modbus/functions/mbutils.c

/****************************************************************************
 * apps/functions/mbutils.c
 *
 * 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.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include "port.h"

#include "modbus/mb.h"
#include "modbus/mbproto.h"

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

#define BITS_uint8_t      8U

/****************************************************************************
 * Public Functions
 ****************************************************************************/

void xMBUtilSetBits(uint8_t *ucByteBuf, uint16_t usBitOffset,
                    uint8_t ucNBits, uint8_t ucValue)
{
  uint16_t usWordBuf;
  uint16_t usMask;
  uint16_t usByteOffset;
  uint16_t usNPreBits;
  uint16_t usValue = ucValue;

  ASSERT(ucNBits <= 8);
  ASSERT((size_t)BITS_uint8_t == sizeof(uint8_t) * 8);

  /* Calculate byte offset for first byte containing the bit values starting
   * at usBitOffset.
   */

  usByteOffset = (uint16_t)((usBitOffset) / BITS_uint8_t);

  /* How many bits precede our bits to set. */

  usNPreBits = (uint16_t)(usBitOffset - usByteOffset * BITS_uint8_t);

  /* Move bit field into position over bits to set */

  usValue <<= usNPreBits;

  /* Prepare a mask for setting the new bits. */

  usMask = (uint16_t)((1 << (uint16_t) ucNBits) - 1);
  usMask <<= usBitOffset - usByteOffset * BITS_uint8_t;

  /* copy bits into temporary storage. */

  usWordBuf = ucByteBuf[usByteOffset];
  usWordBuf |= ucByteBuf[usByteOffset + 1] << BITS_uint8_t;

  /* Zero out bit field bits and then or value bits into them. */

  usWordBuf = (uint16_t)((usWordBuf & (~usMask)) | usValue);

  /* move bits back into storage */

  ucByteBuf[usByteOffset] = (uint8_t)(usWordBuf & 0xFF);
  ucByteBuf[usByteOffset + 1] = (uint8_t)(usWordBuf >> BITS_uint8_t);
}

uint8_t xMBUtilGetBits(uint8_t *ucByteBuf, uint16_t usBitOffset, uint8_t ucNBits)
{
  uint16_t usWordBuf;
  uint16_t usMask;
  uint16_t usByteOffset;
  uint16_t usNPreBits;

  /* Calculate byte offset for first byte containing the bit values starting
   * at usBitOffset.
   */

  usByteOffset = (uint16_t)((usBitOffset) / BITS_uint8_t);

  /* How many bits precede our bits to set. */

  usNPreBits = (uint16_t)(usBitOffset - usByteOffset * BITS_uint8_t);

  /* Prepare a mask for setting the new bits. */

  usMask = (uint16_t)((1 << (uint16_t) ucNBits) - 1);

  /* copy bits into temporary storage. */

  usWordBuf = ucByteBuf[usByteOffset];
  usWordBuf |= ucByteBuf[usByteOffset + 1] << BITS_uint8_t;

  /* throw away unneeded bits. */

  usWordBuf >>= usNPreBits;

  /* mask away bits above the requested bitfield. */

  usWordBuf &= usMask;
  return (uint8_t) usWordBuf;
}

eMBException prveMBError2Exception(eMBErrorCode eErrorCode)
{
  eMBException eStatus;

  switch (eErrorCode)
    {
      case MB_ENOERR:
        eStatus = MB_EX_NONE;
        break;

      case MB_ENOREG:
        eStatus = MB_EX_ILLEGAL_DATA_ADDRESS;
        break;

      case MB_ETIMEDOUT:
        eStatus = MB_EX_SLAVE_BUSY;
        break;

      default:
        eStatus = MB_EX_SLAVE_DEVICE_FAILURE;
        break;
    }

  return eStatus;
}