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105 lines
4.0 KiB
C
105 lines
4.0 KiB
C
/*
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* FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
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* Copyright (c) 2006-2018 Christian Walter <cwalter@embedded-solutions.at>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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/* ----------------------- System includes ----------------------------------*/
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#include "stdint.h"
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/* ----------------------- Defines ------------------------------------------*/
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#define BITS_UINT8 8U
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/* ----------------------- Start implementation -----------------------------*/
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void
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xMBUtilSetBits(uint8_t * ucByteBuf, uint16_t usBitOffset, uint8_t ucNBits,
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uint8_t ucValue)
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{
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uint16_t usWordBuf;
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uint16_t usMask;
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uint16_t usByteOffset;
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uint16_t usNPreBits;
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uint16_t usValue = ucValue;
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// assert( ucNBits <= 8 );
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// assert( ( size_t )BITS_UINT8 == sizeof( uint8_t ) * 8 );
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/* Calculate byte offset for first byte containing the bit values starting
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* at usBitOffset. */
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usByteOffset = (uint16_t)((usBitOffset) / BITS_UINT8);
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/* How many bits precede our bits to set. */
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usNPreBits = (uint16_t)(usBitOffset - usByteOffset * BITS_UINT8);
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/* Move bit field into position over bits to set */
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usValue <<= usNPreBits;
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/* Prepare a mask for setting the new bits. */
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usMask = (uint16_t)((1 << (uint16_t)ucNBits) - 1);
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usMask <<= usBitOffset - usByteOffset * BITS_UINT8;
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/* copy bits into temporary storage. */
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usWordBuf = ucByteBuf[usByteOffset];
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usWordBuf |= ucByteBuf[usByteOffset + 1] << BITS_UINT8;
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/* Zero out bit field bits and then or value bits into them. */
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usWordBuf = (uint16_t)((usWordBuf & (~usMask)) | usValue);
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/* move bits back into storage */
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ucByteBuf[usByteOffset] = (uint8_t)(usWordBuf & 0xFF);
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ucByteBuf[usByteOffset + 1] = (uint8_t)(usWordBuf >> BITS_UINT8);
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}
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uint8_t
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xMBUtilGetBits(uint8_t* ucByteBuf, uint16_t usBitOffset, uint8_t ucNBits)
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{
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uint16_t usWordBuf;
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uint16_t usMask;
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uint16_t usByteOffset;
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uint16_t usNPreBits;
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/* Calculate byte offset for first byte containing the bit values starting
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* at usBitOffset. */
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usByteOffset = (uint16_t)((usBitOffset) / BITS_UINT8);
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/* How many bits precede our bits to set. */
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usNPreBits = (uint16_t)(usBitOffset - usByteOffset * BITS_UINT8);
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/* Prepare a mask for setting the new bits. */
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usMask = (uint16_t)((1 << (uint16_t)ucNBits) - 1);
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/* copy bits into temporary storage. */
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usWordBuf = ucByteBuf[usByteOffset];
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usWordBuf |= ucByteBuf[usByteOffset + 1] << BITS_UINT8;
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/* throw away unneeded bits. */
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usWordBuf >>= usNPreBits;
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/* mask away bits above the requested bitfield. */
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usWordBuf &= usMask;
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return (uint8_t)usWordBuf;
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} |