From: Richard Henderson <rth@twiddle.net>
To: "Chen Gang" <xili_gchen_5257@hotmail.com>,
"Peter Maydell" <peter.maydell@linaro.org>,
"Chris Metcalf" <cmetcalf@ezchip.com>,
"Andreas Färber" <afaerber@suse.de>,
"Riku Voipio" <riku.voipio@iki.fi>,
"walt@tilera.com" <walt@tilera.com>
Cc: qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH 1/6 v6] target-tilegx: Firstly add TILE-Gx with minimized features
Date: Fri, 20 Mar 2015 10:03:51 -0700 [thread overview]
Message-ID: <550C52F7.4040300@twiddle.net> (raw)
In-Reply-To: <BLU436-SMTP153CA5F4AA162B115553228B9010@phx.gbl>
On 03/18/2015 07:04 PM, Chen Gang wrote:
> For me, I am not quite sure about it, the related functional description
> is:
>
> rf[Dest] = signExtend32 ((int32_t) rf[SrcA] * (int32_t) rf[SrcB]);
>
> Do you mean it is equal to:
>
> rf[Dest] = signExtend32 (rf[SrcA] * rf[SrcB]);
Yes, of course.
Think about how multiplication works. Bit N of the input cannot affect any
output bit in [N-1,0]. Thus the first sign-extend cannot affect the output.
r~
next prev parent reply other threads:[~2015-03-20 17:04 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <5509A8CE.2040905@hotmail.com>
2015-03-18 16:34 ` [Qemu-devel] [PATCH 1/6 v6] target-tilegx: Firstly add TILE-Gx with minimized features Chen Gang
2015-03-18 20:06 ` Richard Henderson
2015-03-19 2:04 ` Chen Gang
2015-03-20 17:03 ` Richard Henderson [this message]
2015-03-20 22:55 ` Chen Gang
2015-03-18 16:35 ` [Qemu-devel] [PATCH 2/6 v6] linux-user: tilegx: Firstly add architecture related features Chen Gang
2015-03-18 16:37 ` [Qemu-devel] [PATCH 3/6 v6] linux-user: tilegx: Add target features support within qemu Chen Gang
2015-03-18 16:38 ` [Qemu-devel] [PATCH 4/6 v6] linux-user: Support tilegx architecture in syscall Chen Gang
2015-03-18 16:39 ` [Qemu-devel] [PATCH 5/6 v6] linux-user: Support tilegx architecture in linux-user Chen Gang
2015-03-18 16:39 ` [Qemu-devel] [PATCH 6/6 v6] linux-user/syscall.c: conditionalize syscalls which are not defined in tilegx Chen Gang
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