From e6afc87f804abee7d0479be5e8e31c56d885fafb Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Thu, 19 May 2011 14:46:17 +0100 Subject: softfloat: Add new flag for when denormal result is flushed to zero Add a new float_flag_output_denormal which is set when the result of a floating point operation would be denormal but is flushed to zero because we are in flush_to_zero mode. This is necessary because some architectures signal this condition as an underflow and others signal it as an inexact result. Signed-off-by: Peter Maydell Signed-off-by: Aurelien Jarno --- fpu/softfloat.c | 41 ++++++++++++++++++++++++++++++++++------- 1 file changed, 34 insertions(+), 7 deletions(-) (limited to 'fpu/softfloat.c') diff --git a/fpu/softfloat.c b/fpu/softfloat.c index baba1dc..e3cd8a7 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -341,7 +341,10 @@ static float32 roundAndPackFloat32( flag zSign, int16 zExp, uint32_t zSig STATUS return packFloat32( zSign, 0xFF, - ( roundIncrement == 0 )); } if ( zExp < 0 ) { - if ( STATUS(flush_to_zero) ) return packFloat32( zSign, 0, 0 ); + if (STATUS(flush_to_zero)) { + float_raise(float_flag_output_denormal STATUS_VAR); + return packFloat32(zSign, 0, 0); + } isTiny = ( STATUS(float_detect_tininess) == float_tininess_before_rounding ) || ( zExp < -1 ) @@ -520,7 +523,10 @@ static float64 roundAndPackFloat64( flag zSign, int16 zExp, uint64_t zSig STATUS return packFloat64( zSign, 0x7FF, - ( roundIncrement == 0 )); } if ( zExp < 0 ) { - if ( STATUS(flush_to_zero) ) return packFloat64( zSign, 0, 0 ); + if (STATUS(flush_to_zero)) { + float_raise(float_flag_output_denormal STATUS_VAR); + return packFloat64(zSign, 0, 0); + } isTiny = ( STATUS(float_detect_tininess) == float_tininess_before_rounding ) || ( zExp < -1 ) @@ -699,7 +705,10 @@ static floatx80 goto overflow; } if ( zExp <= 0 ) { - if ( STATUS(flush_to_zero) ) return packFloatx80( zSign, 0, 0 ); + if (STATUS(flush_to_zero)) { + float_raise(float_flag_output_denormal STATUS_VAR); + return packFloatx80(zSign, 0, 0); + } isTiny = ( STATUS(float_detect_tininess) == float_tininess_before_rounding ) || ( zExp < 0 ) @@ -1030,7 +1039,10 @@ static float128 return packFloat128( zSign, 0x7FFF, 0, 0 ); } if ( zExp < 0 ) { - if ( STATUS(flush_to_zero) ) return packFloat128( zSign, 0, 0, 0 ); + if (STATUS(flush_to_zero)) { + float_raise(float_flag_output_denormal STATUS_VAR); + return packFloat128(zSign, 0, 0, 0); + } isTiny = ( STATUS(float_detect_tininess) == float_tininess_before_rounding ) || ( zExp < -1 ) @@ -1761,7 +1773,12 @@ static float32 addFloat32Sigs( float32 a, float32 b, flag zSign STATUS_PARAM) return a; } if ( aExp == 0 ) { - if ( STATUS(flush_to_zero) ) return packFloat32( zSign, 0, 0 ); + if (STATUS(flush_to_zero)) { + if (aSig | bSig) { + float_raise(float_flag_output_denormal STATUS_VAR); + } + return packFloat32(zSign, 0, 0); + } return packFloat32( zSign, 0, ( aSig + bSig )>>6 ); } zSig = 0x40000000 + aSig + bSig; @@ -3120,7 +3137,12 @@ static float64 addFloat64Sigs( float64 a, float64 b, flag zSign STATUS_PARAM ) return a; } if ( aExp == 0 ) { - if ( STATUS(flush_to_zero) ) return packFloat64( zSign, 0, 0 ); + if (STATUS(flush_to_zero)) { + if (aSig | bSig) { + float_raise(float_flag_output_denormal STATUS_VAR); + } + return packFloat64(zSign, 0, 0); + } return packFloat64( zSign, 0, ( aSig + bSig )>>9 ); } zSig = LIT64( 0x4000000000000000 ) + aSig + bSig; @@ -5282,7 +5304,12 @@ static float128 addFloat128Sigs( float128 a, float128 b, flag zSign STATUS_PARAM } add128( aSig0, aSig1, bSig0, bSig1, &zSig0, &zSig1 ); if ( aExp == 0 ) { - if ( STATUS(flush_to_zero) ) return packFloat128( zSign, 0, 0, 0 ); + if (STATUS(flush_to_zero)) { + if (zSig0 | zSig1) { + float_raise(float_flag_output_denormal STATUS_VAR); + } + return packFloat128(zSign, 0, 0, 0); + } return packFloat128( zSign, 0, zSig0, zSig1 ); } zSig2 = 0; -- cgit v1.1