# HG changeset patch
# User Eric Blake <eblake@redhat.com>
# Date 1288965814 21600
# Node ID 2ba13be8e841e762ba207e9185bf7850b83d6e8f
# Parent  ed864b3ac8ec6f58c52eacf0a22e2f43b1bc1001
copysign: enhance tests

* modules/copysign-tests (Files): Add minus-zero.h.
* tests/test-copysign.c (main): Also test zeros.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-11-05  Eric Blake  <eblake@redhat.com>
+
+	copysign: enhance tests
+	* modules/copysign-tests (Files): Add minus-zero.h.
+	* tests/test-copysign.c (main): Also test zeros.
+
 2010-11-04  Eric Blake  <eblake@redhat.com>
 
 	ceil, floor, round, trunc: enhance tests of -0
diff --git a/modules/copysign-tests b/modules/copysign-tests
--- a/modules/copysign-tests
+++ b/modules/copysign-tests
@@ -1,6 +1,7 @@
 Files:
 tests/test-copysign.c
 tests/signature.h
+tests/minus-zero.h
 tests/macros.h
 
 Depends-on:
diff --git a/tests/test-copysign.c b/tests/test-copysign.c
--- a/tests/test-copysign.c
+++ b/tests/test-copysign.c
@@ -24,10 +24,14 @@
 SIGNATURE_CHECK (copysign, double, (double, double));
 
 #include "macros.h"
+#include "minus-zero.h"
+
+#include <string.h>
 
 volatile double x;
 volatile double y;
 double z;
+double zero = 0.0;
 
 int
 main ()
@@ -56,5 +60,52 @@
   z = copysign (x, y);
   ASSERT (z == -0.6);
 
+  /* From signed zero.  */
+  x = 1.0;
+  y = 0.0;
+  z = copysign (x, y);
+  ASSERT (z == 1.0);
+
+  x = 1.0;
+  y = minus_zerod;
+  z = copysign (x, y);
+  /* Assume all gnulib targets support -0.0, until proven otherwise.  */
+  ASSERT (z == -1.0);
+
+  x = -1.0;
+  y = 0.0;
+  z = copysign (x, y);
+  ASSERT (z == 1.0);
+
+  x = -1.0;
+  y = minus_zerod;
+  z = copysign (x, y);
+  ASSERT (z == -1.0);
+
+  /* To signed zero.  */
+  x = 0.0;
+  y = 1.0;
+  z = copysign (x, y);
+  ASSERT (z == 0.0);
+  ASSERT (memcmp (&z, &zero, sizeof z) == 0);
+
+  x = 0.0;
+  y = -1.0;
+  z = copysign (x, y);
+  ASSERT (z == 0.0);
+  ASSERT (memcmp (&z, &zero, sizeof z) != 0);
+
+  x = minus_zerod;
+  y = 1.0;
+  z = copysign (x, y);
+  ASSERT (z == 0.0);
+  ASSERT (memcmp (&z, &zero, sizeof z) == 0);
+
+  x = minus_zerod;
+  y = -1.0;
+  z = copysign (x, y);
+  ASSERT (z == 0.0);
+  ASSERT (memcmp (&z, &zero, sizeof z) != 0);
+
   return 0;
 }