From ada7ea055b221d489ebfbf2b2900b4e39f3fd043 Mon Sep 17 00:00:00 2001
From: rsc <devnull@localhost>
Date: Fri, 6 Apr 2007 13:27:55 +0000
Subject: another day, another __isNaN

---
 src/lib9/fmt/nan64.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/lib9/fmt/nan64.c b/src/lib9/fmt/nan64.c
index 8fad49eb..3a1f2111 100644
--- a/src/lib9/fmt/nan64.c
+++ b/src/lib9/fmt/nan64.c
@@ -31,7 +31,8 @@ __isNaN(double d)
 
 	p = &d;
 	x = *(uvlong*)p;
-	return (ulong)((x>>52)&0x7FF)==0x7FF && !__isInf(d, 0);
+	/* IEEE 754: exponent bits 0x7FF and non-zero mantissa */
+	return (x&uvinf) == uvinf && (x&~uvneginf) != 0;
 }
 
 double
-- 
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