catacomb_LIMIT([SIZET], [=0], [~(size_t)0])
AC_SUBST([limits])
+dnl Figure out other aspects of the implementation's arithmetic.
+AC_CACHE_CHECK([whether negative numbers use two's complement],
+ [catacomb_cv_neg_twoc],
+[AC_TRY_COMPILE(
+[#include <limits.h>],
+[int check[2*!!(-INT_MAX == INT_MIN + 1) - 1];],
+[catacomb_cv_neg_twoc=yes],
+[catacomb_cv_neg_twoc=no])])
+case $catacomb_cv_neg_twoc in
+ yes)
+ AC_DEFINE([NEG_TWOC], [1],
+ [Define if signed numbers are represented in two's complement.])
+ ;;
+esac
+
dnl Functions used for noise-gathering.
AC_CHECK_FUNCS([setgroups])
AC_CHECK_HEADERS([linux/random.h])