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Nk/noise generator #604

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merged 8 commits into from
Aug 25, 2022
Merged

Nk/noise generator #604

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4d94021
implement simple noise generator
nkrackow Aug 25, 2022
234d305
specify as white noise
nkrackow Aug 25, 2022
d426313
refine comments
nkrackow Aug 25, 2022
70fade2
rm comment
nkrackow Aug 25, 2022
94010a3
move over to xorshift crate
nkrackow Aug 25, 2022
c63393b
use ones as seed
nkrackow Aug 25, 2022
8c2b8b7
make short
nkrackow Aug 25, 2022
01de2b1
add comment about seed
nkrackow Aug 25, 2022
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12 changes: 12 additions & 0 deletions src/hardware/signal_generator.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ pub enum Signal {
Cosine,
Square,
Triangle,
WhiteNoise,
}

/// Basic configuration for a generated signal.
Expand Down Expand Up @@ -146,6 +147,7 @@ impl Default for Config {
pub struct SignalGenerator {
phase_accumulator: i32,
config: Config,
noise_state: i32, // state of the xorshift rng
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}

impl SignalGenerator {
Expand All @@ -160,6 +162,7 @@ impl SignalGenerator {
Self {
config,
phase_accumulator: 0,
noise_state: 1,
}
}

Expand All @@ -172,6 +175,14 @@ impl SignalGenerator {
pub fn clear_phase_accumulator(&mut self) {
self.phase_accumulator = 0;
}

// Generate a new random number using xorshift.
fn xorshift(&mut self) -> i32 {
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self.noise_state ^= self.noise_state << 13;
self.noise_state ^= self.noise_state >> 17;
self.noise_state ^= self.noise_state << 5;
self.noise_state
}
}

impl core::iter::Iterator for SignalGenerator {
Expand All @@ -197,6 +208,7 @@ impl core::iter::Iterator for SignalGenerator {
}
}
Signal::Triangle => i16::MIN as i32 + (phase >> 15).abs(),
Signal::WhiteNoise => self.xorshift() >> 16,
};

// Calculate the final output result as an i16.
Expand Down