rstp_prs.c

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/**
 * @file rstp_prs.c
 * @brief Port Role Selection state machine (PRS)
 *
 * @section License
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * Copyright (C) 2019-2024 Oryx Embedded SARL. All rights reserved.
 *
 * This file is part of CycloneSTP Open.
 *
 * 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 2
 * 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, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * @author Oryx Embedded SARL (www.oryx-embedded.com)
 * @version 2.4.0
 **/
 
//Switch to the appropriate trace level
#define TRACE_LEVEL RSTP_TRACE_LEVEL
 
//Dependencies
#include "rstp/rstp.h"
#include "rstp/rstp_fsm.h"
#include "rstp/rstp_prs.h"
#include "rstp/rstp_procedures.h"
#include "rstp/rstp_misc.h"
#include "debug.h"
 
//Check TCP/IP stack configuration
#if (RSTP_SUPPORT == ENABLED)
 
//PRS state machine's states
const RstpParamName rstpPrsStates[] =
{
   {RSTP_PRS_STATE_INIT_BRIDGE,    "INIT_BRIDGE"},
   {RSTP_PRS_STATE_ROLE_SELECTION, "ROLE_SELECTION"}
};
 
 
/**
 * @brief PRS state machine initialization
 * @param[in] context Pointer to the RSTP bridge context
 **/
 
void rstpPrsInit(RstpBridgeContext *context)
{
   //Enter initial state
   rstpPrsChangeState(context, RSTP_PRS_STATE_INIT_BRIDGE);
}
 
 
/**
 * @brief PRS state machine implementation
 * @param[in] context Pointer to the RSTP bridge context
 **/
 
void rstpPrsFsm(RstpBridgeContext *context)
{
   uint_t i;
   bool_t reselect;
 
   //All conditions for the current state are evaluated continuously until one
   //of the conditions is met (refer to IEEE Std 802.1D-2004, section 17.16)
   switch(context->prsState)
   {
   //INIT_BRIDGE state?
   case RSTP_PRS_STATE_INIT_BRIDGE:
      //Unconditional transition (UCT) to ROLE_SELECTION state
      rstpPrsChangeState(context, RSTP_PRS_STATE_ROLE_SELECTION);
      break;
 
   //ROLE_SELECTION state?
   case RSTP_PRS_STATE_ROLE_SELECTION:
      //Check whether the reselect variable is TRUE for any port
      for(reselect = FALSE, i = 0; i < context->numPorts; i++)
      {
         reselect |= context->ports[i].reselect;
      }
 
      //Whenever any bridge port's reselect variable is set by the Port
      //Information state machine, spanning tree information is recomputed
      if(reselect)
      {
         rstpPrsChangeState(context, RSTP_PRS_STATE_ROLE_SELECTION);
      }
 
      break;
 
   //Invalid state?
   default:
      //Just for sanity
      rstpFsmError(context);
      break;
   }
}
 
 
/**
 * @brief Update PRS state machine state
 * @param[in] context Pointer to the RSTP bridge context
 * @param[in] newState New state to switch to
 **/
 
void rstpPrsChangeState(RstpBridgeContext *context, RstpPrsState newState)
{
   //Dump the state transition
   TRACE_VERBOSE("PRS state machine %s -> %s\r\n",
      rstpGetParamName(context->prsState, rstpPrsStates, arraysize(rstpPrsStates)),
      rstpGetParamName(newState, rstpPrsStates, arraysize(rstpPrsStates)));
 
   //Switch to the new state
   context->prsState = newState;
 
   //On entry to a state, the procedures defined for the state are executed
   //exactly once (refer to IEEE Std 802.1D-2004, section 17.16)
   switch(context->prsState)
   {
   //INIT_BRIDGE state?
   case RSTP_PRS_STATE_INIT_BRIDGE:
      //On initialization all ports are assigned the Disabled port role
      rstpUpdtRoleDisabledTree(context);
      break;
 
   //ROLE_SELECTION state?
   case RSTP_PRS_STATE_ROLE_SELECTION:
      //Update spanning tree information and port roles
      rstpClearReselectTree(context);
      rstpUpdtRolesTree(context);
      rstpSetSelectedTree(context);
      break;
 
   //Invalid state?
   default:
      //Just for sanity
      break;
   }
 
   //The RSTP state machine is busy
   context->busy = TRUE;
}
 
#endif