// Keep variables always together
struct S { uint64_t a, b, c, d; } s;
- // Return 64 bit unsigned integer in between [0,2^64-1]
+ uint64_t rot(uint64_t x, uint64_t k) const {
+ return (x << k) | (x >> (64 - k));
+ }
+
+ // Return 64 bit unsigned integer in between [0, 2^64 - 1]
uint64_t rand64() {
- const uint64_t
- e = s.a - ((s.b << 7) | (s.b >> 57));
- s.a = s.b ^ ((s.c << 13) | (s.c >> 51));
- s.b = s.c + ((s.d << 37) | (s.d >> 27));
- s.c = s.d + e;
- return s.d = e + s.a;
+ const uint64_t
+ e = s.a - rot(s.b, 7);
+ s.a = s.b ^ rot(s.c, 13);
+ s.b = s.c + rot(s.d, 37);
+ s.c = s.d + e;
+ return s.d = e + s.a;
}
// Init seed and scramble a few rounds
void raninit() {
- s.a = 0xf1ea5eed;
- s.b = s.c = s.d = 0xd4e12c77;
- for (int i = 0; i < 73; i++)
- rand64();
+ s.a = 0xf1ea5eed;
+ s.b = s.c = s.d = 0xd4e12c77;
+ for (int i = 0; i < 73; i++)
+ rand64();
}
public: