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