Forking https://os.mbed.com/users/cam/code/Modbus/ to work for NUCLEO 64 boards

Fork of Cam's original FreeModbus port (https://os.mbed.com/users/cam/code/Modbus/)

Change: - Serial implementation to work for NUCLEO 64 boards and receive interrupts instead of timer. (see `portserial.cpp`)

Added: - Custom RTU mode. Allows for external implementation of packet receiving and sending. Sends and receives packets as whole frames (address + PDU) (i.e. this was added for a custom LoRa implementation). implement `xMBRTUCustGetPDU` and `xMBRTUCustSendResponse` (see `mbport.h`) and call `eMBRTUCustomInit( address )`. implementations need to be fully initialised as `eMBRTUCustomInit` only sets the address and nothing else.

Revision:
0:0453a0a7e500
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbfuncother.cpp	Thu Apr 15 12:10:34 2010 +0000
@@ -0,0 +1,88 @@
+/* 
+ * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
+ * Copyright (c) 2006 Christian Walter <wolti@sil.at>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * File: $Id: mbfuncother.c,v 1.8 2006/12/07 22:10:34 wolti Exp $
+ */
+
+/* ----------------------- System includes ----------------------------------*/
+#include "stdlib.h"
+#include "string.h"
+
+/* ----------------------- Platform includes --------------------------------*/
+#include "port.h"
+
+/* ----------------------- Modbus includes ----------------------------------*/
+#include "mb.h"
+#include "mbframe.h"
+#include "mbproto.h"
+#include "mbconfig.h"
+
+#if MB_FUNC_OTHER_REP_SLAVEID_ENABLED > 0
+
+/* ----------------------- Static variables ---------------------------------*/
+static UCHAR    ucMBSlaveID[MB_FUNC_OTHER_REP_SLAVEID_BUF];
+static USHORT   usMBSlaveIDLen;
+
+/* ----------------------- Start implementation -----------------------------*/
+
+eMBErrorCode
+eMBSetSlaveID( UCHAR ucSlaveID, BOOL xIsRunning,
+               UCHAR const *pucAdditional, USHORT usAdditionalLen )
+{
+    eMBErrorCode    eStatus = MB_ENOERR;
+
+    /* the first byte and second byte in the buffer is reserved for
+     * the parameter ucSlaveID and the running flag. The rest of
+     * the buffer is available for additional data. */
+    if( usAdditionalLen + 2 < MB_FUNC_OTHER_REP_SLAVEID_BUF )
+    {
+        usMBSlaveIDLen = 0;
+        ucMBSlaveID[usMBSlaveIDLen++] = ucSlaveID;
+        ucMBSlaveID[usMBSlaveIDLen++] = ( UCHAR )( xIsRunning ? 0xFF : 0x00 );
+        if( usAdditionalLen > 0 )
+        {
+            memcpy( &ucMBSlaveID[usMBSlaveIDLen], pucAdditional,
+                    ( size_t )usAdditionalLen );
+            usMBSlaveIDLen += usAdditionalLen;
+        }
+    }
+    else
+    {
+        eStatus = MB_ENORES;
+    }
+    return eStatus;
+}
+
+eMBException
+eMBFuncReportSlaveID( UCHAR * pucFrame, USHORT * usLen )
+{
+    memcpy( &pucFrame[MB_PDU_DATA_OFF], &ucMBSlaveID[0], ( size_t )usMBSlaveIDLen );
+    *usLen = ( USHORT )( MB_PDU_DATA_OFF + usMBSlaveIDLen );
+    return MB_EX_NONE;
+}
+
+#endif