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      1 /*
      2  * Copyright (C) 2012 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 #define LOG_TAG "PipeReader"
     18 //#define LOG_NDEBUG 0
     19 
     20 #include <cutils/compiler.h>
     21 #include <cutils/atomic.h>
     22 #include <utils/Log.h>
     23 #include <media/nbaio/PipeReader.h>
     24 
     25 namespace android {
     26 
     27 PipeReader::PipeReader(Pipe& pipe) :
     28         NBAIO_Source(pipe.mFormat),
     29         mPipe(pipe), mFifoReader(mPipe.mFifo, false /*throttlesWriter*/, true /*flush*/),
     30         mFramesOverrun(0),
     31         mOverruns(0)
     32 {
     33     android_atomic_inc(&pipe.mReaders);
     34 }
     35 
     36 PipeReader::~PipeReader()
     37 {
     38 #if !LOG_NDEBUG
     39     int32_t readers =
     40 #else
     41     (void)
     42 #endif
     43             android_atomic_dec(&mPipe.mReaders);
     44     ALOG_ASSERT(readers > 0);
     45 }
     46 
     47 ssize_t PipeReader::availableToRead()
     48 {
     49     if (CC_UNLIKELY(!mNegotiated)) {
     50         return NEGOTIATE;
     51     }
     52     size_t lost;
     53     ssize_t avail = mFifoReader.available(&lost);
     54     if (avail == -EOVERFLOW || lost > 0) {
     55         mFramesOverrun += lost;
     56         ++mOverruns;
     57         avail = OVERRUN;
     58     }
     59     return avail;
     60 }
     61 
     62 ssize_t PipeReader::read(void *buffer, size_t count)
     63 {
     64     size_t lost;
     65     ssize_t actual = mFifoReader.read(buffer, count, NULL /*timeout*/, &lost);
     66     ALOG_ASSERT(actual <= count);
     67     if (actual == -EOVERFLOW || lost > 0) {
     68         mFramesOverrun += lost;
     69         ++mOverruns;
     70         actual = OVERRUN;
     71     }
     72     if (actual <= 0) {
     73         return actual;
     74     }
     75     mFramesRead += (size_t) actual;
     76     return actual;
     77 }
     78 
     79 ssize_t PipeReader::flush()
     80 {
     81     if (CC_UNLIKELY(!mNegotiated)) {
     82         return NEGOTIATE;
     83     }
     84     size_t lost;
     85     ssize_t flushed = mFifoReader.flush(&lost);
     86     if (flushed == -EOVERFLOW || lost > 0) {
     87         mFramesOverrun += lost;
     88         ++mOverruns;
     89         flushed = OVERRUN;
     90     }
     91     if (flushed <= 0) {
     92         return flushed;
     93     }
     94     mFramesRead += (size_t) flushed;  // we consider flushed frames as read, but not lost frames
     95     return flushed;
     96 }
     97 
     98 }   // namespace android
     99