TX_CMD_A_FIRST_SEG_
tx_cmd_a |= TX_CMD_A_FIRST_SEG_ | TX_CMD_A_LAST_SEG_;
txcmd_a |= TX_CMD_A_FIRST_SEG_ | TX_CMD_A_LAST_SEG_;
tx_cmd_a = tx_cmd_b | TX_CMD_A_FIRST_SEG_ | TX_CMD_A_LAST_SEG_;