Fixed bug 6604 "incorrect directed rounding in mpfr_strtofr"

in strtofr.c (to be checked) and added testcases. Other minor
corrections. [merged -r5655:5658 -r5659:5662 from trunk]

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/branches/2.3@5664 280ebfd0-de03-0410-8827-d642c229c3f4

3 files changed, 79 insertions, 26 deletions

diff --git a/strtofr.c b/strtofr.c
index 6e5abc1ee..9f22e10c2 100644
--- a/strtofr.c
+++ b/strtofr.c
@@ -473,7 +473,7 @@ parsed_string_to_mpfr (mpfr_t x, struct parsed_string *pstr, mp_rnd_t rnd)
 
       if (pstr_size >= pstr->prec)
         pstr_size = pstr->prec;
-      MPFR_ASSERTD ((mp_exp_t) pstr_size == (mp_exp_t) pstr_size);
+      MPFR_ASSERTD (pstr_size == (mp_exp_t) pstr_size);
 
       /* convert str into binary */
       real_ysize = mpn_set_str (y, pstr->mant, pstr_size, pstr->base);
@@ -656,6 +656,19 @@ parsed_string_to_mpfr (mpfr_t x, struct parsed_string *pstr, mp_rnd_t rnd)
           err = 0;
         }
 
+      if (pstr_size < pstr->prec && exact
+          && ((rnd == GMP_RNDN)
+              || ((rnd == GMP_RNDD && pstr->negative)
+                  || (rnd == GMP_RNDU && !pstr->negative))))
+        {
+          /* Some significant digits might have been forgotten, if so result
+             is not exact. */
+          size_t i;
+
+          for (i = pstr_size; exact && i < pstr->prec; i++)
+            exact = pstr->mant[i] == 0;
+        }
+
       /* test if rounding is possible, and if so exit the loop */
       if (exact || mpfr_can_round_raw (result, ysize,
                                        (pstr->negative) ? -1 : 1,
diff --git a/tests/tset_str.c b/tests/tset_str.c
index e0e0f80ea..c83e4f54e 100644
--- a/tests/tset_str.c
+++ b/tests/tset_str.c
@@ -81,6 +81,24 @@ check_underflow (void)
   mpfr_clear (a);
 }
 
+/* Bug found by Christoph Lauter. */
+static void
+bug20081028 (void)
+{
+  mpfr_t x;
+  const char *s = "0.10000000000000000000000000000001E1";
+
+  mpfr_init2 (x, 32);
+  mpfr_set_str (x, "1.00000000000000000006", 10, GMP_RNDU);
+  if (! mpfr_greater_p (x, __gmpfr_one))
+    {
+      printf ("Error in bug20081028:\nExpected %s\nGot      ", s);
+      mpfr_dump (x);
+      exit (1);
+    }
+  mpfr_clear (x);
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -845,6 +863,7 @@ main (int argc, char *argv[])
   mpfr_clear (y);
 
   check_underflow ();
+  bug20081028 ();
 
   tests_end_mpfr ();
   return 0;
diff --git a/tests/tstrtofr.c b/tests/tstrtofr.c
index 3a0862809..2243bef7e 100644
--- a/tests/tstrtofr.c
+++ b/tests/tstrtofr.c
@@ -27,28 +27,7 @@ MA 02110-1301, USA. */
 
 #include "mpfr-test.h"
 
-static void check_reftable (void);
-static void check_special  (void);
-static void check_retval   (void);
-static void check_overflow (void);
-static void check_parse    (void);
-
-int
-main (int argc, char *argv[])
-{
-  tests_start_mpfr ();
-
-  check_special();
-  check_reftable ();
-  check_parse ();
-  check_overflow ();
-  check_retval ();
-
-  tests_end_mpfr ();
-  return 0;
-}
-
-void
+static void
 check_special (void)
 {
   mpfr_t x, y;
@@ -551,8 +530,7 @@ static struct dymmy_test {
 "1.001000010110011011000101100000101111101001100011101101001111110111000010010110010001100e-16920"}
 };
 
-
-void
+static void
 check_reftable ()
 {
   int i, base;
@@ -597,7 +575,7 @@ check_reftable ()
   mpfr_clear (x);
 }
 
-void
+static void
 check_parse (void)
 {
   mpfr_t x;
@@ -951,3 +929,46 @@ check_retval (void)
 
   mpfr_clear (x);
 }
+
+/* Bug found by Christoph Lauter (in mpfr_set_str). */
+static void
+bug20081028 (void)
+{
+  mpfr_t x;
+  const char *s = "0.10000000000000000000000000000001E1";
+  int res, err = 0;
+
+  mpfr_init2 (x, 32);
+  res = mpfr_strtofr (x, "1.00000000000000000006", NULL, 10, GMP_RNDU);
+  if (res <= 0)
+    {
+      printf ("Error in bug20081028: expected positive ternary value,"
+              " got %d\n", res);
+      err = 1;
+    }
+  if (! mpfr_greater_p (x, __gmpfr_one))
+    {
+      printf ("Error in bug20081028:\nExpected %s\nGot      ", s);
+      mpfr_dump (x);
+      err = 1;
+    }
+  mpfr_clear (x);
+  if (err)
+    exit (1);
+}
+
+int
+main (int argc, char *argv[])
+{
+  tests_start_mpfr ();
+
+  check_special();
+  check_reftable ();
+  check_parse ();
+  check_overflow ();
+  check_retval ();
+  bug20081028 ();
+
+  tests_end_mpfr ();
+  return 0;
+}