nuttx-apps/include/modbus/mbutils.h

/****************************************************************************
 * apps/include/modbus/mbutils.h
 *
 * FreeModbus Library: 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.
 *
 ****************************************************************************/

#ifndef __APPS_INCLUDE_MODBUS_MBUTILS_H
#define __APPS_INCLUDE_MODBUS_MBUTILS_H

#ifdef __cplusplus
extern "C"
{
#endif

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* This module contains some utility functions which can be used by
 * the application. It includes some special functions for working with
 * bitfields backed by a character array buffer.
 */

/* Function to set bits in a byte buffer.
 *
 * This function allows the efficient use of an array to implement bitfields.
 * The array used for storing the bits must always be a multiple of two
 * bytes. Up to eight bits can be set or cleared in one operation.
 *
 * Input Parameters:
 *  ucByteBuf A buffer where the bit values are stored. Must be a
 *     multiple of 2 bytes. No length checking is performed and if
 *     usBitOffset / 8 is greater than the size of the buffer memory contents
 *     is overwritten.
 *  usBitOffset The starting address of the bits to set. The first
 *     bit has the offset 0.
 *  ucNBits Number of bits to modify. The value must always be smaller
 *     than 8.
 *  ucValues Thew new values for the bits. The value for the first bit
 *     starting at usBitOffset is the LSB of the value ucValues
 *
 *   ucBits[2] = {0, 0};
 *
 *   // Set bit 4 to 1 (read: set 1 bit starting at bit offset 4 to value 1)
 *
 *   xMBUtilSetBits(ucBits, 4, 1, 1);
 *
 *   // Set bit 7 to 1 and bit 8 to 0.
 *
 *   xMBUtilSetBits(ucBits, 7, 2, 0x01);
 *
 *   // Set bits 8 - 11 to 0x05 and bits 12 - 15 to 0x0A;
 *
 *   xMBUtilSetBits(ucBits, 8, 8, 0x5A);
 */

void xMBUtilSetBits(uint8_t *ucByteBuf, uint16_t usBitOffset,
                    uint8_t ucNBits, uint8_t ucValues);

/* Function to read bits in a byte buffer.
 *
 * This function is used to extract up bit values from an array. Up to eight
 * bit values can be extracted in one step.
 *
 * Input Parameters:
 *  ucByteBuf A buffer where the bit values are stored.
 *  usBitOffset The starting address of the bits to set. The first
 *     bit has the offset 0.
 *  ucNBits Number of bits to modify. The value must always be smaller
 *     than 8.
 *
 *   uint8_t ucBits[2] = {0, 0};
 *   uint8_t ucResult;
 *
 *   // Extract the bits 3 - 10.
 *
 *   ucResult = xMBUtilGetBits(ucBits, 3, 8);
 */

uint8_t xMBUtilGetBits(uint8_t *ucByteBuf, uint16_t usBitOffset, uint8_t ucNBits);

#ifdef __cplusplus
}
#endif

#endif /* __APPS_INCLUDE_MODBUS_MBUTILS_H */