From f9a0e09cf9e44821d15a9ba5263f12de522d9041 Mon Sep 17 00:00:00 2001
From: patrick-radius <p.radius@true.nl>
Date: Sat, 31 Dec 2016 12:53:45 +0100
Subject: [PATCH 1/2] Added mixer

---
 AudioMixer4_F32.cpp | 30 ++++++++++++++++++++++++++++++
 AudioMixer4_F32.h   | 28 ++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 AudioMixer4_F32.cpp
 create mode 100644 AudioMixer4_F32.h

diff --git a/AudioMixer4_F32.cpp b/AudioMixer4_F32.cpp
new file mode 100644
index 0000000..40e9757
--- /dev/null
+++ b/AudioMixer4_F32.cpp
@@ -0,0 +1,30 @@
+#include "AudioMixer4_F32.h"
+
+void AudioMixer4_F32::update(void) {
+  audio_block_f32_t *in, *out=NULL;
+
+  out = receiveWritable_f32(0);
+  if (!out) return;
+
+  arm_scale_f32(out->data, multiplier[0], out->data, AUDIO_BLOCK_SAMPLES);
+
+  for (int channel=1; channel < 4; channel++) {
+    in = receiveReadOnly_f32(channel);
+    if (!in) {
+      continue;
+    }
+
+    audio_block_f32_t *tmp = allocate_f32();
+
+    arm_scale_f32(in->data, multiplier[channel], tmp->data, AUDIO_BLOCK_SAMPLES);
+    arm_add_f32(out->data, tmp->data, out->data, AUDIO_BLOCK_SAMPLES);
+
+    release(tmp);
+    release(in);
+  }
+
+  if (out) {
+    transmit(out);
+    release(out);
+  }
+}
diff --git a/AudioMixer4_F32.h b/AudioMixer4_F32.h
new file mode 100644
index 0000000..524087a
--- /dev/null
+++ b/AudioMixer4_F32.h
@@ -0,0 +1,28 @@
+#ifndef AUDIOMIXER4F32_H
+#define AUDIOMIXER4F32_H
+
+#include <arm_math.h> 
+#include <AudioStream_F32.h>
+
+
+class AudioMixer4_F32 : public AudioStream_F32 {
+public:
+    AudioMixer4_F32() : AudioStream_F32(4, inputQueueArray) {
+      for (int i=0; i<4; i++) multiplier[i] = 0.5;
+    }
+
+    virtual void update(void);
+
+    void gain(unsigned int channel, float gain) {
+      if (channel >= 4) return;
+      if (gain > 127.0f) gain = 127.0f;
+      else if (gain < 0.0f) gain = 0.0f;
+      multiplier[channel] = gain;
+    }
+
+  private:
+    audio_block_f32_t *inputQueueArray[4];
+    float multiplier[4];
+};
+
+#endif
\ No newline at end of file

From dac6bf4ad4763cd7f4031aea5b9ed6777522004b Mon Sep 17 00:00:00 2001
From: patrick-radius <p.radius@true.nl>
Date: Mon, 2 Jan 2017 10:32:05 +0100
Subject: [PATCH 2/2] Added license block and remove arbitrary limits. Added
 array lowerbound check

---
 AudioMixer4_F32.h | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/AudioMixer4_F32.h b/AudioMixer4_F32.h
index 524087a..0b7af83 100644
--- a/AudioMixer4_F32.h
+++ b/AudioMixer4_F32.h
@@ -1,22 +1,31 @@
+/*
+ * AudioMixer4
+ * 
+ * Created: Patrick Radius, December 2016
+ * Purpose: Mix up to 4 audio channels with individual gain controls.
+ * Assumes floating-point data.
+ *          
+ * This processes a single stream fo audio data (ie, it is mono)       
+ *          
+ * MIT License.  use at your own risk.
+*/
+
 #ifndef AUDIOMIXER4F32_H
 #define AUDIOMIXER4F32_H
 
 #include <arm_math.h> 
 #include <AudioStream_F32.h>
 
-
 class AudioMixer4_F32 : public AudioStream_F32 {
 public:
     AudioMixer4_F32() : AudioStream_F32(4, inputQueueArray) {
-      for (int i=0; i<4; i++) multiplier[i] = 0.5;
+      for (int i=0; i<4; i++) multiplier[i] = 1.0;
     }
 
     virtual void update(void);
 
     void gain(unsigned int channel, float gain) {
-      if (channel >= 4) return;
-      if (gain > 127.0f) gain = 127.0f;
-      else if (gain < 0.0f) gain = 0.0f;
+      if (channel >= 4 || channel < 0) return;
       multiplier[channel] = gain;
     }