2 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
9 AC_REQUIRE([gl_MATH_H_DEFAULTS])
10 AC_CACHE_CHECK([for signbit macro], [gl_cv_func_signbit],
15 /* If signbit is defined as a function, don't use it, since calling it for
16 'float' or 'long double' arguments would involve conversions.
17 If signbit is not declared at all but exists as a library function, don't
18 use it, since the prototype may not match.
19 If signbit is not declared at all but exists as a compiler built-in, don't
20 use it, since it's preferable to use __builtin_signbit* (no warnings,
23 # error "signbit should be a macro"
26 ]gl_SIGNBIT_TEST_PROGRAM
28 [gl_cv_func_signbit=yes],
29 [gl_cv_func_signbit=no],
30 [gl_cv_func_signbit="guessing no"])
32 dnl GCC 4.0 and newer provides three built-ins for signbit.
33 dnl They can be used without warnings, also in C++, regardless of <math.h>.
34 dnl But they may expand to calls to functions, which may or may not be in
36 AC_CACHE_CHECK([for signbit compiler built-ins], [gl_cv_func_signbit_gcc],
42 (sizeof (x) == sizeof (long double) ? __builtin_signbitl (x) : \
43 sizeof (x) == sizeof (double) ? __builtin_signbit (x) : \
44 __builtin_signbitf (x))
46 # error "signbit should be three compiler built-ins"
49 ]gl_SIGNBIT_TEST_PROGRAM
51 [gl_cv_func_signbit_gcc=yes],
52 [gl_cv_func_signbit_gcc=no],
53 [gl_cv_func_signbit_gcc="guessing no"])
55 dnl Use the compiler built-ins whenever possible, because they are more
56 dnl efficient than the system library functions (if they exist).
57 if test "$gl_cv_func_signbit_gcc" = yes; then
58 REPLACE_SIGNBIT_USING_GCC=1
60 if test "$gl_cv_func_signbit" != yes; then
61 dnl REPLACE_SIGNBIT=1 makes sure the signbit[fdl] functions get built.
63 gl_FLOAT_SIGN_LOCATION
64 gl_DOUBLE_SIGN_LOCATION
65 gl_LONG_DOUBLE_SIGN_LOCATION
66 if test "$gl_cv_cc_float_signbit" = unknown; then
67 dnl Test whether copysignf() is declared.
68 AC_CHECK_DECLS([copysignf], , , [#include <math.h>])
69 if test "$ac_cv_have_decl_copysignf" = yes; then
70 dnl Test whether copysignf() can be used without libm.
71 AC_CACHE_CHECK([whether copysignf can be used without linking with libm],
72 [gl_cv_func_copysignf_no_libm],
78 [[return copysignf (x, y) < 0;]])],
79 [gl_cv_func_copysignf_no_libm=yes],
80 [gl_cv_func_copysignf_no_libm=no])
82 if test $gl_cv_func_copysignf_no_libm = yes; then
83 AC_DEFINE([HAVE_COPYSIGNF_IN_LIBC], [1],
84 [Define if the copysignf function is declared in <math.h> and available in libc.])
88 if test "$gl_cv_cc_double_signbit" = unknown; then
89 dnl Test whether copysign() is declared.
90 AC_CHECK_DECLS([copysign], , , [#include <math.h>])
91 if test "$ac_cv_have_decl_copysign" = yes; then
92 dnl Test whether copysign() can be used without libm.
93 AC_CACHE_CHECK([whether copysign can be used without linking with libm],
94 [gl_cv_func_copysign_no_libm],
100 [[return copysign (x, y) < 0;]])],
101 [gl_cv_func_copysign_no_libm=yes],
102 [gl_cv_func_copysign_no_libm=no])
104 if test $gl_cv_func_copysign_no_libm = yes; then
105 AC_DEFINE([HAVE_COPYSIGN_IN_LIBC], [1],
106 [Define if the copysign function is declared in <math.h> and available in libc.])
110 if test "$gl_cv_cc_long_double_signbit" = unknown; then
111 dnl Test whether copysignl() is declared.
112 AC_CHECK_DECLS([copysignl], , , [#include <math.h>])
113 if test "$ac_cv_have_decl_copysignl" = yes; then
114 dnl Test whether copysignl() can be used without libm.
115 AC_CACHE_CHECK([whether copysignl can be used without linking with libm],
116 [gl_cv_func_copysignl_no_libm],
122 [[return copysignl (x, y) < 0;]])],
123 [gl_cv_func_copysignl_no_libm=yes],
124 [gl_cv_func_copysignl_no_libm=no])
126 if test $gl_cv_func_copysignl_no_libm = yes; then
127 AC_DEFINE([HAVE_COPYSIGNL_IN_LIBC], [1],
128 [Define if the copysignl function is declared in <math.h> and available in libc.])
136 AC_DEFUN([gl_SIGNBIT_TEST_PROGRAM], [[
138 Needed because GCC 4 constant-folds __builtin_signbitl (literal)
139 but cannot constant-fold __builtin_signbitl (variable). */
145 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
146 So we use -p0f and -p0d instead. */
151 /* On HP-UX 10.20, negating 0.0L does not yield -0.0L.
152 So we use another constant expression instead.
153 But that expression does not work on other platforms, such as when
154 cross-compiling to PowerPC on MacOS X 10.5. */
155 long double p0l = 0.0L;
156 #if defined __hpux || defined __sgi
157 long double m0l = -LDBL_MIN * LDBL_MIN;
159 long double m0l = -p0l;
162 if (signbit (vf)) /* link check */
165 float plus_inf = 1.0f / p0f;
166 float minus_inf = -1.0f / p0f;
167 if (!(!signbit (255.0f)
170 && (memcmp (&m0f, &p0f, sizeof (float)) == 0 || signbit (m0f))
171 && !signbit (plus_inf)
172 && signbit (minus_inf)))
175 if (signbit (vd)) /* link check */
178 double plus_inf = 1.0 / p0d;
179 double minus_inf = -1.0 / p0d;
180 if (!(!signbit (255.0)
183 && (memcmp (&m0d, &p0d, sizeof (double)) == 0 || signbit (m0d))
184 && !signbit (plus_inf)
185 && signbit (minus_inf)))
188 if (signbit (vl)) /* link check */
191 long double plus_inf = 1.0L / p0l;
192 long double minus_inf = -1.0L / p0l;
193 if (signbit (255.0L))
195 if (!signbit (-255.0L))
199 if (!(memcmp (&m0l, &p0l, sizeof (long double)) == 0 || signbit (m0l)))
201 if (signbit (plus_inf))
203 if (!signbit (minus_inf))
210 AC_DEFUN([gl_FLOAT_SIGN_LOCATION],
212 gl_FLOATTYPE_SIGN_LOCATION([float], [gl_cv_cc_float_signbit], [f], [FLT])
215 AC_DEFUN([gl_DOUBLE_SIGN_LOCATION],
217 gl_FLOATTYPE_SIGN_LOCATION([double], [gl_cv_cc_double_signbit], [], [DBL])
220 AC_DEFUN([gl_LONG_DOUBLE_SIGN_LOCATION],
222 gl_FLOATTYPE_SIGN_LOCATION([long double], [gl_cv_cc_long_double_signbit], [L], [LDBL])
225 AC_DEFUN([gl_FLOATTYPE_SIGN_LOCATION],
227 AC_CACHE_CHECK([where to find the sign bit in a '$1'],
235 ((sizeof ($1) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
236 typedef union { $1 value; unsigned int word[NWORDS]; }
238 static memory_float plus = { 1.0$3 };
239 static memory_float minus = { -1.0$3 };
244 FILE *fp = fopen ("conftest.out", "w");
247 /* Find the different bit. */
249 for (j = 0; j < NWORDS; j++)
251 unsigned int x = plus.word[j] ^ minus.word[j];
252 if ((x & (x - 1)) || (x && m))
254 /* More than one bit difference. */
255 fprintf (fp, "unknown");
267 fprintf (fp, "unknown");
270 /* Now m = plus.word[k] ^ ~minus.word[k]. */
271 if (plus.word[k] & ~minus.word[k])
273 /* Oh? The sign bit is set in the positive and cleared in the negative
275 fprintf (fp, "unknown");
281 fprintf (fp, "word %d bit %d", (int) k, (int) i);
282 if (fclose (fp) != 0)
287 [$2=`cat conftest.out`],
290 dnl When cross-compiling, we don't know. It depends on the
291 dnl ABI and compiler version. There are too many cases.
298 word=`echo "$]$2[" | sed -e 's/word //' -e 's/ bit.*//'`
299 bit=`echo "$]$2[" | sed -e 's/word.*bit //'`
300 AC_DEFINE_UNQUOTED([$4][_SIGNBIT_WORD], [$word],
301 [Define as the word index where to find the sign of '$1'.])
302 AC_DEFINE_UNQUOTED([$4][_SIGNBIT_BIT], [$bit],
303 [Define as the bit index in the word where to find the sign of '$1'.])
308 # Expands to code that defines a function signbitf(float).
309 # It extracts the sign bit of a non-NaN value.
310 AC_DEFUN([gl_FLOAT_SIGNBIT_CODE],
312 gl_FLOATTYPE_SIGNBIT_CODE([float], [f], [f])
315 # Expands to code that defines a function signbitd(double).
316 # It extracts the sign bit of a non-NaN value.
317 AC_DEFUN([gl_DOUBLE_SIGNBIT_CODE],
319 gl_FLOATTYPE_SIGNBIT_CODE([double], [d], [])
322 # Expands to code that defines a function signbitl(long double).
323 # It extracts the sign bit of a non-NaN value.
324 AC_DEFUN([gl_LONG_DOUBLE_SIGNBIT_CODE],
326 gl_FLOATTYPE_SIGNBIT_CODE([long double], [l], [L])
329 AC_DEFUN([gl_FLOATTYPE_SIGNBIT_CODE],
334 typedef union { $1 f; unsigned char b[sizeof ($1)]; } float_union;
335 static float_union plus_one = { 1.0$3 }; /* unused bits are zero here */
336 static float_union minus_one = { -1.0$3 }; /* unused bits are zero here */
337 /* Compute the sign bit mask as the XOR of plus_one and minus_one. */
341 for (i = 0; i < sizeof ($1); i++)
342 if (u.b[i] & (plus_one.b[i] ^ minus_one.b[i]))