pieplined read

src/lib.rs

@@ -40,4 +40,39 @@ impl<T: SpiBus> ADIS16475<T> {
         self.write_u8(addr+1, data[1]).await?; // higher byte
         Ok(())
     }
+
+    /// efficiently reads multiple u32s by pipelining the spi bus
+    async fn read_u32_multi<const N: usize>(&mut self, addr: [u8;N]) -> Result<[u32;N], T::Error> {
+        let read = |addr :u8| [(addr & 0x7F), 0];
+
+        // first address
+        self.bus.write(&read(addr[0])).await?;
+
+        let mut responses = [0; N];
+
+        let mut partial: [u16;2] = [0;2];
+        let mut partial_idx = 0;
+
+        let mut buf: [u8;2] = [0;2];
+
+        for i in 1..(addr.len()*2) {
+            let addr = addr[i/2] + (i as u8 % 2) * 2;
+            self.bus.transfer(&mut buf, &read(addr)).await?;
+
+            partial[partial_idx] = u16::from_be_bytes(buf);
+            partial_idx += 1;
+
+            if partial_idx == 2 {
+                partial_idx = 0;
+
+                responses[i/2 -1] = (partial[1] as u32) << 16 + partial[0] as u32;
+            }
+        }
+
+        // last address
+        self.bus.read(&mut buf).await.unwrap();
+        responses[addr.len() - 1] = partial[0] as u32 + (u16::from_be_bytes(buf) as u32) << 16;
+
+        Ok(responses)
+    }
 }