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-rw-r--r--missing/isinf.c44
1 files changed, 44 insertions, 0 deletions
diff --git a/missing/isinf.c b/missing/isinf.c
new file mode 100644
index 0000000..e0cd6ac
--- /dev/null
+++ b/missing/isinf.c
@@ -0,0 +1,44 @@
+#ifdef __osf__
+
+#define _IEEE 1
+#include <nan.h>
+
+int
+isinf(n)
+ double n;
+{
+ if (IsNANorINF(n) && IsINF(n)) {
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+#else
+
+#include "config.h"
+#ifdef HAVE_STRING_H
+# include <string.h>
+#else
+# include <strings.h>
+#endif
+
+static double zero() { return 0.0; }
+static double one() { return 1.0; }
+static double inf() { return one() / zero(); }
+
+int
+isinf(n)
+ double n;
+{
+ static double pinf = 0.0;
+ static double ninf = 0.0;
+
+ if (pinf == 0.0) {
+ pinf = inf();
+ ninf = -pinf;
+ }
+ return memcmp(&n, &pinf, sizeof n) == 0
+ || memcmp(&n, &ninf, sizeof n) == 0;
+}
+#endif