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- #!/usr/bin/ruby
- # https://rosettacode.org/wiki/Pseudo-random_numbers/PCG32
- class PCG32(seed, incr) {
- has state
- define (
- mask32 = (2**32 - 1),
- mask64 = (2**64 - 1),
- N = 6364136223846793005,
- )
- method init {
- incr = (((incr << 1) | 1) & mask64)
- state = (((incr + seed)*N + incr) & mask64)
- }
- method next_int {
- var shift = ((((state >> 18) ^ state) >> 27) & mask32)
- var rotate = ((state >> 59) & mask32)
- state = ((state*N + incr) & mask64)
- ((shift >> rotate) | (shift << (32-rotate))) & mask32
- }
- method next_float {
- self.next_int / (mask32+1) -> float
- }
- }
- say "Seed: 42, Increment: 54, first 5 values:";
- var rng = PCG32(seed: 42, incr: 54)
- var arr = 5.of { rng.next_int }
- assert_eq(arr, [2707161783, 2068313097, 3122475824, 2211639955, 3215226955])
- say arr
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