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dnl Utility macro used by next two tests.
dnl AC_EXAMINE_OBJECT(C source code,
dnl commands examining object file,
dnl [commands to run if compile failed]):
dnl
dnl Compile the source code to an object file; then convert it into a
dnl printable representation. All unprintable characters and
dnl asterisks (*) are replaced by dots (.). All white space is
dnl deleted. Newlines (ASCII 0x10) in the input are preserved in the
dnl output, but runs of newlines are compressed to a single newline.
dnl Finally, line breaks are forcibly inserted so that no line is
dnl longer than 80 columns and the file ends with a newline. The
dnl result of all this processing is in the file conftest.dmp, which
dnl may be examined by the commands in the second argument.
dnl
AC_DEFUN([gcc_AC_EXAMINE_OBJECT],
[AC_LANG_SAVE
AC_LANG_C
dnl Next bit cribbed from AC_TRY_COMPILE.
cat > conftest.$ac_ext <<EOF
[#line __oline__ "configure"
#include "confdefs.h"
$1
]EOF
if AC_TRY_EVAL(ac_compile); then
od -c conftest.o |
sed ['s/^[0-7]*[ ]*/ /
s/\*/./g
s/ \\n/*/g
s/ [0-9][0-9][0-9]/./g
s/ \\[^ ]/./g'] |
tr -d '
' | tr -s '*' '
' | fold | sed '$a\
' > conftest.dmp
$2
ifelse($3, , , else
$3
)dnl
fi
rm -rf conftest*
AC_LANG_RESTORE])
dnl Floating point format probe.
dnl The basic concept is the same as the above: grep the object
dnl file for an interesting string. We have to watch out for
dnl rounding changing the values in the object, however; this is
dnl handled by ignoring the least significant byte of the float.
dnl
dnl Does not know about VAX G-float or C4x idiosyncratic format.
dnl It does know about PDP-10 idiosyncratic format, but this is
dnl not presently supported by GCC. S/390 "binary floating point"
dnl is in fact IEEE (but maybe we should have that in EBCDIC as well
dnl as ASCII?)
AC_DEFUN([gcc_AC_C_FLOAT_FORMAT],
[AC_CACHE_CHECK(floating point format, ac_cv_c_float_format,
[gcc_AC_EXAMINE_OBJECT(
[/* This will not work unless sizeof(double) == 8. */
extern char sizeof_double_must_be_8 [sizeof(double) == 8 ? 1 : -1];
/* This structure must have no internal padding. */
struct possibility {
char prefix[8];
double candidate;
char postfix[8];
};
#define C(cand) { "\nformat:", cand, ":tamrof\n" }
struct possibility table [] =
{
C( 3.25724264705901305206e+01), /* @@IEEEFP - IEEE 754 */
C( 3.53802595280598432000e+18), /* D__float - VAX */
C( 5.32201830133125317057e-19), /* D.PDP-10 - PDP-10 - the dot is 0x13a */
C( 1.77977764695171661377e+10), /* IBMHEXFP - s/390 format, ascii */
C(-5.22995989424860458374e+10) /* IBMHEXFP - s/390 format, EBCDIC */
};],
[if grep 'format:.@IEEEF.:tamrof' conftest.dmp >/dev/null 2>&1; then
ac_cv_c_float_format='IEEE (big-endian)'
elif grep 'format:.I@@PFE.:tamrof' conftest.dmp >/dev/null 2>&1; then
ac_cv_c_float_format='IEEE (big-endian)'
elif grep 'format:.FEEEI@.:tamrof' conftest.dmp >/dev/null 2>&1; then
ac_cv_c_float_format='IEEE (little-endian)'
elif grep 'format:.EFP@@I.:tamrof' conftest.dmp >/dev/null 2>&1; then
ac_cv_c_float_format='IEEE (little-endian)'
elif grep 'format:.__floa.:tamrof' conftest.dmp >/dev/null 2>&1; then
ac_cv_c_float_format='VAX D-float'
elif grep 'format:..PDP-1.:tamrof' conftest.dmp >/dev/null 2>&1; then
ac_cv_c_float_format='PDP-10'
elif grep 'format:.BMHEXF.:tamrof' conftest.dmp >/dev/null 2>&1; then
ac_cv_c_float_format='IBM 370 hex'
else
AC_MSG_ERROR(Unknown floating point format)
fi],
[AC_MSG_ERROR(compile failed)])
])
# IEEE is the default format. If the float endianness isn't the same
# as the integer endianness, we have to set FLOAT_WORDS_BIG_ENDIAN
# (which is a tristate: yes, no, default). This is only an issue with
# IEEE; the other formats are only supported by a few machines each,
# all with the same endianness.
format=IEEE_FLOAT_FORMAT
fbigend=
case $ac_cv_c_float_format in
'IEEE (big-endian)' )
if test $ac_cv_c_bigendian = no; then
fbigend=1
fi
if test $ac_cv_c_bigendian = universal; then
fbigend=WORDS_BIGENDIAN
fi
;;
'IEEE (little-endian)' )
if test $ac_cv_c_bigendian = yes; then
fbigend=0
fi
if test $ac_cv_c_bigendian = universal; then
fbigend='!WORDS_BIGENDIAN'
fi
;;
'VAX D-float' )
format=VAX_FLOAT_FORMAT
;;
'PDP-10' )
format=PDP10_FLOAT_FORMAT
;;
'IBM 370 hex' )
format=IBM_FLOAT_FORMAT
;;
esac
AC_DEFINE_UNQUOTED(HOST_FLOAT_FORMAT, $format,
[Define to the floating point format of the host machine.])
if test -n "$fbigend"; then
AC_DEFINE_UNQUOTED(HOST_FLOAT_WORDS_BIG_ENDIAN, $fbigend,
[Define to 1 if the host machine stores floating point numbers in
memory with the word containing the sign bit at the lowest address,
or to 0 if it does it the other way around.
This macro should not be defined if the ordering is the same as for
multi-word integers.])
fi
])
|
