Chris Muller uploaded a new version of Chronology-Core to project The Inbox:
http://source.squeak.org/inbox/Chronology-Core-cmm.56.mcz

==================== Summary ====================

Name: Chronology-Core-cmm.56
Author: cmm
Time: 4 May 2020, 6:42:27.516151 pm
UUID: 3c97bedc-c192-4872-b0f2-e93199f506ce
Ancestors: Chronology-Core-ul.54

Building on Chronology-Core-ul.54:

- Let #microsecondClockValue complement #millisecondClockValue, to offer higher precision.
- New constructor, DateAndTime class>>#utcMicroseconds:, complements the above.
- Make Time class>>#utcMicrosecondClock private to help avoid accidental improper use with the above.

=============== Diff against Chronology-Core-ul.54 ===============

Item was added:
+ ----- Method: DateAndTime class>>microsecondClockValue (in category 'smalltalk-80') -----
+ microsecondClockValue
+ 	^ self clock microsecondClockValue!

Item was added:
+ ----- Method: DateAndTime class>>utcMicroseconds: (in category 'instance creation') -----
+ utcMicroseconds: microsecondClockValue
+ 	"Instantiate a DateAndTime in UTC from the value of my #microsecondClockValue."
+ 	^ super new
+ 		utcMicroseconds: microsecondClockValue
+ 		offset: 0!

Item was changed:
  ----- Method: Time class>>estimateHighResClockTicksPerMillisecond (in category 'clock') -----
  estimateHighResClockTicksPerMillisecond
  
  	| t0 t1 t2 t3 |
  	
  	"Count the ticks ellapsed during a 10ms busy loop"
+ 	t0 := Time microsecondClockValue + 200.
+ 	[Time microsecondClockValue >= t0] whileFalse.
- 	t0 := Time utcMicrosecondClock + 200.
- 	[Time utcMicrosecondClock >= t0] whileFalse.
  	t1 := self highResClock.
+ 	[Time microsecondClockValue >= (t0 + 10000)] whileFalse.
+ 	t1 := self highResClock - t1 * 1000 // (Time microsecondClockValue - t0).
- 	[Time utcMicrosecondClock >= (t0 + 10000)] whileFalse.
- 	t1 := self highResClock - t1 * 1000 // (Time utcMicrosecondClock - t0).
  	
  	"Count the ticks ellapsed during a 20ms busy loop"
+ 	t0 := Time microsecondClockValue + 200.
+ 	[Time microsecondClockValue >= t0] whileFalse.
- 	t0 := Time utcMicrosecondClock + 200.
- 	[Time utcMicrosecondClock >= t0] whileFalse.
  	t2 := self highResClock.
+ 	[Time microsecondClockValue >= (t0 + 20000)] whileFalse.
+ 	t2 := self highResClock - t2 * 1000 // (Time microsecondClockValue - t0).
- 	[Time utcMicrosecondClock >= (t0 + 20000)] whileFalse.
- 	t2 := self highResClock - t2 * 1000 // (Time utcMicrosecondClock - t0).
  	
  	"Count the ticks ellapsed during a 30ms busy loop"
+ 	t0 := Time microsecondClockValue + 200.
+ 	[Time microsecondClockValue >= t0] whileFalse.
- 	t0 := Time utcMicrosecondClock + 200.
- 	[Time utcMicrosecondClock >= t0] whileFalse.
  	t3 := self highResClock.
+ 	[Time microsecondClockValue >= (t0 + 30000)] whileFalse.
+ 	t3 := self highResClock - t3 * 1000 // (Time microsecondClockValue - t0).
- 	[Time utcMicrosecondClock >= (t0 + 30000)] whileFalse.
- 	t3 := self highResClock - t3 * 1000 // (Time utcMicrosecondClock - t0).
  	
  	"Take the median of the 3 estimates as the best"
  	^ t1 <= t2
  		ifTrue: [t2 <= t3
  				ifTrue: [t2]
  				ifFalse: [t1 <= t3
  						ifTrue: [t3]
  						ifFalse: [t1]]]
  		ifFalse: [t1 <= t3
  				ifTrue: [t1]
  				ifFalse: [t2 <= t3
  						ifTrue: [t3]
  						ifFalse: [t2]]]!

Item was added:
+ ----- Method: Time class>>microsecondClockValue (in category 'general inquiries') -----
+ microsecondClockValue
+ 	"Answer the value of the microsecond clock, the number of microseconds elapsed since 1/1/1901 @ 00:00:00."
+ 	^ self utcMicrosecondClock - MicrosecondsBetweenPosixEpochAndSqueakEpoch!

Item was changed:
  ----- Method: Time class>>microsecondsToRun: (in category 'general inquiries') -----
  microsecondsToRun: timedBlock 
  	"Answer the number of microseconds timedBlock takes to return its value."
  
  	| startUsecs |
  	(self useHighResClockForTiming and: [self highResClock ~= 0])
  		ifTrue: [	^(self nanosecondsToRunHighRes: timedBlock) + 500 // 1000].
+ 	startUsecs := self microsecondClockValue.
- 	startUsecs := self utcMicrosecondClock.
  	timedBlock value.
+ 	^self microsecondClockValue - startUsecs!
- 	^self utcMicrosecondClock - startUsecs!

Item was changed:
  ----- Method: Time class>>millisecondClockValue (in category 'general inquiries') -----
  millisecondClockValue
  	"Answer the value of the millisecond clock."
+ 	^self microsecondClockValue // 1000!
- 
- 	^self utcMicrosecondClock // 1000!

Item was changed:
  ----- Method: Time class>>nanosecondsToRun: (in category 'general inquiries') -----
  nanosecondsToRun: timedBlock
  	"Answer the number of nanoseconds timedBlock takes to return its value.
  	Use high resolution clock if available and preferred."
  
  	| startUsecs |
  	(self useHighResClockForTiming and: [self highResClock ~= 0])
  		ifTrue: [	^(self nanosecondsToRunHighRes: timedBlock)].
  	"Fallback to microseconds clock"
+ 	startUsecs := self microsecondClockValue.
- 	startUsecs := self utcMicrosecondClock.
  	timedBlock value.
+ 	^self microsecondClockValue - startUsecs * 1000!
- 	^self utcMicrosecondClock - startUsecs * 1000!

Item was removed:
- ----- Method: Time class>>posixUtcMicrosecondClock (in category 'clock') -----
- posixUtcMicrosecondClock
- 	"Answer the UTC microseconds since the POSIX epoch (January 1st 1970 00:00:00 UTC)."
- 
- 	^self utcMicrosecondClock - MicrosecondsBetweenPosixEpochAndSqueakEpoch!

Item was changed:
+ ----- Method: Time class>>utcMicrosecondClock (in category 'private') -----
- ----- Method: Time class>>utcMicrosecondClock (in category 'clock') -----
  utcMicrosecondClock
  	"Answer the UTC microseconds since the Smalltalk epoch (January 1st 1901, the start of the 20th century).
  	 The value is derived from the Posix epoch with a constant offset corresponding to elapsed microseconds
  	 between the two epochs according to RFC 868."
  	<primitive: 240>
  	^0!