55 lines
1.2 KiB
Rust
55 lines
1.2 KiB
Rust
use std::cell::Cell;
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pub struct RNG(Cell<(u64, u64, u64, u64)>);
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#[inline]
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fn rol64(x: u64, shift: u64) -> u64
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{
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if shift == 0 || shift == 64 {
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x
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} else {
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(x << shift) | (x >> (64 - shift))
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}
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}
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impl RNG {
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pub fn new(seed: i32) -> Self {
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Self(Cell::new((seed as u64,
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(seed as u64).wrapping_add(0x9e3779b97f4a7c15),
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(seed as u64).wrapping_add(0xbdd3944475a73cf0),
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0
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)))
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}
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pub fn next_u64(&self) -> i32 {
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let mut state = self.0.get();
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let result = rol64(state.1.wrapping_mul(5), 7).wrapping_mul(9);
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let t = state.1 << 17;
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state.2 ^= state.0;
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state.3 ^= state.1;
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state.1 ^= state.2;
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state.0 ^= state.3;
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state.2 ^= t;
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state.3 = rol64(state.3, 45);
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self.0.replace(state);
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result as i32
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}
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#[inline]
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pub fn next(&self) -> i32 {
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self.next_u64() as i32
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}
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#[inline]
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pub fn next_u32(&self) -> u32 {
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self.next_u64() as u32
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}
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pub fn range(&self, range: std::ops::Range<i32>) -> i32 {
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range.start.wrapping_add((self.next_u32() >> 2) as i32 % (range.end.wrapping_sub(range.start).wrapping_add(1)))
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}
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}
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