kc3-lang/gnulib/m4/exp2.m4

• Show log

  Commit

• Hash : 32a72f45
  Author :
  Date : 2023-01-01T01:14:21
  

  maint: run 'make update-copyright'
  

Download

• m4/exp2.m4

• # exp2.m4 serial 3
  dnl Copyright (C) 2010-2023 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_EXP2],
  [
    AC_REQUIRE([gl_MATH_H_DEFAULTS])
  
    dnl Persuade glibc <math.h> to declare exp2().
    AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
  
    EXP2_LIBM=
    AC_CACHE_CHECK([whether exp2() can be used without linking with libm],
      [gl_cv_func_exp2_no_libm],
      [
        AC_LINK_IFELSE(
          [AC_LANG_PROGRAM(
             [[#ifndef __NO_MATH_INLINES
               # define __NO_MATH_INLINES 1 /* for glibc */
               #endif
               #include <math.h>
               extern
               #ifdef __cplusplus
               "C"
               #endif
               double exp2 (double);
               double (* volatile funcptr) (double) = exp2;
               double x;]],
             [[return funcptr (x) > 1.5
                      || exp2 (x) > 1.5;]])],
          [gl_cv_func_exp2_no_libm=yes],
          [gl_cv_func_exp2_no_libm=no])
      ])
    if test $gl_cv_func_exp2_no_libm = no; then
      AC_CACHE_CHECK([whether exp2() can be used with libm],
        [gl_cv_func_exp2_in_libm],
        [
          save_LIBS="$LIBS"
          LIBS="$LIBS -lm"
          AC_LINK_IFELSE(
            [AC_LANG_PROGRAM(
               [[#ifndef __NO_MATH_INLINES
                 # define __NO_MATH_INLINES 1 /* for glibc */
                 #endif
                 #include <math.h>
                 extern
                 #ifdef __cplusplus
                 "C"
                 #endif
                 double exp2 (double);
                 double (* volatile funcptr) (double) = exp2;
                 double x;]],
               [[return funcptr (x) > 1.5
                        || exp2 (x) > 1.5;]])],
            [gl_cv_func_exp2_in_libm=yes],
            [gl_cv_func_exp2_in_libm=no])
          LIBS="$save_LIBS"
        ])
      if test $gl_cv_func_exp2_in_libm = yes; then
        EXP2_LIBM=-lm
      fi
    fi
    if test $gl_cv_func_exp2_no_libm = yes \
       || test $gl_cv_func_exp2_in_libm = yes; then
      HAVE_EXP2=1
      dnl Also check whether it's declared.
      dnl IRIX 6.5 has exp2() in libm but doesn't declare it in <math.h>.
      AC_CHECK_DECL([exp2], , [HAVE_DECL_EXP2=0], [[#include <math.h>]])
      save_LIBS="$LIBS"
      LIBS="$LIBS $EXP2_LIBM"
      gl_FUNC_EXP2_WORKS
      LIBS="$save_LIBS"
      case "$gl_cv_func_exp2_works" in
        *yes) ;;
        *) REPLACE_EXP2=1 ;;
      esac
    else
      HAVE_EXP2=0
      HAVE_DECL_EXP2=0
    fi
    if test $HAVE_EXP2 = 0 || test $REPLACE_EXP2 = 1; then
      dnl Find libraries needed to link lib/exp2.c.
      AC_REQUIRE([gl_FUNC_ISNAND])
      AC_REQUIRE([gl_FUNC_ROUND])
      AC_REQUIRE([gl_FUNC_LDEXP])
      EXP2_LIBM=
      dnl Append $ISNAND_LIBM to EXP2_LIBM, avoiding gratuitous duplicates.
      case " $EXP2_LIBM " in
        *" $ISNAND_LIBM "*) ;;
        *) EXP2_LIBM="$EXP2_LIBM $ISNAND_LIBM" ;;
      esac
      dnl Append $ROUND_LIBM to EXP2_LIBM, avoiding gratuitous duplicates.
      case " $EXP2_LIBM " in
        *" $ROUND_LIBM "*) ;;
        *) EXP2_LIBM="$EXP2_LIBM $ROUND_LIBM" ;;
      esac
      dnl Append $LDEXP_LIBM to EXP2_LIBM, avoiding gratuitous duplicates.
      case " $EXP2_LIBM " in
        *" $LDEXP_LIBM "*) ;;
        *) EXP2_LIBM="$EXP2_LIBM $LDEXP_LIBM" ;;
      esac
    fi
    AC_SUBST([EXP2_LIBM])
  ])
  
  dnl Test whether exp2() works.
  dnl On OpenBSD 4.9, for the argument 0.6, it returns 1.517358639986284397,
  dnl which has a relative error of 0.1%.
  AC_DEFUN([gl_FUNC_EXP2_WORKS],
  [
    AC_REQUIRE([AC_PROG_CC])
    AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
    AC_CACHE_CHECK([whether exp2 works], [gl_cv_func_exp2_works],
      [
        AC_RUN_IFELSE(
          [AC_LANG_SOURCE([[
  #include <math.h>
  extern
  #ifdef __cplusplus
  "C"
  #endif
  double exp2 (double);
  volatile double x;
  double y;
  int main ()
  {
    x = 0.6;
    y = exp2 (x);
    if (y > 1.516)
      return 1;
    return 0;
  }
  ]])],
          [gl_cv_func_exp2_works=yes],
          [gl_cv_func_exp2_works=no],
          [case "$host_os" in
             openbsd*) gl_cv_func_exp2_works="guessing no" ;;
                       # Guess yes on native Windows.
             mingw*)   gl_cv_func_exp2_works="guessing yes" ;;
             *)        gl_cv_func_exp2_works="guessing yes" ;;
           esac
          ])
      ])
  ])
  

Download