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Re: [Qemu-devel] [PATCH v2 02/16] softloat: disable floatx80_invalid_enc

From: Andreas Schwab
Subject: Re: [Qemu-devel] [PATCH v2 02/16] softloat: disable floatx80_invalid_encoding() for m68k
Date: Mon, 30 Jan 2017 23:47:06 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.91 (gnu/linux)

On Jan 30 2017, Peter Maydell <address@hidden> wrote:

> I guess we need to look more carefully at exactly what the
> m68k does for these encodings (maybe have a 'normalize value'
> function which squashes them down to whatever the equivalent
> non-weird encoding is?).

On the m68k, the concept of pseudo-inf/nan doesn't exist, because the
integer bit is don't-care for inf and nan.  The combination of a zero
integer bit with other non-zero biased exponents is called unnormal, and
the 68881/2 will always convert them to normal/denormal/zero on input.
(The 68040/60 don't support denormal/unnormal in hardware and lets the
support library handle them, which presumably works the same way as the


Andreas Schwab, address@hidden
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