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authorPeter Maydell <peter.maydell@linaro.org>2011-05-19 14:46:17 +0100
committerAurelien Jarno <aurelien@aurel32.net>2011-05-23 22:39:35 +0200
commite6afc87f804abee7d0479be5e8e31c56d885fafb (patch)
tree7583efb95a098017efe645d40a81941d1216f671 /fpu/softfloat.c
parent43fe9bdb0f64237187aeab809bb98e1b46807538 (diff)
downloadqemu-arm-e6afc87f804abee7d0479be5e8e31c56d885fafb.tar.gz
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 <peter.maydell@linaro.org> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Diffstat (limited to 'fpu/softfloat.c')
-rw-r--r--fpu/softfloat.c41
1 files changed, 34 insertions, 7 deletions
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index baba1dc44b..e3cd8a7296 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;