max / audiofiles

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1	//! Shared TPDF dither PRNG for audio encoders.
2
3	/// Minimal xorshift64 PRNG for dither — no external dependency needed.
4	pub(crate) struct SimpleRng {
5	state: u64,
6	}
7
8	impl SimpleRng {
9	pub(crate) fn new(seed: u64) -> Self {
10	// xorshift64 is degenerate with state 0 (outputs 0 forever)
11	Self { state: if seed == 0 { 0x5A5A_5A5A_5A5A_5A5A } else { seed } }
12	}
13
14	fn next_u32(&mut self) -> u32 {
15	// xorshift64
16	self.state ^= self.state << 13;
17	self.state ^= self.state >> 7;
18	self.state ^= self.state << 17;
19	(self.state & 0xFFFF_FFFF) as u32
20	}
21
22	pub(crate) fn next_f32(&mut self) -> f32 {
23	self.next_u32() as f32 / u32::MAX as f32
24	}
25	}
26