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From:   David Laight <David.Laight@ACULAB.COM>
To:     'Vincent Chen' <vincentc@andestech.com>,
        "green.hu@gmail.com" <green.hu@gmail.com>,
        "arnd@arndb.de" <arnd@arndb.de>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Nickhu <nickhu@andestech.com>
Subject: RE: [PATCH v4 2/5] nds32: Support FP emulation
Thread-Topic: [PATCH v4 2/5] nds32: Support FP emulation
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Date:   Fri, 23 Nov 2018 10:53:37 +0000
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From: Vincent Chen
> Sent: 22 November 2018 03:15
> 
> The Andes FPU coprocessor does not support denormalized number handling.
> According to the specification, FPU generates a denorm input exception
> that requires the kernel to deal with this instrution operation when it
> encounters denormalized operands. Hence an nds32 FPU ISA emulator in the
> kernel is required to meet requirement.

What does the FPU generate for results near zero?
If it doesn't generate denormalised results (but does detect them)
then I assume it never generates FP values with exponent zero.
(So the gap around zero is even larger than it would be if exponent
zero values had a hidden bit.)
So is it really worth doing anything other than treating
denormalised values as zero?

	David

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