--- a/Integer.st Thu Jun 09 16:28:45 2011 +0100
+++ b/Integer.st Thu Jun 23 16:55:10 2011 +0100
@@ -1139,7 +1139,6 @@
^ self == Integer
! !
-
!Integer methodsFor:'Compatibility-Dolphin'!
& aNumber
@@ -3918,30 +3917,8 @@
100000 isPowerOf:10
100001 isPowerOf:10
"
-!
-
-isPowerOfTwo
- "return true, if the receiver is a power of 2"
-
-"/ mhmh: how about the following
-"/ self == 0 ifTrue:[^ false].
-
- ^ (self bitAnd:(self - 1)) == 0
-
- "
- 0 isPowerOfTwo
- 1 isPowerOfTwo
- 2 isPowerOfTwo
- 3 isPowerOfTwo
- 4 isPowerOfTwo
- 16r8000000000000000 isPowerOfTwo
- 16r8000000000000001 isPowerOfTwo
- "
-
- "Modified: 15.10.1997 / 18:43:49 / cg"
! !
-
!Integer methodsFor:'special access'!
exponent
@@ -4387,6 +4364,32 @@
^ true
!
+isPowerOfTwo
+ "return true, if the receiver is a power of 2"
+
+ "redefined, because the hacker's algorithm in smallInt is much slower for large numbers"
+
+ |maxBytes "{ Class: SmallInteger }"|
+
+ maxBytes := self digitLength.
+ (self digitAt:maxBytes) isPowerOfTwo ifFalse:[^ false].
+ 1 to:maxBytes-1 do:[:byteIndex |
+ (self digitAt:byteIndex) ~~ 0 ifTrue:[^ false].
+ ].
+ ^ true
+
+ "
+ 10000 factorial isPowerOfTwo
+ |n| n := 10000 factorial. Time millisecondsToRun:[1000 timesRepeat:[ n isPowerOfTwo]]
+ "
+ "
+ (2 raisedTo:10000) isPowerOfTwo
+ |n| n := (2 raisedTo:10000). Time millisecondsToRun:[1000 timesRepeat:[ n isPowerOfTwo]]
+ "
+
+ "Modified: / 20-06-2011 / 12:43:05 / cg"
+!
+
isPrime
"return true if I am a prime Number.
This is a q&d hack, which may need optimization if heavily used."
@@ -4720,15 +4723,15 @@
!Integer class methodsFor:'documentation'!
version
- ^ '$Id: Integer.st 10643 2011-06-08 21:53:07Z vranyj1 $'
+ ^ '$Id: Integer.st 10648 2011-06-23 15:55:10Z vranyj1 $'
!
version_CVS
- ^ 'Header: /cvs/stx/stx/libbasic/Integer.st,v 1.252 2011/05/13 13:58:36 stefan Exp '
+ ^ 'Header: /cvs/stx/stx/libbasic/Integer.st,v 1.253 2011/06/20 10:43:28 cg Exp '
!
version_SVN
- ^ '$Id: Integer.st 10643 2011-06-08 21:53:07Z vranyj1 $'
+ ^ '$Id: Integer.st 10648 2011-06-23 15:55:10Z vranyj1 $'
! !
Integer initialize!
@@ -4742,3 +4745,4 @@
+