| Message ID | 1348794721-28534-1-git-send-email-rth@twiddle.net |
|---|---|
| State | New |
| Headers | show |
On 28 September 2012 02:12, Richard Henderson <rth@twiddle.net> wrote: > The interface to normalizeRoundAndPackFloat64 requires that the > high bit be clear. Perform one shift-right-and-jam if needed. > > Signed-off-by: Richard Henderson <rth@twiddle.net> > --- > fpu/softfloat.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/fpu/softfloat.c b/fpu/softfloat.c > index b29256a..45f105a 100644 > --- a/fpu/softfloat.c > +++ b/fpu/softfloat.c > @@ -1273,9 +1273,14 @@ float64 int64_to_float64( int64 a STATUS_PARAM ) > > float64 uint64_to_float64( uint64 a STATUS_PARAM ) > { > - if ( a == 0 ) return float64_zero; > - return normalizeRoundAndPackFloat64( 0, 0x43C, a STATUS_VAR ); > + int exp = 0x43C; > > + if ( a == 0 ) return float64_zero; > + if ( (int64_t)a < 0 ) { > + a = (a >> 1) | (a & 1); > + exp += 1; > + } You could just use shift64RightJamming(a, 1, &a); rather than calculating a like that; gcc is smart enough to emit the same code as your longhand version. > + return normalizeRoundAndPackFloat64( 0, exp, a STATUS_VAR ); I worked through it and I believe this patch does the right thing with raising or not raising the inexact flag... -- PMM
diff --git a/fpu/softfloat.c b/fpu/softfloat.c index b29256a..45f105a 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -1273,9 +1273,14 @@ float64 int64_to_float64( int64 a STATUS_PARAM ) float64 uint64_to_float64( uint64 a STATUS_PARAM ) { - if ( a == 0 ) return float64_zero; - return normalizeRoundAndPackFloat64( 0, 0x43C, a STATUS_VAR ); + int exp = 0x43C; + if ( a == 0 ) return float64_zero; + if ( (int64_t)a < 0 ) { + a = (a >> 1) | (a & 1); + exp += 1; + } + return normalizeRoundAndPackFloat64( 0, exp, a STATUS_VAR ); } /*----------------------------------------------------------------------------
The interface to normalizeRoundAndPackFloat64 requires that the high bit be clear. Perform one shift-right-and-jam if needed. Signed-off-by: Richard Henderson <rth@twiddle.net> --- fpu/softfloat.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)