Working with probably near max speed from CPU feeding TX. Need DMA

src/main.rs

@@ -117,10 +117,17 @@ fn main() -> ! {
     // let pgroup = pgroup.add_pin(pins.gpio12.into_push_pull_output());
     // let mut pgroup = pgroup.add_pin(pins.gpio13.into_push_pull_output());
 
-    let mut processed_wave_table = [0u32; 256];
+    let mut processed_wave_table = [0u32; 64];
 
-    for (i, w) in WAVE_TABLE.iter().enumerate() {
-        processed_wave_table[i] = ((*w as i32) + 127) as u32;
+    for i in 0..256 {
+        let mut packed = 0u32;
+        for j in 0..4 {
+            let val = (WAVE_TABLE[i] as i32) + 127;
+            let val = val as u32;
+
+            packed |= val.rotate_right(8 * j as u32);
+        }
+        processed_wave_table[i / 4] = packed;
     }
 
     println!("alive");
@@ -129,19 +136,9 @@ fn main() -> ! {
     // PIO runs in background, independently from CPU
     loop {
         while !tx.is_full() {
-            let mut out = 0;
-
-            for i in 0..4 {
-                let val = processed_wave_table[tick % 256];
-
-                out |= val.rotate_right(8 * i);
-                // out |= ((tick % 256) as u32).rotate_right(8 * i);
+            let out = processed_wave_table[tick % 64];
             tick = tick.wrapping_add(1);
-                // println!("{}", val);
-            }
             tx.write(out);
         }
-
-        // pgroup.set_u32(out.rotate_left(6));
     }
 }