trunc: Implement result sign according to IEEE 754.

[gnulib.git] / tests / test-trunc-ieee.c

diff --git a/tests/test-trunc-ieee.c b/tests/test-trunc-ieee.c
index c0fc0f2..0828393 100644 (file)
--- a/tests/test-trunc-ieee.c
+++ b/tests/test-trunc-ieee.c
@@ -24,9 +24,20 @@
 int
 main ()
 {
+  /* See IEEE 754, section 6.3:
+       "the sign of the result of the round floating-point number to
+        integral value operation is the sign of the operand. These rules
+        shall apply even when operands or results are zero or infinite."  */
+
   /* Zero.  */
   ASSERT (!signbit (trunc (0.0)));
   ASSERT (!!signbit (trunc (minus_zerod)) == !!signbit (minus_zerod));
+  /* Positive numbers.  */
+  ASSERT (!signbit (trunc (0.3)));
+  ASSERT (!signbit (trunc (0.7)));
+  /* Negative numbers.  */
+  ASSERT (!!signbit (trunc (-0.3)) == !!signbit (minus_zerod));
+  ASSERT (!!signbit (trunc (-0.7)) == !!signbit (minus_zerod));
 
   return 0;
 }