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505 lines
14 KiB
C
505 lines
14 KiB
C
/**
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******************************************************************************
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* @addtogroup OpenPilotSystem OpenPilot System
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* @{
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* @addtogroup OpenPilotLibraries OpenPilot System Libraries
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* @{
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*
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* @file packet_handler.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
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* @brief A packet handler for handeling radio packet transmission.
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* @see The GNU Public License (GPL) Version 3
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*
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*****************************************************************************/
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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 3 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, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "openpilot.h"
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#include "packet_handler.h"
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#include "aes.h"
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#include "ecc.h"
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extern char *debug_msg;
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// Private types and constants
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typedef struct {
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PacketHandlerConfig cfg;
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PHPacket *tx_packets;
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uint8_t tx_win_start;
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uint8_t tx_win_end;
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PHPacket *rx_packets;
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uint8_t rx_win_start;
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uint8_t rx_win_end;
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uint16_t tx_seq_id;
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PHOutputStream stream;
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xSemaphoreHandle lock;
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PHOutputStream output_stream;
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PHDataHandler data_handler;
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PHStatusHandler status_handler;
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PHPPMHandler ppm_handler;
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} PHPacketData, *PHPacketDataHandle;
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// Private functions
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static uint8_t PHLSendAck(PHPacketDataHandle data, PHPacketHandle p);
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static uint8_t PHLSendNAck(PHPacketDataHandle data, PHPacketHandle p);
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static uint8_t PHLTransmitPacket(PHPacketDataHandle data, PHPacketHandle p);
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/**
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* Initialize the Packet Handler library
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* \param[in] txWinSize The transmission window size (number of tx packet buffers).
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* \param[in] streme A callback function for transmitting the packet.
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* \param[in] id The source ID of transmitter.
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* \return PHInstHandle The Pachet Handler instance data.
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* \return 0 Failure
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*/
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PHInstHandle PHInitialize(PacketHandlerConfig *cfg)
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{
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// Allocate the primary structure
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PHPacketDataHandle data = pvPortMalloc(sizeof(PHPacketData));
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if (!data)
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return 0;
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data->cfg = *cfg;
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data->tx_seq_id = 0;
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// Allocate the packet windows
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data->tx_packets = pvPortMalloc(sizeof(PHPacket) * data->cfg.winSize);
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data->rx_packets = pvPortMalloc(sizeof(PHPacket) * data->cfg.winSize);
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// Initialize the windows
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data->tx_win_start = data->tx_win_end = 0;
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data->rx_win_start = data->rx_win_end = 0;
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for (uint8_t i = 0; i < data->cfg.winSize; ++i)
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{
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data->tx_packets[i].header.type = PACKET_TYPE_NONE;
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data->rx_packets[i].header.type = PACKET_TYPE_NONE;
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}
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// Create the lock
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data->lock = xSemaphoreCreateRecursiveMutex();
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// Initialize the ECC library.
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initialize_ecc();
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// Return the structure.
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return (PHInstHandle)data;
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}
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/**
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* Register an output stream handler
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* \param[in] h The packet handler instance data pointer.
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* \param[in] f The output stream handler function
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*/
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void PHRegisterOutputStream(PHInstHandle h, PHOutputStream f)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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data->output_stream = f;
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}
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/**
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* Register a data handler
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* \param[in] h The packet handler instance data pointer.
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* \param[in] f The data handler function
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*/
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void PHRegisterDataHandler(PHInstHandle h, PHDataHandler f)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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data->data_handler = f;
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}
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/**
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* Register a PPM packet handler
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* \param[in] h The packet handler instance data pointer.
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* \param[in] f The PPM handler function
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*/
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void PHRegisterStatusHandler(PHInstHandle h, PHStatusHandler f)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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data->status_handler = f;
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}
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/**
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* Register a PPM packet handler
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* \param[in] h The packet handler instance data pointer.
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* \param[in] f The PPM handler function
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*/
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void PHRegisterPPMHandler(PHInstHandle h, PHPPMHandler f)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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data->ppm_handler = f;
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}
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/**
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* Get a packet out of the transmit buffer.
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* \param[in] h The packet handler instance data pointer.
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* \param[in] dest_id The destination ID of this connection
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* \return PHPacketHandle A pointer to the packet buffer.
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* \return 0 No packets buffers avaiable in the transmit window.
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*/
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uint32_t PHConnect(PHInstHandle h, uint32_t dest_id)
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{
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return 1;
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}
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/**
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* Get a packet out of the transmit buffer.
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* \param[in] h The packet handler instance data pointer.
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* \return PHPacketHandle A pointer to the packet buffer.
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* \return 0 No packets buffers avaiable in the transmit window.
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*/
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PHPacketHandle PHGetTXPacket(PHInstHandle h)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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// Lock
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xSemaphoreTakeRecursive(data->lock, portMAX_DELAY);
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// Find a free packet.
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PHPacketHandle p = NULL;
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for (uint8_t i = 0; i < data->cfg.winSize; ++i)
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if (data->tx_packets[i].header.type == PACKET_TYPE_NONE)
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{
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p = data->tx_packets + i;
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break;
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}
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// Release lock
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xSemaphoreGiveRecursive(data->lock);
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// Return a pointer to the packet at the end of the TX window.
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return p;
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}
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/**
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* Release a packet from the transmit packet buffer window.
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* \param[in] h The packet handler instance data pointer.
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* \param[in] p A pointer to the packet buffer.
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* \return Nothing
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*/
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void PHReleaseTXPacket(PHInstHandle h, PHPacketHandle p)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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// Lock
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xSemaphoreTakeRecursive(data->lock, portMAX_DELAY);
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// Change the packet type so we know this packet is unused.
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p->header.type = PACKET_TYPE_NONE;
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// If this packet is at the start of the window, increment the start index.
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while ((data->tx_win_start != data->tx_win_end) &&
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(data->tx_packets[data->tx_win_start].header.type == PACKET_TYPE_NONE))
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data->tx_win_start = (data->tx_win_start + 1) % data->cfg.winSize;
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// Release lock
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xSemaphoreGiveRecursive(data->lock);
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}
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/**
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* Get a packet out of the receive buffer.
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* \param[in] h The packet handler instance data pointer.
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* \return PHPacketHandle A pointer to the packet buffer.
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* \return 0 No packets buffers avaiable in the transmit window.
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*/
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PHPacketHandle PHGetRXPacket(PHInstHandle h)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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// Lock
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xSemaphoreTakeRecursive(data->lock, portMAX_DELAY);
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// Find a free packet.
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PHPacketHandle p = NULL;
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for (uint8_t i = 0; i < data->cfg.winSize; ++i)
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if (data->rx_packets[i].header.type == PACKET_TYPE_NONE)
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{
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p = data->rx_packets + i;
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break;
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}
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// Release lock
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xSemaphoreGiveRecursive(data->lock);
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// Return a pointer to the packet at the end of the TX window.
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return p;
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}
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/**
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* Release a packet from the receive packet buffer window.
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* \param[in] h The packet handler instance data pointer.
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* \param[in] p A pointer to the packet buffer.
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* \return Nothing
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*/
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void PHReleaseRXPacket(PHInstHandle h, PHPacketHandle p)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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// Lock
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xSemaphoreTakeRecursive(data->lock, portMAX_DELAY);
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// Change the packet type so we know this packet is unused.
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p->header.type = PACKET_TYPE_NONE;
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// If this packet is at the start of the window, increment the start index.
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while ((data->rx_win_start != data->rx_win_end) &&
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(data->rx_packets[data->rx_win_start].header.type == PACKET_TYPE_NONE))
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data->rx_win_start = (data->rx_win_start + 1) % data->cfg.winSize;
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// Release lock
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xSemaphoreGiveRecursive(data->lock);
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}
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/**
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* Transmit a packet from the transmit packet buffer window.
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* \param[in] h The packet handler instance data pointer.
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* \param[in] p A pointer to the packet buffer.
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* \return 1 Success
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* \return 0 Failure
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*/
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uint8_t PHTransmitPacket(PHInstHandle h, PHPacketHandle p)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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// Try to transmit the packet.
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if (!PHLTransmitPacket(data, p))
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return 0;
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// If this packet doesn't require an ACK, remove it from the TX window.
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switch (p->header.type) {
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case PACKET_TYPE_READY:
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case PACKET_TYPE_NOTREADY:
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case PACKET_TYPE_DATA:
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case PACKET_TYPE_PPM:
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PHReleaseTXPacket(h, p);
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break;
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}
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return 1;
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}
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/**
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* Verify that a buffer contains a valid packet.
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* \param[in] h The packet handler instance data pointer.
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* \param[in] p A pointer to the packet buffer.
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* \param[in] received_len The length of data received.
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* \return < 0 Failure
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* \return > 0 Number of bytes consumed.
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*/
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int32_t PHVerifyPacket(PHInstHandle h, PHPacketHandle p, uint16_t received_len)
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{
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// Verify the packet length.
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// Note: The last two bytes should be the RSSI and AFC.
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uint16_t len = PHPacketSizeECC(p);
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if (received_len < (len + 2))
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{
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DEBUG_PRINTF(1, "Packet length error %d %d\n\r", received_len, len + 2);
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return -1;
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}
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// Attempt to correct any errors in the packet.
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decode_data((unsigned char*)p, len);
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// Check that there were no unfixed errors.
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bool rx_error = check_syndrome() != 0;
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if(rx_error)
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{
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DEBUG_PRINTF(1, "Error in packet\n\r");
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return -2;
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}
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return len + 2;
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}
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/**
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* Process a packet that has been received.
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* \param[in] h The packet handler instance data pointer.
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* \param[in] p A pointer to the packet buffer.
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* \param[in] received_len The length of data received.
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* \return 0 Failure
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* \return 1 Success
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*/
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uint8_t PHReceivePacket(PHInstHandle h, PHPacketHandle p, bool rx_error)
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{
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PHPacketDataHandle data = (PHPacketDataHandle)h;
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uint16_t len = PHPacketSizeECC(p);
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// Extract the RSSI and AFC.
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int8_t rssi = *(((int8_t*)p) + len);
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int8_t afc = *(((int8_t*)p) + len + 1);
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switch (p->header.type) {
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case PACKET_TYPE_STATUS:
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if (!rx_error)
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// Pass on the channels to the status handler.
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if(data->status_handler)
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data->status_handler((PHStatusPacketHandle)p, rssi, afc);
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break;
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case PACKET_TYPE_ACKED_DATA:
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// Send the ACK / NACK
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if (rx_error)
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{
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DEBUG_PRINTF(1, "Sending NACK\n\r");
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PHLSendNAck(data, p);
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}
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else
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{
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PHLSendAck(data, p);
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// Pass on the data.
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if(data->data_handler)
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data->data_handler(p->data, p->header.data_size, rssi, afc);
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}
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break;
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case PACKET_TYPE_ACK:
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{
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// Find the packet ID in the TX buffer, and free it.
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unsigned int i = 0;
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for (unsigned int i = 0; i < data->cfg.winSize; ++i)
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if (data->tx_packets[i].header.tx_seq == p->header.rx_seq)
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PHReleaseTXPacket(h, data->tx_packets + i);
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#ifdef DEBUG_LEVEL
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if (i == data->cfg.winSize)
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DEBUG_PRINTF(1, "Error finding acked packet to release\n\r");
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#endif
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}
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break;
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case PACKET_TYPE_NACK:
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{
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// Resend the packet.
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unsigned int i = 0;
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for ( ; i < data->cfg.winSize; ++i)
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if (data->tx_packets[i].header.tx_seq == p->header.rx_seq)
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PHLTransmitPacket(data, data->tx_packets + i);
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#ifdef DEBUG_LEVEL
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if (i == data->cfg.winSize)
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DEBUG_PRINTF(1, "Error finding acked packet to NACK\n\r");
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DEBUG_PRINTF(1, "Resending after NACK\n\r");
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#endif
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}
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break;
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case PACKET_TYPE_PPM:
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if (!rx_error)
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// Pass on the channels to the PPM handler.
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if(data->ppm_handler)
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data->ppm_handler(((PHPpmPacketHandle)p)->channels);
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break;
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case PACKET_TYPE_DATA:
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if (!rx_error)
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// Pass on the data to the data handler.
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if(data->data_handler)
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data->data_handler(p->data, p->header.data_size, rssi, afc);
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break;
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default:
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break;
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}
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// Release the packet.
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PHReleaseRXPacket(h, p);
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return 1;
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}
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/**
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* Transmit a packet from the transmit packet buffer window.
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* \param[in] data The packet handler instance data pointer.
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* \param[in] p A pointer to the packet buffer.
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* \return 1 Success
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* \return 0 Failure
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*/
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static uint8_t PHLTransmitPacket(PHPacketDataHandle data, PHPacketHandle p)
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{
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if(!data->output_stream)
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return 0;
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// Set the sequence ID to the current ID.
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p->header.tx_seq = data->tx_seq_id++;
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// Add the error correcting code.
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encode_data((unsigned char*)p, PHPacketSize(p), (unsigned char*)p);
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// Transmit the packet using the output stream.
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if(data->output_stream(p) == -1)
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return 0;
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return 1;
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}
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/**
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* Send an ACK packet.
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* \param[in] data The packet handler instance data pointer.
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* \param[in] p A pointer to the packet buffer of the packet to be ACKed.
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* \return 1 Success
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* \return 0 Failure
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*/
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static uint8_t PHLSendAck(PHPacketDataHandle data, PHPacketHandle p)
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{
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// Create the ACK message
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PHPacketHeader ack;
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ack.destination_id = p->header.source_id;
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ack.type = PACKET_TYPE_ACK;
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ack.rx_seq = p->header.tx_seq;
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ack.data_size = 0;
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// Send the packet.
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return PHLTransmitPacket(data, (PHPacketHandle)&ack);
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}
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/**
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* Send an NAck packet.
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* \param[in] data The packet handler instance data pointer.
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* \param[in] p A pointer to the packet buffer of the packet to be ACKed.
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* \return 1 Success
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* \return 0 Failure
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*/
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static uint8_t PHLSendNAck(PHPacketDataHandle data, PHPacketHandle p)
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{
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// Create the NAck message
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PHPacketHeader ack;
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ack.destination_id = p->header.source_id;
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ack.type = PACKET_TYPE_NACK;
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ack.rx_seq = p->header.tx_seq;
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ack.data_size = 0;
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// Set the packet.
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return PHLTransmitPacket(data, (PHPacketHandle)&ack);
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}
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