Libc-262.tar.gz

[apple/libc.git] / gen / isnan.c

diff --git a/gen/isnan.c b/gen/isnan.c
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+++ b/gen/isnan.c
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+/*
+ * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * The contents of this file constitute Original Code as defined in and
+ * are subject to the Apple Public Source License Version 1.1 (the
+ * "License").  You may not use this file except in compliance with the
+ * License.  Please obtain a copy of the License at
+ * http://www.apple.com/publicsource and read it before using this file.
+ * 
+ * This Original Code and all software distributed under the License are
+ * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
+ * License for the specific language governing rights and limitations
+ * under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+/* @(#)s_isnan.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+
+#if defined(LIBM_SCCS) && !defined(lint)
+static char rcsid[] = "$NetBSD: s_isnan.c,v 1.8 1995/05/10 20:47:36 jtc Exp $";
+#endif
+
+/*
+ * isnan(x) returns 1 is x is nan, else 0;
+ * no branching!
+ */
+
+#include <sys/types.h>
+
+typedef union
+{
+  double value;
+  struct
+  {
+#if defined(__BIG_ENDIAN__)
+    u_int32_t msw;
+    u_int32_t lsw;
+#else
+    u_int32_t lsw;
+    u_int32_t msw;
+#endif
+  } parts;
+} ieee_double_shape_type;
+/* Get two 32 bit ints from a double.  */
+
+#define EXTRACT_WORDS(ix0,ix1,d)                               \
+do {                                                           \
+  ieee_double_shape_type ew_u;                                 \
+  ew_u.value = (d);                                            \
+  (ix0) = ew_u.parts.msw;                                      \
+  (ix1) = ew_u.parts.lsw;                                      \
+} while (0)
+
+
+#ifdef __STDC__
+       int isnan(double x)
+#else
+       int isnan(x)
+       double x;
+#endif
+{
+       int32_t hx,lx;
+       EXTRACT_WORDS(hx,lx,x);
+       hx &= 0x7fffffff;
+       hx |= (u_int32_t)(lx|(-lx))>>31;        
+       hx = 0x7ff00000 - hx;
+       return (int)((u_int32_t)(hx))>>31;
+}