mbutils.h

00001 /* 
00002  * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
00003  * Copyright (c) 2006 Christian Walter <wolti@sil.at>
00004  * All rights reserved.
00005  *
00006  * Redistribution and use in source and binary forms, with or without
00007  * modification, are permitted provided that the following conditions
00008  * are met:
00009  * 1. Redistributions of source code must retain the above copyright
00010  *    notice, this list of conditions and the following disclaimer.
00011  * 2. Redistributions in binary form must reproduce the above copyright
00012  *    notice, this list of conditions and the following disclaimer in the
00013  *    documentation and/or other materials provided with the distribution.
00014  * 3. The name of the author may not be used to endorse or promote products
00015  *    derived from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
00018  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00019  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
00020  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
00021  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
00022  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
00023  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
00024  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
00025  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
00026  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00027  *
00028  * File: $Id: mbutils.h,v 1.5 2006/12/07 22:10:34 wolti Exp $
00029  */
00030 
00031 #ifndef _MB_UTILS_H
00032 #define _MB_UTILS_H
00033 
00034 #ifdef __cplusplus
00035 PR_BEGIN_EXTERN_C
00036 #endif
00037 /*! \defgroup modbus_utils Utilities
00038  *
00039  * This module contains some utility functions which can be used by
00040  * the application. It includes some special functions for working with
00041  * bitfields backed by a character array buffer.
00042  *
00043  */
00044 /*! \addtogroup modbus_utils
00045  *  @{
00046  */
00047 /*! \brief Function to set bits in a byte buffer.
00048  *
00049  * This function allows the efficient use of an array to implement bitfields.
00050  * The array used for storing the bits must always be a multiple of two
00051  * bytes. Up to eight bits can be set or cleared in one operation.
00052  *
00053  * \param ucByteBuf A buffer where the bit values are stored. Must be a
00054  *   multiple of 2 bytes. No length checking is performed and if
00055  *   usBitOffset / 8 is greater than the size of the buffer memory contents
00056  *   is overwritten.
00057  * \param usBitOffset The starting address of the bits to set. The first
00058  *   bit has the offset 0.
00059  * \param ucNBits Number of bits to modify. The value must always be smaller
00060  *   than 8.
00061  * \param ucValues Thew new values for the bits. The value for the first bit
00062  *   starting at <code>usBitOffset</code> is the LSB of the value
00063  *   <code>ucValues</code>
00064  *
00065  * \code
00066  * ucBits[2] = {0, 0};
00067  *
00068  * // Set bit 4 to 1 (read: set 1 bit starting at bit offset 4 to value 1)
00069  * xMBUtilSetBits( ucBits, 4, 1, 1 );
00070  *
00071  * // Set bit 7 to 1 and bit 8 to 0.
00072  * xMBUtilSetBits( ucBits, 7, 2, 0x01 );
00073  *
00074  * // Set bits 8 - 11 to 0x05 and bits 12 - 15 to 0x0A;
00075  * xMBUtilSetBits( ucBits, 8, 8, 0x5A);
00076  * \endcode
00077  */
00078 void            xMBUtilSetBits( UCHAR * ucByteBuf, USHORT usBitOffset,
00079                                 UCHAR ucNBits, UCHAR ucValues );
00080 
00081 /*! \brief Function to read bits in a byte buffer.
00082  *
00083  * This function is used to extract up bit values from an array. Up to eight
00084  * bit values can be extracted in one step.
00085  *
00086  * \param ucByteBuf A buffer where the bit values are stored.
00087  * \param usBitOffset The starting address of the bits to set. The first
00088  *   bit has the offset 0.
00089  * \param ucNBits Number of bits to modify. The value must always be smaller
00090  *   than 8.
00091  *
00092  * \code
00093  * UCHAR ucBits[2] = {0, 0};
00094  * UCHAR ucResult;
00095  *
00096  * // Extract the bits 3 - 10.
00097  * ucResult = xMBUtilGetBits( ucBits, 3, 8 );
00098  * \endcode
00099  */
00100 UCHAR           xMBUtilGetBits( UCHAR * ucByteBuf, USHORT usBitOffset,
00101                                 UCHAR ucNBits );
00102 
00103 /*! @} */
00104 
00105 #ifdef __cplusplus
00106 PR_END_EXTERN_C
00107 #endif
00108 #endif