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(__mpn_extract_long_double): Handle 80-bit denormalized numbers correct.

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This commit is contained in:
Ulrich Drepper 1995-03-17 12:28:47 +00:00
parent c45e5aa9a4
commit 61cd9516c2
1 changed files with 10 additions and 2 deletions
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12
sysdeps/ieee754/ldbl2mpn.c
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@ -64,6 +64,14 @@ __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
/* It is a denormal number, meaning it has no implicit leading
one bit, and its exponent is in fact the format minimum. */
int cnt;
/* One problem with Intel's 80-bit format is that the explicit
leading one in the normalized representation has to be zero
for denormalized number. If it is one, the number is according
to Intel's specification an invalid number. We make the
representation unique by explicitly clearing this bit. */
res_ptr[N - 1] &= ~(1 << ((LDBL_MANT_DIG - 1) % BITS_PER_MP_LIMB));
if (res_ptr[N - 1] != 0)
{
count_leading_zeros (cnt, res_ptr[N - 1]);
@ -77,14 +85,14 @@ __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
res_ptr[N - 1] <<= cnt;
#endif
}
*expt = LDBL_MIN_EXP - 2 - cnt;
*expt = LDBL_MIN_EXP - 1 - cnt;
}
else
{
count_leading_zeros (cnt, res_ptr[0]);
res_ptr[N - 1] = res_ptr[0] << cnt;
res_ptr[0] = 0;
*expt = LDBL_MIN_EXP - 2 - BITS_PER_MP_LIMB - cnt;
*expt = LDBL_MIN_EXP - 1 - BITS_PER_MP_LIMB - cnt;
}
}
}