[tatan.c] added one test to improve the code coverage, which produces an

	  infinite loop in mpc_atan...
[atan.c] added a check to detect potential infinite loops


git-svn-id: svn://scm.gforge.inria.fr/svn/mpc/trunk@1167 211d60ee-9f03-0410-a15a-8952a2c7a4e4

2 files changed, 35 insertions, 2 deletions

diff --git a/src/atan.c b/src/atan.c
index fb0f067..3177a45 100644
--- a/src/atan.c
+++ b/src/atan.c
@@ -1,6 +1,6 @@
 /* mpc_atan -- arctangent of a complex number.
 
-Copyright (C) 2009, 2010, 2011 INRIA
+Copyright (C) 2009, 2010, 2011, 2012 INRIA
 
 This file is part of GNU MPC.
 
@@ -18,6 +18,7 @@ You should have received a copy of the GNU Lesser General Public License
 along with this program. If not, see http://www.gnu.org/licenses/ .
 */
 
+#include <stdio.h>
 #include "mpc-impl.h"
 
 /* set rop to
@@ -195,6 +196,7 @@ mpc_atan (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
     mpfr_t minus_op_re;
     mpfr_exp_t op_re_exp, op_im_exp;
     mpfr_rnd_t rnd1, rnd2;
+    int loops = 0;
 
     mpfr_inits2 (MPFR_PREC_MIN, a, b, x, y, (mpfr_ptr) 0);
 
@@ -230,6 +232,8 @@ mpc_atan (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
 
     do
       {
+        MPC_ASSERT (++loops < 100);
+
         p += mpc_ceil_log2 (p) + 2;
         mpfr_set_prec (a, p);
         mpfr_set_prec (b, p);
diff --git a/tests/tatan.c b/tests/tatan.c
index b46f694..89e476e 100644
--- a/tests/tatan.c
+++ b/tests/tatan.c
@@ -1,6 +1,6 @@
 /* tatan -- test file for mpc_atan.
 
-Copyright (C) 2009 INRIA
+Copyright (C) 2009, 2012 INRIA
 
 This file is part of GNU MPC.
 
@@ -20,6 +20,33 @@ along with this program. If not, see http://www.gnu.org/licenses/ .
 
 #include "mpc-tests.h"
 
+static int
+test_coverage (void)
+{
+  mpc_t z;
+  mpfr_exp_t emin = mpfr_get_emin ();
+
+  mpfr_set_emin (-10);
+  mpc_init2 (z, 21);
+  mpfr_set_si (mpc_realref(z), -1, GMP_RNDZ);
+  mpfr_set_ui_2exp (mpc_imagref(z), 1, 20, GMP_RNDZ);
+  mpfr_add_ui (mpc_imagref(z), mpc_imagref(z), 1, GMP_RNDZ);
+  mpfr_div_2exp (mpc_imagref(z), mpc_imagref(z), 20, GMP_RNDZ);
+  mpc_atan (z, z, MPC_RNDNN);
+  if (mpfr_cmp_si_2exp (mpc_realref(z), -1066635, 20) != 0 ||
+      mpfr_cmp_si_2exp (mpc_imagref(z), 1687619, 22))
+    {
+      printf ("Error in test_coverage\n");
+      printf ("expected (-1066635/2^20 1687619/2^22)\n");
+      printf ("got      ");
+      mpc_out_str (stdout, 10, 20, z, MPC_RNDNN);
+      printf ("\n");
+      exit (1);
+    }
+  mpc_clear (z);
+  mpfr_set_emin (emin);
+}
+
 int
 main (void)
 {
@@ -27,6 +54,8 @@ main (void)
 
   test_start ();
 
+  test_coverage ();
+
   data_check (f, "atan.dat");
   tgeneric (f, 2, 512, 5, 128);