zahada delky struktury GCC

[Jindroush]

Nechapu? Zamenite dve 32bitove za dve 64bitove (double, FP64), takze 
mate zabrano o 64bitu - 8 bajtu vice, coz odpovida 1032-1024? Divim se, 
kde je co k diveni? :-) Nebo jsem neco nepochopil.
J.

On 11.03.2024 19:41, Jaroslav Buchta wrote:
> Mejme tyto struktury
>
> #define CFG_DATA_LEN    1024
> #define GPS_FIXP_MULT    (10e7)
>
> typedef struct
> {
>     char first_read[9];
>     uint8_t res_valid;
>     uint8_t reserved;
>     char user_card[9];
>     char user_phone[13];
>     char res_time[34];
> } app_data_reservation_t;
>
>
> typedef struct {
>     union {
>         struct {
>             uint32_t     index;                        // index of 
> configuration, count of writes
>             int            gsm_preffered_speed;        // module GSM 
> baudrate
>             char        gsm_apn[32];                // module GSM APN
>             char         car_ident[8];                // car 
> identification
>             char         car_aeskey[65];                // 256b -> 64 
> chars hex encoded
>             app_data_reservation_t    reservation;    // reservation data
>             int32_t        gps_last_latitude;            // car last 
> known latitude, *10^7 (GPS_FIXP_MULT)
>             int32_t        gps_last_longitude;            // car last 
> known longitude, *10^7 (GPS_FIXP_MULT)
>         };
>         uint8_t ba[CFG_DATA_LEN - 4];
>     };
>     uint32_t crc32;
> } app_data_cfg_t;
>
> Takhle je to dle ocekavani, app_data_cfg_t ma delku 1024B
>
> Kdyz ale pro ty GPS souradnice pouziju typ double, neni delka 
> ocekavanych 1024 ale 1032B
>
> Myslel jsem nejdriv, ze je to tou vlozenou strukturu ale dela to ten 
> double.
>
> Tusi nekdo, cim to je? Je to nejaka pro me skryta vlastnost nebo chyba?
>
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-- 
Jindroush <jindroush na seznam.cz>