rem: s32 CARD_GetErrorCode(u32 chn)
add: s32 CARD_GetErrorCode(s32 chn)
context: s32 CARD_GetErrorCode(u32 chn){	card_block *card = NULL;	if(chn<EXI_CHANNEL_0 || chn>=EXI_CHANNEL_2) return CARD_ERROR_NOCARD;	card = &cardmap[chn];	return card->result;}