struct ubrr_values {

uint16_t ubrr;

uint8_t u2x;

};



static const struct ubrr_values PROGMEM baud_to_ubrr[] = {

[ x_PHY_BAUD_9600 ] = UBRR_x(9600),

[ x_PHY_BAUD_19200 ] = UBRR_x(19200),

[ x_PHY_BAUD_45450 ] = UBRR_x(45450),

[ x_PHY_BAUD_93750 ] = UBRR_x(93750),

[ x_PHY_BAUD_187500 ] = UBRR_x(187500),

[ x_PHY_BAUD_500000 ] = UBRR_x(500000),

[ x_PHY_BAUD_1500000 ] = UBRR_x(1500000),

[ x_PHY_BAUD_3000000 ] = UBRR_x(3000000),

[ x_PHY_BAUD_6000000 ] = UBRR_x(6000000),

[ x_PHY_BAUD_12000000 ] = UBRR_x(12000000),

};



이렇게 되어 있는데, 


[ x_PHY_BAUD_9600 ] = UBRR_x(9600),


static const struct ubrr_values PROGMEM baud_to_ubrr[] 



이 두 문장의 뜻이 뭔지좀 알려 주세요.