1 # frexp.m4 serial 14 2 dnl Copyright (C) 2007-2012 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. 6 7 AC_DEFUN([gl_FUNC_FREXP], 8 [ 9 AC_REQUIRE([gl_MATH_H_DEFAULTS]) 10 AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM]) 11 FREXP_LIBM= 12 if test $gl_cv_func_frexp_no_libm = no; then 13 AC_CACHE_CHECK([whether frexp() can be used with libm], 14 [gl_cv_func_frexp_in_libm], 15 [ 16 save_LIBS="$LIBS" 17 LIBS="$LIBS -lm" 18 AC_LINK_IFELSE( 19 [AC_LANG_PROGRAM( 20 [[#include <math.h> 21 double x;]], 22 [[int e; return frexp (x, &e) > 0;]])], 23 [gl_cv_func_frexp_in_libm=yes], 24 [gl_cv_func_frexp_in_libm=no]) 25 LIBS="$save_LIBS" 26 ]) 27 if test $gl_cv_func_frexp_in_libm = yes; then 28 FREXP_LIBM=-lm 29 fi 30 fi 31 if test $gl_cv_func_frexp_no_libm = yes \ 32 || test $gl_cv_func_frexp_in_libm = yes; then 33 save_LIBS="$LIBS" 34 LIBS="$LIBS $FREXP_LIBM" 35 gl_FUNC_FREXP_WORKS 36 LIBS="$save_LIBS" 37 case "$gl_cv_func_frexp_works" in 38 *yes) gl_func_frexp=yes ;; 39 *) gl_func_frexp=no; REPLACE_FREXP=1; FREXP_LIBM= ;; 40 esac 41 else 42 gl_func_frexp=no 43 fi 44 if test $gl_func_frexp = yes; then 45 AC_DEFINE([HAVE_FREXP], [1], 46 [Define if the frexp() function is available and works.]) 47 fi 48 AC_SUBST([FREXP_LIBM]) 49 ]) 50 51 AC_DEFUN([gl_FUNC_FREXP_NO_LIBM], 52 [ 53 AC_REQUIRE([gl_MATH_H_DEFAULTS]) 54 AC_REQUIRE([gl_CHECK_FREXP_NO_LIBM]) 55 if test $gl_cv_func_frexp_no_libm = yes; then 56 gl_FUNC_FREXP_WORKS 57 case "$gl_cv_func_frexp_works" in 58 *yes) gl_func_frexp_no_libm=yes ;; 59 *) gl_func_frexp_no_libm=no; REPLACE_FREXP=1 ;; 60 esac 61 else 62 gl_func_frexp_no_libm=no 63 dnl Set REPLACE_FREXP here because the system may have frexp in libm. 64 REPLACE_FREXP=1 65 fi 66 if test $gl_func_frexp_no_libm = yes; then 67 AC_DEFINE([HAVE_FREXP_IN_LIBC], [1], 68 [Define if the frexp() function is available in libc.]) 69 fi 70 ]) 71 72 dnl Test whether frexp() can be used without linking with libm. 73 dnl Set gl_cv_func_frexp_no_libm to 'yes' or 'no' accordingly. 74 AC_DEFUN([gl_CHECK_FREXP_NO_LIBM], 75 [ 76 AC_CACHE_CHECK([whether frexp() can be used without linking with libm], 77 [gl_cv_func_frexp_no_libm], 78 [ 79 AC_LINK_IFELSE( 80 [AC_LANG_PROGRAM( 81 [[#include <math.h> 82 double x;]], 83 [[int e; return frexp (x, &e) > 0;]])], 84 [gl_cv_func_frexp_no_libm=yes], 85 [gl_cv_func_frexp_no_libm=no]) 86 ]) 87 ]) 88 89 dnl Test whether frexp() works also on denormalized numbers (this fails e.g. on 90 dnl NetBSD 3.0), on infinite numbers (this fails e.g. on IRIX 6.5 and mingw), 91 dnl and on negative zero (this fails e.g. on NetBSD 4.99 and mingw). 92 AC_DEFUN([gl_FUNC_FREXP_WORKS], 93 [ 94 AC_REQUIRE([AC_PROG_CC]) 95 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles 96 AC_CHECK_FUNCS_ONCE([alarm]) 97 AC_CACHE_CHECK([whether frexp works], [gl_cv_func_frexp_works], 98 [ 99 AC_RUN_IFELSE( 100 [AC_LANG_SOURCE([[ 101 #include <float.h> 102 #include <math.h> 103 #include <string.h> 104 #if HAVE_ALARM 105 # include <unistd.h> 106 #endif 107 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0. 108 ICC 10.0 has a bug when optimizing the expression -zero. 109 The expression -DBL_MIN * DBL_MIN does not work when cross-compiling 110 to PowerPC on Mac OS X 10.5. */ 111 #if defined __hpux || defined __sgi || defined __ICC 112 static double 113 compute_minus_zero (void) 114 { 115 return -DBL_MIN * DBL_MIN; 116 } 117 # define minus_zero compute_minus_zero () 118 #else 119 double minus_zero = -0.0; 120 #endif 121 int main() 122 { 123 int result = 0; 124 int i; 125 volatile double x; 126 double zero = 0.0; 127 #if HAVE_ALARM 128 /* NeXTstep 3.3 frexp() runs into an endless loop when called on an infinite 129 number. Let the test fail in this case. */ 130 alarm (5); 131 #endif 132 /* Test on denormalized numbers. */ 133 for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5) 134 ; 135 if (x > 0.0) 136 { 137 int exp; 138 double y = frexp (x, &exp); 139 /* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022. 140 On NetBSD: y = 0.75. Correct: y = 0.5. */ 141 if (y != 0.5) 142 result |= 1; 143 } 144 /* Test on infinite numbers. */ 145 x = 1.0 / zero; 146 { 147 int exp; 148 double y = frexp (x, &exp); 149 if (y != x) 150 result |= 2; 151 } 152 /* Test on negative zero. */ 153 x = minus_zero; 154 { 155 int exp; 156 double y = frexp (x, &exp); 157 if (memcmp (&y, &x, sizeof x)) 158 result |= 4; 159 } 160 return result; 161 }]])], 162 [gl_cv_func_frexp_works=yes], 163 [gl_cv_func_frexp_works=no], 164 [case "$host_os" in 165 netbsd* | irix* | mingw*) gl_cv_func_frexp_works="guessing no";; 166 *) gl_cv_func_frexp_works="guessing yes";; 167 esac 168 ]) 169 ]) 170 ]) 171
