uint64_t a, b, c, d;
- uint64_t rotate(uint64_t x, uint64_t k) const {
+ uint64_t rotate_L(uint64_t x, unsigned k) const {
return (x << k) | (x >> (64 - k));
}
uint64_t rand64() {
- const uint64_t e = a - rotate(b, 7);
- a = b ^ rotate(c, 13);
- b = c + rotate(d, 37);
+ const uint64_t e = a - rotate_L(b, 7);
+ a = b ^ rotate_L(c, 13);
+ b = c + rotate_L(d, 37);
c = d + e;
return d = e + a;
}
}
template<typename T> T rand() { return T(rand64()); }
+
+ /// Special generator used to fast init magic numbers. Here the
+ /// trick is to rotate the randoms of a given quantity 's' known
+ /// to be optimal to quickly find a good magic candidate.
+ template<typename T> T magic_rand(int s) {
+ return rotate_L(rotate_L(rand<T>(), (s >> 0) & 0x3F) & rand<T>()
+ , (s >> 6) & 0x3F) & rand<T>();
+ }
};
#endif // #ifndef RKISS_H_INCLUDED