/***************************************************************************/

typedef union {
   byte byteval[4];
   dword result;
} BCDval;

/* Global variables */
byte RFID[6];

/* Function prototypes */
void disp_data (void);
dword hex2bin (byte *);
dword bin2BCD_conv (dword );
byte BCD_adj (byte );
byte upper_char (byte );
byte lower_char (byte );
void printf_LCD_4bits(byte, byte, char *);

/***************************************************************************/
/* Convert data and display 8-digit result on LCD
   On entry, global array RFID contains the hexadecimal data to be converted.
   Leading zeros are not suppressed.
****************************************************************************/
void disp_data (void)
{
   BCDval temp;
   byte LCDtext[9];
   byte i, j;

   temp.result = bin2BCD_conv (hex2bin (RFID));

   for (i = 0, j = 0; i < 4; i++) {
      LCDtext[j]   = upper_char (temp.byteval[i]);
      LCDtext[j+1] = lower_char (temp.byteval[i]);
      j += 2;
   }
   LCDtext[8] = 0;  /* Null terminate string data */

   printf_LCD_4bits (1,1,LCDtext);
}

/***************************************************************************/
/* Hexadecimal -> binary conversion
   The array data referenced by the pointer hexseq must contain only one
   nybble in each byte of the array, right justified.
   The binary value returned is a 24-bit value, right justified.
*/
dword hex2bin (byte *hexseq)
{
   byte i;
   dword temp = 0;

   for (i = 0; i < 6; i++) {
      temp = (temp << 4) | *hexseq;
      hexseq++;
   )
   return (temp);
}

/***************************************************************************/
/* Binary -> BCD conversion
   A 24-bit binary value is converted to eight BCD digits, with two digits
   packed per return byte.
*/
dword bin2BCD_conv (dword val)
(
   BCDval res;
   byte i;

   res.result = 0;
   for (i = 0; i < 24; i++) {
      res.byteval[0] = BCD_adj (res.byteval[0]);
      res.byteval[1] = BCD_adj (res.byteval[1]);
      res.byteval[2] = BCD_adj (res.byteval[2]);
      res.byteval[3] = BCD_adj (res.byteval[3]);
      res.result <<= 1;
      if (val & 0x800000)
         res.result += 1;
      val <<= 1;
   }
   return (res.result);
}

byte BCD_adj (byte val)
{
   if ((val & 0x0F) >= 5)
      val += 3;
   if ((val & 0xF0) >= 0x50)
      val += 0x30;
   return (val);
}

/***************************************************************************/
/* Unpack BCD digit and convert to ASCII value
*/
byte upper_char (byte value)
{
  return ((value >> 4) + 0x30);
}

byte lower_char (byte value)
{
  return ((value & 0x0F) + 0x30);
}

/***************************************************************************/
/* Write ASCII string to LCD
*/
void printf_LCD_4bits(byte fila, byte columna, char *texto)
{
  byte adrs;

  adrs = columna - 1;
  if (fila == 2)
     adrs = adrs | 0x40;
  Ctrl4bits(adrs | 0x80);

  while (*texto)
     Datos4bits(texto++);
}