gcc cross compiler union compatible issue.

有些platform 的struct or union 預設為4個bytes(一般會預期應該要2個bytes)

目前可用

__attribute__((__packed__))來解決

其它的code要小心有沒有類似的問題

typedef union _MACHTTRANSMIT_SETTING {         unsigned short word;         union //short 2 bytes，但有些可能 assign 4 bytes         {                 unsigned short MCS:7; // MCS                 unsigned short BW:1; //channel bandwidth 20MHz or 40 MHz                 unsigned short ShortGI:1;                 unsigned short STBC:2; //SPACE                 unsigned short rsv:3;                 unsigned short MODE:2; // Use definition MODE_xxx.         } __attribute__((__packed__))field; }__attribute__((__packed__)) MACHTTRANSMIT_SETTING, *PMACHTTRANSMIT_SETTING; int main(int argc, char *argv[]) {         MACHTTRANSMIT_SETTING m;         printf("m: %d, m->word:%d@%p\n", sizeof(m), sizeof(m.word), &m.word);         printf("m: %d, m->:%d@%p\n", sizeof(m), sizeof(m.word), &m.word);         printf("ok: %d, m->:%d@%p\n", sizeof(m), sizeof(m.field), &m.field); }
X86	others
peter@team-server:~$ ./a.out m: 2, m->word:2@0xbff97a32 m: 2, m->:2@0xbff97a32 ok: 2, m->:1@0xbff97a32	/tmp/rootfs # ./a.out m: 2, m->word:2@0x4261fcd4 m: 2, m->:2@0x4261fcd4 ok: 2, m->:1@0x4261fcd4