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Second try: checks whether right shift extends the sign bit.

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Adds caching and reverts back the 'return' to 'exit()' in
AC_TRY_RUN as recommended by the Autoconf documentation.
This commit is contained in:
Vladimir Marangozov 2000-07-12 05:05:06 +00:00
parent 0582df98d3
commit a618028e45
2 changed files with 34 additions and 19 deletions
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14
configure.in
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@ -1139,15 +1139,19 @@ AC_C_BIGENDIAN
# Check whether right shifting a negative integer extends the sign bit
# or fills with zeros (like the Cray J90, according to Tim Peters).
AC_MSG_CHECKING(whether right shift extends the sign bit)
AC_CACHE_VAL(ac_cv_rshift_extends_sign, [
AC_TRY_RUN([
int main()
{
return ((-1)>>3 == -1) ? 1 : 0;
exit(((-1)>>3 == -1) ? 0 : 1);
}
],
[AC_DEFINE(SIGNED_RIGHT_SHIFT_ZERO_FILLS)
AC_MSG_RESULT(yes)],
[AC_MSG_RESULT(no)])
], ac_cv_rshift_extends_sign=yes, ac_cv_rshift_extends_sign=no)])
AC_MSG_RESULT($ac_cv_rshift_extends_sign)
if test "$ac_cv_rshift_extends_sign" = no
then
AC_DEFINE(SIGNED_RIGHT_SHIFT_ZERO_FILLS)
fi
# THIS MUST BE LAST, IT CAN BREAK OTHER TESTS!
# Add sys/socket.h to confdefs.h