On 30.07.24 11:06, Sascha Hauer wrote:
> On Tue, Jul 30, 2024 at 09:19:23AM +0200, Ahmad Fatoum wrote:
>> In preparation for adding more boolean flags, turn the current two bools
>> into two bits sharing the same u8-sized member.
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
>> ---
>> include/mci.h | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/mci.h b/include/mci.h
>> index 773aed896c96..4f1ff9dc57c8 100644
>> --- a/include/mci.h
>> +++ b/include/mci.h
>> @@ -568,8 +568,8 @@ struct mci {
>> unsigned csd[4]; /**< card's "card specific data register" */
>> unsigned cid[4]; /**< card's "card identification register" */
>> unsigned short rca; /**< relative card address */
>> - bool sdio; /**< card is a SDIO card */
>> - bool high_capacity; /**< high capacity card is connected (OCR -> OCR_HCS) */
>> + u8 sdio:1; /**< card is a SDIO card */
>> + u8 high_capacity:1; /**< high capacity card is connected (OCR -> OCR_HCS) */
>
> This doesn't seem to be necessary. They share the same byte in either
> way. From a quick test:
They don't share the same byte, but the size didn't change because of
padding. More members are added into the padding space in subsequent
commits, which would affect structure size.
>
> struct foo {
> u16 a;
> bool b;
> bool c;
> u32 d;
> };
>
> struct bar {
> u16 a;
> u8 b:1;
> u8 c:1;
> u32 d;
> };
>
> printf("%d %d\n", sizeof(struct foo), sizeof(struct bar));
>
> The result is 8 for both structs.
>
> Sascha
>
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
