Support for minus zero in autoconf macros.

[gnulib.git] / m4 / minus-zero.m4

diff --git a/m4/minus-zero.m4 b/m4/minus-zero.m4
new file mode 100644 (file)
index 0000000..f6e9745
--- /dev/null
+++ b/m4/minus-zero.m4
@@ -0,0 +1,76 @@
+# minus-zero.m4 serial 1
+dnl Copyright (C) 2010 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.
+
+# Macros for floating-point negative zero.
+# Keep in sync with tests/minus-zero.h!
+
+# Expands to code that defines a variable or macro minus_zerof.
+AC_DEFUN([gl_FLOAT_MINUS_ZERO_CODE],
+[[
+#include <float.h>
+/* minus_zerof represents the value -0.0f.  */
+/* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0f.
+   ICC 10.0 has a bug when optimizing the expression -zero.
+   The expression -FLT_MIN * FLT_MIN does not work when cross-compiling
+   to PowerPC on MacOS X 10.5.  */
+#if defined __hpux || defined __sgi || defined __ICC
+static float
+compute_minus_zerof (void)
+{
+  return -FLT_MIN * FLT_MIN;
+}
+# define minus_zerof compute_minus_zerof ()
+#else
+float minus_zerof = -0.0f;
+#endif
+]])
+
+# Expands to code that defines a variable or macro minus_zerod.
+AC_DEFUN([gl_DOUBLE_MINUS_ZERO_CODE],
+[[
+#include <float.h>
+/* minus_zerod represents the value -0.0.  */
+/* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
+   ICC 10.0 has a bug when optimizing the expression -zero.
+   The expression -DBL_MIN * DBL_MIN does not work when cross-compiling
+   to PowerPC on MacOS X 10.5.  */
+#if defined __hpux || defined __sgi || defined __ICC
+static double
+compute_minus_zerod (void)
+{
+  return -DBL_MIN * DBL_MIN;
+}
+# define minus_zerod compute_minus_zerod ()
+#else
+double minus_zerod = -0.0;
+#endif
+]])
+
+# Expands to code that defines a variable or macro minus_zerol.
+AC_DEFUN([gl_LONG_DOUBLE_MINUS_ZERO_CODE],
+[[
+#include <float.h>
+#if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__)
+# undef LDBL_MIN
+# define LDBL_MIN        3.3621031431120935063E-4932L
+#endif
+/* minus_zerol represents the value -0.0L.  */
+/* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0L.
+   IRIX cc can't put -0.0L into .data, but can compute at runtime.
+   ICC 10.0 has a bug when optimizing the expression -zero.
+   The expression -LDBL_MIN * LDBL_MIN does not work when cross-compiling
+   to PowerPC on MacOS X 10.5.  */
+#if defined __hpux || defined __sgi || defined __ICC
+static long double
+compute_minus_zerol (void)
+{
+  return -LDBL_MIN * LDBL_MIN;
+}
+# define minus_zerol compute_minus_zerol ()
+#else
+long double minus_zerol = -0.0L;
+#endif
+]])