2 dnl Copyright (C) 2007-2008 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 dnl Check how to get or define isnand() without linking with libm.
9 AC_DEFUN([gl_FUNC_ISNAND_NO_LIBM],
11 AC_CACHE_CHECK([whether isnan(double) can be used without linking with libm],
12 [gl_cv_func_isnand_no_libm],
14 AC_TRY_LINK([#include <math.h>
17 # define isnand(x) __builtin_isnan ((double)(x))
20 # define isnand(x) isnan ((double)(x))
24 [gl_cv_func_isnand_no_libm=yes],
25 [gl_cv_func_isnand_no_libm=no])
27 if test $gl_cv_func_isnand_no_libm = yes; then
28 AC_DEFINE([HAVE_ISNAND_IN_LIBC], 1,
29 [Define if the isnan(double) function is available in libc.])
32 gl_DOUBLE_EXPONENT_LOCATION
36 AC_DEFUN([gl_DOUBLE_EXPONENT_LOCATION],
38 AC_CACHE_CHECK([where to find the exponent in a 'double'],
39 [gl_cv_cc_double_expbit0],
47 ((sizeof (double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
48 typedef union { double value; unsigned int word[NWORDS]; } memory_double;
49 static unsigned int ored_words[NWORDS];
50 static unsigned int anded_words[NWORDS];
51 static void add_to_ored_words (double x)
55 /* Clear it first, in case sizeof (double) < sizeof (memory_double). */
56 memset (&m, 0, sizeof (memory_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 (0.25);
73 add_to_ored_words (0.5);
74 add_to_ored_words (1.0);
75 add_to_ored_words (2.0);
76 add_to_ored_words (4.0);
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_double_expbit0=`cat conftest.out`],
106 [gl_cv_cc_double_expbit0="unknown"],
108 dnl On ARM, there are two 'double' floating-point formats, used by
109 dnl different sets of instructions: The older FPA instructions assume
110 dnl that they are stored in big-endian word order, while the words
111 dnl (like integer types) are stored in little-endian byte order.
112 dnl The newer VFP instructions assume little-endian order consistenly.
113 AC_EGREP_CPP([mixed_endianness], [
114 #if defined arm || defined __arm || defined __arm__
118 [gl_cv_cc_double_expbit0="unknown"],
120 pushdef([AC_MSG_CHECKING],[:])dnl
121 pushdef([AC_MSG_RESULT],[:])dnl
122 pushdef([AC_MSG_RESULT_UNQUOTED],[:])dnl
124 [gl_cv_cc_double_expbit0="word 0 bit 20"],
125 [gl_cv_cc_double_expbit0="word 1 bit 20"],
126 [gl_cv_cc_double_expbit0="unknown"])
127 popdef([AC_MSG_RESULT_UNQUOTED])dnl
128 popdef([AC_MSG_RESULT])dnl
129 popdef([AC_MSG_CHECKING])dnl
134 case "$gl_cv_cc_double_expbit0" in
136 word=`echo "$gl_cv_cc_double_expbit0" | sed -e 's/word //' -e 's/ bit.*//'`
137 bit=`echo "$gl_cv_cc_double_expbit0" | sed -e 's/word.*bit //'`
138 AC_DEFINE_UNQUOTED([DBL_EXPBIT0_WORD], [$word],
139 [Define as the word index where to find the exponent of 'double'.])
140 AC_DEFINE_UNQUOTED([DBL_EXPBIT0_BIT], [$bit],
141 [Define as the bit index in the word where to find bit 0 of the exponent of 'double'.])