An apparatus for video decoding includes processing circuitry. The processing circuitry decodes prediction information of a current block from a coded video bitstream. The prediction information is indicative of an intra block copy mode, the current block is one of a plurality of coding blocks in a coding tree block (CTB) with a right to left coding order being allowed within the current CTB. The processing circuitry determines a block vector that points to a reference block in a same picture as the current block. Then, the processing circuitry ensures the reference block being buffered in a reference sample memory based on at least a determination that a sample that is right of a leftmost sample of the reference block is buffered in the reference sample memory. Further, the processing circuitry reconstructs at least a sample of the current block based on reconstructed samples of the reference block.