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Diffstat (limited to 'sysdeps/i386/fpu/s_ilogb.S')
-rw-r--r--sysdeps/i386/fpu/s_ilogb.S14
1 files changed, 14 insertions, 0 deletions
diff --git a/sysdeps/i386/fpu/s_ilogb.S b/sysdeps/i386/fpu/s_ilogb.S
index 36fb000c02..68d9c1a680 100644
--- a/sysdeps/i386/fpu/s_ilogb.S
+++ b/sysdeps/i386/fpu/s_ilogb.S
@@ -9,6 +9,16 @@ RCSID("$NetBSD: s_ilogb.S,v 1.5 1995/10/12 15:53:09 jtc Exp $")
 
 ENTRY(__ilogb)
 	fldl	4(%esp)
+/* I added the following ugly construct because ilogb(+-Inf) is
+   required to return INT_MAX in ISO C99.
+   -- jakub@redhat.com.  */
+	fxam			/* Is NaN or +-Inf?  */
+	fstsw   %ax
+	movb    $0x45, %dh
+	andb    %ah, %dh
+	cmpb    $0x05, %dh
+	je      1f		/* Is +-Inf, jump.  */
+
 	fxtract
 	pushl	%eax
 	fstp	%st
@@ -18,5 +28,9 @@ ENTRY(__ilogb)
 	popl	%eax
 
 	ret
+
+1:	fstp	%st
+	movl	$0x7fffffff, %eax
+	ret
 END (__ilogb)
 weak_alias (__ilogb, ilogb)