memorybanknvcrc.java

这是一个以JAVA编写的程序,本人还没有试过,是一个简单的温度控制系统

/*---------------------------------------------------------------------------
 * Copyright (C) 1999,2000 Dallas Semiconductor Corporation, All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Except as contained in this notice, the name of Dallas Semiconductor
 * shall not be used except as stated in the Dallas Semiconductor
 * Branding Policy.
 *---------------------------------------------------------------------------
 */

package com.dalsemi.onewire.container;

// imports
import com.dalsemi.onewire.OneWireException;
import com.dalsemi.onewire.adapter.OneWireIOException;
import com.dalsemi.onewire.utils.CRC16;
import com.dalsemi.onewire.container.OneWireContainer;


/**
 * Memory bank class for the NVRAM with build in CRC section of iButtons
 * and 1-Wire devices.
 *
 *  @version    0.00, 28 Aug 2000
 *  @author     DS
 */
class MemoryBankNVCRC
   extends MemoryBankNV
{

   //--------
   //-------- Static Final Variables
   //--------

   /**
     * Write Scratchpad Command
     */
   public static final byte READ_PAGE_WITH_CRC = ( byte ) 0xA5;

   //--------
   //-------- Variables
   //--------

   /**
    * Flag to indicate if read-continue is possible
    */
   protected boolean readContinuePossible;

   /**
    * Number of extra verify byte in the read CRC page
    */
   protected int numVerifyBytes;

   //--------
   //-------- Constructor
   //--------

   /**
    * Memory bank contstuctor.  Requires reference to the OneWireContainer
    * this memory bank resides on.
    */
   public MemoryBankNVCRC (OneWireContainer ibutton, ScratchPad scratch)
   {
      super(ibutton, scratch);

      // initialize attributes of this memory bank
      pageAutoCRC          = true;
      readContinuePossible = true;
      numVerifyBytes       = 0;
   }

   //--------
   //-------- I/O methods
   //--------

   /**
    * Read  page in the current bank with no
    * CRC checking (device or data). The resulting data from this API
    * may or may not be what is on the 1-Wire device.  It is recommends
    * that the data contain some kind of checking (CRC) like in the
    * readPagePacket() method or have the 1-Wire device provide the
    * CRC as in readPageCRC().  readPageCRC() however is not
    * supported on all memory types, see 'hasPageAutoCRC()'.
    * If neither is an option then this method could be called more
    * then once to at least verify that the same thing is read consistantly.
    *
    * @param  page          page number to read packet from
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPage() continious where the last one
    *                       led off and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to place read data into
    * @param  offset        offset into readBuf to place data
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readPage (int page, boolean readContinue, byte[] readBuf,
                         int offset)
      throws OneWireIOException, OneWireException
   {

      // all other pages
      readPageCRC(page, readContinue, readBuf, offset, null, extraInfoLength);
   }

   /**
    * Read  page with extra information in the current bank with no
    * CRC checking (device or data). The resulting data from this API
    * may or may not be what is on the 1-Wire device.  It is recommends
    * that the data contain some kind of checking (CRC) like in the
    * readPagePacket() method or have the 1-Wire device provide the
    * CRC as in readPageCRC().  readPageCRC() however is not
    * supported on all memory types, see 'hasPageAutoCRC()'.
    * If neither is an option then this method could be called more
    * then once to at least verify that the same thing is read consistantly.
    * See the method 'hasExtraInfo()' for a description of the optional
    * extra information some devices have.
    *
    * @param  page          page number to read packet from
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPage() continious where the last one
    *                       led off and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to place read data into
    * @param  offset        offset into readBuf to place data
    * @param  extraInfo     byte array to put extra info read into
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readPage (int page, boolean readContinue, byte[] readBuf,
                         int offset, byte[] extraInfo)
      throws OneWireIOException, OneWireException
   {

      // check if current bank is not scratchpad bank, or not page 0
      if (!this.extraInfo)
         throw new OneWireException(
            "Read extra information not supported on this memory bank");

      readPageCRC(page, readContinue, readBuf, offset, extraInfo,
                  extraInfoLength);
   }

   /**
    * Read a Universal Data Packet and extra information.  See the
    * method 'readPagePacket()' for a description of the packet structure.
    * See the method 'hasExtraInfo()' for a description of the optional
    * extra information some devices have.
    *
    * @param  page          page number to read packet from
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPagePacket() continious where the last one
    *                       stopped and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to put data read. Must have at least
    *                       'getMaxPacketDataLength()' elements.
    * @param  offset        offset into readBuf to place data
    * @param  extraInfo     byte array to put extra info read into
    *
    * @return  number of data bytes written to readBuf at the offset.
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public int readPagePacket (int page, boolean readContinue, byte[] readBuf,
                              int offset, byte[] extraInfo)
      throws OneWireIOException, OneWireException
   {
      byte[] raw_buf = new byte [pageLength];

      // read entire page with read page CRC
      readPageCRC(page, readContinue, raw_buf, 0, extraInfo, extraInfoLength);

      // check if length is realistic
      if (raw_buf [0] > maxPacketDataLength)
      {
         sp.forceVerify();

         throw new OneWireIOException("Invalid length in packet");
      }

      // verify the CRC is correct
      int abs_page = (startPhysicalAddress / pageLength) + page;
      if (CRC16.compute(raw_buf, 0, raw_buf [0] + 3, abs_page) == 0x0000B001)
      {

         // extract the data out of the packet
         System.arraycopy(raw_buf, 1, readBuf, offset, raw_buf [0]);

         // return the length
         return raw_buf [0];
      }
      else
      {
         sp.forceVerify();

         throw new OneWireIOException("Invalid CRC16 in packet read");
      }
   }

   /**
    * Read a complete memory page with CRC verification provided by the
    * device.  Not supported by all devices.  See the method
    * 'hasPageAutoCRC()'.
    *
    * @param  page          page number to read
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPagePacket() continious where the last one
    *                       stopped and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to put data read. Must have at least
    *                       'getMaxPacketDataLength()' elements.
    * @param  offset        offset into readBuf to place data
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readPageCRC (int page, boolean readContinue, byte[] readBuf,
                            int offset)
      throws OneWireIOException, OneWireException
   {
      readPageCRC(page, readContinue, readBuf, offset, null, extraInfoLength);
   }

   /**
    * Read a complete memory page with CRC verification provided by the
    * device with extra information.  Not supported by all devices.
    * See the method 'hasPageAutoCRC()'.
    * See the method 'hasExtraInfo()' for a description of the optional
    * extra information.
    *
    * @param  page          page number to read
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPagePacket() continious where the last one
    *                       stopped and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to put data read. Must have at least
    *                       'getMaxPacketDataLength()' elements.
    * @param  offset        offset into readBuf to place data
    * @param  extraInfo     byte array to put extra info read into
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   public void readPageCRC (int page, boolean readContinue, byte[] readBuf,
                            int offset, byte[] extraInfo)
      throws OneWireIOException, OneWireException
   {
      readPageCRC(page, readContinue, readBuf, offset, extraInfo,
                  extraInfoLength);
   }

   /**
    * Read a complete memory page with CRC verification provided by the
    * device with extra information.  Not supported by all devices.
    * If not extra information available then just call with extraLength=0.
    *
    * @param  page          page number to read
    * @param  readContinue  if 'true' then device read is continued without
    *                       re-selecting.  This can only be used if the new
    *                       readPagePacket() continious where the last one
    *                       stopped and it is inside a
    *                       'beginExclusive/endExclusive' block.
    * @param  readBuf       byte array to put data read. Must have at least
    *                       'getMaxPacketDataLength()' elements.
    * @param  offset        offset into readBuf to place data
    * @param  extraInfo     byte array to put extra info read into
    * @param  extraLength   length of extra information
    *
    * @throws OneWireIOException
    * @throws OneWireException
    */
   protected void readPageCRC (int page, boolean readContinue,
                               byte[] readBuf, int offset, byte[] extraInfo,
                               int extraLength)
      throws OneWireIOException, OneWireException
   {
      int    last_crc = 0;
      byte[] raw_buf;

      // only needs to be implemented if supported by hardware
      if (!pageAutoCRC)
         throw new OneWireException(
            "Read page with CRC not supported in this memory bank");

      // attempt to put device at max desired speed
      if (!readContinue)
         sp.checkSpeed();

      // check if read exceeds memory
      if (page > numberPages)
         throw new OneWireException("Read exceeds memory bank end");

      // see if need to access the device
      if (!readContinue ||!readContinuePossible)
      {

         // select the device
         if (!ib.adapter.select(ib.address))
         {
            sp.forceVerify();

            throw new OneWireIOException("Device select failed");
         }

         // build start reading memory block
         raw_buf     = new byte [3];
         raw_buf [0] = READ_PAGE_WITH_CRC;

         int addr = page * pageLength + startPhysicalAddress;

         raw_buf [1] = ( byte ) (addr & 0xFF);
         raw_buf [2] = ( byte ) (((addr & 0xFFFF) >>> 8) & 0xFF);

         // perform CRC16 on first part
         last_crc = CRC16.compute(raw_buf, 0, raw_buf.length, last_crc);

         // do the first block for command, TA1, TA2
         ib.adapter.dataBlock(raw_buf, 0, 3);
      }

      // pre-fill with 0xFF 
      raw_buf = new byte [pageLength + extraLength + 2 + numVerifyBytes];

      System.arraycopy(ffBlock, 0, raw_buf, 0, raw_buf.length);

      // send block to read data + extra info? + crc
      ib.adapter.dataBlock(raw_buf, 0, raw_buf.length);

      // check the CRC
      if (CRC16.compute(raw_buf, 0, raw_buf.length - numVerifyBytes, last_crc)
              != 0x0000B001)
      {
         sp.forceVerify();

         throw new OneWireIOException("Invalid CRC16 read from device");
      }

      // extract the page data
      System.arraycopy(raw_buf, 0, readBuf, offset, pageLength);

      // optional extract the extra info
      if (extraInfo != null)
         System.arraycopy(raw_buf, pageLength, extraInfo, 0, extraLength);
   }
}