added comments, got rid of compiler warnings

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@5087 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 6 insertions, 3 deletions

diff --git a/round_near_x.c b/round_near_x.c
index 5a81a3435..dfb550daf 100644
--- a/round_near_x.c
+++ b/round_near_x.c
@@ -171,7 +171,7 @@ mpfr_round_near_x (mpfr_ptr y, mpfr_srcptr v, mpfr_uexp_t err, int dir,
             || mpfr_round_p (MPFR_MANT (v), MPFR_LIMB_SIZE (v),
                              (mp_exp_t) err,
                              MPFR_PREC (y) + (rnd == GMP_RNDN)))))
-    /* If we assume we can not round, return 0 */
+    /* If we assume we can not round, return 0, and y is not modified */
     return 0;
 
   /* First round v in y */
@@ -201,7 +201,7 @@ mpfr_round_near_x (mpfr_ptr y, mpfr_srcptr v, mpfr_uexp_t err, int dir,
           inexact = sign;
           if (MPFR_IS_LIKE_RNDZ (rnd, MPFR_IS_NEG_SIGN (sign)))
             {
-            nexttozero:
+              /* case nexttozero */
               /* The underflow flag should be set if the result is zero */
               __gmpfr_flags = old_flags;
               inexact = -sign;
@@ -217,7 +217,7 @@ mpfr_round_near_x (mpfr_ptr y, mpfr_srcptr v, mpfr_uexp_t err, int dir,
           if (rnd != GMP_RNDN && rnd != GMP_RNDZ
               && MPFR_IS_RNDUTEST_OR_RNDDNOTTEST (rnd, MPFR_IS_POS_SIGN(sign)))
             {
-            nexttoinf:
+              /* case nexttoinf */
               /* The overflow flag should be set if the result is infinity */
               inexact = sign;
               mpfr_nexttoinf (y);
@@ -227,5 +227,8 @@ mpfr_round_near_x (mpfr_ptr y, mpfr_srcptr v, mpfr_uexp_t err, int dir,
         }
     }
 
+  /* the inexact flag cannot be 0, since this would mean an exact value,
+     and in this case we cannot round correctly */
+  MPFR_ASSERTD(inexact != 0);
   MPFR_RET (inexact);
 }