purely inline signbit() implementation

1 files changed, 16 insertions, 5 deletions

diff --git a/src/math/signbit.c b/src/math/signbit.c
index 3491a1e2..a5278e77 100644
--- a/src/math/signbit.c
+++ b/src/math/signbit.c
@@ -1,10 +1,21 @@
 #include <math.h>
-                               int __signbitf(float x);
-                              int __signbitd(double x);
-                         int __signbitl(long double x);
 
-#define signbit(x)          ((sizeof (x) == sizeof (float)) ? __signbitf(x) : \
-	(sizeof (x) == sizeof (double)) ? __signbitd(x) : __signbitl(x))
+#define signbit(x) \
+	(sizeof(x) == sizeof(long double) ? \
+		((((union { \
+			long double __f; \
+			char __c[sizeof(x)]; \
+		}){.__f = (x)}).__c[sizeof(x)-1] & 0x80) == 0x80 ? 1 : 0) : \
+	sizeof(x) == sizeof(double) ? \
+		((((union { \
+			double __f; \
+			char __c[sizeof(x)]; \
+		}){.__f = (x)}).__c[sizeof(x)-1] & 0x80) == 0x80 ? 1 : 0) : \
+		(((union { \
+			float __f; \
+			char __c[sizeof(x)]; \
+		}){.__f = (x)}).__c[sizeof(x)-1] & 0x80) == 0x80 ? 1 : 0)
+
 
 /*
 STDC(199901)