113 lines
3.6 KiB
Plaintext
113 lines
3.6 KiB
Plaintext
# exponentl.m4 serial 5
|
|
dnl Copyright (C) 2007-2023 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_LONG_DOUBLE_EXPONENT_LOCATION],
|
|
[
|
|
AC_REQUIRE([gl_BIGENDIAN])
|
|
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
|
|
AC_CACHE_CHECK([where to find the exponent in a 'long double'],
|
|
[gl_cv_cc_long_double_expbit0],
|
|
[
|
|
AC_RUN_IFELSE(
|
|
[AC_LANG_SOURCE([[
|
|
#include <float.h>
|
|
#include <stddef.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#define NWORDS \
|
|
((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
|
|
typedef union { long double value; unsigned int word[NWORDS]; }
|
|
memory_long_double;
|
|
static unsigned int ored_words[NWORDS];
|
|
static unsigned int anded_words[NWORDS];
|
|
static void add_to_ored_words (long double *x)
|
|
{
|
|
memory_long_double m;
|
|
size_t i;
|
|
/* Clear it first, in case
|
|
sizeof (long double) < sizeof (memory_long_double). */
|
|
memset (&m, 0, sizeof (memory_long_double));
|
|
m.value = *x;
|
|
for (i = 0; i < NWORDS; i++)
|
|
{
|
|
ored_words[i] |= m.word[i];
|
|
anded_words[i] &= m.word[i];
|
|
}
|
|
}
|
|
int main ()
|
|
{
|
|
static long double samples[5] = { 0.25L, 0.5L, 1.0L, 2.0L, 4.0L };
|
|
size_t j;
|
|
FILE *fp = fopen ("conftest.out", "w");
|
|
if (fp == NULL)
|
|
return 1;
|
|
for (j = 0; j < NWORDS; j++)
|
|
anded_words[j] = ~ (unsigned int) 0;
|
|
for (j = 0; j < 5; j++)
|
|
add_to_ored_words (&samples[j]);
|
|
/* Remove bits that are common (e.g. if representation of the first mantissa
|
|
bit is explicit). */
|
|
for (j = 0; j < NWORDS; j++)
|
|
ored_words[j] &= ~anded_words[j];
|
|
/* Now find the nonzero word. */
|
|
for (j = 0; j < NWORDS; j++)
|
|
if (ored_words[j] != 0)
|
|
break;
|
|
if (j < NWORDS)
|
|
{
|
|
size_t i;
|
|
for (i = j + 1; i < NWORDS; i++)
|
|
if (ored_words[i] != 0)
|
|
{
|
|
fprintf (fp, "unknown");
|
|
return (fclose (fp) != 0);
|
|
}
|
|
for (i = 0; ; i++)
|
|
if ((ored_words[j] >> i) & 1)
|
|
{
|
|
fprintf (fp, "word %d bit %d", (int) j, (int) i);
|
|
return (fclose (fp) != 0);
|
|
}
|
|
}
|
|
fprintf (fp, "unknown");
|
|
return (fclose (fp) != 0);
|
|
}
|
|
]])],
|
|
[gl_cv_cc_long_double_expbit0=`cat conftest.out`],
|
|
[gl_cv_cc_long_double_expbit0="unknown"],
|
|
[
|
|
dnl When cross-compiling, in general we don't know. It depends on the
|
|
dnl ABI and compiler version. There are too many cases.
|
|
gl_cv_cc_long_double_expbit0="unknown"
|
|
case "$host_os" in
|
|
mingw*) # On native Windows (little-endian), we know the result
|
|
# in two cases: mingw, MSVC.
|
|
AC_EGREP_CPP([Known], [
|
|
#ifdef __MINGW32__
|
|
Known
|
|
#endif
|
|
], [gl_cv_cc_long_double_expbit0="word 2 bit 0"])
|
|
AC_EGREP_CPP([Known], [
|
|
#ifdef _MSC_VER
|
|
Known
|
|
#endif
|
|
], [gl_cv_cc_long_double_expbit0="word 1 bit 20"])
|
|
;;
|
|
esac
|
|
])
|
|
rm -f conftest.out
|
|
])
|
|
case "$gl_cv_cc_long_double_expbit0" in
|
|
word*bit*)
|
|
word=`echo "$gl_cv_cc_long_double_expbit0" | sed -e 's/word //' -e 's/ bit.*//'`
|
|
bit=`echo "$gl_cv_cc_long_double_expbit0" | sed -e 's/word.*bit //'`
|
|
AC_DEFINE_UNQUOTED([LDBL_EXPBIT0_WORD], [$word],
|
|
[Define as the word index where to find the exponent of 'long double'.])
|
|
AC_DEFINE_UNQUOTED([LDBL_EXPBIT0_BIT], [$bit],
|
|
[Define as the bit index in the word where to find bit 0 of the exponent of 'long double'.])
|
|
;;
|
|
esac
|
|
])
|