fork from github

src/AudioOutputI2SNoDAC.h

@@ -0,0 +1,43 @@
+/*
+  AudioOutputI2SNoDAC
+  Audio player using SW delta-sigma to generate "analog" on I2S data
+  
+  Copyright (C) 2017  Earle F. Philhower, III
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include "AudioOutputI2S.h"
+
+class AudioOutputI2SNoDAC : public AudioOutputI2S
+{
+  public:
+    AudioOutputI2SNoDAC(int port = 0);
+    virtual ~AudioOutputI2SNoDAC() override;
+    virtual bool begin() override { return AudioOutputI2S::begin(false); }
+    virtual bool ConsumeSample(int16_t sample[2]) override;
+    
+    bool SetOversampling(int os);
+    
+  protected:
+    virtual int AdjustI2SRate(int hz) override { return hz * oversample/32; }
+    uint8_t oversample;
+    void DeltaSigma(int16_t sample[2], uint32_t dsBuff[4]);
+    typedef int32_t fixed24p8_t;
+    enum {fixedPosValue=0x007fff00}; /* 24.8 of max-signed-int */
+    fixed24p8_t lastSamp; // Last sample value
+    fixed24p8_t cumErr;   // Running cumulative error since time began
+};