2 dnl Copyright (C) 2007-2010 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],
14 /* If signbit is defined as a function, don't use it, since calling it for
15 'float' or 'long double' arguments would involve conversions.
16 If signbit is not declared at all but exists as a library function, don't
17 use it, since the prototype may not match.
18 If signbit is not declared at all but exists as a compiler built-in, don't
19 use it, since it's preferable to use __builtin_signbit* (no warnings,
22 # error "signbit should be a macro"
25 ]gl_SIGNBIT_TEST_PROGRAM
26 , [gl_cv_func_signbit=yes], [gl_cv_func_signbit=no],
27 [gl_cv_func_signbit="guessing no"])
29 dnl GCC 4.0 and newer provides three built-ins for signbit.
30 dnl They can be used without warnings, also in C++, regardless of <math.h>.
31 dnl But they may expand to calls to functions, which may or may not be in
33 AC_CACHE_CHECK([for signbit compiler built-ins], [gl_cv_func_signbit_gcc],
38 (sizeof (x) == sizeof (long double) ? __builtin_signbitl (x) : \
39 sizeof (x) == sizeof (double) ? __builtin_signbit (x) : \
40 __builtin_signbitf (x))
42 # error "signbit should be three compiler built-ins"
45 ]gl_SIGNBIT_TEST_PROGRAM
46 , [gl_cv_func_signbit_gcc=yes], [gl_cv_func_signbit_gcc=no],
47 [gl_cv_func_signbit_gcc="guessing no"])
49 dnl Use the compiler built-ins whenever possible, because they are more
50 dnl efficient than the system library functions (if they exist).
51 if test "$gl_cv_func_signbit_gcc" = yes; then
52 REPLACE_SIGNBIT_USING_GCC=1
54 if test "$gl_cv_func_signbit" != yes; then
59 gl_FLOAT_SIGN_LOCATION
60 gl_DOUBLE_SIGN_LOCATION
61 gl_LONG_DOUBLE_SIGN_LOCATION
62 if test "$gl_cv_cc_float_signbit" = unknown; then
63 dnl Test whether copysignf() is declared.
64 AC_CHECK_DECLS([copysignf], , , [#include <math.h>])
65 if test "$ac_cv_have_decl_copysignf" = yes; then
66 dnl Test whether copysignf() can be used without libm.
67 AC_CACHE_CHECK([whether copysignf can be used without linking with libm],
68 [gl_cv_func_copysignf_no_libm],
74 [[return copysignf (x, y) < 0;]])],
75 [gl_cv_func_copysignf_no_libm=yes],
76 [gl_cv_func_copysignf_no_libm=no])
78 if test $gl_cv_func_copysignf_no_libm = yes; then
79 AC_DEFINE([HAVE_COPYSIGNF_IN_LIBC], [1],
80 [Define if the copysignf function is declared in <math.h> and available in libc.])
84 if test "$gl_cv_cc_double_signbit" = unknown; then
85 dnl Test whether copysign() is declared.
86 AC_CHECK_DECLS([copysign], , , [#include <math.h>])
87 if test "$ac_cv_have_decl_copysign" = yes; then
88 dnl Test whether copysign() can be used without libm.
89 AC_CACHE_CHECK([whether copysign can be used without linking with libm],
90 [gl_cv_func_copysign_no_libm],
96 [[return copysign (x, y) < 0;]])],
97 [gl_cv_func_copysign_no_libm=yes],
98 [gl_cv_func_copysign_no_libm=no])
100 if test $gl_cv_func_copysign_no_libm = yes; then
101 AC_DEFINE([HAVE_COPYSIGN_IN_LIBC], [1],
102 [Define if the copysign function is declared in <math.h> and available in libc.])
106 if test "$gl_cv_cc_long_double_signbit" = unknown; then
107 dnl Test whether copysignl() is declared.
108 AC_CHECK_DECLS([copysignl], , , [#include <math.h>])
109 if test "$ac_cv_have_decl_copysignl" = yes; then
110 dnl Test whether copysignl() can be used without libm.
111 AC_CACHE_CHECK([whether copysignl can be used without linking with libm],
112 [gl_cv_func_copysignl_no_libm],
118 [[return copysignl (x, y) < 0;]])],
119 [gl_cv_func_copysignl_no_libm=yes],
120 [gl_cv_func_copysignl_no_libm=no])
122 if test $gl_cv_func_copysignl_no_libm = yes; then
123 AC_DEFINE([HAVE_COPYSIGNL_IN_LIBC], [1],
124 [Define if the copysignl function is declared in <math.h> and available in libc.])
132 AC_DEFUN([gl_SIGNBIT_TEST_PROGRAM], [[
134 Needed because GCC 4 constant-folds __builtin_signbitl (literal)
135 but cannot constant-fold __builtin_signbitl (variable). */
141 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0.
142 So we use -p0f and -p0d instead. */
147 /* On HP-UX 10.20, negating 0.0L does not yield -0.0L.
148 So we use another constant expression instead.
149 But that expression does not work on other platforms, such as when
150 cross-compiling to PowerPC on MacOS X 10.5. */
151 long double p0l = 0.0L;
152 #if defined __hpux || defined __sgi
153 long double m0l = -LDBL_MIN * LDBL_MIN;
155 long double m0l = -p0l;
160 float plus_inf = 1.0f / p0f;
161 float minus_inf = -1.0f / p0f;
162 if (!(!signbit (255.0f)
165 && (memcmp (&m0f, &p0f, sizeof (float)) == 0 || signbit (m0f))
166 && !signbit (plus_inf)
167 && signbit (minus_inf)))
173 double plus_inf = 1.0 / p0d;
174 double minus_inf = -1.0 / p0d;
175 if (!(!signbit (255.0)
178 && (memcmp (&m0d, &p0d, sizeof (double)) == 0 || signbit (m0d))
179 && !signbit (plus_inf)
180 && signbit (minus_inf)))
186 long double plus_inf = 1.0L / p0l;
187 long double minus_inf = -1.0L / p0l;
188 if (!(!signbit (255.0L)
191 && (memcmp (&m0l, &p0l, sizeof (long double)) == 0 || signbit (m0l))
192 && !signbit (plus_inf)
193 && signbit (minus_inf)))
200 AC_DEFUN([gl_FLOAT_SIGN_LOCATION],
202 gl_FLOATTYPE_SIGN_LOCATION([float], [gl_cv_cc_float_signbit], [f], [FLT])
205 AC_DEFUN([gl_DOUBLE_SIGN_LOCATION],
207 gl_FLOATTYPE_SIGN_LOCATION([double], [gl_cv_cc_double_signbit], [], [DBL])
210 AC_DEFUN([gl_LONG_DOUBLE_SIGN_LOCATION],
212 gl_FLOATTYPE_SIGN_LOCATION([long double], [gl_cv_cc_long_double_signbit], [L], [LDBL])
215 AC_DEFUN([gl_FLOATTYPE_SIGN_LOCATION],
217 AC_CACHE_CHECK([where to find the sign bit in a '$1'],
224 ((sizeof ($1) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
225 typedef union { $1 value; unsigned int word[NWORDS]; }
227 static memory_float plus = { 1.0$3 };
228 static memory_float minus = { -1.0$3 };
233 FILE *fp = fopen ("conftest.out", "w");
236 /* Find the different bit. */
238 for (j = 0; j < NWORDS; j++)
240 unsigned int x = plus.word[j] ^ minus.word[j];
241 if ((x & (x - 1)) || (x && m))
243 /* More than one bit difference. */
244 fprintf (fp, "unknown");
256 fprintf (fp, "unknown");
259 /* Now m = plus.word[k] ^ ~minus.word[k]. */
260 if (plus.word[k] & ~minus.word[k])
262 /* Oh? The sign bit is set in the positive and cleared in the negative
264 fprintf (fp, "unknown");
270 fprintf (fp, "word %d bit %d", (int) k, (int) i);
271 return (fclose (fp) != 0);
274 [$2=`cat conftest.out`],
277 dnl When cross-compiling, we don't know. It depends on the
278 dnl ABI and compiler version. There are too many cases.
285 word=`echo "$]$2[" | sed -e 's/word //' -e 's/ bit.*//'`
286 bit=`echo "$]$2[" | sed -e 's/word.*bit //'`
287 AC_DEFINE_UNQUOTED([$4][_SIGNBIT_WORD], [$word],
288 [Define as the word index where to find the sign of '$1'.])
289 AC_DEFINE_UNQUOTED([$4][_SIGNBIT_BIT], [$bit],
290 [Define as the bit index in the word where to find the sign of '$1'.])