diff options
| -rw-r--r-- | src/sum.c | 19 |
1 files changed, 15 insertions, 4 deletions
@@ -843,9 +843,21 @@ sum_aux (mpfr_ptr sum, mpfr_ptr *const x, unsigned long n, mpfr_rnd_t rnd, else if (maxexp != MPFR_EXP_MIN) sst = 1; else - do - sst = wp[ws] != 0; - while (sst == 0 && ws-- > 0); + { + do + sst = wp[ws] != 0; + while (sst == 0 && ws-- > 0); + if (sst == 0 && tmd == 2) + { + /* For halfway cases, let's virtually eliminate them + by setting a sst equivalent to a non-halfway case, + which depends on the last bit of the pre-rounded + result and the sign. */ + MPFR_ASSERTD (rnd == MPFR_RNDN); + sst = (sump[0] & MPFR_LIMB_ONE) ? + (pos ? 1 : -1) : (pos ? -1 : 1); + } + } MPFR_LOG_MSG (("[Step 8] tmd=%d rbit=%d sst=%d\n", tmd, rbit != 0, sst)); @@ -855,7 +867,6 @@ sum_aux (mpfr_ptr sum, mpfr_ptr *const x, unsigned long n, mpfr_rnd_t rnd, MPFR_IS_LIKE_RNDU (rnd, pos ? 1 : -1) ? (sst ? 1 : 0) : (MPFR_ASSERTD (rnd == MPFR_RNDN), tmd == 1 ? - sst : sst); - /* Note: halfway cases may have to be corrected. */ /* TODO: possible correction of the value (+/- 1 ulp)... */ |