# signbit.m4 serial 2
dnl Copyright (C) 2007 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_SIGNBIT],
[
  AC_REQUIRE([gl_MATH_H_DEFAULTS])
  AC_CACHE_CHECK([for signbit macro], [gl_cv_func_signbit],
    [
      AC_TRY_RUN([
#include <math.h>
#include <string.h>
float p0f = 0.0f;
float m0f = -0.0f;
double p0d = 0.0;
double m0d = -0.0;
long double p0l = 0.0L;
long double m0l = -0.0L;
int main ()
{
  {
    float plus_inf = 1.0f / p0f;
    float minus_inf = -1.0f / p0f;
    if (!(!signbit (255.0f)
          && signbit (-255.0f)
          && !signbit (p0f)
          && (memcmp (&m0f, &p0f, sizeof (float)) == 0 || signbit (m0f))
          && !signbit (plus_inf)
          && signbit (minus_inf)))
      return 1;
  }
  {
    double plus_inf = 1.0 / p0d;
    double minus_inf = -1.0 / p0d;
    if (!(!signbit (255.0)
          && signbit (-255.0)
          && !signbit (p0d)
          && (memcmp (&m0d, &p0d, sizeof (double)) == 0 || signbit (m0d))
          && !signbit (plus_inf)
          && signbit (minus_inf)))
      return 1;
  }
  {
    long double plus_inf = 1.0L / p0l;
    long double minus_inf = -1.0L / p0l;
    if (!(!signbit (255.0L)
          && signbit (-255.0L)
          && !signbit (p0l)
          && (memcmp (&m0l, &p0l, sizeof (long double)) == 0 || signbit (m0l))
          && !signbit (plus_inf)
          && signbit (minus_inf)))
      return 1;
  }
  return 0;
}], [gl_cv_func_signbit=yes], [gl_cv_func_signbit=no],
        [gl_cv_func_signbit="guessing no"])
    ])
  if test "$gl_cv_func_signbit" != yes; then
    REPLACE_SIGNBIT=1
    AC_LIBOBJ([signbitf])
    AC_LIBOBJ([signbitd])
    AC_LIBOBJ([signbitl])
    gl_FLOAT_SIGN_LOCATION
    gl_DOUBLE_SIGN_LOCATION
    gl_LONG_DOUBLE_SIGN_LOCATION
    if test "$gl_cv_cc_float_signbit" = unknown; then
      dnl Test whether copysignf() is declared.
      AC_CHECK_DECLS([copysignf], , , [#include <math.h>])
      if test "$ac_cv_have_decl_copysignf" = yes; then
        dnl Test whether copysignf() can be used without libm.
        AC_CACHE_CHECK([whether copysignf can be used without linking with libm],
          [gl_cv_func_copysignf_no_libm],
          [
            AC_TRY_LINK([#include <math.h>
                         float x, y;],
                        [return copysignf (x, y) < 0;],
              [gl_cv_func_copysignf_no_libm=yes],
              [gl_cv_func_copysignf_no_libm=no])
          ])
        if test $gl_cv_func_copysignf_no_libm = yes; then
          AC_DEFINE([HAVE_COPYSIGNF_IN_LIBC], 1,
            [Define if the copysignf function is declared in <math.h> and available in libc.])
        fi
      fi
    fi
    if test "$gl_cv_cc_double_signbit" = unknown; then
      dnl Test whether copysign() is declared.
      AC_CHECK_DECLS([copysign], , , [#include <math.h>])
      if test "$ac_cv_have_decl_copysign" = yes; then
        dnl Test whether copysign() can be used without libm.
        AC_CACHE_CHECK([whether copysign can be used without linking with libm],
          [gl_cv_func_copysign_no_libm],
          [
            AC_TRY_LINK([#include <math.h>
                         double x, y;],
                        [return copysign (x, y) < 0;],
              [gl_cv_func_copysign_no_libm=yes],
              [gl_cv_func_copysign_no_libm=no])
          ])
        if test $gl_cv_func_copysign_no_libm = yes; then
          AC_DEFINE([HAVE_COPYSIGN_IN_LIBC], 1,
            [Define if the copysign function is declared in <math.h> and available in libc.])
        fi
      fi
    fi
    if test "$gl_cv_cc_long_double_signbit" = unknown; then
      dnl Test whether copysignl() is declared.
      AC_CHECK_DECLS([copysignl], , , [#include <math.h>])
      if test "$ac_cv_have_decl_copysignl" = yes; then
        dnl Test whether copysignl() can be used without libm.
        AC_CACHE_CHECK([whether copysignl can be used without linking with libm],
          [gl_cv_func_copysignl_no_libm],
          [
            AC_TRY_LINK([#include <math.h>
                         long double x, y;],
                        [return copysignl (x, y) < 0;],
              [gl_cv_func_copysignl_no_libm=yes],
              [gl_cv_func_copysignl_no_libm=no])
          ])
        if test $gl_cv_func_copysignl_no_libm = yes; then
          AC_DEFINE([HAVE_COPYSIGNL_IN_LIBC], 1,
            [Define if the copysignl function is declared in <math.h> and available in libc.])
        fi
      fi
    fi
  fi
])

AC_DEFUN([gl_FLOAT_SIGN_LOCATION],
[
  gl_FLOATTYPE_SIGN_LOCATION([float], [gl_cv_cc_float_signbit], [f], [FLT])
])

AC_DEFUN([gl_DOUBLE_SIGN_LOCATION],
[
  gl_FLOATTYPE_SIGN_LOCATION([double], [gl_cv_cc_double_signbit], [], [DBL])
])

AC_DEFUN([gl_LONG_DOUBLE_SIGN_LOCATION],
[
  gl_FLOATTYPE_SIGN_LOCATION([long double], [gl_cv_cc_long_double_signbit], [L], [LDBL])
])

AC_DEFUN([gl_FLOATTYPE_SIGN_LOCATION],
[
  AC_CACHE_CHECK([where to find the sign bit in a '$1'],
    [$2],
    [
      AC_TRY_RUN([
#include <stddef.h>
#include <stdio.h>
#define NWORDS \
  ((sizeof ($1) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
typedef union { $1 value; unsigned int word[NWORDS]; }
        memory_float;
static memory_float plus = { 1.0$3 };
static memory_float minus = { -1.0$3 };
int main ()
{
  size_t j, k, i;
  unsigned int m;
  FILE *fp = fopen ("conftest.out", "w");
  if (fp == NULL)
    return 1;
  /* Find the different bit.  */
  k = 0; m = 0;
  for (j = 0; j < NWORDS; j++)
    {
      unsigned int x = plus.word[j] ^ minus.word[j];
      if ((x & (x - 1)) || (x && m))
        {
          /* More than one bit difference.  */
          fprintf (fp, "unknown");
          return 1;
        }
      if (x)
        {
          k = j;
          m = x;
        }
    }
  if (m == 0)
    {
      /* No difference.  */
      fprintf (fp, "unknown");
      return 1;
    }
  /* Now m = plus.word[k] ^ ~minus.word[k].  */
  if (plus.word[k] & ~minus.word[k])
    {
      /* Oh? The sign bit is set in the positive and cleared in the negative
         numbers?  */
      fprintf (fp, "unknown");
      return 1;
    }
  for (i = 0; ; i++)
    if ((m >> i) & 1)
      break;
  fprintf (fp, "word %d bit %d", (int) k, (int) i);
  return (fclose (fp) != 0);
}
        ],
        [$2=`cat conftest.out`],
        [$2="unknown"],
        [
          dnl When cross-compiling, we don't know. It depends on the
          dnl ABI and compiler version. There are too many cases.
          $2="unknown"
        ])
      rm -f conftest.out
    ])
  case "$]$2[" in
    word*bit*)
      word=`echo "$]$2[" | sed -e 's/word //' -e 's/ bit.*//'`
      bit=`echo "$]$2[" | sed -e 's/word.*bit //'`
      AC_DEFINE_UNQUOTED([$4][_SIGNBIT_WORD], [$word],
        [Define as the word index where to find the sign of '$1'.])
      AC_DEFINE_UNQUOTED([$4][_SIGNBIT_BIT], [$bit],
        [Define as the bit index in the word where to find the sign of '$1'.])
      ;;
  esac
])