162 lines
3.2 KiB
C++
162 lines
3.2 KiB
C++
/*
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Triple buffering data structure
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Example writing:
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----------------
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DMXTripleBuffer buffer;
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bytes_written = producer.write(
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buffer.fill_buffer + buffer.fill_pos, // destination pointer
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512 - buffer.fill_pos // maximum allowed
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);
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buffer.fill_pos += bytes_written;
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if buffer.fill_pos == 512 {
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buffer.on_fill_complete(); // swap buffers
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buffer.fill_pos = 0; // reset fill pos
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}
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*/
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struct InternalBuffer {
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char data[512] = {0};
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bool is_fresh = false;
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};
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class DMXTripleBuffer
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{
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public:
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DMXTripleBuffer() {
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fill_buffer = &_buffers[0];
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drain_buffer = &_buffers[1];
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off_buffer = &_buffers[2];
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}
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void on_fill_complete() {
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fill_pos = 0;
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fill_buffer->is_fresh = true;
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std::swap(fill_buffer, off_buffer);
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}
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void on_drain_complete() {
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drain_pos = 0;
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drain_buffer->is_fresh = false;
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if (off_buffer->is_fresh) {
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std::swap(drain_buffer, off_buffer);
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}
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}
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InternalBuffer *fill_buffer, *drain_buffer, *off_buffer;
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size_t fill_pos = 0, drain_pos = 0;
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private:
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InternalBuffer _buffers[3];
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};
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/*
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Some globals
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*/
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unsigned long time_since_last_sync;
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const unsigned long SYNC_TIMEOUT = 1000;
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const unsigned int FRAME_TIME = 20; // 20 ms -> 50 FPS
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DMXTripleBuffer buffer;
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bool packet_ready = true;
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unsigned long pkt_count = 0;
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/*
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main
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*/
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void setup()
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{
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Serial.begin(500000); // USB
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Serial.setRxBufferSize(512); // to fit the full DMX packet. (default is 128)
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while (!Serial)
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{
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// spin until serial is up
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}
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Serial1.begin(250000, SERIAL_8N2); // DMX
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while (!Serial1)
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{
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// spin until serial1 is up
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}
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Serial.println();
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Serial.println("Sync.");
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time_since_last_sync = millis();
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}
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void loop()
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{
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// output
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if (packet_ready)
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{
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send_dmx_header();
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packet_ready = false;
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pkt_count += 1;
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}
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size_t n = Serial1.availableForWrite();
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size_t written = Serial1.write(
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buffer.drain_buffer->data + buffer.drain_pos,
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std::min(n, 512 - buffer.drain_pos));
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buffer.drain_pos += written;
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if (buffer.drain_pos == 512)
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{
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buffer.on_drain_complete();
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packet_ready = true;
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}
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// input
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n = Serial.available();
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unsigned long now = millis();
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if (!n)
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{
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if (now - time_since_last_sync > 1000)
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{
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buffer.fill_pos = 0;
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Serial.println("Sync.");
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time_since_last_sync = now;
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}
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return;
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}
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time_since_last_sync = now;
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size_t read = Serial.read(
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buffer.fill_buffer->data + buffer.fill_pos,
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std::min(n, 512 - buffer.fill_pos));
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buffer.fill_pos += read;
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if (buffer.fill_pos == 512)
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{
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buffer.on_fill_complete();
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Serial.println("Ack.");
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}
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}
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void send_dmx_header()
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{
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Serial1.flush();
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Serial1.begin(90000, SERIAL_8N2);
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// send the break as a "slow" byte
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Serial1.write(0);
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// switch back to the original baud rate
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Serial1.flush();
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Serial1.begin(250000, SERIAL_8N2);
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Serial1.write(0); // Start-Byte
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} |