commit ed99c2b5a99a8bfc163a6ffa0b767c82032b09b5
author Glenn Kasten <gkasten@google.com> Mon Dec 12 08:31:24 2016 -0800
committer Glenn Kasten <gkasten@google.com> Fri Dec 16 15:42:28 2016 -0800
tree 83282572ca34b0e9c03acf1f5d5f39336e74cac2
parent ae9f2761b79b112f42c285a288b3ecb7f919b345

NBAIO: re-implement NBAIO Pipe and MonoPipe using fifo

Also removed const from NBAIO_Sink::availableToWrite() because
at least one implementation can no longer implement the const-ness.

Test: normal mixer, tee sink, and remote submix still work
Change-Id: I8461177efdf53bba8295b147e97835b018804903

media/libnbaio/MonoPipeReader.cpp

diff --git a/media/libnbaio/MonoPipeReader.cpp b/media/libnbaio/MonoPipeReader.cpp
index 01dc524..a9b4d18 100644
--- a/media/libnbaio/MonoPipeReader.cpp
+++ b/media/libnbaio/MonoPipeReader.cpp
@@ -25,7 +25,7 @@
 
 MonoPipeReader::MonoPipeReader(MonoPipe* pipe) :
         NBAIO_Source(pipe->mFormat),
-        mPipe(pipe)
+        mPipe(pipe), mFifoReader(mPipe->mFifo, true /*throttlesWriter*/)
 {
 }
 
@@ -38,38 +38,21 @@
     if (CC_UNLIKELY(!mNegotiated)) {
         return NEGOTIATE;
     }
-    ssize_t ret = android_atomic_acquire_load(&mPipe->mRear) - mPipe->mFront;
-    ALOG_ASSERT((0 <= ret) && ((size_t) ret <= mPipe->mMaxFrames));
+    ssize_t ret = mFifoReader.available();
+    ALOG_ASSERT(ret <= mPipe->mMaxFrames);
     return ret;
 }
 
 ssize_t MonoPipeReader::read(void *buffer, size_t count)
 {
     // count == 0 is unlikely and not worth checking for explicitly; will be handled automatically
-    ssize_t red = availableToRead();
-    if (CC_UNLIKELY(red <= 0)) {
-        return red;
+    ssize_t actual = mFifoReader.read(buffer, count);
+    ALOG_ASSERT(actual <= count);
+    if (CC_UNLIKELY(actual <= 0)) {
+        return actual;
     }
-    if (CC_LIKELY((size_t) red > count)) {
-        red = count;
-    }
-    size_t front = mPipe->mFront & (mPipe->mMaxFrames - 1);
-    size_t part1 = mPipe->mMaxFrames - front;
-    if (part1 > (size_t) red) {
-        part1 = red;
-    }
-    if (CC_LIKELY(part1 > 0)) {
-        memcpy(buffer, (char *) mPipe->mBuffer + (front * mFrameSize), part1 * mFrameSize);
-        if (CC_UNLIKELY(front + part1 == mPipe->mMaxFrames)) {
-            size_t part2 = red - part1;
-            if (CC_LIKELY(part2 > 0)) {
-                memcpy((char *) buffer + (part1 * mFrameSize), mPipe->mBuffer, part2 * mFrameSize);
-            }
-        }
-        android_atomic_release_store(red + mPipe->mFront, &mPipe->mFront);
-        mFramesRead += red;
-    }
-    return red;
+    mFramesRead += (size_t) actual;
+    return actual;
 }
 
 void MonoPipeReader::onTimestamp(const ExtendedTimestamp &timestamp)