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softfloat: add float128_is_{normal,denormal}

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Needed on s390x, to test for the data class of a number. So it will
gain soon a user.

A number is considered normal if the exponent is neither 0 nor all 1's.
That can be checked by adding 1 to the exponent, and comparing against
>= 2 after dropping an eventual overflow into the sign bit.

While at it, convert the other floatXX_is_normal functions to use a
similar, less error prone calculation, as suggested by Richard H.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
This commit is contained in:
David Hildenbrand 2019-02-06 10:10:43 +01:00 committed by Alex Bennée
parent 3acf04f899
commit 4739318160
1 changed files with 12 additions and 2 deletions
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14
include/fpu/softfloat.h
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@ -466,7 +466,7 @@ static inline int float32_is_zero_or_denormal(float32 a)
static inline bool float32_is_normal(float32 a)
{
return ((float32_val(a) + 0x00800000) & 0x7fffffff) >= 0x01000000;
return (((float32_val(a) >> 23) + 1) & 0xff) >= 2;
}
static inline bool float32_is_denormal(float32 a)
@ -622,7 +622,7 @@ static inline int float64_is_zero_or_denormal(float64 a)
static inline bool float64_is_normal(float64 a)
{
return ((float64_val(a) + (1ULL << 52)) & -1ULL >> 1) >= 1ULL << 53;
return (((float64_val(a) >> 52) + 1) & 0x7ff) >= 2;
}
static inline bool float64_is_denormal(float64 a)
@ -940,6 +940,16 @@ static inline int float128_is_zero_or_denormal(float128 a)
return (a.high & 0x7fff000000000000LL) == 0;
}
static inline bool float128_is_normal(float128 a)
{
return (((a.high >> 48) + 1) & 0x7fff) >= 2;
}
static inline bool float128_is_denormal(float128 a)
{
return float128_is_zero_or_denormal(a) && !float128_is_zero(a);
}
static inline int float128_is_any_nan(float128 a)
{
return ((a.high >> 48) & 0x7fff) == 0x7fff &&