1# log10f.m4 serial 12
2dnl Copyright (C) 2011-2021 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7AC_DEFUN([gl_FUNC_LOG10F],
8[
9  m4_divert_text([DEFAULTS], [gl_log10f_required=plain])
10  AC_REQUIRE([gl_MATH_H_DEFAULTS])
11  AC_REQUIRE([gl_FUNC_LOG10])
12
13  dnl Persuade glibc <math.h> to declare log10f().
14  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
15
16  dnl Test whether log10f() exists. Assume that log10f(), if it exists, is
17  dnl defined in the same library as log10().
18  save_LIBS="$LIBS"
19  LIBS="$LIBS $LOG10_LIBM"
20  AC_CHECK_FUNCS([log10f])
21  LIBS="$save_LIBS"
22  if test $ac_cv_func_log10f = yes; then
23    LOG10F_LIBM="$LOG10_LIBM"
24
25    save_LIBS="$LIBS"
26    LIBS="$LIBS $LOG10F_LIBM"
27    gl_FUNC_LOG10F_WORKS
28    LIBS="$save_LIBS"
29    case "$gl_cv_func_log10f_works" in
30      *yes) ;;
31      *) REPLACE_LOG10F=1 ;;
32    esac
33
34    m4_ifdef([gl_FUNC_LOG10F_IEEE], [
35      if test $gl_log10f_required = ieee && test $REPLACE_LOG10F = 0; then
36        AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
37        AC_CACHE_CHECK([whether log10f works according to ISO C 99 with IEC 60559],
38          [gl_cv_func_log10f_ieee],
39          [
40            save_LIBS="$LIBS"
41            LIBS="$LIBS $LOG10F_LIBM"
42            AC_RUN_IFELSE(
43              [AC_LANG_SOURCE([[
44#ifndef __NO_MATH_INLINES
45# define __NO_MATH_INLINES 1 /* for glibc */
46#endif
47#include <math.h>
48/* Compare two numbers with ==.
49   This is a separate function because IRIX 6.5 "cc -O" miscompiles an
50   'x == x' test.  */
51static int
52numeric_equal (float x, float y)
53{
54  return x == y;
55}
56static float dummy (float x) { return 0; }
57int main (int argc, char *argv[])
58{
59  float (* volatile my_log10f) (float) = argc ? log10f : dummy;
60  /* Test log10f(negative).
61     This test fails on NetBSD 5.1.  */
62  float y = my_log10f (-1.0f);
63  if (numeric_equal (y, y))
64    return 1;
65  return 0;
66}
67              ]])],
68              [gl_cv_func_log10f_ieee=yes],
69              [gl_cv_func_log10f_ieee=no],
70              [case "$host_os" in
71                                # Guess yes on glibc systems.
72                 *-gnu* | gnu*) gl_cv_func_log10f_ieee="guessing yes" ;;
73                                # Guess yes on musl systems.
74                 *-musl*)       gl_cv_func_log10f_ieee="guessing yes" ;;
75                                # Guess yes on native Windows.
76                 mingw*)        gl_cv_func_log10f_ieee="guessing yes" ;;
77                                # If we don't know, obey --enable-cross-guesses.
78                 *)             gl_cv_func_log10f_ieee="$gl_cross_guess_normal" ;;
79               esac
80              ])
81            LIBS="$save_LIBS"
82          ])
83        case "$gl_cv_func_log10f_ieee" in
84          *yes) ;;
85          *) REPLACE_LOG10F=1 ;;
86        esac
87      fi
88    ])
89  else
90    HAVE_LOG10F=0
91    dnl If the function is declared but does not appear to exist, it may be
92    dnl defined as an inline function. In order to avoid a conflict, we have
93    dnl to define rpl_log10f, not log10f.
94    AC_CHECK_DECLS([log10f], [REPLACE_LOG10F=1], , [[#include <math.h>]])
95  fi
96  if test $HAVE_LOG10F = 0 || test $REPLACE_LOG10F = 1; then
97    dnl Find libraries needed to link lib/log10f.c.
98    if test $HAVE_LOG10F = 0; then
99      LOG10F_LIBM="$LOG10_LIBM"
100    fi
101  fi
102  AC_SUBST([LOG10F_LIBM])
103])
104
105dnl Test whether log10f() works.
106dnl On OSF/1 5.1, log10f(-0.0f) is NaN.
107AC_DEFUN([gl_FUNC_LOG10F_WORKS],
108[
109  AC_REQUIRE([AC_PROG_CC])
110  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
111  AC_CACHE_CHECK([whether log10f works], [gl_cv_func_log10f_works],
112    [
113      AC_RUN_IFELSE(
114        [AC_LANG_SOURCE([[
115#include <math.h>
116volatile float x;
117float y;
118int main ()
119{
120  x = -0.0f;
121  y = log10f (x);
122  if (!(y + y == y))
123    return 1;
124  return 0;
125}
126]])],
127        [gl_cv_func_log10f_works=yes],
128        [gl_cv_func_log10f_works=no],
129        [case "$host_os" in
130           osf*)   gl_cv_func_log10f_works="guessing no" ;;
131                   # Guess yes on native Windows.
132           mingw*) gl_cv_func_log10f_works="guessing yes" ;;
133           *)      gl_cv_func_log10f_works="guessing yes" ;;
134         esac
135        ])
136    ])
137])
138