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From: hm279he@uni-duisburg.de (Heckes)
Newsgroups: comp.lang.smalltalk
Subject: Integer / Float arithmetic in ST80
Keywords: number classes, speed of floats, primitives
Message-ID: <hm279he.674308622@duc220>
Date: 15 May 91 11:57:02 GMT
Sender: @unidui.uni-duisburg.de
Organization: Rechenzentrum Uni-Duisburg
Lines: 27


	I am using ST80 from ParcPlace on 386PC under Windows. I plan
	to use the system for prototyping of numerical algorithems and    
	if we get ST80 for our IBM6000 I will surely use them. To get
	an impression of the speed in number crunching, I performed some
	benchmarks with variables from the classes *Integer, Float and 
	Double. As my PC is equipped with a coprocessor I expected class  
	Float and SmallInteger to perform similar. I was very surprised, 
	when it turned out that the simple integer arithmetic, like +,* 
	etc, was 10 times faster then the equivalent messages in class
	Float. After looking a while around in the source code, I find 
	that also both classes implement the messages as primitives, the 
	messages in class SmallInteger are handled somewhat different.
	The messages in SmallInteger are marked essential and seem to
	be called in a different way as other primitives. There is a thing
	named Special Byte Code Selector which, as I understand, is send
	to the Compiler to make execution faster. 
	My question is: Is it possible to make the Float messages perform
	as fast as the SmallInteger ones?

	Dirk


	dirk@hal9000.uni-duisburg.de
	Dirk Talkenberger
	Physics Department / Theoretical Low Temperature Physics