/*--------------------------------------------------------------------------- * 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 Scratchpad section of NVRAM iButtons and * 1-Wire devices. * * @version 0.00, 28 Aug 2000 * @author DS */ class MemoryBankScratchCRC extends MemoryBankScratchEx { //-------- //-------- Constructor //-------- /** * Memory bank contstuctor. Requires reference to the OneWireContainer * this memory bank resides on. */ public MemoryBankScratchCRC (OneWireContainer ibutton) { super(ibutton); // initialize attributes of this memory bank - DEFAULT: DS1963L scratchapd bankDescription = "Scratchpad with CRC"; pageAutoCRC = true; // default copy scratchpad command COPY_SCRATCHPAD_COMMAND = ( byte ) 0x55; } //-------- //-------- PagedMemoryBank I/O methods //-------- /** * 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 { byte[] extraInfo = new byte [extraInfoLength]; readPageCRC(page, readContinue, readBuf, offset, extraInfo); } /** * 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 'haveExtraInfo()' 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 { // 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) checkSpeed(); // check if read exceeds memory if (page > numberPages) throw new OneWireException("Read exceeds memory bank end"); // read the scratchpad readScratchpad(readBuf, offset, pageLength, extraInfo); } //-------- //-------- ScratchPad methods //-------- /** * Read the scratchpad page of memory from a NVRAM device * This method reads and returns the entire scratchpad after the byte * offset regardless of the actual ending offset * * @param readBuf byte array to place read data into * length of array is always pageLength. * @param offset offset into readBuf to pug data * @param len length in bytes to read * @param extraInfo byte array to put extra info read into * (TA1, TA2, e/s byte) * length of array is always extraInfoLength. * Can be 'null' if extra info is not needed. * * @throws OneWireIOException * @throws OneWireException */ public void readScratchpad (byte[] readBuf, int offset, int len, byte[] extraInfo) throws OneWireIOException, OneWireException { int i; // select the device if (!ib.adapter.select(ib.address)) { forceVerify(); throw new OneWireIOException("Device select failed"); } // build block byte[] raw_buf = new byte [extraInfoLength + pageLength + 3]; raw_buf [0] = READ_SCRATCHPAD_COMMAND; System.arraycopy(ffBlock, 0, raw_buf, 1, raw_buf.length - 1); // send block, command + (extra) + page data + CRC ib.adapter.dataBlock(raw_buf, 0, raw_buf.length); // get the starting offset to see when the crc will show up int addr = raw_buf [1]; addr = (addr | ((raw_buf [2] << 8) & 0xFF00)) & 0xFFFF; int num_crc = 35 - (addr & 0x001F) + extraInfoLength; // check crc of entire block if (CRC16.compute(raw_buf, 0, num_crc, 0) != 0x0000B001) { forceVerify(); throw new OneWireIOException("Invalid CRC16 read from device"); } // optionally extract the extra info if (extraInfo != null) System.arraycopy(raw_buf, 1, extraInfo, 0, extraInfoLength); // extract the page data System.arraycopy(raw_buf, extraInfoLength + 1, readBuf, 0, pageLength); } }