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From: c20@nmtvax.UUCP
Newsgroups: net.lang.c
Subject: Re: Can C default to float? Are there float regs?
Message-ID: <766@nmtvax.UUCP>
Date: Mon, 16-Sep-85 19:47:05 EDT
Article-I.D.: nmtvax.766
Posted: Mon Sep 16 19:47:05 1985
Date-Received: Thu, 19-Sep-85 04:39:16 EDT
References: <418@phri.UUCP> <700002@fthood> <187@graffiti.UUCP> <175@mit-bug.UUCP>
Organization: New Mexico Tech, Socorro
Lines: 30

> << first part of message here >>
>
> On a related note, it appears that register declarations for float variables 
> have no effect on our compiler (they don't cause the variables to be stored
> in registers).  It has been hypothesized that those who write the compiler
> don't feel that making "register float" do something is worth the effort.
> 
> Is there anyone who has made "register float" work?  Is it impossible?

New Mexico Tech's v7 C compiler for TOPS-20 supports register floats.
It also supports register doubles, but does so by treating a "double"
declaration as being synonymous with "float":

    "Single-precision floating point (float) and double-precision floating
     point (double) may be synonymous in some implementations."
                                                K & R, page 183, line 6

It's not impossible;  it's just more or less difficult, depending upon
what the underlying architecture provides the C compiler author in
the way of support for floating-point.

greg
-- 

Greg Titus                  ..!ucbvax!unmvax!nmtvax!c20     (uucp)
NM Tech Computer Center     ..!cmcl2!lanl!nmtvax!c20        (uucp)
Box W209 C/S                c20@nmt                         (CSnet)
Socorro, NM 87801           c20.nmt@csnet-relay             (arpa)
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