-# signbit.m4 serial 8
-dnl Copyright (C) 2007-2010 Free Software Foundation, Inc.
+# signbit.m4 serial 10
+dnl Copyright (C) 2007-2011 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.
REPLACE_SIGNBIT_USING_GCC=1
else
if test "$gl_cv_func_signbit" != yes; then
+ dnl REPLACE_SIGNBIT=1 makes sure the signbit[fdl] functions get built.
REPLACE_SIGNBIT=1
- AC_LIBOBJ([signbitf])
- AC_LIBOBJ([signbitd])
- AC_LIBOBJ([signbitl])
gl_FLOAT_SIGN_LOCATION
gl_DOUBLE_SIGN_LOCATION
gl_LONG_DOUBLE_SIGN_LOCATION
;;
esac
])
+
+# Expands to code that defines a function signbitf(float).
+# It extracts the sign bit of a non-NaN value.
+AC_DEFUN([gl_FLOAT_SIGNBIT_CODE],
+[
+ gl_FLOATTYPE_SIGNBIT_CODE([float], [f], [f])
+])
+
+# Expands to code that defines a function signbitd(double).
+# It extracts the sign bit of a non-NaN value.
+AC_DEFUN([gl_DOUBLE_SIGNBIT_CODE],
+[
+ gl_FLOATTYPE_SIGNBIT_CODE([double], [d], [])
+])
+
+# Expands to code that defines a function signbitl(long double).
+# It extracts the sign bit of a non-NaN value.
+AC_DEFUN([gl_LONG_DOUBLE_SIGNBIT_CODE],
+[
+ gl_FLOATTYPE_SIGNBIT_CODE([long double], [l], [L])
+])
+
+AC_DEFUN([gl_FLOATTYPE_SIGNBIT_CODE],
+[[
+static int
+signbit$2 ($1 value)
+{
+ typedef union { $1 f; unsigned char b[sizeof ($1)]; } float_union;
+ static float_union plus_one = { 1.0$3 }; /* unused bits are zero here */
+ static float_union minus_one = { -1.0$3 }; /* unused bits are zero here */
+ /* Compute the sign bit mask as the XOR of plus_one and minus_one. */
+ float_union u;
+ unsigned int i;
+ u.f = value;
+ for (i = 0; i < sizeof ($1); i++)
+ if (u.b[i] & (plus_one.b[i] ^ minus_one.b[i]))
+ return 1;
+ return 0;
+}
+]])