+#elif !defined(USE_BSFQ)
+
+static CACHE_LINE_ALIGNMENT
+const int BitTable[64] = {
+ 63, 30, 3, 32, 25, 41, 22, 33, 15, 50, 42, 13, 11, 53, 19, 34, 61, 29, 2,
+ 51, 21, 43, 45, 10, 18, 47, 1, 54, 9, 57, 0, 35, 62, 31, 40, 4, 49, 5, 52,
+ 26, 60, 6, 23, 44, 46, 27, 56, 16, 7, 39, 48, 24, 59, 14, 12, 55, 38, 28,
+ 58, 20, 37, 17, 36, 8
+};
+
+Square first_1(Bitboard b) {
+
+ b ^= (b - 1);
+ uint32_t fold = int(b) ^ int(b >> 32);
+ return Square(BitTable[(fold * 0x783a9b23) >> 26]);
+}