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From: Tom Musta <tommusta@gmail.com>
To: QEMU Developers <qemu-devel@nongnu.org>,
	"qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>
Subject: [Qemu-devel] PowerPC Decimal Floating Point
Date: Tue, 11 Feb 2014 11:14:13 -0600	[thread overview]
Message-ID: <52FA5A65.5080004@gmail.com> (raw)

QEMU is currently lacking support for the Decimal Floating Point category of instructions
(see Power ISA V2.07 Chapter 6).  I intend to add this support.

Has this topic been investigated before and if so can anyone point me to that discussion?
A Google search came up empty for me.

My proposal is to incorporate the libdecnumber component of libdfp
(http://www.eglibc.org/cgi-bin/viewvc.cgi/libdfp/trunk/) in a manner analogous to how
softfloat is used for binary floating point.  So, for example, the helper for the dadd
instruction would look something like the following:

   - map FPSCR state to a decContext.
   - convert the contents of the source FPRs to decNumbers (decimal64ToNumber).
   - call decNumberAdd
   - convert the resultant decNumber to DPD (decimal64FromNumber)
   - update FPSCR per the decContext.status and result.

Comments?

             reply	other threads:[~2014-02-11 17:14 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-11 17:14 Tom Musta [this message]
2014-02-12  7:38 ` [Qemu-devel] [Qemu-ppc] PowerPC Decimal Floating Point Alexander Graf
2014-02-14 21:22   ` Richard Henderson
2014-02-14 22:22     ` Tom Musta

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