--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/g23m-aci/l2p/l2p.c	Sun Jul 15 04:40:46 2018 +0000
@@ -0,0 +1,943 @@
+/* 
++----------------------------------------------------------------------------- 
+|  Project :  BAT L2P ()
+|  Modul   :  BAT_L2P
++----------------------------------------------------------------------------- 
+|  Copyright 2005 Texas Instruments Berlin, AG 
+|                 All rights reserved. 
+| 
+|                 This file is confidential and a trade secret of Texas 
+|                 Instruments Berlin, AG 
+|                 The receipt of or possession of this file does not convey 
+|                 any rights to reproduce or disclose its contents or to 
+|                 manufacture, use, or sell anything it may describe, in 
+|                 whole, or in part, without the specific written consent of 
+|                 Texas Instruments Berlin, AG. 
++----------------------------------------------------------------------------- 
+|  Purpose :  L2P function definitions
++----------------------------------------------------------------------------- 
+*/ 
+#include "typedefs.h"   /* to get TI data types */
+#include "vsi.h"        /* to get a lot of macros */
+#include "l2p_types.h"
+#include "l2p.h"
+
+#include "string.h"
+
+T_L2P_CONTROL_BLOCK *l2p_control_block_list = (T_L2P_CONTROL_BLOCK *)0;
+
+/*
+** Local function declarations
+*/
+static char *L2P_write_data_to_seg(char *writePtr, char *dataPtr, U16 dataSize, U16 remain_seg_size,
+                                   U16 *bytesWritten);
+
+static char *L2P_read_data_from_seg(char *readPtr, char *writePtr, U16 dataSize, U16 remain_seg_size,
+                                    U16 *bytesWritten);
+
+
+/*
+** L2P function definitions
+*/
+
+/*
++--------------------------------------------------------------------+
+| PROJECT: BAT L2P                  MODULE:   L2P                    |
+| STATE  : code                     ROUTINE:  L2P_Configure          |
++--------------------------------------------------------------------+
+
+   PURPOSE : L2P_Configure will initiaise the L2P for each instance of BAT Lib or BAT Module
+             that wishes to use its services. The following is a list of the parameters, and their uses:
+
+             batId : A identifer to uniquely identify each instance of BAT using this L2P
+             mem : A block of memory for L2P to use as a Control Block (L2P cannot allocate its own memory)
+             num_mux_chnls: The number of clients being supported at the application end (this information is
+             passed to BAT Module as part of the startup process)
+             protocolId : The protocol being used to communicate with the peer entity
+             maxMTU : Maximum size of a transport unit.
+             xxx_CB : These are callback functions, provided by the BAT Lib or BAT Module, to provide necessary
+                      services to L2P to get Send and Receive buffers, Send the Frames and receive fully
+                      completed packets
+
+*/
+T_L2P_STATUS L2P_Configure(U8 batid, void *mem,
+                           T_L2P_SUPPORTED_PROTOCOLS protocolId,
+                           U16 maxMTU,
+                           L2P_Get_Tx_Buf_CB  Get_Tx_Buf_Cb,
+                           L2P_Get_Rx_Buf_CB Get_Rx_Buf_Cb,
+                           L2P_Get_Next_Seg_CB Get_Next_Seg_Cb,
+                           L2P_Send_Frame_CB Send_Frame_Cb,
+                           L2P_Msg_Rxd_CB Msg_Rxd_Cb)
+{
+  T_L2P_CONTROL_BLOCK **curr_lcb_next_ptr;
+  T_L2P_CONTROL_BLOCK *current_l2p_cntrl_block;
+  T_L2P_CONTROL_BLOCK *this_l2p_cntrl_block = (T_L2P_CONTROL_BLOCK *)mem;
+
+  TRACE_EVENT("L2P_Configure");
+  /*
+  ** check the incoming paramters to ensure they are valid 
+  */
+  if (mem == (void *)0)
+  {
+    TRACE_EVENT("L2P_Configure - Mem pointer Invalid");
+    return L2P_STAT_INVALID_PARAMETER;
+  }
+
+  /* protocolId is a non-negative value(so <0 check not reqd) */
+  if ( protocolId >= L2P_SP_MAX_NUM )
+  {
+    TRACE_EVENT("L2P_Configure - Protocol Id Invalid");
+    return L2P_STAT_INVALID_PARAMETER;
+  }
+
+    if (maxMTU <= (L2P_FRAME_CONTROL_SIZE)) 
+  {
+    TRACE_EVENT("L2P_Configure - Max MTU value Invalid");
+    return L2P_STAT_INVALID_PARAMETER;
+  }
+
+  if (Get_Tx_Buf_Cb == (L2P_Get_Tx_Buf_CB)0)
+  {
+    TRACE_EVENT("L2P_Configure - Get Tx Buffer Callback Invalid");
+    return L2P_STAT_INVALID_PARAMETER;
+  }
+
+  if (Get_Rx_Buf_Cb == (L2P_Get_Rx_Buf_CB)0)
+  {
+    TRACE_EVENT("L2P_Configure - Get Rx Buffer Callback Invalid");
+    return L2P_STAT_INVALID_PARAMETER;
+  }
+
+  if (Get_Next_Seg_Cb == (L2P_Get_Next_Seg_CB)0)
+  {
+    TRACE_EVENT("L2P_Configure - Get Next Segment Callback Invalid");
+    return L2P_STAT_INVALID_PARAMETER;
+  }
+
+  if (Send_Frame_Cb == (L2P_Send_Frame_CB)0)
+  {
+    TRACE_EVENT("L2P_Configure - Send Frame Callback Invalid");
+    return L2P_STAT_INVALID_PARAMETER;
+  }
+
+  if (Msg_Rxd_Cb == (L2P_Msg_Rxd_CB)0)
+  {
+    TRACE_EVENT("L2P_Configure - Message Received Callback Invalid");
+    return L2P_STAT_INVALID_PARAMETER;
+  }
+
+  /*
+  ** initialise the data in the passed block of data
+  */
+  this_l2p_cntrl_block->batId = batid;
+  this_l2p_cntrl_block->frameId = 0;
+  this_l2p_cntrl_block->protocolId = protocolId;
+  this_l2p_cntrl_block->maxMTU = maxMTU;
+  this_l2p_cntrl_block->rxBuf = (char *)0;
+  this_l2p_cntrl_block->muxId = 0xFD; /* Any value here will be a valid client Id, but this one is unlikely ... it MUST be initialised correctly before each use */
+  this_l2p_cntrl_block->cmdTagReceived = 0;
+  this_l2p_cntrl_block->receivedCmdTag = 0;
+  this_l2p_cntrl_block->dataSize = 0;
+  this_l2p_cntrl_block->bytesToBeRead = 0;
+  this_l2p_cntrl_block->dataToBeRead = (char *)0;
+  
+  this_l2p_cntrl_block->callbacks.Get_TxBuf_Cb = Get_Tx_Buf_Cb;
+  this_l2p_cntrl_block->callbacks.Get_RxBuf_Cb = Get_Rx_Buf_Cb;
+  this_l2p_cntrl_block->callbacks.Get_Next_Seg_Cb = Get_Next_Seg_Cb;
+  this_l2p_cntrl_block->callbacks.Send_Frame_Cb = Send_Frame_Cb;
+  this_l2p_cntrl_block->callbacks.Msg_Rxd_Cb = Msg_Rxd_Cb;
+  
+  this_l2p_cntrl_block->next = (void *)0;
+  
+  /*
+  ** Check that the batId is not already in use
+  */
+  if (l2p_control_block_list != (T_L2P_CONTROL_BLOCK *)0)
+  {
+    /*
+    ** Parse the list until either the batId is found (which would be an error)
+    ** or the batId is larger than the one passed (ie the current batId is not in the list, and is thereofre valid)
+    */
+    curr_lcb_next_ptr = &l2p_control_block_list;
+    current_l2p_cntrl_block = l2p_control_block_list;
+
+    while ((current_l2p_cntrl_block != (T_L2P_CONTROL_BLOCK *)0) &&
+           (current_l2p_cntrl_block->batId < batid))
+    {
+      /*
+      ** Jump to the next node on the linked list,
+      ** keeping track of the previous node so we can add in the details later
+      */
+      curr_lcb_next_ptr = &current_l2p_cntrl_block->next;
+      current_l2p_cntrl_block = current_l2p_cntrl_block->next;
+    }
+
+    if (current_l2p_cntrl_block == (T_L2P_CONTROL_BLOCK *)0)
+    {
+      /*
+      ** BAT Id was not found ... and we've reached the end of the list
+      ** need to add the details at the end of the linked list
+      */
+      *curr_lcb_next_ptr = this_l2p_cntrl_block;
+    }
+    else if (current_l2p_cntrl_block->batId == batid)
+    {
+      /*
+      ** BAT Id was found in the current list ... it is already configured ... send an error
+      */
+      TRACE_EVENT("L2P_Configure - BAT Id Already In Use");
+      return L2P_STAT_BAT_ID_ALREADY_EXISTS;
+    }
+    else
+    {
+      /*
+      ** BAT Id was not found ... but we haven't reached the end of the list
+      ** need to add the details in the middle of the linked list
+      */
+      this_l2p_cntrl_block->next = *curr_lcb_next_ptr;
+      *curr_lcb_next_ptr = this_l2p_cntrl_block;
+    }
+  }
+  else
+  {
+    /*
+    ** The linked list of BAT and L2P Control blocks is empty, this is the first instance of BAT
+    ** to register with the L2P. Add the details as the first entry to the linked list.
+    */
+    l2p_control_block_list = this_l2p_cntrl_block;
+  }
+    return L2P_STAT_SUCCESS;
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT: BAT L2P                  MODULE:   L2P                    |
+| STATE  : code                     ROUTINE:  L2P_Remove             |
++--------------------------------------------------------------------+
+
+   PURPOSE : L2P_Remove will delete a BAT from L2Ps service list. The following is a list of
+             the parameters, and their uses:
+
+             batId : A identifer to uniquely identify each instance of BAT using this L2P
+
+*/
+T_L2P_STATUS L2P_Remove(U8 batid)
+{
+    T_L2P_CONTROL_BLOCK **curr_lcb_next_ptr;
+    T_L2P_CONTROL_BLOCK *current_l2p_cntrl_block;
+
+    TRACE_EVENT("L2P_Remove()");
+    
+    if (l2p_control_block_list == (T_L2P_CONTROL_BLOCK *)0)
+    {
+        return L2P_STAT_NO_SUCH_BAT_ID;
+    }
+
+    if (l2p_control_block_list->batId == batid)
+    {
+        l2p_control_block_list = l2p_control_block_list->next;
+        return L2P_STAT_SUCCESS;
+    }
+
+    /*
+    ** Parse the list until either the batId is found 
+    ** or the batId is larger than the one passed (which would be an error)
+    */
+    curr_lcb_next_ptr = &l2p_control_block_list;
+    current_l2p_cntrl_block = l2p_control_block_list;
+
+    while ((current_l2p_cntrl_block != (T_L2P_CONTROL_BLOCK *)0) &&
+               (current_l2p_cntrl_block->batId < batid))
+    {
+        /*
+        ** Jump to the next node on the linked list,
+        ** keeping track of the previous node so we can add in the details later
+        */
+        curr_lcb_next_ptr = &current_l2p_cntrl_block->next;
+        current_l2p_cntrl_block = current_l2p_cntrl_block->next;
+    }
+
+    if (current_l2p_cntrl_block == (T_L2P_CONTROL_BLOCK *)0)
+    {
+        /*
+        ** BAT Id was not found and we've reached the end of the list
+        */
+        return L2P_STAT_NO_SUCH_BAT_ID;
+    }
+    else if (current_l2p_cntrl_block->batId == batid)
+    {
+        /*
+        ** BAT Id was found in the current list ... remove the control balock from the linked list
+        */
+        *curr_lcb_next_ptr = current_l2p_cntrl_block->next;
+    }
+    else
+    {
+        /*
+         ** BAT Id was not found ... the current batid must be greater tahn the one passed
+        */
+        return L2P_STAT_NO_SUCH_BAT_ID;
+    }
+    
+    return L2P_STAT_SUCCESS;
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT: BAT L2P                  MODULE:   L2P                    |
+| STATE  : code                     ROUTINE:  L2P_Send               |
++--------------------------------------------------------------------+
+
+   PURPOSE : L2P_Send will receive an AT Command Tag and its data from the L2P User, and depending on the
+             MTU size of the communications link being used, split the data into multiple frames and send those
+             Frames across the link. The following is a list of the parameters, and their uses:
+
+             batId   : A identifer to uniquely identify each instance of BAT using this L2P
+             muxId   : A client identifier to identify which clinet of the BAT instance either sent, or is to receive, the data.
+             dataTag : This is a BAT Command or Response TAG to identify which AT command is being sent. This TAG
+                       will be sent to the peer along with the data.
+             dataBuf : pointer to the payload data to send
+             dataLen : length of the data in the 'dataBuf'
+             errVal  : If there is a driver error, L2P_Send will return L2P_STAT_UNKNOWN_ERROR and will provide
+                       the driver error code in errVal. This is because the number may be positive, and all errors in
+                       T_L2P_STATUS are negative.
+
+*/
+T_L2P_STATUS L2P_Send(U8 batId, U8 muxId, U32 dataTag, void *dataBuf, U16 dataLen, int *errVal)
+{
+    T_L2P_CONTROL_BLOCK *curr_l2p_cntrl_block;
+    T_L2P_FRAME_CONTROL_BYTES frameCntrlBytes;
+    U16    bytesRemainingToBeSent;
+    U16    frameCntrlBytesToBeWritten;
+    U16    bytesToBeWritten = 0;
+    U16    bytesWritten;
+    U16    frameSizeReq;
+    U16    totalBufSize;
+    U16    segSize;
+    U16    remainingSegSize;
+    U16    totalSegSize;
+    char   *curTxSeg;
+    char   *dataToBeWritten = NULL;
+    char   *frameCntrlDataToBeWritten;
+    void   *seg_hdr;
+    char   *txWritePtr;
+    char   cmdTagWritten = 0;
+    int    drvRetVal = 0;
+
+    TRACE_EVENT("L2P_Send()");
+    
+    /*
+    ** Check that the Bat Id is valid
+    */
+
+    curr_l2p_cntrl_block = l2p_control_block_list;
+
+    while ((curr_l2p_cntrl_block != (T_L2P_CONTROL_BLOCK *)0) &&
+               (curr_l2p_cntrl_block->batId != batId))
+    {
+        curr_l2p_cntrl_block = curr_l2p_cntrl_block->next;
+    }
+
+    if (curr_l2p_cntrl_block == (T_L2P_CONTROL_BLOCK *)0)
+    {
+        return L2P_STAT_NO_SUCH_BAT_ID;
+    }
+
+    /*
+    ** Check the rest of the parameters
+    */
+    if ((dataBuf == (void *)0) && (dataLen != 0))
+    {
+        TRACE_EVENT("L2P_Send() - Invalid Data Buffer Pointer");
+        return L2P_STAT_INVALID_PARAMETER;
+    }
+
+    if (errVal == (int *)0)
+    {
+        TRACE_EVENT("L2P_Send() - Invalid Error Return Pointer");
+        return L2P_STAT_INVALID_PARAMETER;
+    }
+
+    /*
+    ** The format of an L2 frame for BAT will be as follows :
+    **
+    **     For the first frame
+    **     ----------------------------------------------------------------
+    **     |  L2 Control Bytes | BAT Cmd TAG |     BAT Command Data       |
+    **     |      (n Bytes)    |    4 Bytes  |     (Remaining Bytes)      |
+    **     ----------------------------------------------------------------
+    **
+    **     For any subsequent frames
+    **     ----------------------------------------------------------------
+    **     |  L2 Control Bytes |     BAT Command Data                     |
+    **     |      (n Bytes)    |     (Remaining Bytes)                    |
+    **     ----------------------------------------------------------------
+    */
+
+    bytesRemainingToBeSent = dataLen + sizeof(int);
+
+    /*
+    ** Fill in the Frame Control Bytes
+    */
+    frameCntrlBytes.dataLen = dataLen;
+    frameCntrlBytes.frame_id = 0;           /* Each new packet will start with a frame Id of 0 */
+    frameCntrlBytes.frame_type = L2P_FT_UNKNOWN_FRAME_TYPE;
+    frameCntrlBytes.mux_id = muxId;
+    frameCntrlBytes.protocol_id = (U8)curr_l2p_cntrl_block->protocolId;
+
+    while (bytesRemainingToBeSent >0)
+    {
+        /*
+        ** Calculate the required size of Transmit buffer and how many frames will be required
+        */
+        if ((bytesRemainingToBeSent + L2P_FRAME_CONTROL_SIZE) > curr_l2p_cntrl_block->maxMTU)
+        {
+            /*
+            ** Data will not fit in a single frame, so will need to be fragmented and reassembled
+            */
+            frameSizeReq = curr_l2p_cntrl_block->maxMTU;
+        }
+        else
+        {
+            /*
+            ** Data will  fit in a single frame, so will be sent complete
+            */
+            frameSizeReq = bytesRemainingToBeSent + L2P_FRAME_CONTROL_SIZE;
+        }
+
+        /*
+        ** Request the Transmit frame from the buffer
+        */
+        curTxSeg = (char *)curr_l2p_cntrl_block->callbacks.Get_TxBuf_Cb(batId, frameSizeReq,
+                                                                                                  &seg_hdr,  &totalBufSize, &segSize);
+
+        if (curTxSeg == (char *)0)
+        {
+            return L2P_STAT_UNABLE_TO_GET_BUFFER;
+        }
+
+        totalSegSize = remainingSegSize = segSize;
+
+        /*
+        ** Now we know the size of buffer given so we can tell whether the entire message will fit in a single frame
+        */
+        if (totalBufSize >= (bytesRemainingToBeSent + L2P_FRAME_CONTROL_SIZE))
+        {
+            if (frameCntrlBytes.frame_type == L2P_FT_UNKNOWN_FRAME_TYPE)
+                frameCntrlBytes.frame_type = (U8)L2P_FT_COMPLETE_FRAME;
+            else
+                frameCntrlBytes.frame_type = (U8)L2P_FT_END_FRAME;
+
+            frameCntrlBytes.frameLen = bytesRemainingToBeSent + L2P_FRAME_CONTROL_SIZE;
+        }
+        else
+        {
+            if (frameCntrlBytes.frame_type == L2P_FT_UNKNOWN_FRAME_TYPE)
+                frameCntrlBytes.frame_type = (U8)L2P_FT_START_FRAME;
+            else
+                frameCntrlBytes.frame_type = L2P_FT_CONTINUATION_FRAME;
+
+            frameCntrlBytes.frameLen = totalBufSize;
+        }
+
+        txWritePtr = curTxSeg;
+
+        /*
+        ** We can assume that the buffer will be at least big enough for the L2 Frame Header plus some data
+        **
+        ** Write the L2 Frames Control Bytes
+        */
+        frameCntrlBytesToBeWritten = L2P_FRAME_CONTROL_SIZE;
+        frameCntrlDataToBeWritten = (char *)&frameCntrlBytes;
+
+        while (frameCntrlBytesToBeWritten > 0)
+        {
+            txWritePtr = L2P_write_data_to_seg(txWritePtr, frameCntrlDataToBeWritten, frameCntrlBytesToBeWritten,
+                                                                      remainingSegSize, &bytesWritten);
+            frameCntrlBytesToBeWritten -= bytesWritten;
+            remainingSegSize -= bytesWritten;
+            frameCntrlDataToBeWritten += bytesWritten;
+
+            /*
+            ** Frame Control Bytes are NOT included in the bytesRemainingToBeSent count so do not decrease the size!
+            */
+
+            if (txWritePtr == (char *)0)
+            {
+                /*
+                ** We have reached the end of the current Segment, so get the next.
+                */
+                curTxSeg = curr_l2p_cntrl_block->callbacks.Get_Next_Seg_Cb(batId, seg_hdr, &seg_hdr,  &segSize);
+                txWritePtr = curTxSeg;
+                totalSegSize +=segSize;
+                remainingSegSize = segSize;
+            }
+        }
+
+        /*
+        ** if necessary, write the cmd Tag into the Buffer
+        */
+        if ((frameCntrlBytes.frame_type == L2P_FT_COMPLETE_FRAME) ||
+             (frameCntrlBytes.frame_type == L2P_FT_START_FRAME))
+        {
+            bytesToBeWritten = sizeof(dataTag);
+            dataToBeWritten = (char *)&dataTag;
+
+            while ((txWritePtr != (char *)0) &&     /* There is still space in the buffer segement */
+                   (!cmdTagWritten))                /* The command Tag has not completed */
+            {
+                txWritePtr = L2P_write_data_to_seg(txWritePtr, dataToBeWritten, bytesToBeWritten,
+                                                   remainingSegSize, &bytesWritten);
+                bytesToBeWritten -= bytesWritten;
+                remainingSegSize -= bytesWritten;
+                dataToBeWritten += bytesWritten;
+
+                /*
+                ** Decrement the bytesRemainingToBeSent counter
+                */
+                bytesRemainingToBeSent -= bytesWritten;
+
+                if ((txWritePtr == (char *)0) && (totalSegSize < totalBufSize))
+                {
+                    /*
+                    ** We have reached the end of the current Segment, so get the next.
+                    */
+                    curTxSeg = curr_l2p_cntrl_block->callbacks.Get_Next_Seg_Cb(batId, seg_hdr, &seg_hdr,  &segSize);
+                    txWritePtr = curTxSeg;
+                    totalSegSize +=segSize;
+                    remainingSegSize = segSize;
+                }
+
+                /*
+                ** If the Command Tag has been completed set a flag
+                */
+                if (bytesToBeWritten == (U16)0)
+                {
+                    cmdTagWritten = 1;
+                    dataToBeWritten = (char *)dataBuf;    /* Next Write the AT Command Data */
+                    bytesToBeWritten = dataLen;
+                }
+            }
+        }
+       
+	if (dataToBeWritten EQ NULL)
+	{
+	    return L2P_STAT_INVALID_PARAMETER;
+        }	
+        /*
+        ** if txWritePtr is NULL at this point it is because a buffer has been completed ... drop out and perform
+        ** the next loop of the while statement to create the next L2 Frame in an new buffer.
+        */
+       	while ((bytesToBeWritten > 0) &&    /* There is still data to write */
+               (txWritePtr != (char *)0))   /* There is still space in the buffer segement */
+        {
+            txWritePtr = L2P_write_data_to_seg(txWritePtr, dataToBeWritten, bytesToBeWritten,
+                                               remainingSegSize, &bytesWritten);
+            bytesToBeWritten -= bytesWritten;
+            remainingSegSize -= bytesWritten;
+            dataToBeWritten += bytesWritten;
+	
+            /*
+            ** Decrement the bytesRemainingToBeSent counter
+            */
+            bytesRemainingToBeSent -= bytesWritten;
+
+            if ((txWritePtr == (char *)0) && (totalSegSize < totalBufSize))
+            {
+                /*
+                ** We have reached the end of the current Segment, so get the next.
+                */
+                curTxSeg = curr_l2p_cntrl_block->callbacks.Get_Next_Seg_Cb(batId, seg_hdr, &seg_hdr,  &segSize);
+                txWritePtr = curTxSeg;
+                totalSegSize +=segSize;
+                remainingSegSize = segSize;
+            }
+
+            if ((bytesToBeWritten == (U16)0) &&     /* We've finished writing the data */
+                (!cmdTagWritten))                   /* but that data was the Command Tag  */
+            {
+                /*
+                ** now we have to write the AT Command Data
+                */
+                cmdTagWritten = 1;
+                dataToBeWritten = (char *)dataBuf;
+                bytesToBeWritten = dataLen;
+            }
+        }
+
+        /*
+        ** We have built a complete L2 Frame ... that it may or may not include the complete packet it isn't important
+        ** but we need to send it ... 
+        */
+        drvRetVal = curr_l2p_cntrl_block->callbacks.Send_Frame_Cb(batId);
+        frameCntrlBytes.frame_id ++;
+	
+	if (drvRetVal != 0)
+        {
+            /*
+            ** There was an error sending the frame
+            */
+            *errVal = drvRetVal;
+            return L2P_STAT_UNKNOWN_ERROR;
+        }
+   }
+
+    return L2P_STAT_SUCCESS;
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT: BAT L2P                  MODULE:   L2P                    |
+| STATE  : code                     ROUTINE:  L2P_Receive            |
++--------------------------------------------------------------------+
+
+   PURPOSE : L2P_Receive is called on receipt of data by the BAT, BAT Command Tag is extracted and the rest
+             of the L2 frames are combined into a buffer and passed, complete, to the BAT. The following is a
+             list of the parameters, and their uses:
+
+             batId : A identifer to uniquely identify each instance of BAT using this L2P
+             inBuf : pointer to the received buffer
+             dataLen : length of the data in the 'inBuf'
+
+*/
+T_L2P_STATUS L2P_Receive(U8 batId, void *dataBuf, void *seg_hdr_ptr, U16 totalsize, U16 segSize)
+{
+    T_L2P_CONTROL_BLOCK *curr_l2p_cntrl_block;
+    T_L2P_FRAME_CONTROL_BYTES frameCntrlBytes;
+    U16  frameCntrlBytesToBeRead;
+    U16  bytesRead;
+    U16  remainingSegSize;
+    U16  totalSegSize;
+    char *curRxSeg;
+    char *rxReadPtr;
+    char *frameCntrlDataToBeRead;
+
+    TRACE_EVENT("L2P_Receive()");
+
+    /*
+    ** Check that the Bat Id is valid
+    */
+    curr_l2p_cntrl_block = l2p_control_block_list;
+
+    while ((curr_l2p_cntrl_block != (T_L2P_CONTROL_BLOCK *)0) &&
+           (curr_l2p_cntrl_block->batId != batId))
+    {
+        curr_l2p_cntrl_block = curr_l2p_cntrl_block->next;
+    }
+
+    if (curr_l2p_cntrl_block == (T_L2P_CONTROL_BLOCK *)0)
+    {
+        return L2P_STAT_NO_SUCH_BAT_ID;
+    }
+
+    /*
+    ** Check the rest of the parameters
+    */
+    if (dataBuf == (void *)0)
+    {
+        TRACE_EVENT("L2P_Receive() - Invalid Data Buffer Pointer");
+        return L2P_STAT_INVALID_PARAMETER;
+    }
+
+    /*
+    ** Don't check the Segment Header Pointer, it is User Data and down to the
+    ** BAT Lib or BAT Module which pointer they pass :
+    **      pointer to current segment - never NULL
+    **      pointer to the next segment - may be NULL
+    **
+    if (seg_hdr_ptr == (void *)0)
+    {
+        TRACE_EVENT("L2P_Receive() - Invalid Segment Header Pointer");
+        return L2P_STAT_INVALID_PARAMETER;
+    }
+    */
+
+    if (totalsize <= (U16)L2P_FRAME_CONTROL_SIZE)
+    {
+        TRACE_EVENT("L2P_Receive() - Invalid Buffer Length");
+        return L2P_STAT_INVALID_PARAMETER;
+    }
+
+    if (segSize == (U16)0)
+    {
+        TRACE_EVENT("L2P_Receive() - Invalid Segment Size");
+        return L2P_STAT_INVALID_PARAMETER;
+    }
+
+    /*
+    ** The format of an L2 frame for BAT will be as follows :
+    **
+    **     For the first frame
+    **     ----------------------------------------------------------------
+    **     |  L2 Control Bytes | BAT Cmd TAG |     BAT Command Data       |
+    **     |      (n Bytes)    |    4 Bytes  |       (Remaining Bytes)    |
+    **     ----------------------------------------------------------------
+    **
+    **     For any subsequent frames
+    **     ----------------------------------------------------------------
+    **     |  L2 Control Bytes |       BAT Command Data                   |
+    **     |      (n Bytes)    |       (Remaining Bytes)                  |
+    **     ----------------------------------------------------------------
+    */
+
+    /*
+    ** Read the L2 Frames Control Bytes
+    */
+    curRxSeg = (char *)dataBuf;
+    frameCntrlBytesToBeRead = L2P_FRAME_CONTROL_SIZE;
+    frameCntrlDataToBeRead = (char *)&frameCntrlBytes;
+    totalSegSize = remainingSegSize = segSize;
+    rxReadPtr = dataBuf;
+
+    while (frameCntrlBytesToBeRead > 0)
+    {
+        rxReadPtr = L2P_read_data_from_seg(rxReadPtr, frameCntrlDataToBeRead, frameCntrlBytesToBeRead,
+                                           remainingSegSize, &bytesRead);
+        frameCntrlBytesToBeRead-= bytesRead;
+        remainingSegSize -= bytesRead;
+        frameCntrlDataToBeRead += bytesRead;
+
+        if (rxReadPtr == (char *)0)
+        {
+            /*
+            ** We have reached the end of the current Segment, so get the next.
+            */
+            curRxSeg = curr_l2p_cntrl_block->callbacks.Get_Next_Seg_Cb(batId, seg_hdr_ptr, &seg_hdr_ptr,
+                                                                       &segSize);
+            rxReadPtr = curRxSeg;
+            totalSegSize +=segSize;
+            remainingSegSize = segSize;
+        }
+    }
+
+    /*
+    ** Now we have the frame Control Bytes ... so we need to determine whether we need a
+    ** new Rx Buffer from the user
+    */
+
+    /*
+    ** If the frame Id is zero, this is a new message
+    */
+    if ((frameCntrlBytes.frame_id == (U8)0) && 
+        ((frameCntrlBytes.frame_type == L2P_FT_START_FRAME) ||
+         (frameCntrlBytes.frame_type == L2P_FT_COMPLETE_FRAME)))
+    {
+        /*
+        ** Do we already have an Rx Buffer
+        */
+        if (curr_l2p_cntrl_block->rxBuf == (char *)0)
+        {
+            /*
+            ** No -- Use the callback function to get an Rx Buffer
+            */
+            curr_l2p_cntrl_block->rxBuf = (char *)curr_l2p_cntrl_block->callbacks.Get_RxBuf_Cb(batId);
+
+            if (curr_l2p_cntrl_block->rxBuf == (char *)0)
+            {
+                /*
+                ** Failed to allocate a Rx Buffer
+                */
+                return L2P_STAT_UNABLE_TO_GET_BUFFER;
+            }
+        }
+            /* comment out the 'else block' because there is no functionality to go inside it
+        else
+        {
+            ** Yes -- We will overwrite it automatically ... the previous message was lost!
+        }
+            */
+
+        /*
+        ** Pull the necessary data from the Frame Control Bytes
+        */
+        curr_l2p_cntrl_block->dataSize = frameCntrlBytes.dataLen; /* length of the Command Data (excl the CmdTag) */
+        curr_l2p_cntrl_block->muxId = frameCntrlBytes.mux_id;     /* Sender or receipient of the message */
+        curr_l2p_cntrl_block->cmdTagReceived = 0;
+    }
+
+    /*
+    ** if necessary, read the cmd Tag from the Buffer
+    */
+    if ((frameCntrlBytes.frame_type == L2P_FT_COMPLETE_FRAME) ||
+         (frameCntrlBytes.frame_type == L2P_FT_START_FRAME))
+    {
+        curr_l2p_cntrl_block->bytesToBeRead = sizeof(curr_l2p_cntrl_block->receivedCmdTag);
+        curr_l2p_cntrl_block->dataToBeRead = (char *)&curr_l2p_cntrl_block->receivedCmdTag;
+
+        while ((rxReadPtr != (char *)0) &&                  /* There is still data in the buffer segement */
+                   (!curr_l2p_cntrl_block->cmdTagReceived)) /* The command Tag has not completed */
+        {
+            rxReadPtr = L2P_read_data_from_seg(rxReadPtr, curr_l2p_cntrl_block->dataToBeRead,
+                                               curr_l2p_cntrl_block->bytesToBeRead,
+                                               remainingSegSize, &bytesRead);
+            curr_l2p_cntrl_block->bytesToBeRead -= bytesRead;
+            remainingSegSize -= bytesRead;
+            curr_l2p_cntrl_block->dataToBeRead += bytesRead;
+
+            if ((rxReadPtr == (char *)0) && (totalSegSize < totalsize) && (curr_l2p_cntrl_block->bytesToBeRead != (U16)0))
+            {
+                /*
+                ** We have reached the end of the current Segment, so get the next.
+                */
+                curRxSeg = curr_l2p_cntrl_block->callbacks.Get_Next_Seg_Cb(batId, seg_hdr_ptr, &seg_hdr_ptr,  &segSize);
+                rxReadPtr = curRxSeg;
+                totalSegSize +=segSize;
+                remainingSegSize = segSize;
+            }
+
+            /*
+            ** If the Command Tag has been completed set a flag
+            */
+            if (curr_l2p_cntrl_block->bytesToBeRead == (U16)0)
+            {
+                curr_l2p_cntrl_block->cmdTagReceived = 1;
+                curr_l2p_cntrl_block->dataToBeRead = (char *)curr_l2p_cntrl_block->rxBuf;    /* Next Write the AT Command Data */
+                curr_l2p_cntrl_block->bytesToBeRead = curr_l2p_cntrl_block->dataSize;
+            }
+        }
+    }
+
+    /*
+    ** if txWritePtr is NULL at this point it is because a buffer has been completed ... drop out and
+    ** wait for the next buffer which will contain the next frame.
+    */
+    while ((curr_l2p_cntrl_block->bytesToBeRead > 0) && /* There is still data to read */
+           (rxReadPtr != (char *)0))                    /* There is still data in the buffer segement */
+    {
+        rxReadPtr = L2P_read_data_from_seg(rxReadPtr, curr_l2p_cntrl_block->dataToBeRead,
+                                           curr_l2p_cntrl_block->bytesToBeRead,
+                                           remainingSegSize, &bytesRead);
+        curr_l2p_cntrl_block->bytesToBeRead -= bytesRead;
+        remainingSegSize -= bytesRead;
+        curr_l2p_cntrl_block->dataToBeRead += bytesRead;
+
+        if ((rxReadPtr == (char *)0) && (totalSegSize < totalsize) && (curr_l2p_cntrl_block->bytesToBeRead != (U16)0))
+
+        {
+            /*
+            ** We have reached the end of the current Segment, so get the next.
+            */
+            curRxSeg = curr_l2p_cntrl_block->callbacks.Get_Next_Seg_Cb(batId, seg_hdr_ptr, &seg_hdr_ptr,  &segSize);
+            rxReadPtr = curRxSeg;
+            totalSegSize +=segSize;
+            remainingSegSize = segSize;
+        }
+
+        if ((curr_l2p_cntrl_block->bytesToBeRead == (U16)0) &&  /* We've finished writing the data */
+             (!curr_l2p_cntrl_block->cmdTagReceived))           /* but that data was the Command Tag  */
+        {
+            /*
+            ** now we have to write the AT Command Data
+            */
+            curr_l2p_cntrl_block->cmdTagReceived = 1;
+            curr_l2p_cntrl_block->dataToBeRead = (char *)curr_l2p_cntrl_block->rxBuf;    /* Next Write the AT Command Data */
+            curr_l2p_cntrl_block->bytesToBeRead = curr_l2p_cntrl_block->dataSize;
+        }
+    }
+
+    if (curr_l2p_cntrl_block->bytesToBeRead == (U16)0)
+    {
+        /*
+        ** We have built a complete message ... send it to the user .. 
+        */
+        curr_l2p_cntrl_block->callbacks.Msg_Rxd_Cb(batId, curr_l2p_cntrl_block->muxId,
+                                                    curr_l2p_cntrl_block->receivedCmdTag,
+                                                    curr_l2p_cntrl_block->rxBuf,
+                                                    curr_l2p_cntrl_block->dataSize);
+
+        /*
+        ** reset the Rx values
+        */
+        curr_l2p_cntrl_block->rxBuf = (char *)0;
+        curr_l2p_cntrl_block->muxId = 0;
+        curr_l2p_cntrl_block->cmdTagReceived = 0;
+        curr_l2p_cntrl_block->receivedCmdTag = 0;
+        curr_l2p_cntrl_block->dataSize = 0;
+        curr_l2p_cntrl_block->dataToBeRead = (char *)0;
+    }
+        
+    return L2P_STAT_SUCCESS;
+}
+
+
+/*
++--------------------------------------------------------------------+
+| PROJECT: BAT L2P          MODULE:   L2P                            |
+| STATE  : code             ROUTINE:  L2P_write_data_to_seg          |
++--------------------------------------------------------------------+
+
+   PURPOSE : L2P_write_data_to_seg is a local function to write a piece of data into a buffer segment. The buffer
+             segment may, or may not be big enough to hold the entire piece of data. If the segment is full when
+             the data has been written then the function will return a NULL pointer, otherwise it will return a pointer
+             to the next location to receive data.
+             The following is a list of the parameters, and their uses:
+
+             writePtr        : pointer to the start location to write the data to
+             dataPtr         : pointer to the data to be written
+             dataSize        : length of the data in dataPtr
+             remain_seg_size : The size of remaining space in the buffer segment
+             bytesWritten    : output parameter in order to return the actual number of bytes written into the segment.
+
+*/
+static char *L2P_write_data_to_seg(char *writePtr, char *dataPtr, U16 dataSize, U16 remain_seg_size,
+                                                               U16 *bytesWritten)
+{
+    char *retPtr;
+
+    if (remain_seg_size <= dataSize)
+    {
+        retPtr = (char *)0;
+        *bytesWritten = remain_seg_size;
+    }
+    else
+    {
+        retPtr = writePtr + dataSize;
+        *bytesWritten = dataSize;
+    }
+
+    memcpy(writePtr, dataPtr, *bytesWritten);
+
+    return retPtr;
+}
+
+
+/*
++--------------------------------------------------------------------+
+| PROJECT: BAT L2P          MODULE:   L2P                            |
+| STATE  : code             ROUTINE:  L2P_write_data_to_seg          |
++--------------------------------------------------------------------+
+
+   PURPOSE : L2P_read_data_from_seg is a local function to read a piece of data from a buffer segment, and write
+             it into a data structure (pointed to by writePtr). The buffer segment may, or may not be big enough to
+             hold the entire piece of data. If the end of the segment is reached when the data has been read then
+             the function will return a NULL pointer, otherwise it will return a pointer to the next location to read data
+             from. The following is a list of the parameters, and their uses:
+
+             readPtr         : pointer to the position in the segment to read from
+             writePtr        : pointer to the start location to write the data to
+             dataSize        : length of the data to be read from the segment
+             remain_seg_size : The size of remaining space in the buffer segment
+             bytesWritten    : output parameter in order to return the actual number of bytes written.
+
+*/
+static char *L2P_read_data_from_seg(char *readPtr, char *writePtr, U16 dataSize, U16 remain_seg_size,
+                                                                    U16 *bytesWritten)
+{
+    char *retPtr;
+
+    if (remain_seg_size <= dataSize)
+    {
+        retPtr = (char *)0;
+        *bytesWritten = remain_seg_size;
+    }
+    else
+    {
+        retPtr = readPtr + dataSize;
+        *bytesWritten = dataSize;
+    }
+
+    memcpy(writePtr, readPtr, *bytesWritten);
+
+    return retPtr;
+}
+