diff options
Diffstat (limited to 'src/sub.c')
| -rw-r--r-- | src/sub.c | 24 |
1 files changed, 21 insertions, 3 deletions
@@ -31,7 +31,7 @@ mpfr_sub (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode) mpfr_get_prec (c), mpfr_log_prec, c, rnd_mode), ("a[%Pu]=%.*Rg", mpfr_get_prec (a), mpfr_log_prec, a)); - if (MPFR_ARE_SINGULAR (b,c)) + if (MPFR_ARE_SINGULAR_OR_UBF (b,c)) { if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c)) { @@ -72,11 +72,29 @@ mpfr_sub (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode) else return mpfr_neg (a, c, rnd_mode); } - else + else if (MPFR_IS_ZERO (c)) { - MPFR_ASSERTD (MPFR_IS_ZERO (c)); return mpfr_set (a, b, rnd_mode); } + else + { + MPFR_ASSERTD (MPFR_IS_PURE_UBF (b)); + MPFR_ASSERTD (MPFR_IS_PURE_UBF (c)); + /* mpfr_sub1sp and mpfr_add1sp are not intended to support UBF, + for which optimization is less important. */ + if (MPFR_SIGN(b) == MPFR_SIGN(c)) + return mpfr_sub1 (a, b, c, rnd_mode); + else if (MPFR_EXP_LESS_P (b, c)) + { + int inexact; + rnd_mode = MPFR_INVERT_RND (rnd_mode); + inexact = mpfr_add1 (a, c, b, rnd_mode); + MPFR_CHANGE_SIGN (a); + return -inexact; + } + else + return mpfr_add1 (a, b, c, rnd_mode); + } } MPFR_ASSERTD (MPFR_IS_PURE_FP (b)); |