It could be positive
256		// or negative
257		)
258	0	{
259		// We expect the caller should only use a fixed set of constant values to
260		// adjust the rate
261	0	switch(adjust)
262	0	{
263	0	case CLOCK_ADJUST_COARSE:
264	0	s_adjustRate += CLOCK_ADJUST_COARSE;
265	0	break;
266	0	case -CLOCK_ADJUST_COARSE:
267	0	s_adjustRate -= CLOCK_ADJUST_COARSE;
268	0	break;
269	0	case CLOCK_ADJUST_MEDIUM:
270	0	s_adjustRate += CLOCK_ADJUST_MEDIUM;
271	0	break;
272	0	case -CLOCK_ADJUST_MEDIUM:
273	0	s_adjustRate -= CLOCK_ADJUST_MEDIUM;
274	0	break;
275	0	case CLOCK_ADJUST_FINE:
276	0	s_adjustRate += CLOCK_ADJUST_FINE;
277	0	break;
278	0	case -CLOCK_ADJUST_FINE:
279	0	s_adjustRate -= CLOCK_ADJUST_FINE;
280	0	break;
281	0	default:
282		// ignore any other values;
283	0	break;
284	0	}
285	0	if(s_adjustRate > (CLOCK_NOMINAL + CLOCK_ADJUST_LIMIT))
286	0	s_adjustRate = CLOCK_NOMINAL + CLOCK_ADJUST_LIMIT;
287	0	if(s_adjustRate < (CLOCK_NOMINAL - CLOCK_ADJUST_LIMIT))
288	0	s_adjustRate = CLOCK_NOMINAL - CLOCK_ADJUST_LIMIT;
289	0	return;
290	0	}