From 785030df963c9071a51fbc6e57e545faccc483c1 Mon Sep 17 00:00:00 2001
From: huntc <huntchr@gmail.com>
Date: Sun, 17 Oct 2021 07:51:53 +1100
Subject: [PATCH] Use types to strengthen the buffer dimensioning

---
 embassy-nrf/src/saadc.rs                 | 22 +++++++++-------------
 examples/nrf/src/bin/saadc_continuous.rs | 10 ++++------
 2 files changed, 13 insertions(+), 19 deletions(-)

diff --git a/embassy-nrf/src/saadc.rs b/embassy-nrf/src/saadc.rs
index 6e0bcc16..fd7e64e7 100644
--- a/embassy-nrf/src/saadc.rs
+++ b/embassy-nrf/src/saadc.rs
@@ -249,25 +249,21 @@ impl<'d, const N: usize> Saadc<'d, N> {
     /// should continue or stop.
     pub async fn run_task_sampler<S, const N0: usize>(
         &mut self,
-        bufs: &mut [[i16; N0]; 2],
+        bufs: &mut [[[i16; N]; N0]; 2],
         sampler: S,
     ) where
-        S: FnMut(&[i16]) -> SamplerState,
+        S: FnMut(&[[i16; N]]) -> SamplerState,
     {
-        assert!(
-            N0 % N == 0,
-            "The buffer size must be a multiple of the number of channels"
-        );
         self.run_sampler(bufs, None, sampler).await;
     }
 
     async fn run_sampler<S, const N0: usize>(
         &mut self,
-        bufs: &mut [[i16; N0]; 2],
+        bufs: &mut [[[i16; N]; N0]; 2],
         sample_rate: Option<u16>,
         mut sampler: S,
     ) where
-        S: FnMut(&[i16]) -> SamplerState,
+        S: FnMut(&[[i16; N]]) -> SamplerState,
     {
         let r = Self::regs();
 
@@ -294,7 +290,7 @@ impl<'d, const N: usize> Saadc<'d, N> {
             .write(|w| unsafe { w.ptr().bits(bufs[0].as_mut_ptr() as u32) });
         r.result
             .maxcnt
-            .write(|w| unsafe { w.maxcnt().bits(N0 as _) });
+            .write(|w| unsafe { w.maxcnt().bits((N0 * N) as _) });
 
         // Reset and enable the events
         r.events_end.reset();
@@ -323,7 +319,7 @@ impl<'d, const N: usize> Saadc<'d, N> {
                 r.events_end.reset();
                 r.intenset.write(|w| w.end().set());
 
-                if sampler(&bufs[current_buffer][0..r.result.amount.read().bits() as usize])
+                if sampler(&bufs[current_buffer][0..r.result.amount.read().bits() as usize / N])
                     == SamplerState::Sampled
                 {
                     let next_buffer = 1 - current_buffer;
@@ -358,7 +354,7 @@ impl<'d, const N: usize> Saadc<'d, N> {
 }
 
 impl<'d> Saadc<'d, 1> {
-    /// Continuous sampling on a single channel with double buffers. The sample 
+    /// Continuous sampling on a single channel with double buffers. The sample
     /// buffers generally should be a multiple of the number of channels configured.
     ///
     /// The internal clock is to be used with a sample rate expressed as a divisor of
@@ -371,11 +367,11 @@ impl<'d> Saadc<'d, 1> {
     /// should continue or stop.
     pub async fn run_timer_sampler<S, const N0: usize>(
         &mut self,
-        bufs: &mut [[i16; N0]; 2],
+        bufs: &mut [[[i16; 1]; N0]; 2],
         sample_rate: u16,
         sampler: S,
     ) where
-        S: FnMut(&[i16]) -> SamplerState,
+        S: FnMut(&[[i16; 1]]) -> SamplerState,
     {
         self.run_sampler(bufs, Some(sample_rate), sampler).await;
     }
diff --git a/examples/nrf/src/bin/saadc_continuous.rs b/examples/nrf/src/bin/saadc_continuous.rs
index d936a7d2..149b9c60 100644
--- a/examples/nrf/src/bin/saadc_continuous.rs
+++ b/examples/nrf/src/bin/saadc_continuous.rs
@@ -39,19 +39,17 @@ async fn main(_spawner: Spawner, mut p: Peripherals) {
 
     timer.start();
 
-    let mut bufs = [[0; 3 * 50]; 2]; // Each buffer of the double buffer has to be large enough for all channels.
+    let mut bufs = [[[0; 3]; 50]; 2];
 
     let mut c = 0;
     let mut a: i32 = 0;
 
     saadc
         .run_task_sampler(&mut bufs, move |buf| {
-            for (i, b) in buf.iter().enumerate() {
-                if i % 3 == 0 {
-                    a += *b as i32;
-                    c += 1;
-                }
+            for b in buf {
+                a += b[0] as i32;
             }
+            c += buf.len();
             if c > 10000 {
                 a = a / c as i32;
                 info!("channel 1: {=i32}", a);