[Qemu-devel] PowerPC Decimal Floating Point

[Tom Musta]

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?