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libraries/NeoPixelBus_by_Makuna/src/internal/DotStarAvrMethod.h

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+/*-------------------------------------------------------------------------
+NeoPixel library helper functions for DotStars on AVR (APA102).
+
+Written by Michael C. Miller.
+
+I invest time and resources providing this open source code,
+please support me by dontating (see https://github.com/Makuna/NeoPixelBus)
+
+-------------------------------------------------------------------------
+This file is part of the Makuna/NeoPixelBus library.
+
+NeoPixelBus is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as
+published by the Free Software Foundation, either version 3 of
+the License, or (at your option) any later version.
+
+NeoPixelBus 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with NeoPixel.  If not, see
+<http://www.gnu.org/licenses/>.
+-------------------------------------------------------------------------*/
+
+#pragma once
+
+// must also check for arm due to Teensy incorrectly having ARDUINO_ARCH_AVR set
+#if defined(ARDUINO_ARCH_AVR) && !defined(__arm__)
+
+class DotStarAvrMethod
+{
+public:
+    DotStarAvrMethod(uint8_t pinClock, uint8_t pinData, uint16_t pixelCount, size_t elementSize) :
+        _pinClock(pinClock),
+        _pinData(pinData),
+        _sizePixels(pixelCount * elementSize)
+    {
+        pinMode(pinClock, OUTPUT);
+        pinMode(pinData, OUTPUT);
+
+        _pixels = (uint8_t*)malloc(_sizePixels);
+        memset(_pixels, 0, _sizePixels);
+
+        _portClock = portOutputRegister(digitalPinToPort(_pinClock));
+        _pinMaskClock = digitalPinToBitMask(_pinClock);
+        _portData = portOutputRegister(digitalPinToPort(_pinData));
+        _pinMaskData = digitalPinToBitMask(_pinData);
+    }
+
+    ~DotStarAvrMethod()
+    {
+        pinMode(_pinClock, INPUT);
+        pinMode(_pinData, INPUT);
+
+        free(_pixels);
+    }
+
+    bool IsReadyToUpdate() const
+    {
+        return true; // dot stars don't have a required delay
+    }
+
+    void Initialize()
+    {
+        digitalWrite(_pinClock, LOW);
+        digitalWrite(_pinData, LOW);
+    }
+
+    void Update()
+    {
+        // start frame
+        for (int startFrameByte = 0; startFrameByte < 4; startFrameByte++)
+        {
+            _transmitByte(0x00);
+        }
+        
+        // data
+        uint8_t* data = _pixels;
+        const uint8_t* endData = _pixels + _sizePixels;
+        while (data < endData)
+        {
+            _transmitByte(*data++);
+        }
+        
+        // end frame 
+        // one bit for every two pixels with no less than 1 byte
+        const uint16_t countEndFrameBytes = ((_sizePixels / 4) + 15) / 16;
+        for (uint16_t endFrameByte = 0; endFrameByte < countEndFrameBytes; endFrameByte++)
+        {
+           _transmitByte(0xff);
+        }
+
+        // set clock and data back to low between updates
+        digitalWrite(_pinData, LOW);
+    }
+
+    uint8_t* getPixels() const
+    {
+        return _pixels;
+    };
+
+    size_t getPixelsSize() const
+    {
+        return _sizePixels;
+    };
+
+private:
+    const uint8_t  _pinClock;     // output pin number for clock line
+    const uint8_t  _pinData;      // output pin number for data line
+    const size_t   _sizePixels;   // Size of '_pixels' buffer below
+
+    uint8_t* _pixels;       // Holds LED color values
+
+    volatile uint8_t* _portData;  // Output PORT register
+    uint8_t  _pinMaskData;        // Output PORT bitmask
+    volatile uint8_t* _portClock;  // Output PORT register
+    uint8_t  _pinMaskClock;        // Output PORT bitmask
+
+    void _transmitByte(uint8_t data)
+    {
+        for (int bit = 7; bit >= 0; bit--)
+        {
+            // set data bit on pin
+            // digitalWrite(_pinData, (data & 0x80) == 0x80 ? HIGH : LOW);
+            if (data & 0x80)
+            {
+                *_portData |= _pinMaskData;
+            }
+            else
+            {
+                *_portData &= ~_pinMaskData;
+            }
+            
+
+            // set clock high as data is ready
+            // digitalWrite(_pinClock, HIGH);
+            *_portClock |= _pinMaskClock;
+
+            // done between clock toggle to give a little time
+            data <<= 1;
+
+            // set clock low as data pin is changed
+            // digitalWrite(_pinClock, LOW);
+            *_portClock &= ~_pinMaskClock;
+        }
+    }
+};
+
+typedef DotStarAvrMethod DotStarMethod;
+
+#endif