sdcard.h

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#ifndef _SDCARD_H_
#define _SDCARD_H_
#define VERBOSE 0
 
struct dirent {
  char name[8];
  char ext[3];
  byte attribute;
  byte reserved[8];
  uint16_t cluster_hi;  // FAT32 only
  uint16_t time;
  uint16_t date;
  uint16_t cluster;
  uint32_t size;
};
 
// https://www.sdcard.org/downloads/pls/simplified_specs/Part_1_Physical_Layer_Simplified_Specification_Ver_3.01_Final_100518.pdf
// page 22
// http://mac6.ma.psu.edu/space2008/RockSat/microController/sdcard_appnote_foust.pdf
// http://elm-chan.org/docs/mmc/mmc_e.html
// http://www.pjrc.com/tech/8051/ide/fat32.html
 
#define FAT16 0
#define FAT32 1
 
class sdcard {
  public:
  void sel() { digitalWrite(pin, LOW); }
  void desel() {
    digitalWrite(pin, HIGH);
    SPI.transfer(0xff); // force DO release
  }
  void sd_delay(byte n) {
    while (n--)
      SPI.transfer(0xff);
  }
 
  void cmd(byte cmd, uint32_t lba = 0, uint8_t crc = 0x95) {
#if VERBOSE
    Serial.print("cmd ");
    Serial.print(cmd, DEC);
    Serial.print(" ");
    Serial.print(lba, HEX);
    Serial.println();
#endif
 
    sel();
    SPI.transfer(0xff);
    SPI.transfer(0x40 | cmd);
    SPI.transfer(0xff & (lba >> 24));
    SPI.transfer(0xff & (lba >> 16));
    SPI.transfer(0xff & (lba >> 8));
    SPI.transfer(0xff & (lba));
    SPI.transfer(crc);
    SPI.transfer(0xff);
  }
 
  byte R1() 
  {     // read response R1
    byte r;
    
   while ((r = SPI.transfer(0xff)) & 0x80);
      desel();
      SPI.transfer(0xff);  
    return r;
  }
 
  byte sdR3(uint32_t &ocr) {  // read response R3
    uint32_t r;
    while ((r = SPI.transfer(0xff)) & 0x80)
      ;
    for (byte i = 4; i; i--)
      ocr = (ocr << 8) | SPI.transfer(0xff);
    SPI.transfer(0xff);   // trailing byte
 
    desel();
    return r;
  }
 
  byte sdR7() {  // read response R3
    uint32_t r;
    while ((r = SPI.transfer(0xff)) & 0x80)
      ;
    for (byte i = 4; i; i--)
      // Serial.println(SPI.transfer(0xff), HEX);
      SPI.transfer(0xff);
    desel();
 
    return r;
  }
 
  void appcmd(byte cc, uint32_t lba = 0) {
    cmd(55); R1();
    cmd(cc, lba);
  }
 
  uint8_t begin(byte p)
  {
    uint16_t cts=2000;
    pin = p;
 
    pinMode(pin, OUTPUT);
    SPI.begin();
    SPI.setClockDivider(SPI_CLOCK_DIV64);
    desel();
 
    delay(10);      // wait for boot
    sd_delay(10);   // deselected, 80 pulses
 
    // Tty.printf("Attempting card reset... ");
    // attempt reset
    byte r1,r;
    do
    {       // reset, enter idle
      cmd(0);
      do
      {      
         if(cts>0) cts--; else 
         {
           desel();
           return  0;
         }  
       }while ((r = SPI.transfer(0xff)) & 0x80);
      desel();
      SPI.transfer(0xff);   // trailing byte
      r1 = r;
    }while(r1!=1);
    // Tty.printf("reset ok\n");
 
    byte sdhc = 0;
    cmd(8, 0x1aa, 0x87);
    r1 = sdR7();
    sdhc = (r1 == 1);
 
    // Tty.printf("card %s SDHC\n", sdhc ? "is" : "is not");
 
    // Tty.printf("Sending card init command... ");
    while (1) {
      appcmd(41, sdhc ? (1UL << 30) : 0); // card init
      r1 = R1();
      if ((r1 & 1) == 0)
        break;
      delay(100);
    }
    // Tty.printf("OK\n");
 
    if (sdhc) {
      cmd(58);
      uint32_t OCR;
      sdR3(OCR);
      ccs = 1UL & (OCR >> 30);
      // Tty.printf("OCR register is %#010lx\n", long(OCR));
    } else {
      ccs = 0;
    }
    // Tty.printf("ccs = %d\n", ccs);
 
    byte type_code = rd(0x1be + 0x4);
    switch (type_code) {
      default:
        type = FAT16;
        break;
      case 0x0b:
      case 0x0c:
        type = FAT32;
        break;
    }
    // Tty.printf("Type code %#02x means FAT%d\n", type_code, (type == FAT16) ? 16 : 32);
 
    o_partition = 512L * rd4(0x1be + 0x8);
    sectors_per_cluster = rd(o_partition + 0xd);
    reserved_sectors = rd2(o_partition + 0xe);
    cluster_size = 512L * sectors_per_cluster;
 
    // Tty.printf("Bytes per sector:    %d\n", rd2(o_partition + 0xb));
    // Tty.printf("Sectors per cluster: %d\n", sectors_per_cluster);
 
    if (type == FAT16) {
      max_root_dir_entries = rd2(o_partition + 0x11);
      sectors_per_fat = rd2(o_partition + 0x16);
      o_fat = o_partition + 512L * reserved_sectors;
      o_root = o_fat + (2 * 512L * sectors_per_fat);
      // data area starts with cluster 2, so offset it here
      o_data = o_root + (max_root_dir_entries * 32L) - (2L * cluster_size); 
    } else {
      uint32_t sectors_per_fat = rd4(o_partition + 0x24);
      root_dir_first_cluster = rd4(o_partition + 0x2c);
      uint32_t fat_begin_lba = (o_partition >> 9) + reserved_sectors;
      uint32_t cluster_begin_lba = (o_partition >> 9) + reserved_sectors + (2 * sectors_per_fat);
 
      o_fat = 512L * fat_begin_lba;
      o_root = (512L * (cluster_begin_lba + (root_dir_first_cluster - 2) * sectors_per_cluster));
      o_data = (512L * (cluster_begin_lba - 2 * sectors_per_cluster));
    }
    return 1;
  }
  void cmd17(uint32_t off) {
    if (ccs)
      cmd(17, off >> 9);
    else
      cmd(17, off & ~511L);
    R1();
    sel();
    while (SPI.transfer(0xff) != 0xfe)
      ;
  }
  void rdn(byte *d, uint32_t off, uint16_t n) {
    cmd17(off);
    uint16_t i;
    uint16_t bo = (off & 511);
    for (i = 0; i < bo; i++)
      SPI.transfer(0xff);
    for (i = 0; i < n; i++)
      *d++ = SPI.transfer(0xff);
    for (i = 0; i < (514 - bo - n); i++)
      SPI.transfer(0xff);
    desel();
  }
 
  uint32_t rd4(uint32_t off) {
    uint32_t r;
    rdn((byte*)&r, off, sizeof(r));
    return r;
  }
 
  uint16_t rd2(uint32_t off) {
    uint16_t r;
    rdn((byte*)&r, off, sizeof(r));
    return r;
  }
 
  byte rd(uint32_t off) {
    byte r;
    rdn((byte*)&r, off, sizeof(r));
    return r;
  }
  byte pin;
  byte ccs;
 
  byte type;
  uint16_t sectors_per_cluster;
  uint16_t reserved_sectors;
  uint16_t max_root_dir_entries;
  uint16_t sectors_per_fat;
  uint16_t cluster_size;
  uint32_t root_dir_first_cluster;
 
  // These are all linear addresses, hence the o_ prefix
  uint32_t o_partition;
  uint32_t o_fat;
  uint32_t o_root;
  uint32_t o_data;
};
 
static void dos83(byte dst[11], const char *ps)
{
  byte i = 0;
  while (*ps) {
    if (*ps != '.')
      dst[i++] = toupper(*ps);
    else {
      while (i < 8)
        dst[i++] = ' ';
    }
    ps++;
  }
  while (i < 11)
    dst[i++] = ' ';
}
 
class Reader {
public:
    sdcard SD;
    int openfile(const char *filename) {
    int i = 0;
    byte dosname[11];
    dirent de;
 
    dos83(dosname, filename);
    do {
      SD.rdn((byte*)&de, SD.o_root + i * 32, sizeof(de));
      // Serial.println(de.name);
      if (0 == memcmp(de.name, dosname, 11)) {
        begin(de);
        return 1;
      }
      i++;
    } while (de.name[0]);
    return 0;
  }
  
  void begin(dirent &de) {
    size = de.size;
    cluster = de.cluster;
    if (SD.type == FAT32)
      cluster |= ((long)de.cluster_hi << 16);
    sector = 0;
    offset = 0;
  }
  void nextcluster() {
    if (SD.type == FAT16)
      cluster = SD.rd2(SD.o_fat + 2 * cluster);
    else
      cluster = SD.rd4(SD.o_fat + 4 * cluster);
#if VERBOSE
    Serial.print("nextcluster=");
    Serial.println(cluster, DEC);
#endif
  }
  void skipcluster() {
    nextcluster();
    offset += SD.cluster_size;
  }
  void skipsector() {
    if (sector == SD.sectors_per_cluster) {
      sector = 0;
      nextcluster();
    }
    sector++;
    offset += 512;
  }
  void seek(uint32_t o) {
    while (offset < o) {
      if ((sector == SD.sectors_per_cluster) && ((o - offset) > (long)SD.cluster_size))
        skipcluster();
      else
        skipsector();
    }
  }
  void readsector() {
    if (sector == SD.sectors_per_cluster) {
      sector = 0;
      nextcluster();
    }
    uint32_t off = SD.o_data + ((long)SD.cluster_size * cluster) + (512L * sector);
#if VERBOSE
    Serial.print("off=0x");
    Serial.println(off, HEX);
#endif
    SD.cmd17(off & ~511L);
// Serial.println(2 * (micros() - t0), DEC);
    sector++;
    offset += 512;
  }
  void readsector(byte *dst) {
    readsector();
    for (int i = 0; i < 64; i++) {
      *dst++ = SPI.transfer(0xff);
      *dst++ = SPI.transfer(0xff);
      *dst++ = SPI.transfer(0xff);
      *dst++ = SPI.transfer(0xff);
      *dst++ = SPI.transfer(0xff);
      *dst++ = SPI.transfer(0xff);
      *dst++ = SPI.transfer(0xff);
      *dst++ = SPI.transfer(0xff);
    }
    SPI.transfer(0xff);   // consume CRC
    SPI.transfer(0xff);
    SD.desel();
  }
  uint32_t cluster;
  uint32_t offset;
  uint32_t size;
  byte sector;
};
 
#endif