summaryrefslogtreecommitdiff
path: root/gnulib-m4/ldexpl.m4
blob: 30547db9c0489d223084781e5117aa09de18ed74 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
# ldexpl.m4 serial 16
dnl Copyright (C) 2007-2015 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_LDEXPL],
[
  AC_REQUIRE([gl_MATH_H_DEFAULTS])
  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
  AC_REQUIRE([gl_FUNC_ISNANL]) dnl for ISNANL_LIBM

  dnl Persuade glibc <math.h> to declare ldexpl().
  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

  dnl Check whether it's declared.
  dnl Mac OS X 10.3 has ldexpl() in libc but doesn't declare it in <math.h>.
  AC_CHECK_DECL([ldexpl], , [HAVE_DECL_LDEXPL=0], [[#include <math.h>]])

  LDEXPL_LIBM=
  if test $HAVE_DECL_LDEXPL = 1; then
    gl_CHECK_LDEXPL_NO_LIBM
    if test $gl_cv_func_ldexpl_no_libm = no; then
      AC_CACHE_CHECK([whether ldexpl() can be used with libm],
        [gl_cv_func_ldexpl_in_libm],
        [
          save_LIBS="$LIBS"
          LIBS="$LIBS -lm"
          AC_LINK_IFELSE(
            [AC_LANG_PROGRAM(
               [[#include <math.h>
                 long double x;]],
               [[return ldexpl (x, -1) > 0;]])],
            [gl_cv_func_ldexpl_in_libm=yes],
            [gl_cv_func_ldexpl_in_libm=no])
          LIBS="$save_LIBS"
        ])
      if test $gl_cv_func_ldexpl_in_libm = yes; then
        LDEXPL_LIBM=-lm
      fi
    fi
    if test $gl_cv_func_ldexpl_no_libm = yes \
       || test $gl_cv_func_ldexpl_in_libm = yes; then
      save_LIBS="$LIBS"
      LIBS="$LIBS $LDEXPL_LIBM"
      gl_FUNC_LDEXPL_WORKS
      LIBS="$save_LIBS"
      case "$gl_cv_func_ldexpl_works" in
        *yes) gl_func_ldexpl=yes ;;
        *)    gl_func_ldexpl=no; REPLACE_LDEXPL=1 ;;
      esac
    else
      gl_func_ldexpl=no
    fi
    if test $gl_func_ldexpl = yes; then
      AC_DEFINE([HAVE_LDEXPL], [1],
        [Define if the ldexpl() function is available.])
    fi
  fi
  if test $HAVE_DECL_LDEXPL = 0 || test $gl_func_ldexpl = no; then
    dnl Find libraries needed to link lib/ldexpl.c.
    if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
      AC_REQUIRE([gl_FUNC_LDEXP])
      LDEXPL_LIBM="$LDEXP_LIBM"
    else
      LDEXPL_LIBM="$ISNANL_LIBM"
    fi
  fi
  AC_SUBST([LDEXPL_LIBM])
])

dnl Test whether ldexpl() can be used without linking with libm.
dnl Set gl_cv_func_ldexpl_no_libm to 'yes' or 'no' accordingly.
AC_DEFUN([gl_CHECK_LDEXPL_NO_LIBM],
[
  AC_CACHE_CHECK([whether ldexpl() can be used without linking with libm],
    [gl_cv_func_ldexpl_no_libm],
    [
      AC_LINK_IFELSE(
        [AC_LANG_PROGRAM(
           [[#include <math.h>
             long double x;]],
           [[return ldexpl (x, -1) > 0;]])],
        [gl_cv_func_ldexpl_no_libm=yes],
        [gl_cv_func_ldexpl_no_libm=no])
    ])
])

dnl Test whether ldexpl() works on finite numbers (this fails on AIX 5.1
dnl and Mac OS X 10.4/PowerPC).
AC_DEFUN([gl_FUNC_LDEXPL_WORKS],
[
  AC_REQUIRE([AC_PROG_CC])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  AC_CACHE_CHECK([whether ldexpl works], [gl_cv_func_ldexpl_works],
    [
      AC_RUN_IFELSE(
        [AC_LANG_SOURCE([[
#include <math.h>
extern
#ifdef __cplusplus
"C"
#endif
long double ldexpl (long double, int);
int main()
{
  int result = 0;
  {
    volatile long double x = 1.0;
    volatile long double y = ldexpl (x, -1);
    if (y != 0.5L)
      result |= 1;
  }
  {
    volatile long double x = 1.73205L;
    volatile long double y = ldexpl (x, 0);
    if (y != x)
      result |= 2;
  }
  return result;
}]])],
        [gl_cv_func_ldexpl_works=yes],
        [gl_cv_func_ldexpl_works=no],
        [
changequote(,)dnl
         case "$host_os" in
           aix | aix[3-6]*) gl_cv_func_ldexpl_works="guessing no";;
           *)               gl_cv_func_ldexpl_works="guessing yes";;
         esac
changequote([,])dnl
        ])
    ])
])