diff options
Diffstat (limited to 'src/sub1.c')
| -rw-r--r-- | src/sub1.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/src/sub1.c b/src/sub1.c index 9337cc235..5b475d9d3 100644 --- a/src/sub1.c +++ b/src/sub1.c @@ -123,11 +123,11 @@ mpfr_sub1 (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode) if (rnd_mode == MPFR_RNDF) return mpfr_set4 (a, b, MPFR_RNDZ, MPFR_SIGN (a)); - MPFR_EXP (a) = exp_b; /* may be up to MPFR_EXP_MAX */ + exp_a = exp_b; /* may be any out-of-range value due to UBF */ MPFR_RNDRAW_EVEN (inexact, a, MPFR_MANT (b), bq, rnd_mode, MPFR_SIGN (a), - if (MPFR_EXP (a) != MPFR_EXP_MAX) - ++ MPFR_EXP (a)); + if (exp_a != MPFR_EXP_MAX) + exp_a ++); MPFR_LOG_MSG (("inexact=%d\n", inexact)); if (inexact == 0) { @@ -139,7 +139,7 @@ mpfr_sub1 (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode) if (! MPFR_IS_LIKE_RNDZ (rnd_mode, MPFR_IS_NEG (a))) { inexact = MPFR_INT_SIGN (a); - goto check_overflow; + goto end_of_c_small; } } else /* inexact != 0 */ @@ -164,7 +164,7 @@ mpfr_sub1 (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode) which means we get a wrong rounded result if x == 1, i.e. inexact == MPFR_EVEN_INEX (for positive numbers). */ if (MPFR_LIKELY (inexact != MPFR_EVEN_INEX * MPFR_INT_SIGN (a))) - goto check_overflow; + goto end_of_c_small; } /* We need to take the value preceding |a|. We can't use mpfr_nexttozero due to a possible out-of-range exponent. @@ -174,16 +174,20 @@ mpfr_sub1 (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode) mpn_sub_1 (ap, ap, an, MPFR_LIMB_ONE << sh); if (MPFR_UNLIKELY (MPFR_LIMB_MSB (ap[an-1]) == 0)) { - MPFR_EXP (a) --; + exp_a --; /* The following is valid whether an = 1 or an > 1. */ ap[an-1] |= MPFR_LIMB_HIGHBIT; } inexact = - MPFR_INT_SIGN (a); - check_overflow: - if (MPFR_UNLIKELY (MPFR_EXP (a) > __gmpfr_emax)) + end_of_c_small: + /* The underflow case is possibly only with UBF. The overflow case + is also possible with normal FP due to rounding. */ + if (MPFR_UNLIKELY (exp_a > __gmpfr_emax)) return mpfr_overflow (a, rnd_mode, MPFR_SIGN (a)); - else - MPFR_RET (inexact); + if (MPFR_UNLIKELY (exp_a < __gmpfr_emin)) + goto underflow; + MPFR_SET_EXP (a, exp_a); + MPFR_RET (inexact); } /* reserve a space to store b aligned with the result, i.e. shifted by |