Hi Levente,

    please rewrite using a temp to hold the raw bits, a class var to hold the float array and hexadecimal.  Then one can understand much easier.  Also is inlining isFinite that important for performance?

rawBits := FloatArrayBuffer at: 1 put: self; basicAt: 1
etc...


Eliot (phone hence not writing the full method)

On Dec 20, 2014, at 7:27 PM, Levente Uzonyi <leves at elte.hu> wrote:

> 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
> 
>