On Thu, Jan 19, 2017 at 07:29:54AM -0800, Richard Henderson wrote: > On 01/18/2017 09:14 PM, Bharata B Rao wrote: > > Power ISA 3.0 introduces a few quadruple precision floating point > > instructions that support round-to-add rounding mode. The > > round-to-odd mode is explained as under: > > > > Let Z be the intermediate arithmetic result or the operand of a convert > > operation. If Z can be represented exactly in the target format, the > > result is Z. Otherwise the result is either Z1 or Z2 whichever is odd. > > Here Z1 and Z2 are the next larger and smaller numbers representable > > in the target format respectively. > > > > Signed-off-by: Bharata B Rao <[email protected]> > > --- > > - I am not fully sure if this the correct implementation for the above > > described round-to-odd rounding method. Any help is appreciated. > > - Didn't bother to add round-to-odd to other floating point precision > > variants as round-to-odd option is currently supported only for some > > instructions that work on quad precision. > > > > fpu/softfloat.c | 6 ++++++ > > include/fpu/softfloat.h | 1 + > > 2 files changed, 7 insertions(+) > > > > diff --git a/fpu/softfloat.c b/fpu/softfloat.c > > index c295f31..05932a9 100644 > > --- a/fpu/softfloat.c > > +++ b/fpu/softfloat.c > > @@ -1149,6 +1149,9 @@ static float128 roundAndPackFloat128(flag zSign, > > int32_t zExp, > > case float_round_down: > > increment = zSign && zSig2; > > break; > > + case float_round_to_odd: > > + increment = !(zSig1 & 0x1) && zSig2; > > + break; > > default: > > abort(); > > } > > @@ -1215,6 +1218,9 @@ static float128 roundAndPackFloat128(flag zSign, > > int32_t zExp, > > case float_round_down: > > increment = zSign && zSig2; > > break; > > + case float_round_to_odd: > > + increment = !(zSig1 & 0x1) && zSig2; > > + break; > > default: > > abort(); > > } > > I believe you've missed the section in between that deals with > round-to-largest or to infinity: > > if ( ( roundingMode == float_round_to_zero ) > || ( zSign && ( roundingMode == float_round_up ) ) > || ( ! zSign && ( roundingMode == float_round_down ) ) > ) {
Addresed in v1. Thanks Richard and Peter for pointing this out. > > The description in see in the manual on page 387 is more precise than what > you quote above: Right. I quoted from page 385 as it is more concise for patch description. However if you think the more precise definition of page 387 is appropriate in commit, I can put it. Regards, Bharata.
