/* ibuttonid.c */
/* Copyright Nicholas Redgrave 2005
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>

#define BAUDRATE B115200
#define MODEMDEVICE "/dev/ttyUSB0"
#define _POSIX_SOURCE 1 /* POSIX compliant source */
#define FALSE 0
#define TRUE 1

#define PRESENCE 240
#define WRITE0     0
#define WRITE1   255

int iCheckCRC(unsigned short * usROMID);


volatile int STOP=FALSE;

main()
{
  int fd,c, res;
  struct termios newtio;
  unsigned char buf[255];
  int i,j,k,m;
  unsigned char ucData[64];         /* data buffer */
  unsigned char ucReadROM[8] = {1,1,0,0,1,1,0,0}; /* read ROM command */
  char chID[80];
  short shHexID[8];

  fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY );
  if (fd <0) {perror(MODEMDEVICE); exit(-1); }


  memset(&newtio, 0, sizeof(newtio));
  newtio.c_cflag = BAUDRATE | CS8 | CLOCAL | CREAD;
  newtio.c_iflag = IGNPAR;
  newtio.c_oflag = 0;

  /* set input mode (non-canonical, no echo,...) */
  newtio.c_lflag = 0;

  newtio.c_cc[VTIME]    = 0;   /* inter-character timer unused */
  newtio.c_cc[VMIN]     = 8;   /* blocking read until 8 chars received */

  tcflush(fd, TCIOFLUSH);
  tcsetattr(fd,TCSANOW,&newtio);


  do
  {

    tcsendbreak(fd, 0);


    /* Set up data */
    for(i=0; i<8; i++)
    {
      if( ucReadROM[i] == 0 )
      {
        ucData[i] = WRITE0;
      }
      else
      {
        ucData[i] = WRITE1;
      }
    }

    newtio.c_cc[VMIN]     = 8;   /* blocking read until 8 chars received */

    tcflush(fd, TCIFLUSH);
    tcsetattr(fd,TCSANOW,&newtio);


    res = write(fd,ucData,8);
//  printf("ReadROM sent %d\n",res);
    res = read(fd,buf,255);   /* returns after 8 chars have been input */
//  printf("ReadROM received %d\n",res);

    newtio.c_cc[VMIN]     = 64;   /* blocking read until 64 chars received */

    tcflush(fd, TCIFLUSH);
    tcsetattr(fd,TCSANOW,&newtio);

    /* Allow reception of data */
    for(i=0; i<64; i++)
    {
      ucData[i] = WRITE1;
    }
    res = write(fd,ucData,64);
//  printf("Write slots sent %d\n",res);

    res = read(fd,buf,255);   /* returns after 64 chars have been input */
//  printf("Write slots received %d\n",res);


    for(i=63,j=0; i>=0; i--,j++)
    {
      if( (buf[i] & 1) == 0 )
      {
        chID[j] = 48;
      }
      else
      {
        chID[j] = 49;
      }
    }
    chID[64] = 0;

    memset(&shHexID[0], 0, 8*sizeof(short));
    for(i=0,j=128,k=0,m=0; i<64; i++)
    {
      if( chID[i] == 49 )
      {
        shHexID[k] += (short)j;
      }
      j /= 2;
      m++;
      if( m == 8)
      {
        m=0;
        j = 128;
        k++;
      }
    }

    sprintf(chID, "%02X %02X %02X %02X %02X %02X %02X %02X",
       shHexID[0],shHexID[1],shHexID[2],shHexID[3],
       shHexID[4],shHexID[5],shHexID[6],shHexID[7]);


  }while( iCheckCRC((unsigned short * )shHexID) != 1 );


  printf("%s\n",chID);


  close(fd);

}
/* end of main **********************************************/

static unsigned char ucCRC8[256] = {

   0,  94, 188, 226,  97,  63, 221, 131, 194, 156, 126,  32, 163, 253,  31,  65,
 157, 195,  33, 127, 252, 162,  64,  30,  95,   1, 227, 189,  62,  96, 130, 220,
  35, 125, 159, 193,  66,  28, 254, 160, 225, 191,  93,   3, 128, 222,  60,  98,
 190, 224,   2,  92, 223, 129,  99,  61, 124,  34, 192, 158,  29,  67, 161, 255,
  70,  24, 250, 164,  39, 121, 155, 197, 132, 218,  56, 102, 229, 187,  89,   7,
 219, 133, 103,  57, 186, 228,   6,  88,  25,  71, 165, 251, 120,  38, 196, 154,
 101,  59, 217, 135,   4,  90, 184, 230, 167, 249,  27,  69, 198, 152, 122,  36,
 248, 166,  68,  26, 153, 199,  37, 123,  58, 100, 134, 216,  91,   5, 231, 185,
 140, 210,  48, 110, 237, 179,  81,  15,  78,  16, 242, 172,  47, 113, 147, 205,
  17,  79, 173, 243, 112,  46, 204, 146, 211, 141, 111,  49, 178, 236,  14,  80,
 175, 241,  19,  77, 206, 144, 114,  44, 109,  51, 209, 143,  12,  82, 176, 238,
  50, 108, 142, 208,  83,  13, 239, 177, 240, 174,  76,  18, 145, 207,  45, 115,
 202, 148, 118,  40, 171, 245,  23,  73,   8,  86, 180, 234, 105,  55, 213, 139,
  87,   9, 235, 181,  54, 104, 138, 212, 149, 203,  41, 119, 244, 170,  72,  22,
 233, 183,  85,  11, 136, 214,  52, 106,  43, 117, 151, 201,  74,  20, 246, 168,
 116,  42, 200, 150,  21,  75, 169, 247, 182, 232,  10,  84, 215, 137, 107,  53 };


int iCheckCRC(unsigned short * usROMID)
{
  int i;
  unsigned char ucCRC, ucCRCcheck;

  // Check the iButton ROM CRC



  /* loop round ROM bytes (starting from family code backwards) */
  for(i=7,ucCRC=0; i>0; i--)
  {
    ucCRC = ucCRC8[ (ucCRC ^ usROMID[i]) ];
  }
  ucCRCcheck = ucCRC8[ (ucCRC ^ usROMID[0]) ];


  if( (ucCRC == usROMID[0]) &&
      (ucCRCcheck == 0) )
  {
    /* CRC is good */
    return 1;
  }
  else
  {
    /* CRC is bad */
    return 0;
  }


}
/* end of iCheckCRC **********************************************/