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# isinf.m4 serial 11
dnl Copyright (C) 2007-2017 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_ISINF],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
dnl Persuade glibc <math.h> to declare isinf.
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_CHECK_DECLS([isinf], , ,
[[#include <math.h>
#ifndef isinf
#error "isinf must be a macro, not a function"
#endif
]])
if test "$ac_cv_have_decl_isinf" = yes; then
gl_CHECK_MATH_LIB([ISINF_LIBM], [x = isinf (x) + isinf ((float) x);])
if test "$ISINF_LIBM" != missing; then
dnl Test whether isinf() on 'long double' works.
gl_ISINFL_WORKS
case "$gl_cv_func_isinfl_works" in
*yes) ;;
*) ISINF_LIBM=missing;;
esac
fi
fi
if test "$ac_cv_have_decl_isinf" != yes ||
test "$ISINF_LIBM" = missing; then
REPLACE_ISINF=1
dnl No libraries are needed to link lib/isinf.c.
ISINF_LIBM=
fi
AC_SUBST([ISINF_LIBM])
])
dnl Test whether isinf() works:
dnl 1) Whether it correctly returns false for LDBL_MAX.
dnl 2) Whether on 'long double' recognizes all canonical values which are
dnl infinite.
AC_DEFUN([gl_ISINFL_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([gl_BIGENDIAN])
AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether isinf(long double) works], [gl_cv_func_isinfl_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <float.h>
#include <limits.h>
#include <math.h>
#define NWORDS \
((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
typedef union { unsigned int word[NWORDS]; long double value; }
memory_long_double;
/* On Irix 6.5, gcc 3.4.3 can't compute compile-time NaN, and needs the
runtime type conversion. */
#ifdef __sgi
static long double NaNl ()
{
double zero = 0.0;
return zero / zero;
}
#else
# define NaNl() (0.0L / 0.0L)
#endif
int main ()
{
int result = 0;
if (isinf (LDBL_MAX))
result |= 1;
{
memory_long_double m;
unsigned int i;
/* The isinf macro should be immune against changes in the sign bit and
in the mantissa bits. The xor operation twiddles a bit that can only be
a sign bit or a mantissa bit (since the exponent never extends to
bit 31). */
m.value = NaNl ();
m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1);
for (i = 0; i < NWORDS; i++)
m.word[i] |= 1;
if (isinf (m.value))
result |= 2;
}
#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
/* Representation of an 80-bit 'long double' as an initializer for a sequence
of 'unsigned int' words. */
# ifdef WORDS_BIGENDIAN
# define LDBL80_WORDS(exponent,manthi,mantlo) \
{ ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \
((unsigned int) (manthi) << 16) | ((unsigned int) (mantlo) >> 16), \
(unsigned int) (mantlo) << 16 \
}
# else
# define LDBL80_WORDS(exponent,manthi,mantlo) \
{ mantlo, manthi, exponent }
# endif
{ /* Quiet NaN. */
static memory_long_double x =
{ LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) };
if (isinf (x.value))
result |= 2;
}
{
/* Signalling NaN. */
static memory_long_double x =
{ LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) };
if (isinf (x.value))
result |= 2;
}
/* isinf should return something even for noncanonical values. */
{ /* Pseudo-NaN. */
static memory_long_double x =
{ LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) };
if (isinf (x.value) && !isinf (x.value))
result |= 4;
}
{ /* Pseudo-Infinity. */
static memory_long_double x =
{ LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) };
if (isinf (x.value) && !isinf (x.value))
result |= 8;
}
{ /* Pseudo-Zero. */
static memory_long_double x =
{ LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) };
if (isinf (x.value) && !isinf (x.value))
result |= 16;
}
{ /* Unnormalized number. */
static memory_long_double x =
{ LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) };
if (isinf (x.value) && !isinf (x.value))
result |= 32;
}
{ /* Pseudo-Denormal. */
static memory_long_double x =
{ LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
if (isinf (x.value) && !isinf (x.value))
result |= 64;
}
#endif
return result;
}]])], [gl_cv_func_isinfl_works=yes], [gl_cv_func_isinfl_works=no],
[gl_cv_func_isinfl_works="guessing yes"])
])
])
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