82 lines
2.4 KiB
Rust
82 lines
2.4 KiB
Rust
use wasm_bindgen::prelude::*;
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use web_sys::console;
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// When the `wee_alloc` feature is enabled, this uses `wee_alloc` as the global
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// allocator.
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//
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// If you don't want to use `wee_alloc`, you can safely delete this.
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#[cfg(feature = "wee_alloc")]
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#[global_allocator]
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static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
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// This is like the `main` function, except for JavaScript.
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#[wasm_bindgen(start)]
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pub fn main_js() -> Result<(), JsValue> {
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// This provides better error messages in debug mode.
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// It's disabled in release mode so it doesn't bloat up the file size.
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#[cfg(debug_assertions)]
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console_error_panic_hook::set_once();
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Ok(())
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}
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use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
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use cpal::Stream;
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#[wasm_bindgen]
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pub struct Handle(Stream);
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#[wasm_bindgen]
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pub fn beep() -> Handle {
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let host = cpal::default_host();
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let device = host
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.default_output_device()
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.expect("failed to find a default output device");
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let config = device.default_output_config().unwrap();
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Handle(match config.sample_format() {
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cpal::SampleFormat::F32 => run::<f32>(&device, &config.into()),
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cpal::SampleFormat::I16 => run::<i16>(&device, &config.into()),
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cpal::SampleFormat::U16 => run::<u16>(&device, &config.into()),
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})
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}
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fn run<T>(device: &cpal::Device, config: &cpal::StreamConfig) -> Stream
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where
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T: cpal::Sample,
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{
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let sample_rate = config.sample_rate.0 as f32;
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let channels = config.channels as usize;
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// Produce a sinusoid of maximum amplitude.
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let mut sample_clock = 0f32;
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let mut next_value = move || {
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sample_clock = (sample_clock + 1.0) % sample_rate;
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(sample_clock * 440.0 * 2.0 * 3.141592 / sample_rate).sin()
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};
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let err_fn = |err| console::error_1(&format!("an error occurred on stream: {}", err).into());
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let stream = device
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.build_output_stream(
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config,
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move |data: &mut [T]| write_data(data, channels, &mut next_value),
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err_fn,
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)
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.unwrap();
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stream.play().unwrap();
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stream
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}
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fn write_data<T>(output: &mut [T], channels: usize, next_sample: &mut dyn FnMut() -> f32)
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where
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T: cpal::Sample,
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{
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for frame in output.chunks_mut(channels) {
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let value: T = cpal::Sample::from::<f32>(&next_sample());
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for sample in frame.iter_mut() {
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*sample = value;
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}
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}
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}
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