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Date: Tue, 27 Nov 2018 13:52:01 +0100
From: Szabolcs Nagy <nsz@...t70.net>
To: musl@...ts.openwall.com
Subject: Re: 32-bit double and long double

* Rich Felker <dalias@...c.org> [2018-11-26 21:32:11 -0500]:
> On Mon, Nov 26, 2018 at 05:36:58PM +0000, Jon Chesterfield wrote:
> > Arguments to variadic functions promote to double. Again I would prefer 32
> > bit float.
> 
> Indeed this is a hard limitation of the language. I suppose it comes
> in mostly/only for passing floating point values to printf. The
> promotion should at least be nothing more than a few 64-bit shift/or
> ops.

well floating-point is usually tricky..

conversion to double should signal an invalid exception for snan.

subnormal range values need different logic than normal range ones
and likely require a clz operation.

if you support flush-to-zero arithmetics then subnormal input
should raise an input-denormal exception and treat it as zero.

..but all this is implemented in libgcc soft-fp support.

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