On Sat, 20 Dec 2014, Chris Muller wrote:

> On Fri, Dec 19, 2014 at 4:01 PM, Louis LaBrunda
> <Lou at keystone-software.com> wrote:
>> Hi Chris,
>>
>> Is this any faster?
>>
>> Float>>#hashKey32
>>
>> ^self isFinite ifTrue: [
>>         self negative ifTrue: [4286578688 - self asIEEE32BitWord] ifFalse: [self
>> asIEEE32BitWord + 2147483651]
>> ] ifFalse: [self negative ifTrue: [0] ifFalse: [4294967294]].
>
> About the same, but I think I like your code better.  Thanks.

Dave has already suggested to use a FloatArray for conversion instead of 
#asIEEE32BitWord. We use this technique in various network protocol 
implementations, and it works great.

Here's a significantly faster, optimized version:

hashKey32: aFloatArray

 	self - self = 0.0 ifTrue: [
 		self < 0.0 ifTrue: [ ^4286578688 - (aFloatArray at: 1 put: self; basicAt: 1) ].
 		^2147483651 + (aFloatArray at: 1 put: self; basicAt: 1) ].
 	self < 0.0 ifTrue: [ ^0 ].
 	^4294967294

The argument is any FloatArray instance with at least one slot.


Levente

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