1 # frexp.m4 serial 16 2 dnl Copyright (C) 2007-2022 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_DECLS_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_DECL_ALARM 105 # include <signal.h> 106 # include <unistd.h> 107 #endif 108 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0. 109 ICC 10.0 has a bug when optimizing the expression -zero. 110 The expression -DBL_MIN * DBL_MIN does not work when cross-compiling 111 to PowerPC on Mac OS X 10.5. */ 112 #if defined __hpux || defined __sgi || defined __ICC 113 static double 114 compute_minus_zero (void) 115 { 116 return -DBL_MIN * DBL_MIN; 117 } 118 # define minus_zero compute_minus_zero () 119 #else 120 double minus_zero = -0.0; 121 #endif 122 int main() 123 { 124 int result = 0; 125 int i; 126 volatile double x; 127 double zero = 0.0; 128 #if HAVE_DECL_ALARM 129 /* NeXTstep 3.3 frexp() runs into an endless loop when called on an infinite 130 number. Let the test fail in this case. */ 131 signal (SIGALRM, SIG_DFL); 132 alarm (5); 133 #endif 134 /* Test on denormalized numbers. */ 135 for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5) 136 ; 137 if (x > 0.0) 138 { 139 int exp; 140 double y = frexp (x, &exp); 141 /* On machines with IEEE754 arithmetic: x = 1.11254e-308, exp = -1022. 142 On NetBSD: y = 0.75. Correct: y = 0.5. */ 143 if (y != 0.5) 144 result |= 1; 145 } 146 /* Test on infinite numbers. */ 147 x = 1.0 / zero; 148 { 149 int exp; 150 double y = frexp (x, &exp); 151 if (y != x) 152 result |= 2; 153 } 154 /* Test on negative zero. */ 155 x = minus_zero; 156 { 157 int exp; 158 double y = frexp (x, &exp); 159 if (memcmp (&y, &x, sizeof x)) 160 result |= 4; 161 } 162 return result; 163 }]])], 164 [gl_cv_func_frexp_works=yes], 165 [gl_cv_func_frexp_works=no], 166 [case "$host_os" in 167 netbsd* | irix*) gl_cv_func_frexp_works="guessing no" ;; 168 mingw*) # Guess yes with MSVC, no with mingw. 169 AC_EGREP_CPP([Good], [ 170 #ifdef _MSC_VER 171 Good 172 #endif 173 ], 174 [gl_cv_func_frexp_works="guessing yes"], 175 [gl_cv_func_frexp_works="guessing no"]) 176 ;; 177 *) gl_cv_func_frexp_works="guessing yes" ;; 178 esac 179 ]) 180 ]) 181 ]) 182
Indexes created Sun May 03 00:22:47 UTC 2026