diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl2mpn.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl2mpn.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/sysdeps/ieee754/ldbl2mpn.c b/sysdeps/ieee754/ldbl2mpn.c index 29e8a3b2ce..029a92a556 100644 --- a/sysdeps/ieee754/ldbl2mpn.c +++ b/sysdeps/ieee754/ldbl2mpn.c @@ -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; } } } |