diff --git a/services/audioflinger/MonoPipe.cpp b/services/audioflinger/MonoPipe.cpp
new file mode 100644
index 0000000..b0ddf83
--- /dev/null
+++ b/services/audioflinger/MonoPipe.cpp
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "MonoPipe"
+//#define LOG_NDEBUG 0
+
+#include <cutils/atomic.h>
+#include <cutils/compiler.h>
+#include <utils/Log.h>
+#include "MonoPipe.h"
+#include "roundup.h"
+
+namespace android {
+
+MonoPipe::MonoPipe(size_t maxFrames, NBAIO_Format format, bool writeCanBlock) :
+        NBAIO_Sink(format),
+        mMaxFrames(roundup(maxFrames)),
+        mBuffer(malloc(mMaxFrames * Format_frameSize(format))),
+        mFront(0),
+        mRear(0),
+        mWriteCanBlock(writeCanBlock)
+{
+    if (writeCanBlock) {
+        // compute sleep time to be about 2/3 of a full pipe;
+        // this gives a balance between risk of underrun vs. too-frequent wakeups
+        mSleep.tv_sec = 0;
+        uint64_t ns = mMaxFrames * (666666667 / Format_sampleRate(format));
+        if (ns > 999999999) {
+            ns = 999999999;
+        }
+        mSleep.tv_nsec = ns;
+    }
+}
+
+MonoPipe::~MonoPipe()
+{
+    free(mBuffer);
+}
+
+ssize_t MonoPipe::availableToWrite() const
+{
+    if (CC_UNLIKELY(!mNegotiated)) {
+        return NEGOTIATE;
+    }
+    ssize_t ret = mMaxFrames - (mRear - android_atomic_acquire_load(&mFront));
+    ALOG_ASSERT((0 <= ret) && (ret <= mMaxFrames));
+    return ret;
+}
+
+ssize_t MonoPipe::write(const void *buffer, size_t count)
+{
+    // count == 0 is unlikely and not worth checking for explicitly; will be handled automatically
+    if (CC_UNLIKELY(!mNegotiated)) {
+        return NEGOTIATE;
+    }
+    size_t totalFramesWritten = 0;
+    for (;;) {
+        size_t written = availableToWrite();
+        if (CC_LIKELY(written > count)) {
+            written = count;
+        }
+        size_t rear = mRear & (mMaxFrames - 1);
+        size_t part1 = mMaxFrames - rear;
+        if (part1 > written) {
+            part1 = written;
+        }
+        if (CC_LIKELY(part1 > 0)) {
+            memcpy((char *) mBuffer + (rear << mBitShift), buffer, part1 << mBitShift);
+            if (CC_UNLIKELY(rear + part1 == mMaxFrames)) {
+                size_t part2 = written - part1;
+                if (CC_LIKELY(part2 > 0)) {
+                    memcpy(mBuffer, (char *) buffer + (part1 << mBitShift), part2 << mBitShift);
+                }
+            }
+            android_atomic_release_store(written + mRear, &mRear);
+            totalFramesWritten += written;
+        }
+        if ((count -= written) == 0 || !mWriteCanBlock) {
+            break;
+        }
+        buffer = (char *) buffer + (written << mBitShift);
+        // simulate blocking I/O by sleeping
+        nanosleep(&mSleep, NULL);
+    }
+    mFramesWritten += totalFramesWritten;
+    return totalFramesWritten;
+}
+
+}   // namespace android