[Pkg] The Trunk: Kernel-ul.1192.mcz

[commits at source.squeak.org]

Levente Uzonyi uploaded a new version of Kernel to project The Trunk:
http://source.squeak.org/trunk/Kernel-ul.1192.mcz

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

Name: Kernel-ul.1192
Author: ul
Time: 24 October 2018, 10:50:43.875546 pm
UUID: 72dfb776-3d77-4b84-9d69-d000e9a67ae1
Ancestors: Kernel-eem.1191

- improved Integer >> #isPrime's performance
- slightly faster Categorizer >> #numberOfCategoryOfElement:

=============== Diff against Kernel-eem.1191 ===============

Item was changed:
  ----- Method: Categorizer>>numberOfCategoryOfElement: (in category 'accessing') -----
  numberOfCategoryOfElement: element 
  	"Answer the index of the category with which the argument, element, is 
  	associated."
  
+ 	| categoryIndex elementIndex elementArraySize |
- 	| categoryIndex elementIndex |
  	categoryIndex := 1.
  	elementIndex := 0.
+ 	elementArraySize := elementArray size.
+ 	[(elementIndex := elementIndex + 1) <= elementArraySize]
- 	[(elementIndex := elementIndex + 1) <= elementArray size]
  		whileTrue: 
  			["point to correct category"
  			[elementIndex > (categoryStops at: categoryIndex)]
  				whileTrue: [categoryIndex := categoryIndex + 1].
  			"see if this is element"
  			element = (elementArray at: elementIndex) ifTrue: [^categoryIndex]].
  	^0!

Item was changed:
  ----- Method: Integer>>isPrime (in category 'testing') -----
  isPrime
  	"Answer true if the receiver is a prime number. See isProbablyPrime for a probabilistic
  	implementation that is much faster for large integers, and that is correct to an extremely
  	high statistical level of confidence (effectively deterministic)."
  	
+ 	| probe step limit |
+ 	self <= 3 ifTrue: [ ^self >= 2 ].
+ 	self \\ 2 = 0 ifTrue: [ ^false ].
+ 	self \\ 3 = 0 ifTrue: [ ^false ].
+ 	self <= 1073741823 ifFalse: [ "1 << 30 - 1. For numbers larger than this (on 64-bit platforms) #isProbablyPrime is usually quicker."
- 	self <= 1 ifTrue: [ ^false ].
- 	self even ifTrue: [ ^self = 2].
- 	self <= 1073741823 ifFalse: [ "1 << 30 - 1. For numbers larger than this, the calculation takes longer than #isProbablyPrime when the receiver is a prime. The absolue turning point is about at 1 << 35 - 1."
  		^self isProbablyPrime ].
+ 	probe := 5.
+ 	step := 2. "Step will oscillate between 2 and 4 because at this point self \\ 6 is either 1 or 5."
+ 	limit := self sqrtFloor. "On 64-bit platforms this could be written as self asFloat sqrt truncated (+ 1), which is faster because it creates no intermediate objects. Knowing that self has at most 30 bits because of the check above, this value will never be larger than 32767."
+ 	[ probe <= limit ] whileTrue: [
+ 		self \\ probe = 0 ifTrue: [ ^false ].
+ 		probe := probe + step.
+ 		step := 6 - step ].
- 	3 to: self sqrtFloor by: 2 do: [ :each |
- 		self \\ each = 0 ifTrue: [ ^false ] ].
  	^true!

Item was added:
+ ----- Method: LargeNegativeInteger>>isPrime (in category 'testing') -----
+ isPrime
+ 
+ 	^false!