1 files changed, 53 insertions, 0 deletions
diff --git a/include/math.h b/include/math.h
index 79ebbae359..a274f2bdfd 100644
--- a/include/math.h
+++ b/include/math.h
@@ -54,6 +54,59 @@ libm_hidden_proto (__expf128)
 libm_hidden_proto (__expm1f128)
 # endif
 
+#include <stdint.h>
+#include <nan-high-order-bit.h>
+
+/* A union which permits us to convert between a float and a 32 bit
+   int.  */
+
+typedef union
+{
+  float value;
+  uint32_t word;
+} ieee_float_shape_type;
+
+/* Get a 32 bit int from a float.  */
+#ifndef GET_FLOAT_WORD
+# define GET_FLOAT_WORD(i,d)					\
+do {								\
+  ieee_float_shape_type gf_u;					\
+  gf_u.value = (d);						\
+  (i) = gf_u.word;						\
+} while (0)
+#endif
+
+/* Set a float from a 32 bit int.  */
+#ifndef SET_FLOAT_WORD
+# define SET_FLOAT_WORD(d,i)					\
+do {								\
+  ieee_float_shape_type sf_u;					\
+  sf_u.word = (i);						\
+  (d) = sf_u.value;						\
+} while (0)
+#endif
+
+extern inline int
+__issignalingf (float x)
+{
+  uint32_t xi;
+  GET_FLOAT_WORD (xi, x);
+#if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
+  /* We only have to care about the high-order bit of x's significand, because
+     having it set (sNaN) already makes the significand different from that
+     used to designate infinity.  */
+  return (xi & 0x7fc00000) == 0x7fc00000;
+#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).  */
+  xi ^= 0x00400000;
+  /* We have to compare for greater (instead of greater or equal), because x's
+     significand being all-zero designates infinity not NaN.  */
+  return (xi & 0x7fffffff) > 0x7fc00000;
+#endif
+}
+
 # if __HAVE_DISTINCT_FLOAT128
 
 /* __builtin_isinf_sign is broken in GCC < 7 for float128.  */