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74 lines
2.6 KiB
74 lines
2.6 KiB
/*
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* Copyright (C) 2011,2014 by Jonathan Naylor G4KLX
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef OutputQueue_H
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#define OutputQueue_H
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#include "RingBuffer.h"
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#include "HeaderData.h"
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/*
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* FIFO queue for outbound D-Star frames with type/length/data encoding.
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*
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* Each frame is stored in the ring buffer as a 2-byte header followed by the
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* frame payload:
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* byte 0: end flag — 1 if this is the last frame of the transmission, else 0
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* byte 1: payload length in bytes
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* [payload bytes]
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*
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* A separate m_header pointer holds the pending CHeaderData for the next
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* transmission. Playback is gated by a threshold: neither the header nor data
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* frames are released to the transmitter until m_count >= m_threshold, which
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* ensures there is a small buffer of frames pre-queued before TX begins (to
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* absorb jitter in frame delivery from the network). Receiving an end-of-
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* stream frame immediately raises the count to the threshold so the remaining
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* frames drain promptly.
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*/
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class COutputQueue {
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public:
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COutputQueue(unsigned int space, unsigned int threshold);
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~COutputQueue();
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// Takes ownership of header; replaces any previously pending header.
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void setHeader(CHeaderData* header);
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// Returns the pending header and relinquishes ownership (caller must delete).
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CHeaderData* getHeader();
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unsigned int getData(unsigned char* data, unsigned int length, bool& end);
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unsigned int addData(const unsigned char* data, unsigned int length, bool end);
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// True when a header is queued and the pre-fill threshold has been reached.
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bool headerReady() const;
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// True when data frames are queued and no header is pending (mid-stream).
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bool dataReady() const;
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bool isEmpty();
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void reset();
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void setThreshold(unsigned int threshold);
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private:
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CRingBuffer<unsigned char> m_data;
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unsigned int m_threshold;
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CHeaderData* m_header;
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unsigned int m_count; // Frames added since the last header; triggers playback start.
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};
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#endif
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