dnl -*- Autoconf -*-
dnl Copyright (C) 1993-2008 Free Software Foundation, Inc.
dnl This file is free software, distributed under the terms of the GNU
dnl General Public License.  As a special exception to the GNU General
dnl Public License, this file may be distributed as part of a program
dnl that contains a configuration script generated by Autoconf, under
dnl the same distribution terms as the rest of that program.

dnl From Richard B. Kreckel.

AC_PREREQ(2.13)

dnl Is the gmp header file new enough? (should be implemented with an argument)
AC_DEFUN([CL_GMP_H_VERSION],
[AC_CACHE_CHECK([for recent enough gmp.h], cl_cv_new_gmp_h, [
  AC_TRY_CPP([#include <gmp.h>
#if !defined(__GNU_MP_VERSION) || (__GNU_MP_VERSION < 3)
 #error "ancient gmp.h"
#endif],
cl_cv_new_gmp_h="yes", cl_cv_new_gmp_h="no")
])])dnl

dnl Does libgmp provide some functionality introduced in version 3.0?
AC_DEFUN([CL_GMP_CHECK],
[AC_CACHE_CHECK([for working libgmp], cl_cv_new_libgmp, [
    SAVELIBS=$LIBS
    LIBS="$LIBS -lgmp"
    AC_TRY_LINK([#include <gmp.h>],[mpn_divexact_by3(0,0,0)],
cl_cv_new_libgmp="yes", cl_cv_new_libgmp="no")
    LIBS=$SAVELIBS])
    if test "$cl_cv_new_libgmp" = yes; then
      LIBS="$LIBS -lgmp"
    fi
])

dnl What is sizeof(mp_limb_t)?  (It has to match sizeof(uintD) later.)
AC_DEFUN([CL_GMP_SET_UINTD],
[AC_CACHE_CHECK([how large gmp demands uintD to be], cl_cv_gmp_set_uintd, [
    dnl Note: we don't run any of compiled programs here, so this method
    dnl both works for native and cross compilation
    cl_gmp_demands="UNKNOWN"
    cl_gmp_has_nails="no"
    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <gmp.h>
	 template<bool COND> struct Static_Assert;
	 template<> struct Static_Assert<true> { };
	 #if defined(__GMP_BITS_PER_MP_LIMB)
         Static_Assert<8*sizeof(mp_limb_t) == __GMP_BITS_PER_MP_LIMB> check;
	 #endif]], [[]])], [], [cl_gmp_has_nails="yes"])
    if test "x$cl_gmp_has_nails" = "xyes"; then
        AC_MSG_ERROR([nails in MP libms are unsupported.])
    fi
    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <gmp.h>
	 template<bool COND> struct Static_Assert;
	 template<> struct Static_Assert<true> { };
	 Static_Assert<sizeof(mp_limb_t) > sizeof(long)> check;]], [[]])],
	 [cl_gmp_demands='GMP_DEMANDS_UINTD_LONG_LONG'], [])
    if test "x$cl_gmp_demands" = "xUNKNOWN"; then
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <gmp.h>
	     template<bool COND> struct Static_Assert;
	     template<> struct Static_Assert<true> { };
	     Static_Assert<sizeof(mp_limb_t) == sizeof(long)> check;]], [[]])],
	     [cl_gmp_demands='GMP_DEMANDS_UINTD_LONG'], [])
    fi
    if test "x$cl_gmp_demands" = "xUNKNOWN"; then
        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
             #include <gmp.h>
	     template<bool COND> struct Static_Assert;
	     template<> struct Static_Assert<true> { };
	     Static_Assert<sizeof(mp_limb_t) == sizeof(int)> check;]], [[]])],
	     [cl_gmp_demands='GMP_DEMANDS_UINTD_INT'], [])
    fi
    if test "x$cl_gmp_demands" = "xUNKNOWN"; then
	AC_MSG_ERROR([Don't know which C-type has sizeof(mp_limb_t)])
    else
        cl_cv_gmp_set_uintd="$cl_gmp_demands"
    fi 
    ])
AC_DEFINE_UNQUOTED($cl_cv_gmp_set_uintd)
])

dnl Whether or not to use GMP. Sets CL_USE_GMP.
dnl Also sets CPPFLAGS, LDFLAGS if --with-gmp=DIR was specified.
AC_DEFUN([CL_LIBGMP],
[AC_ARG_WITH(gmp, AS_HELP_STRING([--with-gmp@<:@=DIR@:>@],
  [use external low-level functions from GNU MP (installed in prefix DIR) @<:@default=yes@:>@.]),[
    with_gmp="$withval"
  ],
  with_gmp="yes")
case $with_gmp in
  yes)
    dnl --with-gmp
    CL_GMP_H_VERSION
    if test "$cl_cv_new_gmp_h" = yes; then
      CL_GMP_CHECK
      if test "$cl_cv_new_libgmp" = yes; then
        CL_GMP_SET_UINTD
        AC_DEFINE(CL_USE_GMP, 1, [Define if GNU MP library is available])
      else
        AC_MSG_WARN([The GNU MP library is too old to be used.])
      fi
    else
      AC_MSG_WARN([The header file <gmp.h> is too old to be used.])
    fi
  ;;
  no)
    dnl --without-gmp
  ;;
  *)
    dnl --with-gmp=DIR
    case $withval in
      [[\\/$]]* | ?:[[\\/]]* )
      ;;
      *) AC_MSG_ERROR([expected an absolute directory name for --with-gmp: $withval])
      ;;
    esac
    saved_CPPFLAGS="$CPPFLAGS"
    CPPFLAGS="$CPPFLAGS -I${withval}/include"
    saved_LDFLAGS="$LDFLAGS"
    LDFLAGS="$LDFLAGS -L${withval}/lib"
    AC_LIB_LINKFLAGS_FROM_LIBS([GMP_RPATH_CFG], [$LDFLAGS])
    LDFLAGS="$GMP_RPATH_CFG $LDFLAGS"
    AC_MSG_NOTICE([Using "\"$LDFLAGS\"" rpath to link with GMP])
    CL_GMP_H_VERSION
    if test "$cl_cv_new_gmp_h" = yes; then
      CL_GMP_CHECK
      if test "$cl_cv_new_libgmp" = yes; then
        CL_GMP_SET_UINTD
        AC_DEFINE(CL_USE_GMP)
      else
        AC_MSG_WARN([The GNU MP library is too old to be used.])
        CPPFLAGS="$saved_CPPFLAGS"
        LDFLAGS="$saved_LDFLAGS"
      fi
    else
      AC_MSG_WARN([The header file <gmp.h> is too old to be used.])
      CPPFLAGS="$saved_CPPFLAGS"
      LDFLAGS="$saved_LDFLAGS"
    fi
  ;;
esac
])