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      1 /*
      2  * Copyright (C) 2008-2014 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 <errno.h>
     18 #include <poll.h>
     19 #include <stdint.h>
     20 #include <string.h>
     21 #include <sys/cdefs.h>
     22 #include <sys/types.h>
     23 #include <unistd.h>
     24 
     25 #include <cutils/log.h>
     26 
     27 #include "InputEventReader.h"
     28 
     29 /*****************************************************************************/
     30 
     31 struct cw_event;
     32 
     33 InputEventCircularReader::InputEventCircularReader(size_t numEvents)
     34     : mBuffer(new cw_event[numEvents * 2])
     35     , mBufferEnd(mBuffer + numEvents)
     36     , mHead(mBuffer)
     37     , mCurr(mBuffer)
     38     , mFreeSpace(numEvents)
     39 {
     40 }
     41 
     42 InputEventCircularReader::~InputEventCircularReader()
     43 {
     44     delete [] mBuffer;
     45 }
     46 
     47 ssize_t InputEventCircularReader::fill(int fd)
     48 {
     49     size_t numEventsRead = 0;
     50     if (mFreeSpace) {
     51         const ssize_t nread = read(fd, mHead, mFreeSpace * sizeof(cw_event));
     52         if (nread<0 || nread % sizeof(cw_event)) {
     53             // we got a partial event!!
     54             return nread<0 ? -errno : -EINVAL;
     55         }
     56 
     57         numEventsRead = nread / sizeof(cw_event);
     58         if (numEventsRead) {
     59             mHead += numEventsRead;
     60             mFreeSpace -= numEventsRead;
     61             if (mHead > mBufferEnd) {
     62                 size_t s = mHead - mBufferEnd;
     63                 memcpy(mBuffer, mBufferEnd, s * sizeof(cw_event));
     64                 mHead = mBuffer + s;
     65             }
     66         }
     67     }
     68 
     69     return numEventsRead;
     70 }
     71 
     72 ssize_t InputEventCircularReader::readEvent(cw_event const** events)
     73 {
     74     *events = mCurr;
     75     ssize_t available = (mBufferEnd - mBuffer) - mFreeSpace;
     76     return available ? 1 : 0;
     77 }
     78 
     79 void InputEventCircularReader::next()
     80 {
     81     mCurr++;
     82     mFreeSpace++;
     83     if (mCurr >= mBufferEnd) {
     84         mCurr = mBuffer;
     85     }
     86 }
     87