new audio_duplex example to quickly test audio implementation

example/Makefile.inc

@@ -114,6 +114,7 @@ HXCMOD_PLAYER = \
 	nao-deceased_by_disease.c 	\
 
 EXAMPLES = 					\
+	audio_duplex 			\
 	a2dp_sink_demo			\
 	a2dp_source_demo        \
 	ancs_client_demo		\
@@ -332,6 +333,9 @@ mod_player: ${CORE_OBJ} ${COMMON_OBJ} ${HXCMOD_PLAYER_OBJ} btstack_audio.o mod_p
 sine_player: ${CORE_OBJ} ${COMMON_OBJ} btstack_audio.o sine_player.c
 	${CC} $^ ${CFLAGS} ${LDFLAGS} -o $@
 
+audio_duplex: ${CORE_OBJ} ${COMMON_OBJ} btstack_audio.o btstack_ring_buffer.o audio_duplex.c
+	${CC} $^ ${CFLAGS} ${LDFLAGS} -o $@
+
 nordic_spp_le_counter: nordic_spp_le_counter.h ${CORE_OBJ} ${COMMON_OBJ} ${ATT_OBJ} ${GATT_SERVER_OBJ} ${SM_OBJ} nordic_spp_service_server.o nordic_spp_le_counter.c
 	${CC} $(filter-out nordic_spp_le_counter.h,$^) ${CFLAGS} ${LDFLAGS} -o $@
 

example/audio_duplex.c

@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2014 BlueKitchen GmbH
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holders nor the names of
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ * 4. Any redistribution, use, or modification is done solely for
+ *    personal benefit and not for any commercial purpose or for
+ *    monetary gain.
+ *
+ * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
+ * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * Please inquire about commercial licensing options at 
+ * contact@bluekitchen-gmbh.com
+ *
+ */
+
+/*
+ * Audio Duplex: forward audio from BTstack audio source to audio sink - test for audio interface
+ *
+ */
+
+#include "btstack.h"
+
+// samplerate
+const uint32_t samplerate = 16000;
+
+// ring buffer for audio
+#define BUFFER_SAMPLES 1024
+static uint16_t              audio_buffer_storage[BUFFER_SAMPLES];
+static btstack_ring_buffer_t audio_buffer;
+
+// mono buffer
+#define MONO_BUFFER_LEN 128
+static int16_t mono_buffer[MONO_BUFFER_LEN];
+
+// playback starts after audio_buffer is half full
+static int playback_started;
+
+// sample couners
+static int count_recording;
+static int count_playback;
+
+static void audio_recording(const int16_t * pcm_buffer, uint16_t num_samples_to_write){
+    count_recording += num_samples_to_write;
+    int err = btstack_ring_buffer_write(&audio_buffer, (uint8_t *) pcm_buffer, num_samples_to_write * 2);
+    if (err){
+        printf("Failed to store %u samples\n", num_samples_to_write);
+    }
+}
+
+static void audio_playback(int16_t * pcm_buffer, uint16_t num_samples_to_write){
+    int num_samples_in_buffer = btstack_ring_buffer_bytes_available(&audio_buffer) / 2;
+    if (playback_started == 0){
+        if ( num_samples_in_buffer < (BUFFER_SAMPLES / 2)) return;
+        playback_started = 1;
+    }
+    count_playback += num_samples_to_write;
+    while (num_samples_to_write){
+        num_samples_in_buffer = btstack_ring_buffer_bytes_available(&audio_buffer) / 2;
+        int num_samples_ready = btstack_min(num_samples_in_buffer, num_samples_to_write);
+        // limit by mono_buffer
+        int num_samples_from_buffer = btstack_min(num_samples_ready, MONO_BUFFER_LEN);
+        if (!num_samples_from_buffer) break;
+        uint32_t bytes_read;
+        btstack_ring_buffer_read(&audio_buffer, (uint8_t *) mono_buffer, num_samples_from_buffer * 2, &bytes_read);
+        // duplicate samples for stereo output
+        int i;
+        for (i=0; i < num_samples_from_buffer;i++){
+            *pcm_buffer++ = mono_buffer[i];
+            *pcm_buffer++ = mono_buffer[i];
+            num_samples_to_write--;
+        }
+    }
+
+    // warn about underrun
+    if (num_samples_to_write){
+        printf("Buffer underrun - recording %u, playback %u - delta %d!\n", count_recording, count_playback, count_recording - count_playback);
+    }
+
+    // fill rest with silence
+    while (num_samples_to_write){
+        *pcm_buffer++ = 0;
+        *pcm_buffer++ = 0;
+        num_samples_to_write--;
+    }
+}
+
+int btstack_main(int argc, const char * argv[]);
+int btstack_main(int argc, const char * argv[]){
+    (void)argc;
+    (void)argv;
+
+    // check audio interface
+    const btstack_audio_sink_t * audio_sink   = btstack_audio_sink_get_instance();
+    if (!audio_sink){
+        printf("BTstack Audio Sink not setup\n");
+        return 10;
+    }
+
+    const btstack_audio_source_t * audio_source = btstack_audio_source_get_instance();
+    if (!audio_source){
+        printf("BTstack Audio Source not setup\n");
+        return 10;
+    }
+
+    // prepare audio buffer
+    btstack_ring_buffer_init(&audio_buffer, (uint8_t*) &audio_buffer_storage[0], sizeof(audio_buffer_storage));
+
+    // setup audio: mono input -> stereo output
+    audio_source->init(1, samplerate, &audio_recording);
+    audio_sink->init(2, samplerate, &audio_playback);
+
+    // start duplex
+    audio_source->start_stream();
+    audio_sink->start_stream();
+
+    return 0;
+}