+ int cnt;
+ for (c = 1, l = len, cnt = 0; l >>= 2; c <<= 1, cnt++) {}
+ if (cnt >= 31 || c >= MAX_BLOCK_SIZE)
+ blength = MAX_BLOCK_SIZE;
+ else {
+ blength = 0;
+ do {
+ blength |= c;
+ if (len < (uint64)blength * blength)
+ blength &= ~c;
+ c >>= 1;
+ } while (c >= 8); /* round to multiple of 8 */
+ blength = MAX(blength, BLOCK_SIZE);