Diff: TransLayer.cpp

Revision:

0:fe5850ccdb6f

Child:

1:9d3340bcd863

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TransLayer.cpp	Tue Feb 26 03:45:52 2013 +0000
@@ -0,0 +1,166 @@
+/*
+ * 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.
+ *
+ */
+
+
+
+/**
+*     \file            Trans_layer.cpp
+*     \brief           Implements a simple protocol for communication with PC
+*     \author          Navin Bhaskar
+*/
+
+#include "TransLayer.h"
+
+
+
+/**
+*     \fn              TransLayer()
+*     \brief           constructor for trans layer. Initializes the pointers
+*     \param           none
+*     \return          none
+*/
+
+TransLayer::TransLayer()
+{
+    _head =_tail = NULL;
+}
+
+/**
+*     \fn               AddService(call_back_ptr cb, char flag)
+*     \brief            Adds a service to the layer. The arguments are passed to
+*                       the call back function
+*     \param[in]        cb    call back pointer
+*     \param[in]        flag  flag to which this packet must respond
+*     \return           -1 on error
+*/
+
+int TransLayer::AddService(call_back_ptr cb, char flag)
+{
+    service_ptr temp=_head, mid;
+
+    if (NULL == cb) {
+        return -1;
+    }
+
+    // we are going to maintain a linked list of services
+    mid = (service_ptr)malloc(sizeof(service_list));
+
+    if (NULL == mid) {
+        return -1;
+    }
+
+    // record entries
+    mid->service_function = cb;
+    mid->service_flag = flag;
+    if (NULL == _head) {
+        // first entry ever
+        _head = mid;
+        mid->next_service = NULL;
+    } else {
+        // traverese to end of the list for insertion
+        while (temp->next_service != NULL) {
+            temp = temp->next_service;
+        }
+        temp->next_service = mid;
+        mid->next_service = NULL;
+    }
+    return 0;
+}
+
+
+
+/**
+*    \fn          LookForService(char flag)
+*    \brief       This function looks for a service that services given flag
+*    \param[in]    flag   flag of the service
+*    \return      service ptr containing that has info on service or NULL if service flag
+*                 was not found
+*/
+
+service_ptr TransLayer::LookForService(char flag)
+{
+    service_ptr temp = _head;
+
+    while(temp != NULL) {
+        if(temp->service_flag == flag) {
+            return temp;
+        }
+        temp = temp->next_service;
+    }
+
+    return NULL;
+}
+
+
+/**
+*    \fn          MainLoop(void)
+*    \brief       This function waits for a flag and then calls appropraite service
+*    \param       none
+*    \return      none
+*    \note        This function never returns has a while(1) at its heart
+*/
+
+void TransLayer::MainLoop(Console * cons, PerAccess * per)
+{
+    char temp, cmd=0;
+    char data_buff[20];
+    bool start_flag = false, data_start_flag=false, packet_formed = false;
+    int i =0;
+
+
+    while(1) {
+        if(cons->available() > 0) {
+            temp = cons->getCh();
+            if(PACKET_START == temp && data_start_flag == false) {
+                // start of packet, siganl the starting of packet
+                start_flag = true;
+                i=0;
+            } else if (start_flag == true) {
+                cmd = temp;        // this the flag that is going to indicate the service
+                start_flag = false;
+                data_start_flag = true;
+            } else if(data_start_flag == true) {
+
+                if(temp != 0x0d || temp != 0x0a || temp != '\n') {
+                    data_buff[i] = temp;
+                    i++;
+                }
+                if(temp == 0x0d || temp == 0x0a) {
+                    data_buff[i] = '\0';
+                    packet_formed = true;
+                    data_start_flag = false;
+                }
+
+            }
+            if(packet_formed == true) {
+                service_ptr ser;
+                //SeeServices();
+                ser =  LookForService(cmd);
+                if(ser != NULL) {
+                    ser->service_function(cons, per, data_buff, i);
+                }
+                packet_formed = false;
+            }
+        }
+    }
+}
+
+
+
+
+