Hi,
On 19. 01. 24, 10:43, Tudor Ambarus wrote:
If using unsigned int the bitfied is combined with the previous u8
fields, whereas if using u8 the bitfield will be independently defined.
So no benefit in terms of memory footprint, it's just a cosmetic change
to align the bitfield with the previous u8 fields. Allowing u32 for just
a bit can be misleading as one would ask itself where are the other
bits. Between a u32 bitfield and a bool a u8 bitfield seems like a good
compromise.
Why? What's wrong with bool? bitfields have terrible semantics wrt
atomic writes for example.
Bool occupies a byte and if more port features will ever be added we'll
occupy more bytes. Here's how the structure will look like with a bool:
struct s3c24xx_uart_info {
const char * name; /* 0 8 */
enum s3c24xx_port_type type; /* 8 4 */
unsigned int port_type; /* 12 4 */
unsigned int fifosize; /* 16 4 */
u32 rx_fifomask; /* 20 4 */
u32 rx_fifoshift; /* 24 4 */
u32 rx_fifofull; /* 28 4 */
u32 tx_fifomask; /* 32 4 */
u32 tx_fifoshift; /* 36 4 */
u32 tx_fifofull; /* 40 4 */
u32 clksel_mask; /* 44 4 */
u32 clksel_shift; /* 48 4 */
u32 ucon_mask; /* 52 4 */
u8 def_clk_sel; /* 56 1 */
u8 num_clks; /* 57 1 */
u8 iotype; /* 58 1 */
bool has_divslot; /* 59 1 */
/* size: 64, cachelines: 1, members: 17 */
/* padding: 4 */
};
What's your preference?
bool :).
--
js
suse labs
