1 files changed, 107 insertions, 0 deletions
diff --git a/m4/ilogbf.m4 b/m4/ilogbf.m4
new file mode 100644
index 0000000000..1044dfa283
--- /dev/null
+++ b/m4/ilogbf.m4
@@ -0,0 +1,107 @@
+# ilogbf.m4 serial 1
+dnl Copyright (C) 2010-2012 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_ILOGBF],
+[
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+
+  dnl Persuade glibc <math.h> to declare ilogbf().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  dnl Determine ILOGBF_LIBM.
+  gl_MATHFUNC([ilogbf], [int], [(float)])
+  if test $gl_cv_func_ilogbf_no_libm = yes \
+     || test $gl_cv_func_ilogbf_in_libm = yes; then
+    save_LIBS="$LIBS"
+    LIBS="$LIBS $ILOGBF_LIBM"
+    gl_FUNC_ILOGBF_WORKS
+    LIBS="$save_LIBS"
+    case "$gl_cv_func_ilogbf_works" in
+      *yes) ;;
+      *) REPLACE_ILOGBF=1 ;;
+    esac
+  else
+    HAVE_ILOGBF=0
+  fi
+  if test $HAVE_ILOGBF = 0 || test $REPLACE_ILOGBF = 1; then
+    dnl Find libraries needed to link lib/ilogbf.c.
+    AC_REQUIRE([gl_FUNC_FREXPF])
+    AC_REQUIRE([gl_FUNC_ISNANF])
+    ILOGBF_LIBM=
+    dnl Append $FREXPF_LIBM to ILOGBF_LIBM, avoiding gratuitous duplicates.
+    case " $ILOGBF_LIBM " in
+      *" $FREXPF_LIBM "*) ;;
+      *) ILOGBF_LIBM="$ILOGBF_LIBM $FREXPF_LIBM" ;;
+    esac
+    dnl Append $ISNANF_LIBM to ILOGBF_LIBM, avoiding gratuitous duplicates.
+    case " $ILOGBF_LIBM " in
+      *" $ISNANF_LIBM "*) ;;
+      *) ILOGBF_LIBM="$ILOGBF_LIBM $ISNANF_LIBM" ;;
+    esac
+  fi
+  AC_SUBST([ILOGBF_LIBM])
+])
+
+dnl Test whether ilogbf() works.
+dnl On OpenBSD 4.9, ilogbf(0.0) is wrong.
+dnl On NetBSD 5.1, OpenBSD 4.9, ilogbf(Infinity) is wrong.
+AC_DEFUN([gl_FUNC_ILOGBF_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether ilogbf works], [gl_cv_func_ilogbf_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <limits.h>
+#include <math.h>
+/* Provide FP_ILOGB0, FP_ILOGBNAN, like in math.in.h.  */
+#if !(defined FP_ILOGB0 && defined FP_ILOGBNAN)
+# if defined __NetBSD__ || defined __sgi
+  /* NetBSD, IRIX 6.5: match what ilogbf() does */
+#  define FP_ILOGB0   INT_MIN
+#  define FP_ILOGBNAN INT_MIN
+# elif defined _AIX
+  /* AIX 5.1: match what ilogbf() does in AIX >= 5.2 */
+#  define FP_ILOGB0   INT_MIN
+#  define FP_ILOGBNAN INT_MAX
+# elif defined __sun
+  /* Solaris 9: match what ilogbf() does */
+#  define FP_ILOGB0   (- INT_MAX)
+#  define FP_ILOGBNAN INT_MAX
+# endif
+#endif
+volatile float x;
+static float zero;
+static int dummy (float x) { return 0; }
+int main (int argc, char *argv[])
+{
+  int (*my_ilogbf) (float) = argc ? ilogbf : dummy;
+  int result = 0;
+  /* This test fails on OpenBSD 4.9.  */
+  {
+    x = 0.0f;
+    if (my_ilogbf (x) != FP_ILOGB0)
+      result |= 1;
+  }
+  /* This test fails on NetBSD 5.1, OpenBSD 4.9.  */
+  {
+    x = 1.0f / zero;
+    if (my_ilogbf (x) != INT_MAX)
+      result |= 2;
+  }
+  return result;
+}
+]])],
+        [gl_cv_func_ilogbf_works=yes],
+        [gl_cv_func_ilogbf_works=no],
+        [case "$host_os" in
+           openbsd* | netbsd*) gl_cv_func_ilogbf_works="guessing no";;
+           *)                  gl_cv_func_ilogbf_works="guessing yes";;
+         esac
+        ])
+    ])
+])