about summary refs log tree commit diff
path: root/sysdeps/ieee754/ldbl-96/s_issignalingl.c
diff options
context:
space:
mode:
authorThomas Schwinge <thomas@codesourcery.com>2013-04-02 13:51:02 +0200
committerThomas Schwinge <thomas@codesourcery.com>2013-04-02 13:51:02 +0200
commit572676160d5639edc0ecb663147bd291841458d1 (patch)
tree26abea75b21e81f568075075249aa3dbedad20c7 /sysdeps/ieee754/ldbl-96/s_issignalingl.c
parent60c414c346a1d5ef0510ffbdc0ab75f288ee4d3f (diff)
downloadglibc-572676160d5639edc0ecb663147bd291841458d1.tar.gz
glibc-572676160d5639edc0ecb663147bd291841458d1.tar.xz
glibc-572676160d5639edc0ecb663147bd291841458d1.zip
New <math.h> macro named issignaling to check for a signaling NaN (sNaN).
It is based on draft TS 18661 and currently enabled as a GNU extension.
Diffstat (limited to 'sysdeps/ieee754/ldbl-96/s_issignalingl.c')
-rw-r--r--sysdeps/ieee754/ldbl-96/s_issignalingl.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-96/s_issignalingl.c b/sysdeps/ieee754/ldbl-96/s_issignalingl.c
new file mode 100644
index 0000000000..107aff1516
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-96/s_issignalingl.c
@@ -0,0 +1,43 @@
+/* Test for signaling NaN.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+#include <math_private.h>
+
+int
+__issignalingl (long double x)
+{
+  u_int32_t exi, hxi, lxi;
+  GET_LDOUBLE_WORDS (exi, hxi, lxi, x);
+#ifdef HIGH_ORDER_BIT_IS_SET_FOR_SNAN
+# error not implemented
+#else
+  /* To keep the following comparison simple, toggle the quiet/signaling bit,
+     so that it is set for sNaNs.  This is inverse to IEEE 754-2008 (as well as
+     common practice for IEEE 754-1985).  */
+  hxi ^= 0x40000000;
+  /* If lxi != 0, then set any suitable bit of the significand in hxi.  */
+  hxi |= (lxi | -lxi) >> 31;
+  /* We do not recognize a pseudo NaN as sNaN; they're invalid on 80387 and
+     later.  */
+  /* We have to compare for greater (instead of greater or equal), because x's
+     significand being all-zero designates infinity not NaN.  */
+  return ((exi & 0x7fff) == 0x7fff) && (hxi > 0xc0000000);
+#endif
+}
+libm_hidden_def (__issignalingl)