78     mReadDirection   = kForward;  in Clear()
550         mReadDirection = HasFrame(kPriorityHigh) ? kBackward : kForward;  in OutFrameSelectReadDirection()
566         EXPECT(mReadSegmentHead != mWriteFrameStart[mReadDirection], error = OT_ERROR_NOT_FOUND);  in OutFramePrepareSegment()
569         header = ReadUint16At(mReadSegmentHead, mReadDirection);  in OutFramePrepareSegment()
575             EXPECT(mReadSegmentHead == mReadFrameStart[mReadDirection], error = OT_ERROR_NOT_FOUND);  in OutFramePrepareSegment()
580                                             mReadDirection);  in OutFramePrepareSegment()
583         mReadPointer = GetUpdatedBufPtr(mReadSegmentHead, kSegmentHeaderSize, mReadDirection);  in OutFramePrepareSegment()
624     header = ReadUint16At(mReadSegmentHead, mReadDirection);  in OutFramePrepareMessage()
630     mReadMessage = (mReadMessage == nullptr) ? otMessageQueueGetHead(&mMessageQueue[mReadDirection])  in OutFramePrepareMessage()
631 …                             : otMessageQueueGetNext(&mMessageQueue[mReadDirection], mReadMessage);  in OutFramePrepareMessage()
686     mReadSegmentHead = mReadSegmentTail = mReadFrameStart[mReadDirection];  in OutFrameBegin()
721         mReadPointer = GetUpdatedBufPtr(mReadPointer, 1, mReadDirection);  in OutFrameReadByte()
792     tag = mReadFrameStart[mReadDirection];  in OutFrameRemove()
796     bufPtr      = mReadFrameStart[mReadDirection];  in OutFrameRemove()
799     while (bufPtr != mWriteFrameStart[mReadDirection])  in OutFrameRemove()
802         header = ReadUint16At(bufPtr, mReadDirection);  in OutFrameRemove()
808             if (bufPtr != mReadFrameStart[mReadDirection])  in OutFrameRemove()
820             if ((message = otMessageQueueGetHead(&mMessageQueue[mReadDirection])) != nullptr)  in OutFrameRemove()
822                 otMessageQueueDequeue(&mMessageQueue[mReadDirection], message);  in OutFrameRemove()
829 …GetUpdatedBufPtr(bufPtr, kSegmentHeaderSize + (header & kSegmentHeaderLengthMask), mReadDirection);  in OutFrameRemove()
838     mReadFrameStart[mReadDirection] = bufPtr;  in OutFrameRemove()
847 …     mFrameRemovedCallback(mFrameRemovedContext, tag, static_cast<Priority>(mReadDirection), this);  in OutFrameRemove()
896     bufPtr      = mReadFrameStart[mReadDirection];  in OutFrameGetLength()
899     while (bufPtr != mWriteFrameStart[mReadDirection])  in OutFrameGetLength()
902         header = ReadUint16At(bufPtr, mReadDirection);  in OutFrameGetLength()
908             if (bufPtr != mReadFrameStart[mReadDirection])  in OutFrameGetLength()
918             message = (message == nullptr) ? otMessageQueueGetHead(&mMessageQueue[mReadDirection])  in OutFrameGetLength()
919 …                                  : otMessageQueueGetNext(&mMessageQueue[mReadDirection], message);  in OutFrameGetLength()
932 …GetUpdatedBufPtr(bufPtr, kSegmentHeaderSize + (header & kSegmentHeaderLengthMask), mReadDirection);  in OutFrameGetLength()
958     return IsEmpty() ? kInvalidTag : mReadFrameStart[mReadDirection];  in OutFrameGetTag()