[src/sum.c] Added a comment about shiftq.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@11380 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 1 insertions, 0 deletions

diff --git a/src/sum.c b/src/sum.c
index 03cc22170..4762d10fb 100644
--- a/src/sum.c
+++ b/src/sum.c
@@ -484,6 +484,7 @@ sum_raw (mp_limb_t *wp, mp_size_t ws, mpfr_prec_t wq, const mpfr_ptr *x,
 
                 MPFR_ASSERTD (diffexp < cancel - 2);
                 shiftq = cancel - 2 - (mpfr_prec_t) diffexp;
+                /* equivalent to: minexp + wq - 2 - max(e,err) */
                 MPFR_ASSERTD (shiftq > 0);
                 shifts = shiftq / GMP_NUMB_BITS;
                 shiftc = shiftq % GMP_NUMB_BITS;