+ if (protocol_version < 27) {
+ s2length = csum_length;
+ } else if (csum_length == SUM_LENGTH) {
+ s2length = SUM_LENGTH;
+ } else {
+ int b = BLOCKSUM_BIAS;
+ l = len;
+ while (l >>= 1) {
+ b += 2;
+ }
+ c = blength;
+ while (c >>= 1 && b) {
+ b--;
+ }
+ s2length = (b + 1 - 32 + 7) / 8; /* add a bit,
+ * subtract rollsum,
+ * round up
+ * --optimize in compiler--
+ */
+ s2length = MAX(s2length, csum_length);
+ s2length = MIN(s2length, SUM_LENGTH);
+ }
+
+ sum->flength = len;
+ sum->blength = blength;
+ sum->s2length = s2length;
+ sum->count = (len + (blength - 1)) / blength;
+ sum->remainder = (len % blength);