1 files changed, 135 insertions, 0 deletions
diff --git a/m4/ldexpl.m4 b/m4/ldexpl.m4
new file mode 100644
index 0000000..d46acc4
--- /dev/null
+++ b/m4/ldexpl.m4
@@ -0,0 +1,135 @@
+# ldexpl.m4 serial 17
+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.
+
+AC_DEFUN([gl_FUNC_LDEXPL],
+[
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
+  AC_REQUIRE([gl_FUNC_ISNANL]) dnl for ISNANL_LIBM
+
+  dnl Persuade glibc <math.h> to declare ldexpl().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  dnl Check whether it's declared.
+  dnl Mac OS X 10.3 has ldexpl() in libc but doesn't declare it in <math.h>.
+  AC_CHECK_DECL([ldexpl], , [HAVE_DECL_LDEXPL=0], [[#include <math.h>]])
+
+  LDEXPL_LIBM=
+  if test $HAVE_DECL_LDEXPL = 1; then
+    gl_CHECK_LDEXPL_NO_LIBM
+    if test $gl_cv_func_ldexpl_no_libm = no; then
+      AC_CACHE_CHECK([whether ldexpl() can be used with libm],
+        [gl_cv_func_ldexpl_in_libm],
+        [
+          save_LIBS="$LIBS"
+          LIBS="$LIBS -lm"
+          AC_LINK_IFELSE(
+            [AC_LANG_PROGRAM(
+               [[#include <math.h>
+                 long double x;]],
+               [[return ldexpl (x, -1) > 0;]])],
+            [gl_cv_func_ldexpl_in_libm=yes],
+            [gl_cv_func_ldexpl_in_libm=no])
+          LIBS="$save_LIBS"
+        ])
+      if test $gl_cv_func_ldexpl_in_libm = yes; then
+        LDEXPL_LIBM=-lm
+      fi
+    fi
+    if test $gl_cv_func_ldexpl_no_libm = yes \
+       || test $gl_cv_func_ldexpl_in_libm = yes; then
+      save_LIBS="$LIBS"
+      LIBS="$LIBS $LDEXPL_LIBM"
+      gl_FUNC_LDEXPL_WORKS
+      LIBS="$save_LIBS"
+      case "$gl_cv_func_ldexpl_works" in
+        *yes) gl_func_ldexpl=yes ;;
+        *)    gl_func_ldexpl=no; REPLACE_LDEXPL=1 ;;
+      esac
+    else
+      gl_func_ldexpl=no
+    fi
+    if test $gl_func_ldexpl = yes; then
+      AC_DEFINE([HAVE_LDEXPL], [1],
+        [Define if the ldexpl() function is available.])
+    fi
+  fi
+  if test $HAVE_DECL_LDEXPL = 0 || test $gl_func_ldexpl = no; then
+    dnl Find libraries needed to link lib/ldexpl.c.
+    if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
+      AC_REQUIRE([gl_FUNC_LDEXP])
+      LDEXPL_LIBM="$LDEXP_LIBM"
+    else
+      LDEXPL_LIBM="$ISNANL_LIBM"
+    fi
+  fi
+  AC_SUBST([LDEXPL_LIBM])
+])
+
+dnl Test whether ldexpl() can be used without linking with libm.
+dnl Set gl_cv_func_ldexpl_no_libm to 'yes' or 'no' accordingly.
+AC_DEFUN([gl_CHECK_LDEXPL_NO_LIBM],
+[
+  AC_CACHE_CHECK([whether ldexpl() can be used without linking with libm],
+    [gl_cv_func_ldexpl_no_libm],
+    [
+      AC_LINK_IFELSE(
+        [AC_LANG_PROGRAM(
+           [[#include <math.h>
+             long double x;]],
+           [[return ldexpl (x, -1) > 0;]])],
+        [gl_cv_func_ldexpl_no_libm=yes],
+        [gl_cv_func_ldexpl_no_libm=no])
+    ])
+])
+
+dnl Test whether ldexpl() works on finite numbers (this fails on AIX 5.1
+dnl and Mac OS X 10.4/PowerPC).
+AC_DEFUN([gl_FUNC_LDEXPL_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether ldexpl works], [gl_cv_func_ldexpl_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <math.h>
+extern
+#ifdef __cplusplus
+"C"
+#endif
+long double ldexpl (long double, int);
+int main()
+{
+  int result = 0;
+  {
+    volatile long double x = 1.0;
+    volatile long double y = ldexpl (x, -1);
+    if (y != 0.5L)
+      result |= 1;
+  }
+  {
+    volatile long double x = 1.73205L;
+    volatile long double y = ldexpl (x, 0);
+    if (y != x)
+      result |= 2;
+  }
+  return result;
+}]])],
+        [gl_cv_func_ldexpl_works=yes],
+        [gl_cv_func_ldexpl_works=no],
+        [
+changequote(,)dnl
+         case "$host_os" in
+           aix | aix[3-6]*) gl_cv_func_ldexpl_works="guessing no" ;;
+                            # Guess yes on native Windows.
+           mingw*)          gl_cv_func_ldexpl_works="guessing yes" ;;
+           *)               gl_cv_func_ldexpl_works="guessing yes" ;;
+         esac
+changequote([,])dnl
+        ])
+    ])
+])