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
65 gl_FLOAT_SIGN_LOCATION
66 gl_DOUBLE_SIGN_LOCATION
67 gl_LONG_DOUBLE_SIGN_LOCATION
68 if test "$gl_cv_cc_float_signbit" = unknown; then
69 dnl Test whether copysignf() is declared.
70 AC_CHECK_DECLS([copysignf], , , [#include <math.h>])
71 if test "$ac_cv_have_decl_copysignf" = yes; then
72 dnl Test whether copysignf() can be used without libm.
73 AC_CACHE_CHECK([whether copysignf can be used without linking with libm],
74 [gl_cv_func_copysignf_no_libm],
80 [[return copysignf (x, y) < 0;]])],
81 [gl_cv_func_copysignf_no_libm=yes],
82 [gl_cv_func_copysignf_no_libm=no])
84 if test $gl_cv_func_copysignf_no_libm = yes; then
85 AC_DEFINE([HAVE_COPYSIGNF_IN_LIBC], [1],
86 [Define if the copysignf function is declared in <math.h> and available in libc.])
90 if test "$gl_cv_cc_double_signbit" = unknown; then
91 dnl Test whether copysign() is declared.
92 AC_CHECK_DECLS([copysign], , , [#include <math.h>])
93 if test "$ac_cv_have_decl_copysign" = yes; then
94 dnl Test whether copysign() can be used without libm.
95 AC_CACHE_CHECK([whether copysign can be used without linking with libm],
96 [gl_cv_func_copysign_no_libm],
102 [[return copysign (x, y) < 0;]])],
103 [gl_cv_func_copysign_no_libm=yes],
104 [gl_cv_func_copysign_no_libm=no])
106 if test $gl_cv_func_copysign_no_libm = yes; then
107 AC_DEFINE([HAVE_COPYSIGN_IN_LIBC], [1],
108 [Define if the copysign function is declared in <math.h> and available in libc.])
112 if test "$gl_cv_cc_long_double_signbit" = unknown; then
113 dnl Test whether copysignl() is declared.
114 AC_CHECK_DECLS([copysignl], , , [#include <math.h>])
115 if test "$ac_cv_have_decl_copysignl" = yes; then
116 dnl Test whether copysignl() can be used without libm.
117 AC_CACHE_CHECK([whether copysignl can be used without linking with libm],
118 [gl_cv_func_copysignl_no_libm],
124 [[return copysignl (x, y) < 0;]])],
125 [gl_cv_func_copysignl_no_libm=yes],
126 [gl_cv_func_copysignl_no_libm=no])
128 if test $gl_cv_func_copysignl_no_libm = yes; then
129 AC_DEFINE([HAVE_COPYSIGNL_IN_LIBC], [1],
130 [Define if the copysignl function is declared in <math.h> and available in libc.])
138 AC_DEFUN([gl_SIGNBIT_TEST_PROGRAM], [[
140 Needed because GCC 4 constant-folds __builtin_signbitl (literal)
141 but cannot constant-fold __builtin_signbitl (variable). */
147 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
148 So we use -p0f and -p0d instead. */
153 /* On HP-UX 10.20, negating 0.0L does not yield -0.0L.
154 So we use another constant expression instead.
155 But that expression does not work on other platforms, such as when
156 cross-compiling to PowerPC on MacOS X 10.5. */
157 long double p0l = 0.0L;
158 #if defined __hpux || defined __sgi
159 long double m0l = -LDBL_MIN * LDBL_MIN;
161 long double m0l = -p0l;
164 if (signbit (vf)) /* link check */
167 float plus_inf = 1.0f / p0f;
168 float minus_inf = -1.0f / p0f;
169 if (!(!signbit (255.0f)
172 && (memcmp (&m0f, &p0f, sizeof (float)) == 0 || signbit (m0f))
173 && !signbit (plus_inf)
174 && signbit (minus_inf)))
177 if (signbit (vd)) /* link check */
180 double plus_inf = 1.0 / p0d;
181 double minus_inf = -1.0 / p0d;
182 if (!(!signbit (255.0)
185 && (memcmp (&m0d, &p0d, sizeof (double)) == 0 || signbit (m0d))
186 && !signbit (plus_inf)
187 && signbit (minus_inf)))
190 if (signbit (vl)) /* link check */
193 long double plus_inf = 1.0L / p0l;
194 long double minus_inf = -1.0L / p0l;
195 if (signbit (255.0L))
197 if (!signbit (-255.0L))
201 if (!(memcmp (&m0l, &p0l, sizeof (long double)) == 0 || signbit (m0l)))
203 if (signbit (plus_inf))
205 if (!signbit (minus_inf))
212 AC_DEFUN([gl_FLOAT_SIGN_LOCATION],
214 gl_FLOATTYPE_SIGN_LOCATION([float], [gl_cv_cc_float_signbit], [f], [FLT])
217 AC_DEFUN([gl_DOUBLE_SIGN_LOCATION],
219 gl_FLOATTYPE_SIGN_LOCATION([double], [gl_cv_cc_double_signbit], [], [DBL])
222 AC_DEFUN([gl_LONG_DOUBLE_SIGN_LOCATION],
224 gl_FLOATTYPE_SIGN_LOCATION([long double], [gl_cv_cc_long_double_signbit], [L], [LDBL])
227 AC_DEFUN([gl_FLOATTYPE_SIGN_LOCATION],
229 AC_CACHE_CHECK([where to find the sign bit in a '$1'],
237 ((sizeof ($1) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
238 typedef union { $1 value; unsigned int word[NWORDS]; }
240 static memory_float plus = { 1.0$3 };
241 static memory_float minus = { -1.0$3 };
246 FILE *fp = fopen ("conftest.out", "w");
249 /* Find the different bit. */
251 for (j = 0; j < NWORDS; j++)
253 unsigned int x = plus.word[j] ^ minus.word[j];
254 if ((x & (x - 1)) || (x && m))
256 /* More than one bit difference. */
257 fprintf (fp, "unknown");
269 fprintf (fp, "unknown");
272 /* Now m = plus.word[k] ^ ~minus.word[k]. */
273 if (plus.word[k] & ~minus.word[k])
275 /* Oh? The sign bit is set in the positive and cleared in the negative
277 fprintf (fp, "unknown");
283 fprintf (fp, "word %d bit %d", (int) k, (int) i);
284 if (fclose (fp) != 0)
289 [$2=`cat conftest.out`],
292 dnl When cross-compiling, we don't know. It depends on the
293 dnl ABI and compiler version. There are too many cases.
300 word=`echo "$]$2[" | sed -e 's/word //' -e 's/ bit.*//'`
301 bit=`echo "$]$2[" | sed -e 's/word.*bit //'`
302 AC_DEFINE_UNQUOTED([$4][_SIGNBIT_WORD], [$word],
303 [Define as the word index where to find the sign of '$1'.])
304 AC_DEFINE_UNQUOTED([$4][_SIGNBIT_BIT], [$bit],
305 [Define as the bit index in the word where to find the sign of '$1'.])
310 # Expands to code that defines a function signbitf(float).
311 # It extracts the sign bit of a non-NaN value.
312 AC_DEFUN([gl_FLOAT_SIGNBIT_CODE],
314 gl_FLOATTYPE_SIGNBIT_CODE([float], [f], [f])
317 # Expands to code that defines a function signbitd(double).
318 # It extracts the sign bit of a non-NaN value.
319 AC_DEFUN([gl_DOUBLE_SIGNBIT_CODE],
321 gl_FLOATTYPE_SIGNBIT_CODE([double], [d], [])
324 # Expands to code that defines a function signbitl(long double).
325 # It extracts the sign bit of a non-NaN value.
326 AC_DEFUN([gl_LONG_DOUBLE_SIGNBIT_CODE],
328 gl_FLOATTYPE_SIGNBIT_CODE([long double], [l], [L])
331 AC_DEFUN([gl_FLOATTYPE_SIGNBIT_CODE],
336 typedef union { $1 f; unsigned char b[sizeof ($1)]; } float_union;
337 static float_union plus_one = { 1.0$3 }; /* unused bits are zero here */
338 static float_union minus_one = { -1.0$3 }; /* unused bits are zero here */
339 /* Compute the sign bit mask as the XOR of plus_one and minus_one. */
343 for (i = 0; i < sizeof ($1); i++)
344 if (u.b[i] & (plus_one.b[i] ^ minus_one.b[i]))