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Revise the autoconf tests for double middle endianness.
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The previous iteration didn't work for big-endian systems.  Now use
code very close to what Erts does internally.

Also, only warn when the double endianness is unknown - i.e. when
we're cross-compiling.
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@mikesperber
mikesperber committed Jul 20, 2012
1 parent cab9edd commit eba4d24
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Showing 5 changed files with 270 additions and 55 deletions.
65 changes: 54 additions & 11 deletions aclocal.m4
View file
Original file line number Diff line number Diff line change
Expand Up @@ -621,25 +621,68 @@ AC_DEFUN([AC_C_DOUBLE_MIDDLE_ENDIAN],
[AC_CACHE_CHECK(whether double word ordering is middle-endian, ac_cv_c_double_middle_endian,
[# It does not; compile a test program.
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[int
[AC_LANG_SOURCE([[#include <stdlib.h>
int
main(void)
{
int i = 0;
int zero = 0;
int bigendian;
int zero_index = 0;
union
{
long int l;
char c[sizeof (long int)];
} u;
/* we'll use the one with 32-bit words */
union
{
double d;
unsigned int c[2];
} vint;
union
{
double d;
unsigned long c[2];
} vlong;
union
{
double d;
char c[sizeof (double)];
} v;
v.d = 1.0;
while (i < sizeof(double) / 2)
unsigned short c[2];
} vshort;
/* Are we little or big endian? From Harbison&Steele. */
u.l = 1;
bigendian = (u.c[sizeof (long int) - 1] == 1);
zero_index = bigendian ? 1 : 0;
vint.d = 1.0;
vlong.d = 1.0;
vshort.d = 1.0;
if (sizeof(unsigned int) == 4)
{
if (vint.c[zero_index] != 0)
zero = 1;
}
else if (sizeof(unsigned long) == 4)
{
if (vlong.c[zero_index] != 0)
zero = 1;
}
else if (sizeof(unsigned short) == 4)
{
if (v.c[i] != 0)
if (vshort.c[zero_index] != 0)
zero = 1;
++i;
}
exit (zero);
}
]])],
Expand All @@ -656,7 +699,7 @@ case $ac_cv_c_double_middle_endian in
$2 ;;
*)
m4_default([$3],
[AC_MSG_ERROR([unknown double endianness
[AC_MSG_WARN([unknown double endianness
presetting ac_cv_c_double_middle_endian=no (or yes) will help])]) ;;
esac
])# AC_C_DOUBLE_MIDDLE_ENDIAN
Expand Down Expand Up @@ -1394,7 +1437,7 @@ fi
case X$erl_xcomp_double_middle_endian in
X) ;;
Xyes|Xno) ac_cv_c_double_middle_endian=$erl_xcomp_double_middle_endian;;
Xyes|Xno|Xunknown) ac_cv_c_double_middle_endian=$erl_xcomp_double_middle_endian;;
*) AC_MSG_ERROR([Bad erl_xcomp_double_middle_endian value: $erl_xcomp_double_middle_endian]);;
esac
Expand Down
65 changes: 54 additions & 11 deletions erts/aclocal.m4
View file
Original file line number Diff line number Diff line change
Expand Up @@ -621,25 +621,68 @@ AC_DEFUN([AC_C_DOUBLE_MIDDLE_ENDIAN],
[AC_CACHE_CHECK(whether double word ordering is middle-endian, ac_cv_c_double_middle_endian,
[# It does not; compile a test program.
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[int
[AC_LANG_SOURCE([[#include <stdlib.h>
int
main(void)
{
int i = 0;
int zero = 0;
int bigendian;
int zero_index = 0;
union
{
long int l;
char c[sizeof (long int)];
} u;
/* we'll use the one with 32-bit words */
union
{
double d;
unsigned int c[2];
} vint;
union
{
double d;
unsigned long c[2];
} vlong;
union
{
double d;
char c[sizeof (double)];
} v;
v.d = 1.0;
while (i < sizeof(double) / 2)
unsigned short c[2];
} vshort;
/* Are we little or big endian? From Harbison&Steele. */
u.l = 1;
bigendian = (u.c[sizeof (long int) - 1] == 1);
zero_index = bigendian ? 1 : 0;
vint.d = 1.0;
vlong.d = 1.0;
vshort.d = 1.0;
if (sizeof(unsigned int) == 4)
{
if (vint.c[zero_index] != 0)
zero = 1;
}
else if (sizeof(unsigned long) == 4)
{
if (vlong.c[zero_index] != 0)
zero = 1;
}
else if (sizeof(unsigned short) == 4)
{
if (v.c[i] != 0)
if (vshort.c[zero_index] != 0)
zero = 1;
++i;
}
exit (zero);
}
]])],
Expand All @@ -656,7 +699,7 @@ case $ac_cv_c_double_middle_endian in
$2 ;;
*)
m4_default([$3],
[AC_MSG_ERROR([unknown double endianness
[AC_MSG_WARN([unknown double endianness
presetting ac_cv_c_double_middle_endian=no (or yes) will help])]) ;;
esac
])# AC_C_DOUBLE_MIDDLE_ENDIAN
Expand Down Expand Up @@ -1394,7 +1437,7 @@ fi
case X$erl_xcomp_double_middle_endian in
X) ;;
Xyes|Xno) ac_cv_c_double_middle_endian=$erl_xcomp_double_middle_endian;;
Xyes|Xno|Xunknown) ac_cv_c_double_middle_endian=$erl_xcomp_double_middle_endian;;
*) AC_MSG_ERROR([Bad erl_xcomp_double_middle_endian value: $erl_xcomp_double_middle_endian]);;
esac
Expand Down
65 changes: 54 additions & 11 deletions lib/erl_interface/aclocal.m4
View file
Original file line number Diff line number Diff line change
Expand Up @@ -621,25 +621,68 @@ AC_DEFUN([AC_C_DOUBLE_MIDDLE_ENDIAN],
[AC_CACHE_CHECK(whether double word ordering is middle-endian, ac_cv_c_double_middle_endian,
[# It does not; compile a test program.
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[int
[AC_LANG_SOURCE([[#include <stdlib.h>
int
main(void)
{
int i = 0;
int zero = 0;
int bigendian;
int zero_index = 0;
union
{
long int l;
char c[sizeof (long int)];
} u;
/* we'll use the one with 32-bit words */
union
{
double d;
unsigned int c[2];
} vint;
union
{
double d;
unsigned long c[2];
} vlong;
union
{
double d;
char c[sizeof (double)];
} v;
v.d = 1.0;
while (i < sizeof(double) / 2)
unsigned short c[2];
} vshort;
/* Are we little or big endian? From Harbison&Steele. */
u.l = 1;
bigendian = (u.c[sizeof (long int) - 1] == 1);
zero_index = bigendian ? 1 : 0;
vint.d = 1.0;
vlong.d = 1.0;
vshort.d = 1.0;
if (sizeof(unsigned int) == 4)
{
if (vint.c[zero_index] != 0)
zero = 1;
}
else if (sizeof(unsigned long) == 4)
{
if (vlong.c[zero_index] != 0)
zero = 1;
}
else if (sizeof(unsigned short) == 4)
{
if (v.c[i] != 0)
if (vshort.c[zero_index] != 0)
zero = 1;
++i;
}
exit (zero);
}
]])],
Expand All @@ -656,7 +699,7 @@ case $ac_cv_c_double_middle_endian in
$2 ;;
*)
m4_default([$3],
[AC_MSG_ERROR([unknown double endianness
[AC_MSG_WARN([unknown double endianness
presetting ac_cv_c_double_middle_endian=no (or yes) will help])]) ;;
esac
])# AC_C_DOUBLE_MIDDLE_ENDIAN
Expand Down Expand Up @@ -1394,7 +1437,7 @@ fi
case X$erl_xcomp_double_middle_endian in
X) ;;
Xyes|Xno) ac_cv_c_double_middle_endian=$erl_xcomp_double_middle_endian;;
Xyes|Xno|Xunknown) ac_cv_c_double_middle_endian=$erl_xcomp_double_middle_endian;;
*) AC_MSG_ERROR([Bad erl_xcomp_double_middle_endian value: $erl_xcomp_double_middle_endian]);;
esac
Expand Down
65 changes: 54 additions & 11 deletions lib/odbc/aclocal.m4
View file
Original file line number Diff line number Diff line change
Expand Up @@ -621,25 +621,68 @@ AC_DEFUN([AC_C_DOUBLE_MIDDLE_ENDIAN],
[AC_CACHE_CHECK(whether double word ordering is middle-endian, ac_cv_c_double_middle_endian,
[# It does not; compile a test program.
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[int
[AC_LANG_SOURCE([[#include <stdlib.h>
int
main(void)
{
int i = 0;
int zero = 0;
int bigendian;
int zero_index = 0;
union
{
long int l;
char c[sizeof (long int)];
} u;
/* we'll use the one with 32-bit words */
union
{
double d;
unsigned int c[2];
} vint;
union
{
double d;
unsigned long c[2];
} vlong;
union
{
double d;
char c[sizeof (double)];
} v;
v.d = 1.0;
while (i < sizeof(double) / 2)
unsigned short c[2];
} vshort;
/* Are we little or big endian? From Harbison&Steele. */
u.l = 1;
bigendian = (u.c[sizeof (long int) - 1] == 1);
zero_index = bigendian ? 1 : 0;
vint.d = 1.0;
vlong.d = 1.0;
vshort.d = 1.0;
if (sizeof(unsigned int) == 4)
{
if (vint.c[zero_index] != 0)
zero = 1;
}
else if (sizeof(unsigned long) == 4)
{
if (vlong.c[zero_index] != 0)
zero = 1;
}
else if (sizeof(unsigned short) == 4)
{
if (v.c[i] != 0)
if (vshort.c[zero_index] != 0)
zero = 1;
++i;
}
exit (zero);
}
]])],
Expand All @@ -656,7 +699,7 @@ case $ac_cv_c_double_middle_endian in
$2 ;;
*)
m4_default([$3],
[AC_MSG_ERROR([unknown double endianness
[AC_MSG_WARN([unknown double endianness
presetting ac_cv_c_double_middle_endian=no (or yes) will help])]) ;;
esac
])# AC_C_DOUBLE_MIDDLE_ENDIAN
Expand Down Expand Up @@ -1394,7 +1437,7 @@ fi
case X$erl_xcomp_double_middle_endian in
X) ;;
Xyes|Xno) ac_cv_c_double_middle_endian=$erl_xcomp_double_middle_endian;;
Xyes|Xno|Xunknown) ac_cv_c_double_middle_endian=$erl_xcomp_double_middle_endian;;
*) AC_MSG_ERROR([Bad erl_xcomp_double_middle_endian value: $erl_xcomp_double_middle_endian]);;
esac
Expand Down
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