1 files changed, 96 insertions, 0 deletions
diff --git a/m4/isnand.m4 b/m4/isnand.m4
new file mode 100644
index 0000000..c74795e
--- /dev/null
+++ b/m4/isnand.m4
@@ -0,0 +1,96 @@
+# isnand.m4 serial 11
+dnl Copyright (C) 2007-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Check how to get or define isnand().
+
+AC_DEFUN([gl_FUNC_ISNAND],
+[
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  ISNAND_LIBM=
+  gl_HAVE_ISNAND_NO_LIBM
+  if test $gl_cv_func_isnand_no_libm = no; then
+    gl_HAVE_ISNAND_IN_LIBM
+    if test $gl_cv_func_isnand_in_libm = yes; then
+      ISNAND_LIBM=-lm
+    fi
+  fi
+  dnl The variable gl_func_isnand set here is used by isnan.m4.
+  if test $gl_cv_func_isnand_no_libm = yes \
+     || test $gl_cv_func_isnand_in_libm = yes; then
+    gl_func_isnand=yes
+  else
+    gl_func_isnand=no
+    HAVE_ISNAND=0
+  fi
+  AC_SUBST([ISNAND_LIBM])
+])
+
+dnl Check how to get or define isnand() without linking with libm.
+
+AC_DEFUN([gl_FUNC_ISNAND_NO_LIBM],
+[
+  gl_HAVE_ISNAND_NO_LIBM
+  gl_func_isnand_no_libm=$gl_cv_func_isnand_no_libm
+  if test $gl_cv_func_isnand_no_libm = yes; then
+    AC_DEFINE([HAVE_ISNAND_IN_LIBC], [1],
+      [Define if the isnan(double) function is available in libc.])
+  fi
+])
+
+dnl Prerequisites of replacement isnand definition. It does not need -lm.
+AC_DEFUN([gl_PREREQ_ISNAND],
+[
+  AC_REQUIRE([gl_DOUBLE_EXPONENT_LOCATION])
+])
+
+dnl Test whether isnand() can be used with libm.
+
+AC_DEFUN([gl_HAVE_ISNAND_IN_LIBM],
+[
+  AC_CACHE_CHECK([whether isnan(double) can be used with libm],
+    [gl_cv_func_isnand_in_libm],
+    [
+      save_LIBS="$LIBS"
+      LIBS="$LIBS -lm"
+      AC_LINK_IFELSE(
+        [AC_LANG_PROGRAM(
+           [[#include <math.h>
+             #if __GNUC__ >= 4
+             # undef isnand
+             # define isnand(x) __builtin_isnan ((double)(x))
+             #elif defined isnan
+             # undef isnand
+             # define isnand(x) isnan ((double)(x))
+             #endif
+             double x;]],
+           [[return isnand (x);]])],
+        [gl_cv_func_isnand_in_libm=yes],
+        [gl_cv_func_isnand_in_libm=no])
+      LIBS="$save_LIBS"
+    ])
+])
+
+AC_DEFUN([gl_HAVE_ISNAND_NO_LIBM],
+[
+  AC_CACHE_CHECK([whether isnan(double) can be used without linking with libm],
+    [gl_cv_func_isnand_no_libm],
+    [
+      AC_LINK_IFELSE(
+        [AC_LANG_PROGRAM(
+           [[#include <math.h>
+             #if __GNUC__ >= 4
+             # undef isnand
+             # define isnand(x) __builtin_isnan ((double)(x))
+             #else
+             # undef isnand
+             # define isnand(x) isnan ((double)(x))
+             #endif
+             double x;]],
+           [[return isnand (x);]])],
+        [gl_cv_func_isnand_no_libm=yes],
+        [gl_cv_func_isnand_no_libm=no])
+    ])
+])