softfloat: fix floatx80_is_{quiet,signaling}_nan()

floatx80_is_{quiet,signaling}_nan() functions are incorrectly detecting
the type of NaN, depending on SNAN_BIT_IS_ONE, one of the two is
returning the correct value, and the other true for any kind of NaN.

This patch fixes that by applying the same kind of comparison as for
other float formats, but taking into account the explicit bit.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h
index 11521cebf4..eb644b2273 100644
--- a/fpu/softfloat-specialize.h
+++ b/fpu/softfloat-specialize.h
@@ -468,7 +468,8 @@ static float64 propagateFloat64NaN( float64 a, float64 b STATUS_PARAM)
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the extended double-precision floating-point value `a' is a
-| quiet NaN; otherwise returns 0.
+| quiet NaN; otherwise returns 0. This slightly differs from the same
+| function for other types as floatx80 has an explicit bit.
 *----------------------------------------------------------------------------*/
 
 int floatx80_is_quiet_nan( floatx80 a )
@@ -482,19 +483,22 @@ int floatx80_is_quiet_nan( floatx80 a )
         && (bits64) ( aLow<<1 )
         && ( a.low == aLow );
 #else
-    return ( ( a.high & 0x7FFF ) == 0x7FFF ) && (bits64) ( a.low<<1 );
+    return ( ( a.high & 0x7FFF ) == 0x7FFF )
+        && (LIT64( 0x8000000000000000 ) <= ((bits64) ( a.low<<1 )));
 #endif
 }
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the extended double-precision floating-point value `a' is a
-| signaling NaN; otherwise returns 0.
+| signaling NaN; otherwise returns 0. This slightly differs from the same
+| function for other types as floatx80 has an explicit bit.
 *----------------------------------------------------------------------------*/
 
 int floatx80_is_signaling_nan( floatx80 a )
 {
 #if SNAN_BIT_IS_ONE
-    return ( ( a.high & 0x7FFF ) == 0x7FFF ) && (bits64) ( a.low<<1 );
+    return ( ( a.high & 0x7FFF ) == 0x7FFF )
+        && (LIT64( 0x8000000000000000 ) <= ((bits64) ( a.low<<1 )));
 #else
     bits64 aLow;