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120 lines
3.3 KiB
C
120 lines
3.3 KiB
C
/*
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* OpenMODBUS/TCP to RS-232/485 MODBUS RTU gateway
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*
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* queue.c - connections queue management procedures
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*
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* Copyright (c) 2002-2003, 2013, Victor Antonovich (v.antonovich@gmail.com)
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $Id: queue.c,v 1.3 2015/02/25 10:33:57 kapyar Exp $
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*/
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#include "queue.h"
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/*
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* Queue structure initialization
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*/
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void
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queue_init(queue_t *queue)
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{
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queue->beg = NULL;
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queue->end = NULL;
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queue->len = 0;
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}
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/*
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* Add new element to queue
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*/
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conn_t *
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queue_new_elem(queue_t *queue)
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{
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conn_t *newconn = (conn_t *)malloc(sizeof(conn_t));
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if (!newconn)
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{ /* Aborting program execution */
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#ifdef LOG
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logw(0, "queue_new_elem(): out of memory for new element (%s)",
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strerror(errno));
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#endif
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exit(errno);
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}
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newconn->next = NULL;
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if ((newconn->prev = queue->end) != NULL)
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queue->end->next = newconn;
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else /* we add first element */
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queue->beg = newconn;
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queue->end = newconn;
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queue->len++;
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#ifdef DEBUG
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logw(5, "queue_new_elem(): length now is %d", queue->len);
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#endif
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return newconn;
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}
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/*
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* Remove element from queue
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*/
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void
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queue_delete_elem(queue_t *queue, conn_t *conn)
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{
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if (queue->len <= 0)
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{ /* queue is empty */
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#ifdef LOG
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logw(1, "queue_delete_elem(): queue empty!");
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#endif
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return;
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}
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if (conn->prev == NULL)
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{ /* deleting first element */
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if ((queue->beg = queue->beg->next) != NULL)
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queue->beg->prev = NULL;
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}
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else
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conn->prev->next = conn->next;
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if (conn->next == NULL)
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{ /* deleting last element */
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if ((queue->end = queue->end->prev) != NULL)
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queue->end->next = NULL;
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}
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else
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conn->next->prev = conn->prev;
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queue->len--;
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free((void *)conn);
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#ifdef DEBUG
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logw(5, "queue_delete_elem(): length now is %d", queue->len);
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#endif
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return;
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}
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/*
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* Obtain pointer to next element in the QUEUE (with wrapping)
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* Parameters: CONN - pointer to current queue element
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* Return: pointer to next queue element
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*/
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conn_t *
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queue_next_elem(queue_t *queue, conn_t *conn)
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{
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return (conn == NULL || conn->next == NULL) ? queue->beg : conn->next;
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}
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