receiving, by a first transmission interface, a first command from a second transmission interface, wherein the first transmission interface is a memory interface of a first memory controller, the second transmission interface is a memory interface of a second memory controller, the first memory controller and the second memory controller are comprised inside of a bridge device, the second transmission interface is connected to the first transmission interface through a bus, the first transmission interface and the second transmission interface are both a flash memory interface, the bus is a flash memory bus, the first transmission interface operates in a slave mode and the second transmission interface operates in a master mode, and a value of the first command is optionally set to a first value or a second value, the first value indicates a memory command transfer operation in a first direction and the second value indicates a memory data transfer operation in the first direction;

obtaining, by the first transmission interface, first transfer data from the bus in response to the first command, wherein the first transfer data comprises at least one transfer data chunk generated in compliance with a common bridge transfer format; and

processing, by the first transmission interface, the first transfer data according to the value of the first command to obtain a memory command or written data,

wherein for the memory command transfer operation in the first direction, a data portion of the transfer data chunk carries one or more command packets, each command packet is a combination of a bridge command and the memory command, the bridge command is a command provided by the second transmission interface to the first transmission interface and the memory command is a command to be further transferred to the data storage device through the first transmission interface, and

wherein for the memory command transfer operation in the first direction, step of processing, by the first transmission interface, the first transfer data according to the value of the first command to obtain a memory command or written data further comprises:

upon receiving the transfer data chunk, parsing the bridge command to obtain content of an instruction instructed by the second transmission interface and to obtain the memory command.