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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.nfc.tech;
     18 
     19 import android.nfc.Tag;
     20 import android.os.Bundle;
     21 import android.os.RemoteException;
     22 
     23 import java.io.IOException;
     24 
     25 /**
     26  * Provides access to NFC-V (ISO 15693) properties and I/O operations on a {@link Tag}.
     27  *
     28  * <p>Acquire a {@link NfcV} object using {@link #get}.
     29  * <p>The primary NFC-V I/O operation is {@link #transceive}. Applications must
     30  * implement their own protocol stack on top of {@link #transceive}.
     31  *
     32  * <p class="note"><strong>Note:</strong> Methods that perform I/O operations
     33  * require the {@link android.Manifest.permission#NFC} permission.
     34  */
     35 public final class NfcV extends BasicTagTechnology {
     36     /** @hide */
     37     public static final String EXTRA_RESP_FLAGS = "respflags";
     38 
     39     /** @hide */
     40     public static final String EXTRA_DSFID = "dsfid";
     41 
     42     private byte mRespFlags;
     43     private byte mDsfId;
     44 
     45     /**
     46      * Get an instance of {@link NfcV} for the given tag.
     47      * <p>Returns null if {@link NfcV} was not enumerated in {@link Tag#getTechList}.
     48      * This indicates the tag does not support NFC-V.
     49      * <p>Does not cause any RF activity and does not block.
     50      *
     51      * @param tag an NFC-V compatible tag
     52      * @return NFC-V object
     53      */
     54     public static NfcV get(Tag tag) {
     55         if (!tag.hasTech(TagTechnology.NFC_V)) return null;
     56         try {
     57             return new NfcV(tag);
     58         } catch (RemoteException e) {
     59             return null;
     60         }
     61     }
     62 
     63     /** @hide */
     64     public NfcV(Tag tag) throws RemoteException {
     65         super(tag, TagTechnology.NFC_V);
     66         Bundle extras = tag.getTechExtras(TagTechnology.NFC_V);
     67         mRespFlags = extras.getByte(EXTRA_RESP_FLAGS);
     68         mDsfId = extras.getByte(EXTRA_DSFID);
     69     }
     70 
     71     /**
     72      * Return the Response Flag bytes from tag discovery.
     73      *
     74      * <p>Does not cause any RF activity and does not block.
     75      *
     76      * @return Response Flag bytes
     77      */
     78     public byte getResponseFlags() {
     79         return mRespFlags;
     80     }
     81 
     82     /**
     83      * Return the DSF ID bytes from tag discovery.
     84      *
     85      * <p>Does not cause any RF activity and does not block.
     86      *
     87      * @return DSF ID bytes
     88      */
     89     public byte getDsfId() {
     90         return mDsfId;
     91     }
     92 
     93     /**
     94      * Send raw NFC-V commands to the tag and receive the response.
     95      *
     96      * <p>Applications must not append the CRC to the payload,
     97      * it will be automatically calculated. The application does
     98      * provide FLAGS, CMD and PARAMETER bytes.
     99      *
    100      * <p>Use {@link #getMaxTransceiveLength} to retrieve the maximum amount of bytes
    101      * that can be sent with {@link #transceive}.
    102      *
    103      * <p>This is an I/O operation and will block until complete. It must
    104      * not be called from the main application thread. A blocked call will be canceled with
    105      * {@link IOException} if {@link #close} is called from another thread.
    106      *
    107      * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
    108      *
    109      * @param data bytes to send
    110      * @return bytes received in response
    111      * @throws TagLostException if the tag leaves the field
    112      * @throws IOException if there is an I/O failure, or this operation is canceled
    113      */
    114     public byte[] transceive(byte[] data) throws IOException {
    115         return transceive(data, true);
    116     }
    117 
    118 
    119     /**
    120      * Return the maximum number of bytes that can be sent with {@link #transceive}.
    121      * @return the maximum number of bytes that can be sent with {@link #transceive}.
    122      */
    123     public int getMaxTransceiveLength() {
    124         return getMaxTransceiveLengthInternal();
    125     }
    126 }
    127