Libc-262.tar.gz

[apple/libc.git] / ppc / gen / isinf.c

diff --git a/ppc/gen/isinf.c b/ppc/gen/isinf.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@
+ */
+/* Copyright (c) 1992, 1997 NeXT Software, Inc.  All rights reserved.
+ *
+ *     File:   libc/gen/ppc/isinf.c
+ *     Author: Derek B Clegg, NeXT Software, Inc.
+ *
+ * HISTORY
+*  24-Jan-1997 Umesh Vaishampayan (umeshv@NeXT.com)
+*      Ported to PPC.
+ *  11-Nov-92  Derek B Clegg (dclegg@next.com)
+ *     Created.
+ *
+ * int isinf(double value);
+ *
+ * Returns 1 if `value' is equal to positive IEEE infinity, -1 if `value'
+ * is equal to negative IEEE infinity, 0 otherwise.
+ *
+ * An IEEE infinity is a double value with the maximum biased exponent value
+ * (2047) and a zero fraction value.
+ */
+#import "fp.h"
+
+int
+isinf(double value)
+{
+    union dbl d;
+
+    d.value = value;
+    if (d.u[0] == 0x7FF00000 && d.u[1] == 0)
+       return 1;
+    if (d.u[0] == 0xFFF00000 && d.u[1] == 0)
+       return -1;
+    return 0;
+}