am 3bf99265: Merge "Fix AudioTrack flush pointer wrap" into mnc-dev

    size_t increment = mFrameCountP2 << 1;

    size_t mask = increment - 1;

    audio_track_cblk_t* cblk = mCblk;

    // mFlush is 32 bits concatenated as [ flush_counter ] [ newfront_offset ]

    // Should newFlush = cblk->u.mStreaming.mRear?  Only problem is

    // if you want to flush twice to the same rear location after a 32 bit wrap.

    int32_t newFlush = (cblk->u.mStreaming.mRear & mask) |

                        ((cblk->u.mStreaming.mFlush & ~mask) + increment);

    android_atomic_release_store(newFlush, &cblk->u.mStreaming.mFlush);

        front = cblk->u.mStreaming.mFront;

        if (flush != mFlush) {

            // effectively obtain then release whatever is in the buffer

            size_t mask = (mFrameCountP2 << 1) - 1;

            const size_t overflowBit = mFrameCountP2 << 1;

            const size_t mask = overflowBit - 1;

            int32_t newFront = (front & ~mask) | (flush & mask);

            ssize_t filled = rear - newFront;

            if (filled >= (ssize_t)overflowBit) {

                // front and rear offsets span the overflow bit of the p2 mask

                // so rebasing newFront on the front offset is off by the overflow bit.

                // adjust newFront to match rear offset.

                ALOGV("flush wrap: filled %#x >= overflowBit %#x", filled, overflowBit);

                newFront += overflowBit;

                filled -= overflowBit;

            }

            // Rather than shutting down on a corrupt flush, just treat it as a full flush

            if (!(0 <= filled && (size_t) filled <= mFrameCount)) {

                ALOGE("mFlush %#x -> %#x, front %#x, rear %#x, mask %#x, newFront %#x, "