72     mWriteDirection                 = kUnknown;  in Clear()
230     assert(mWriteDirection != kUnknown);  in InFrameAppend()
232     newTail = GetUpdatedBufPtr(mWriteSegmentTail, 1, mWriteDirection);  in InFrameAppend()
235     if (newTail != mWriteFrameStart[(mWriteDirection == kForward) ? kBackward : kForward])  in InFrameAppend()
259     if (mWriteFrameStart[mWriteDirection] == mWriteSegmentHead)  in InFrameBeginSegment()
271     WriteUint16At(mWriteSegmentHead, headerFlags, mWriteDirection);  in InFrameBeginSegment()
283     segmentLength = GetDistance(mWriteSegmentHead, mWriteSegmentTail, mWriteDirection);  in InFrameEndSegment()
291         header = ReadUint16At(mWriteSegmentHead, mWriteDirection);  in InFrameEndSegment()
294         WriteUint16At(mWriteSegmentHead, header, mWriteDirection);  in InFrameEndSegment()
313     EXPECT(mWriteDirection != kUnknown, NO_ACTION);  in InFrameDiscard()
316     mWriteSegmentHead = mWriteSegmentTail = mWriteFrameStart[mWriteDirection];  in InFrameDiscard()
329     mWriteDirection = kUnknown;  in InFrameDiscard()
338     return (mWriteDirection == static_cast<Direction>(aPriority));  in InFrameIsWriting()
349         mWriteDirection = kBackward;  in InFrameBegin()
353         mWriteDirection = kForward;  in InFrameBegin()
358     mWriteSegmentHead = mWriteSegmentTail = mWriteFrameStart[mWriteDirection];  in InFrameBegin()
365     EXPECT(mWriteDirection != kUnknown, error = OT_ERROR_INVALID_STATE);  in InFrameFeedByte()
380     EXPECT(mWriteDirection != kUnknown, error = OT_ERROR_INVALID_STATE);  in InFrameFeedData()
401     EXPECT(mWriteDirection != kUnknown, error = OT_ERROR_INVALID_STATE);  in InFrameFeedMessage()
421     EXPECT(mWriteDirection != kUnknown, error = OT_ERROR_INVALID_STATE);  in InFrameGetPosition()
440     EXPECT(mWriteDirection != kUnknown, error = OT_ERROR_INVALID_STATE);  in InFrameOverwrite()
445     segmentLength = GetDistance(mWriteSegmentHead, mWriteSegmentTail, mWriteDirection);  in InFrameOverwrite()
446     distance      = GetDistance(mWriteSegmentHead, aPosition.mPosition, mWriteDirection);  in InFrameOverwrite()
457         bufPtr = GetUpdatedBufPtr(bufPtr, 1, mWriteDirection);  in InFrameOverwrite()
470     EXPECT(mWriteDirection != kUnknown, NO_ACTION);  in InFrameGetDistance()
473     segmentLength = GetDistance(mWriteSegmentHead, mWriteSegmentTail, mWriteDirection);  in InFrameGetDistance()
474     offset        = GetDistance(mWriteSegmentHead, aPosition.mPosition, mWriteDirection);  in InFrameGetDistance()
477     distance = GetDistance(aPosition.mPosition, mWriteSegmentTail, mWriteDirection);  in InFrameGetDistance()
489     EXPECT(mWriteDirection != kUnknown, error = OT_ERROR_INVALID_STATE);  in InFrameReset()
492     segmentLength = GetDistance(mWriteSegmentHead, mWriteSegmentTail, mWriteDirection);  in InFrameReset()
493     offset        = GetDistance(mWriteSegmentHead, aPosition.mPosition, mWriteDirection);  in InFrameReset()
509     EXPECT(mWriteDirection != kUnknown, error = OT_ERROR_INVALID_STATE);  in InFrameEnd()
515     mWriteFrameTag = mWriteFrameStart[mWriteDirection];  in InFrameEnd()
518     mWriteFrameStart[mWriteDirection] = mWriteSegmentHead;  in InFrameEnd()
525         otMessageQueueEnqueue(&mMessageQueue[mWriteDirection], message);  in InFrameEnd()
531 …ameAddedCallback(mFrameAddedContext, mWriteFrameTag, static_cast<Priority>(mWriteDirection), this);  in InFrameEnd()
534     mWriteDirection = kUnknown;  in InFrameEnd()