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[Qemu-devel] Re: [PATCH 2/3] target-ppc: fix default qNaN
From: |
Alexander Graf |
Subject: |
[Qemu-devel] Re: [PATCH 2/3] target-ppc: fix default qNaN |
Date: |
Wed, 5 Jan 2011 18:09:34 +0100 |
On 02.01.2011, at 15:39, Aurelien Jarno wrote:
> On PPC the default qNaN doesn't have the sign bit set.
The spec says "don't care" for the sign bit. Did you extract the value
empirically? I'm not saying it's wrong - the default 32 Bit value seems to be
0x7FC0_0000 (2.06 ISA 6.6.2.2).
Hrm ... reading section 5.4.2:
A special QNaN is sometimes supplied as the default QNaN for a disabled
invalid-operation exception; it has a plus sign, the leftmost 6 bits of the
combination field set to 0b111110 and remaining bits in the combination field
and the trailing significand field set to zero.
So I guess you're right.
Acked-by: Alexander Graf <address@hidden>
Alex