+$echo "Checking to find the largest integer value your NVs can hold..." >&4
+: volatile so that the compiler has to store it out to memory.
+if test X"$d_volatile" = X"$define"; then
+ volatile=volatile
+fi
+$cat <<EOP >try.c
+#include <stdio.h>
+
+typedef $nvtype NV;
+
+int
+main() {
+ NV value = 2;
+ int count = 1;
+
+ while(count < 256) {
+ $volatile NV up = value + 1.0;
+ $volatile NV negated = -value;
+ $volatile NV down = negated - 1.0;
+ $volatile NV got_up = up - value;
+ int up_good = got_up == 1.0;
+ int got_down = down - negated;
+ int down_good = got_down == -1.0;
+
+ if (down_good != up_good) {
+ fprintf(stderr,
+ "Inconsistency - up %d %f; down %d %f; for 2**%d (%.20f)\n",
+ up_good, (double) got_up, down_good, (double) got_down,
+ count, (double) value);
+ return 1;
+ }
+ if (!up_good) {
+ while (1) {
+ if (count > 8) {
+ count -= 8;
+ fputs("256.0", stdout);
+ } else {
+ count--;
+ fputs("2.0", stdout);
+ }
+ if (!count) {
+ puts("");
+ return 0;
+ }
+ fputs("*", stdout);
+ }
+ }
+ value *= 2;
+ ++count;
+ }
+ fprintf(stderr, "Cannot overflow integer range, even at 2**%d (%.20f)\n",
+ count, (double) value);
+ return 1;
+}
+EOP
+set try
+
+nv_overflows_integers_at='0'
+if eval $compile; then
+ xxx="`$run ./try`"
+ case "$?" in
+ 0)
+ case "$xxx" in
+ 2*) cat >&4 <<EOM
+The largest integer your NVs can preserve is equal to $xxx
+EOM
+ nv_overflows_integers_at="$xxx"
+ ;;
+ *) cat >&4 <<EOM
+Cannot determine the largest integer value your NVs can hold, unexpected output
+'$xxx'
+EOM
+ ;;
+ esac
+ ;;
+ *) cat >&4 <<EOM
+Cannot determine the largest integer value your NVs can hold
+EOM
+ ;;
+ esac
+fi
+$rm_try