Feels like hell in here

ctru-rs/examples/audio_filters.rs

@@ -5,7 +5,7 @@ use std::f32::consts::PI;
 use ctru::linear::LinearAllocator;
 use ctru::prelude::*;
 use ctru::services::ndsp::{
-    wave::{WaveBuffer, WaveInfo},
+    wave::{WaveBuffer, WaveInfo, WaveStatus},
     AudioFormat, InterpolationType, Ndsp, OutputMode,
 };
 
@@ -19,15 +19,20 @@ const NOTEFREQ: [u32; 7] = [220, 440, 880, 1760, 3520, 7040, 14080];
 
 // audioBuffer is stereo PCM16
 fn fill_buffer(audioData: &mut [u8], frequency: u32) {
-	let formatted_data: Vec<i16> = audioData.chunks_exact(2).map(|s| i16::from_le_bytes(s.try_into().unwrap())).collect();
+	let formatted_data = audioData.chunks_exact_mut(2);
 
-    for i in 0..audioData.len() {
+	let mut i = 0;
-        // This is a simple sine wave, with a frequency of `frequency` Hz, and an amplitude 30% of maximum.
+	for chunk in formatted_data {
-        let sample: i16 = (0.3 * i16::MAX as f32 * (frequency as f32 * (2f32 * PI) * (i / SAMPLE_RATE as usize) as f32).sin()) as i16;
+		// This is a simple sine wave, with a frequency of `frequency` Hz, and an amplitude 30% of maximum.
+		let sample: i16 = (0.3 * i16::MAX as f32 * (frequency as f32 * (2f32 * PI) * (i as f32 / SAMPLE_RATE as f32)).sin()) as i16;
 
-        // Stereo samples are interleaved: left and right channels.
+		// This operation is safe, since we are writing to a slice of exactly 16 bits
-        formatted_data[i] = (sample << 16) | (sample & 0xffff);
+		let chunk_ptr: &mut i16 = unsafe { std::mem::transmute(chunk.as_mut_ptr()) };
-    }
+		// Stereo samples are interleaved: left and right channels.
+		*chunk_ptr = (sample << 16) | (sample & 0xffff);
+
+		i += 1;
+	}
 }
 
 fn main() {
@@ -39,19 +44,16 @@ fn main() {
 
     println!("libctru filtered streamed audio\n");
 
-    let audioBuffer = Box::new_in(
+    let mut audioBuffer = Box::new_in(
         [0u8; AUDIO_WAVE_LENGTH],
         LinearAllocator,
     );
-    fill_buffer(&mut audioBuffer, NOTEFREQ[4]);
+    fill_buffer(&mut audioBuffer[..], NOTEFREQ[4]);
-
-    let audioBuffer1 =
-        WaveBuffer::new(audioBuffer, AudioFormat::PCM16Stereo).expect("Couldn't sync DSP cache");
-    let audioBuffer2 = audioBuffer1.clone();
 
-    let fillBlock = false;
+	let mut audioBuffer1 = WaveBuffer::new(audioBuffer, AudioFormat::PCM16Stereo).expect("Couldn't sync DSP cache");
+    let mut audioBuffer2 = audioBuffer1.clone();
 
-    let ndsp = Ndsp::init().expect("Couldn't obtain NDSP controller");
+    let mut ndsp = Ndsp::init().expect("Couldn't obtain NDSP controller");
 
     // This line isn't needed since the default NDSP configuration already sets the output mode to `Stereo`
     ndsp.set_output_mode(OutputMode::Stereo);
@@ -63,12 +65,12 @@ fn main() {
 
     // Output at 100% on the first pair of left and right channels.
 
-    let mix = [0f32; 12];
+    let mut mix: [f32; 12] = [0f32; 12];
     mix[0] = 1.0;
     mix[1] = 1.0;
     channel_zero.set_mix(&mix);
 
-    let note: usize = 4;
+    let mut note: usize = 4;
 
     // Filters
 
@@ -81,24 +83,23 @@ fn main() {
         "Peaking",
     ];
 
-    let filter = 0;
+    let mut filter = 0;
 
     // We set up two wave buffers and alternate between the two,
     // effectively streaming an infinitely long sine wave.
 
-    let mut buf1 = WaveInfo::new(&mut audioBuffer1, false);
+    let mut bufs: [WaveInfo; 2] = [ WaveInfo::new(&mut audioBuffer1, false), WaveInfo::new(&mut audioBuffer2, false)];
-    let mut buf2 = WaveInfo::new(&mut audioBuffer2, false);
 
-    unsafe {
+    channel_zero.queue_wave(&mut bufs[0]);
-        channel_zero.queue_wave(&mut buf1);
+	channel_zero.queue_wave(&mut bufs[1]);
-        channel_zero.queue_wave(&mut buf2);
-    };
 
     println!("Press up/down to change tone frequency\n");
     println!("Press left/right to change filter\n");
     println!("\x1b[6;1Hnote = {} Hz        ", NOTEFREQ[note]);
     println!("\x1b[7;1Hfilter = {}         ", filter_names[filter]);
 
+	let mut fillBlock = false;
+
     while apt.main_loop() {
         hid.scan_input();
         let keys_down = hid.keys_down();
@@ -124,7 +125,7 @@ fn main() {
         // Check for upper limit
         note = std::cmp::max(note, NOTEFREQ.len() - 1);
 
-        let update_params = false;
+        let mut update_params = false;
         if keys_down.contains(KeyPad::KEY_LEFT) {
             filter = filter.saturating_sub(1);
             if filter < 0 {
@@ -151,15 +152,12 @@ fn main() {
             }
         }
 
-        if waveBuf[fillBlock].status == NDSP_WBUF_DONE {
+		let status = bufs[fillBlock as usize].get_status();
-            if fillBlock {
+        if let WaveStatus::Done = status {
-                fill_buffer(buf1.get_mut_wavebuffer().get_mut_data(), NOTEFREQ[note]);
+			fillBlock = !fillBlock;
-                channel_zero.queue_wave(&mut buf1);
+
-            } else {
+            fill_buffer(bufs[fillBlock as usize].get_mut_wavebuffer().get_mut_data(), NOTEFREQ[note]);
-                fill_buffer(buf2.get_mut_wavebuffer().get_mut_data(), NOTEFREQ[note]);
+            channel_zero.queue_wave(&mut bufs[fillBlock as usize]);
-                channel_zero.queue_wave(&mut buf2);
-            }
-            fillBlock = !fillBlock;
         }
 
         // Flush and swap framebuffers