44 lines
1.4 KiB
Rust
44 lines
1.4 KiB
Rust
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use std::fs::File;
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use std::path::Path;
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use std::io::prelude::*;
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use std::f64::consts::PI;
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const TABLE_DEPTH: usize = 8;
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const TABLE_SIZE: usize = 1 << TABLE_DEPTH;
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// Treat sin and cos as unsigned values since the sign will always be
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// positive in the range [0, pi/4).
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const SINCOS_MAX: f64 = u16::MAX as f64;
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fn main() {
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let path = Path::new("src").join("cossin_table.txt");
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let display = path.display();
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let mut file = match File::create(&path) {
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Err(why) => panic!("failed to write to {}: {}", display, why),
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Ok(file) => file,
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};
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match file.write_all("[\n".as_bytes()) {
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Err(why) => panic!("failed to write to {}: {}", display, why),
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Ok(_) => (),
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}
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let phase_delta = PI / 4. / TABLE_SIZE as f64;
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let phase_offset = phase_delta / 2.;
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for i in 0..TABLE_SIZE {
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let phase = phase_offset + phase_delta * (i as f64);
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let cos = ((phase.cos() - 0.5) * 2. * SINCOS_MAX).round() as u16;
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let sin = (phase.sin() * SINCOS_MAX).round() as u16;
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let s = format!(" ({}, {}),\n", cos, sin);
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match file.write_all(s.as_bytes()) {
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Err(why) => panic!("failed to write to {}: {}", display, why),
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Ok(_) => (),
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}
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}
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match file.write_all("]\n".as_bytes()) {
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Err(why) => panic!("failed to write to {}: {}", display, why),
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Ok(_) => (),
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}
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}
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