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      1 /*
      2  * Copyright (C) 2008 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 #include <stdint.h>
     18 #include <errno.h>
     19 #include <poll.h>
     20 #include <string.h>
     21 #include <unistd.h>
     22 
     23 #include <sys/cdefs.h>
     24 #include <sys/types.h>
     25 
     26 #include <linux/input.h>
     27 
     28 #include <cutils/log.h>
     29 
     30 #include "InputEventReader.h"
     31 
     32 /*****************************************************************************/
     33 
     34 struct input_event;
     35 
     36 InputEventCircularReader::InputEventCircularReader(size_t numEvents)
     37     : mBuffer(new input_event[numEvents * 2]),
     38       mBufferEnd(mBuffer + numEvents),
     39       mHead(mBuffer),
     40       mCurr(mBuffer),
     41       mFreeSpace(numEvents)
     42 {
     43 }
     44 
     45 InputEventCircularReader::~InputEventCircularReader()
     46 {
     47     delete [] mBuffer;
     48 }
     49 
     50 ssize_t InputEventCircularReader::fill(int fd)
     51 {
     52     size_t numEventsRead = 0;
     53     if (mFreeSpace) {
     54         const ssize_t nread = read(fd, mHead, mFreeSpace * sizeof(input_event));
     55         if (nread<0 || nread % sizeof(input_event)) {
     56             // we got a partial event!!
     57             return nread<0 ? -errno : -EINVAL;
     58         }
     59 
     60         numEventsRead = nread / sizeof(input_event);
     61         if (numEventsRead) {
     62             mHead += numEventsRead;
     63             mFreeSpace -= numEventsRead;
     64             if (mHead > mBufferEnd) {
     65                 size_t s = mHead - mBufferEnd;
     66                 memcpy(mBuffer, mBufferEnd, s * sizeof(input_event));
     67                 mHead = mBuffer + s;
     68             }
     69         }
     70     }
     71 
     72     return numEventsRead;
     73 }
     74 
     75 ssize_t InputEventCircularReader::readEvent(input_event const** events)
     76 {
     77     *events = mCurr;
     78     ssize_t available = (mBufferEnd - mBuffer) - mFreeSpace;
     79     return available ? 1 : 0;
     80 }
     81 
     82 void InputEventCircularReader::next()
     83 {
     84     mCurr++;
     85     mFreeSpace++;
     86     if (mCurr >= mBufferEnd) {
     87         mCurr = mBuffer;
     88     }
     89 }
     90