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Diffstat (limited to 'sysdeps/ieee754/ldbl-128/s_ilogbl.c')
-rw-r--r--sysdeps/ieee754/ldbl-128/s_ilogbl.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/sysdeps/ieee754/ldbl-128/s_ilogbl.c b/sysdeps/ieee754/ldbl-128/s_ilogbl.c
index d2acfd3105..c042aa43d8 100644
--- a/sysdeps/ieee754/ldbl-128/s_ilogbl.c
+++ b/sysdeps/ieee754/ldbl-128/s_ilogbl.c
@@ -19,8 +19,9 @@ static char rcsid[] = "$NetBSD: $";
 
 /* ilogbl(long double x)
  * return the binary exponent of non-zero x
- * ilogbl(0) = 0x80000001
- * ilogbl(inf/NaN) = 0x7fffffff (no signal is raised)
+ * ilogbl(0) = FP_ILOGB0
+ * ilogbl(NaN) = FP_ILOGBNAN (no signal is raised)
+ * ilogbl(+-Inf) = INT_MAX (no signal is raised)
  */
 
 #include "math.h"
@@ -50,6 +51,11 @@ static char rcsid[] = "$NetBSD: $";
 	    return ix;
 	}
 	else if (hx<0x7fff000000000000LL) return (hx>>48)-0x3fff;
-	else return FP_ILOGBNAN;
+	else if (FP_ILOGBNAN != INT_MAX) {
+	    /* ISO C99 requires ilogbl(+-Inf) == INT_MAX.  */
+	    if (((hx^0x7fff000000000000LL)|lx) == 0)
+		return INT_MAX;
+	}
+	return FP_ILOGBNAN;
 }
 weak_alias (__ilogbl, ilogbl)