2 dnl Copyright (C) 2007 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.
7 AC_DEFUN([gl_FUNC_ISNANL_NO_LIBM],
9 AC_REQUIRE([gt_TYPE_LONGDOUBLE])
10 if test $gt_cv_c_long_double = yes; then
11 AC_CACHE_CHECK([whether isnan(long double) can be used without linking with libm],
12 [gl_cv_func_isnanl_no_libm],
14 AC_TRY_LINK([#include <math.h>
17 # define isnanl(x) isnan ((long double)(x))
21 [gl_cv_func_isnanl_no_libm=yes],
22 [gl_cv_func_isnanl_no_libm=no])
24 if test $gl_cv_func_isnanl_no_libm = yes; then
25 AC_DEFINE([HAVE_ISNANL_IN_LIBC], 1,
26 [Define if the isnan(long double) function is available in libc.])
29 gl_LONG_DOUBLE_EXPONENT_LOCATION
34 AC_DEFUN([gl_LONG_DOUBLE_EXPONENT_LOCATION],
36 AC_CACHE_CHECK([where to find the exponent in a 'long double'],
37 [gl_cv_cc_long_double_expbit0],
45 ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
46 typedef union { long double value; unsigned int word[NWORDS]; }
48 static unsigned int ored_words[NWORDS];
49 static unsigned int anded_words[NWORDS];
50 static void add_to_ored_words (long double x)
54 /* Clear it first, in case
55 sizeof (long double) < sizeof (memory_long_double). */
56 memset (&m, 0, sizeof (memory_long_double));
58 for (i = 0; i < NWORDS; i++)
60 ored_words[i] |= m.word[i];
61 anded_words[i] &= m.word[i];
67 FILE *fp = fopen ("conftest.out", "w");
70 for (j = 0; j < NWORDS; j++)
71 anded_words[j] = ~ (unsigned int) 0;
72 add_to_ored_words (0.25L);
73 add_to_ored_words (0.5L);
74 add_to_ored_words (1.0L);
75 add_to_ored_words (2.0L);
76 add_to_ored_words (4.0L);
77 /* Remove bits that are common (e.g. if representation of the first mantissa
79 for (j = 0; j < NWORDS; j++)
80 ored_words[j] &= ~anded_words[j];
81 /* Now find the nonzero word. */
82 for (j = 0; j < NWORDS; j++)
83 if (ored_words[j] != 0)
88 for (i = j + 1; i < NWORDS; i++)
89 if (ored_words[i] != 0)
91 fprintf (fp, "unknown");
92 return (fclose (fp) != 0);
95 if ((ored_words[j] >> i) & 1)
97 fprintf (fp, "word %d bit %d", (int) j, (int) i);
98 return (fclose (fp) != 0);
101 fprintf (fp, "unknown");
102 return (fclose (fp) != 0);
105 [gl_cv_cc_long_double_expbit0=`cat conftest.out`],
106 [gl_cv_cc_long_double_expbit0="unknown"],
108 dnl When cross-compiling, we don't know. It depends on the
109 dnl ABI and compiler version. There are too many cases.
110 gl_cv_cc_long_double_expbit0="unknown"
114 case "$gl_cv_cc_long_double_expbit0" in
116 word=`echo "$gl_cv_cc_long_double_expbit0" | sed -e 's/word //' -e 's/ bit.*//'`
117 bit=`echo "$gl_cv_cc_long_double_expbit0" | sed -e 's/word.*bit //'`
118 AC_DEFINE_UNQUOTED([LDBL_EXPBIT0_WORD], [$word],
119 [Define as the word index where to find the exponent of 'long double'.])
120 AC_DEFINE_UNQUOTED([LDBL_EXPBIT0_BIT], [$bit],
121 [Define as the bit index in the word where to find bit 0 of the exponent of 'long double'.])