struct {
    U8   ver;      //CSD version: CSD_V1, CSD_V2
    U8   csd[16];  //last CSD state (CMD9)
    U32  sectors;  //number of sectors
} sd;
enum {CSD_V1=0, CSD_V2=1};
void sd_update_csd(void) {
    sd.sectors = 0;
    if (sd_ok()) {
        sd.ver = sd.csd[0] >> 6;
        if (sd.ver == CSD_V1) {
            U32 size = 1UL << (sd.csd[5] & 0xF);
            size *= 1UL << (((sd.csd[9] & 0x3) << 1) + (sd.csd[10] >> 7) + 2);
            size *= (U32)((((U16)(sd.csd[6] & 3)) << 10) + ((U16)sd.csd[7] << 2) + ((U16)(sd.csd[8] & 0xC0) >> 6) + 1);
            sd.sectors = size >> 9;
        } else if (sd.ver == CSD_V2) {
            sd.sectors = ((((U32)(sd.csd[7] & 0x3F)) << 16) + (((U32)sd.csd[8]) << 8) + (U32)sd.csd[9]) << 10;
        }
    }
}