Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ncar!tank!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: bitfields considered harmful?
Message-ID: <17334@mimsy.UUCP>
Date: 6 May 89 03:57:29 GMT
References: <1473@uwbull.uwbln.UUCP> <705@cf-cm.UUCP> <6047@asterix.UUCP>
Distribution: comp
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 11

In article <6047@asterix.UUCP> jimp@asterix.UUCP (Jim Patterson) writes:
>many [machines] have instructions that implement bitfields directly.

And on many of these, the special instructions are *slower* than the
equivalent sequence of and/or/shifts....

That is why we leave the instruction choice to the compiler, and merely
include bitfields as a convenience to the programmer.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris