From 931f6d0ad42a5a5809284ad991f811528c5d3803 Mon Sep 17 00:00:00 2001
From: Dennis Heimbigner <dmh@ucar.edu>
Date: Tue, 4 Aug 2020 19:22:42 -0600
Subject: [PATCH] Define isnan and isinf for OSX

---
 include/isnan.h     |  6 +++++-
 libdispatch/dutil.c | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/include/isnan.h b/include/isnan.h
index cd72b3673..e5770190f 100644
--- a/include/isnan.h
+++ b/include/isnan.h
@@ -25,7 +25,10 @@
 #ifndef INFINITYF
 #define INFINITYF ((float)INFINITY)
 #endif
-
+#ifdef __APPLE__
+extern int isinf(double x);
+extern int isnan(double x);
+#else
 #if ! (defined(isinf) || HAVE_DECL_ISINF)
 #define isinf(x) (DBL_MAX/((double)(x))==0.0)
 #endif /* !HAVE_DECL_ISINF */
@@ -35,5 +38,6 @@
 #if ! (defined(isfinite) || HAVE_DECL_ISFINITE)
 #define isfinite(x) (!(isinf(x)||isnan(x)))
 #endif /* !HAVE_DECL_ISFINITE */
+#endif /*!APPLE*/
 
 #endif /* _ISNAN_H */
diff --git a/libdispatch/dutil.c b/libdispatch/dutil.c
index 79da2ad81..3e6126201 100644
--- a/libdispatch/dutil.c
+++ b/libdispatch/dutil.c
@@ -351,3 +351,22 @@ done:
     nclistfreeall(modelist);
     return found;
 }
+
+#ifdef __APPLE__
+int isinf(double x)
+{
+    union { unsigned long long u; double f; } ieee754;
+    ieee754.f = x;
+    return ( (unsigned)(ieee754.u >> 32) & 0x7fffffff ) == 0x7ff00000 &&
+           ( (unsigned)ieee754.u == 0 );
+}
+
+int isnan(double x)
+{
+    union { unsigned long long u; double f; } ieee754;
+    ieee754.f = x;
+    return ( (unsigned)(ieee754.u >> 32) & 0x7fffffff ) +
+           ( (unsigned)ieee754.u != 0 ) > 0x7ff00000;
+}
+
+#endif /*APPLE*/