From 52bcf3f5fb3251dca4df5b97b01543160340b31b Mon Sep 17 00:00:00 2001
From: Szabolcs Nagy <nsz@port70.net>
Date: Tue, 13 Nov 2012 00:45:51 +0100
Subject: math: fix logb*.c exceptions now that ilogb raises invalid

---
 src/math/logb.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

(limited to 'src/math/logb.c')

diff --git a/src/math/logb.c b/src/math/logb.c
index f7cd7613..624425a8 100644
--- a/src/math/logb.c
+++ b/src/math/logb.c
@@ -1,20 +1,17 @@
-#include <limits.h>
 #include "libm.h"
 
 /*
 special cases:
-	logb(+-0) = -inf
+	logb(+-0) = -inf, and raise divbyzero
 	logb(+-inf) = +inf
 	logb(nan) = nan
-these are calculated at runtime to raise fp exceptions
 */
 
-double logb(double x) {
-	int i = ilogb(x);
-
-	if (i == FP_ILOGB0)
-		return -1.0/fabs(x);
-	if (i == FP_ILOGBNAN || i == INT_MAX)
+double logb(double x)
+{
+	if (!isfinite(x))
 		return x * x;
-	return i;
+	if (x == 0)
+		return -1/(x+0);
+	return ilogb(x);
 }
-- 
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