SD卡初始化代码中一个奇怪的地方

zhangjw258

在"SD_Error SD_GetCardInfo(SD_CardInfo *cardinfo)"函数中
................

  /*!< Byte 12 */
  tmp = (uint8_t)((CSD_Tab[3] & 0xFF000000) >> 24);
  cardinfo->SD_csd.WrProtectGrEnable = (tmp & 0x80) >> 7;
  cardinfo->SD_csd.ManDeflECC = (tmp & 0x60) >> 5;
  cardinfo->SD_csd.WrSpeedFact = (tmp & 0x1C) >> 2;
  cardinfo->SD_csd.MaxWrBlockLen = (tmp & 0x03) << 2;
  /*!< Byte 13 */
  tmp = (uint8_t)((CSD_Tab[3] & 0x00FF0000) >> 16);
  cardinfo->SD_csd.MaxWrBlockLen |= (tmp & 0xC0) >> 6;
  cardinfo->SD_csd.WriteBlockPaPartial = (tmp & 0x20) >> 5;
  cardinfo->SD_csd.Reserved3 = 0;
cardinfo->SD_csd.ContentProtectAppli = (tmp & 0x01);//关注这一句
  /*!< Byte 14 */
  tmp = (uint8_t)((CSD_Tab[3] & 0x0000FF00) >> 8);
  cardinfo->SD_csd.FileFormatGrouop = (tmp & 0x80) >> 7;
  cardinfo->SD_csd.CopyFlag = (tmp & 0x40) >> 6;
  cardinfo->SD_csd.PermWrProtect = (tmp & 0x20) >> 5;
  cardinfo->SD_csd.TempWrProtect = (tmp & 0x10) >> 4;
  cardinfo->SD_csd.FileFormat = (tmp & 0x0C) >> 2;
  cardinfo->SD_csd.ECC = (tmp & 0x03);
......................
" Byte 13 "已经用完了8位,(tmp & 0x01)又是什么?

Reserved3 已经占5bits,这个字节已处理完,何来(tmp & 0x01).
有哪位老师能回答我?
我居然把这么枯燥的代码读了一遍.

zhangjw258

附图:

zhangjw258

sd card sdhc: