坏块判断

static u_size8 is_bad_block(u_size32 addr)
{
      u_size32 i;
      u_size8 tmp;
      EN_NANDFLASH;
      WCMD(READ1);
        rNFADDR = 2048 & 0xff;
        rNFADDR = (2048 >> 8) & 0xf;
        rNFADDR = (addr >> 12) & 0xff;
        rNFADDR = (addr >> 20) & 0xff;
        rNFADDR = (addr >> 28) & 0x1;
      WCMD(READ2);
      delay(10);
      noBUSY;
      tmp = rNFDATA;
        if(tmp != 0xff){
          DIS_NANDFLASH;
          return 1;
    }
      DIS_NANDFLASH;
      return 0;
}