Use ARM neon intrinsics for AudioBufferMixdown

common/JackAudioPort.cpp

@@ -28,6 +28,8 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 #include <Accelerate/Accelerate.h>
 #elif defined (__SSE__) && !defined (__sun__)
 #include <xmmintrin.h>
+#elif defined (__ARM_NEON__)
+#include <arm_neon.h>
 #endif
 
 namespace Jack
@@ -51,6 +53,13 @@ static inline void MixAudioBuffer(jack_default_audio_sample_t* mixbuffer, jack_d
         __m128 vec = _mm_add_ps(_mm_load_ps(mixbuffer), _mm_load_ps(buffer));
         _mm_store_ps(mixbuffer, vec);
 
+        mixbuffer += 4;
+        buffer += 4;
+        frames_group--;
+    #elif defined (__ARM_NEON__)
+        float32x4_t vec = vaddq_f32(vld1q_f32(mixbuffer), vld1q_f32(buffer));
+        vst1q_f32(mixbuffer, vec);
+
         mixbuffer += 4;
         buffer += 4;
         frames_group--;
@@ -116,7 +125,24 @@ static void AudioBufferMixdown(void* mixbuffer, void** src_buffers, int src_coun
     for (jack_nframes_t i = 0; i != remaining_frames; ++i) {
         target[i] = source[i];
     }
+#elif defined (__ARM_NEON__)
+    jack_nframes_t frames_group = nframes / 4;
+    jack_nframes_t remaining_frames = nframes % 4;
+
+    jack_default_audio_sample_t* source = static_cast<jack_default_audio_sample_t*>(src_buffers[0]);
+    jack_default_audio_sample_t* target = static_cast<jack_default_audio_sample_t*>(mixbuffer);
+
+    while (frames_group > 0) {
+        float32x4_t vec = vld1q_f32(source);
+        vst1q_f32(target, vec);
+        source += 4;
+        target += 4;
+        --frames_group;
+    }
 
+    for (jack_nframes_t i = 0; i != remaining_frames; ++i) {
+        target[i] = source[i];
+    }
 #else
     memcpy(mixbuffer, src_buffers[0], nframes * sizeof(jack_default_audio_sample_t));
 #endif