The Trunk: Kernel-nice.694.mcz

Nicolas Cellier uploaded a new version of Kernel to project The Trunk:
http://source.squeak.org/trunk/Kernel-nice.694.mcz

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

Name: Kernel-nice.694
Author: nice
Time: 3 June 2012, 5:31:52.95 pm
UUID: faa4f8ea-259e-47d4-adc7-eeb195787cad
Ancestors: Kernel-nice.693

Protect floorLog: 2 for case of exceptional float values (because exponent does not)
Change exponent primitive fallback code to avoid a recursion with floorLog2:
Note that I created a separate selector #exponentFromBitPattern for handling fallback, because it's easier to test.

=============== Diff against Kernel-nice.693 ===============

Item was changed:
  ----- Method: Float>>exponent (in category 'truncation and round off') -----
  exponent
  "Primitive. Consider the receiver to be represented as a power of two
  multiplied by a mantissa (between one and two). Answer with the
  SmallInteger to whose power two is raised. Optional. See Object
  documentation whatIsAPrimitive."
 
- | positive |
  <primitive: 53>
+ ^self exponentFromBitPattern!
- self >= 1.0 ifTrue: [^self floorLog: 2].
- self > 0.0
- ifTrue:
- [positive := (1.0 / self) exponent.
- self = (1.0 / (1.0 timesTwoPower: positive))
- ifTrue: [^positive negated]
- ifFalse: [^positive negated - 1]].
- self = 0.0 ifTrue: [^-1].
- ^self negated exponent!

Item was added:
+ ----- Method: Float>>exponentFromBitPattern (in category 'truncation and round off') -----
+ exponentFromBitPattern
+ "Extract the exponent from the bit pattern.
+ This is used only when primitive fails"
+
+ | exponent word1 |
+ self isFinite ifFalse: [^self error: 'cannot take the exponent of non finite Float'].
+ self = 0.0 ifTrue: [^-1].
+ word1 := self basicAt: 1.
+ exponent := (word1 bitShift: -20) bitAnd: 16r7FF.
+ ^exponent = 0
+ ifTrue:
+ [| high |
+ high := (word1 bitAnd: 16rFFFFF) highBit.
+ high := high = 0
+ ifTrue: [(self basicAt: 2) highBit]
+ ifFalse: [high + 32].
+ self class emin - self class precision + high]
+ ifFalse:
+ [exponent + self class emin - 1]!

Item was changed:
  ----- Method: Float>>floorLog: (in category 'mathematical functions') -----
  floorLog: radix
  "Answer the floor of the log base radix of the receiver.
  The result may be off by one due to rounding errors, except in base 2."
 
+ (radix = 2 and: [self > 0.0 and: [self isFinite]]) ifTrue: [^self exponent].
- (radix = 2 and: [self > 0.0]) ifTrue: [^self exponent].
  ^ (self log: radix) floor
  !