2 dnl Copyright (C) 2010-2013 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_ILOGB],
9 AC_REQUIRE([gl_MATH_H_DEFAULTS])
11 dnl Determine ILOGB_LIBM.
12 gl_MATHFUNC([ilogb], [int], [(double)])
13 if test $gl_cv_func_ilogb_no_libm = yes \
14 || test $gl_cv_func_ilogb_in_libm = yes; then
16 LIBS="$LIBS $ILOGB_LIBM"
19 case "$gl_cv_func_ilogb_works" in
26 if test $HAVE_ILOGB = 0 || test $REPLACE_ILOGB = 1; then
27 dnl Find libraries needed to link lib/ilogb.c.
28 AC_REQUIRE([gl_FUNC_FREXP])
29 AC_REQUIRE([gl_FUNC_ISNAND])
31 dnl Append $FREXP_LIBM to ILOGB_LIBM, avoiding gratuitous duplicates.
32 case " $ILOGB_LIBM " in
34 *) ILOGB_LIBM="$ILOGB_LIBM $FREXP_LIBM" ;;
36 dnl Append $ISNAND_LIBM to ILOGB_LIBM, avoiding gratuitous duplicates.
37 case " $ILOGB_LIBM " in
38 *" $ISNAND_LIBM "*) ;;
39 *) ILOGB_LIBM="$ILOGB_LIBM $ISNAND_LIBM" ;;
42 AC_SUBST([ILOGB_LIBM])
45 dnl Test whether ilogb() works.
46 dnl On OpenBSD 4.9, AIX 5.1, ilogb(0.0) is wrong.
47 dnl On NetBSD 5.1, OpenBSD 4.9, ilogb(Infinity) is wrong.
48 dnl On OpenBSD 4.9, ilogb(NaN) is wrong.
49 AC_DEFUN([gl_FUNC_ILOGB_WORKS],
51 AC_REQUIRE([AC_PROG_CC])
52 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
53 AC_CACHE_CHECK([whether ilogb works], [gl_cv_func_ilogb_works],
59 /* Provide FP_ILOGB0, FP_ILOGBNAN, like in math.in.h. */
60 #if !(defined FP_ILOGB0 && defined FP_ILOGBNAN)
61 # if defined __NetBSD__ || defined __sgi
62 /* NetBSD, IRIX 6.5: match what ilogb() does */
63 # define FP_ILOGB0 INT_MIN
64 # define FP_ILOGBNAN INT_MIN
66 /* AIX 5.1: match what ilogb() does in AIX >= 5.2 */
67 # define FP_ILOGB0 INT_MIN
68 # define FP_ILOGBNAN INT_MAX
70 /* Solaris 9: match what ilogb() does */
71 # define FP_ILOGB0 (- INT_MAX)
72 # define FP_ILOGBNAN INT_MAX
77 static int dummy (double x) { return 0; }
78 int main (int argc, char *argv[])
80 int (*my_ilogb) (double) = argc ? ilogb : dummy;
82 /* This test fails on OpenBSD 4.9, AIX 5.1. */
85 if (my_ilogb (x) != FP_ILOGB0)
88 /* This test fails on NetBSD 5.1, OpenBSD 4.9. */
91 if (my_ilogb (x) != INT_MAX)
94 /* This test fails on OpenBSD 4.9. */
97 if (my_ilogb (x) != FP_ILOGBNAN)
103 [gl_cv_func_ilogb_works=yes],
104 [gl_cv_func_ilogb_works=no],
106 aix* | openbsd* | netbsd* | solaris*)
107 gl_cv_func_ilogb_works="guessing no";;
108 *) gl_cv_func_ilogb_works="guessing yes";;