atmel-samd: Fix AudioOut buffer playback by supporting bytes_per_sample.

Thanks to @ntoll for finding this bug!

atmel-samd/common-hal/audioio/AudioOut.c

@@ -103,6 +103,7 @@ void audioout_reset(void) {
 void audioout_background(void) {
     if (MP_STATE_VM(audioout_block_counter) != NULL &&
             active_audioout != NULL &&
+            active_audioout->second_buffer != NULL &&
             active_audioout->last_loaded_block < tc_get_count_value(MP_STATE_VM(audioout_block_counter))) {
         uint8_t* buffer;
         if (tc_get_count_value(MP_STATE_VM(audioout_block_counter)) % 2 == 1) {
@@ -132,6 +133,7 @@ void audioout_background(void) {
                     descriptor = active_audioout->second_descriptor;
                 }
                 descriptor->BTCNT.reg = length_read / active_audioout->bytes_per_sample;
+                descriptor->SRCADDR.reg = ((uint32_t) buffer) + length_read;
                 descriptor->DESCADDR.reg = 0;
             }
         }
@@ -348,7 +350,8 @@ static void shared_construct(audioio_audioout_obj_t* self, const mcu_pin_obj_t*
 void common_hal_audioio_audioout_construct_from_buffer(audioio_audioout_obj_t* self,
                                                        const mcu_pin_obj_t* pin,
                                                        uint16_t* buffer,
-                                                       uint32_t len) {
+                                                       uint32_t len,
+                                                       uint8_t bytes_per_sample) {
     self->pin = pin;
     if (pin != &pin_PA02) {
         mp_raise_ValueError("Invalid pin");
@@ -360,8 +363,8 @@ void common_hal_audioio_audioout_construct_from_buffer(audioio_audioout_obj_t* s
 
     self->buffer = (uint8_t*) buffer;
     self->second_buffer = NULL;
-    // Input len is a count. Internal len is in bytes.
-    self->len = 2 * len;
+    self->bytes_per_sample = bytes_per_sample;
+    self->len = len;
     self->frequency = 8000;
 }
 

shared-bindings/audioio/AudioOut.c

@@ -27,6 +27,7 @@
 #include <stdint.h>
 
 #include "lib/utils/context_manager_helpers.h"
+#include "py/binary.h"
 #include "py/objproperty.h"
 #include "py/runtime.h"
 #include "shared-bindings/microcontroller/Pin.h"
@@ -62,11 +63,11 @@
 //|
 //|     # Generate one period of sine wav.
 //|     length = 8000 // 440
-//|     b = array.array("H", [0] * length)
+//|     sine_wave = array.array("H", [0] * length)
 //|     for i in range(length):
-//|         b[i] = int(math.sin(math.pi * 2 * i / 18) * (2 ** 15) + 2 ** 15)
+//|         sine_wave[i] = int(math.sin(math.pi * 2 * i / 18) * (2 ** 15) + 2 ** 15)
 //|
-//|     sample = audioio.AudioOut(board.SPEAKER, sin_wave)
+//|     sample = audioio.AudioOut(board.SPEAKER, sine_wave)
 //|     sample.play(loop=True)
 //|     time.sleep(1)
 //|     sample.stop()
@@ -106,12 +107,15 @@ STATIC mp_obj_t audioio_audioout_make_new(const mp_obj_type_t *type, size_t n_ar
     if (MP_OBJ_IS_TYPE(args[1], &fatfs_type_fileio)) {
         common_hal_audioio_audioout_construct_from_file(self, pin, MP_OBJ_TO_PTR(args[1]));
     } else if (mp_get_buffer(args[1], &bufinfo, MP_BUFFER_READ)) {
-        if (bufinfo.len % 2 == 1) {
-            mp_raise_ValueError("sample_source must be an even number of bytes (two per sample)");
+        uint8_t bytes_per_sample = 1;
+        if (bufinfo.typecode == 'H') {
+            bytes_per_sample = 2;
+        } else if (bufinfo.typecode != 'B' && bufinfo.typecode != BYTEARRAY_TYPECODE) {
+            mp_raise_ValueError("sample_source buffer must be a bytearray or array of type 'H' or 'B'");
         }
-        common_hal_audioio_audioout_construct_from_buffer(self, pin, ((uint16_t*)bufinfo.buf), bufinfo.len / 2);
+        common_hal_audioio_audioout_construct_from_buffer(self, pin, ((uint16_t*)bufinfo.buf), bufinfo.len, bytes_per_sample);
     } else {
-        mp_raise_TypeError("sample_source must be a file or bytes-like object.");
+        mp_raise_TypeError("sample_source must be a file or bytes-like object");
     }
 
     return MP_OBJ_FROM_PTR(self);

shared-bindings/audioio/AudioOut.h

@@ -33,8 +33,10 @@
 
 extern const mp_obj_type_t audioio_audioout_type;
 
-void common_hal_audioio_audioout_construct_from_buffer(audioio_audioout_obj_t* self, const mcu_pin_obj_t* pin, uint16_t* buffer, uint32_t len);
-void common_hal_audioio_audioout_construct_from_file(audioio_audioout_obj_t* self, const mcu_pin_obj_t* pin, pyb_file_obj_t* file);
+void common_hal_audioio_audioout_construct_from_buffer(audioio_audioout_obj_t* self,
+    const mcu_pin_obj_t* pin, uint16_t* buffer, uint32_t len, uint8_t bytes_per_sample);
+void common_hal_audioio_audioout_construct_from_file(audioio_audioout_obj_t* self,
+    const mcu_pin_obj_t* pin, pyb_file_obj_t* file);
 
 void common_hal_audioio_audioout_deinit(audioio_audioout_obj_t* self);
 void common_hal_audioio_audioout_play(audioio_audioout_obj_t* self, bool loop);