int Field_decimal::store(const char *from_arg, uint len, CHARSET_INFO *cs)
{
  ASSERT_COLUMN_MARKED_FOR_WRITE_OR_COMPUTED;
  char buff[STRING_BUFFER_USUAL_SIZE];
  String tmp(buff,sizeof(buff), &my_charset_bin);
  const uchar *from= (uchar*) from_arg;

  /* Convert character set if the old one is multi uchar */
  if (cs->mbmaxlen > 1)
  { 
    uint dummy_errors;
    tmp.copy((char*) from, len, cs, &my_charset_bin, &dummy_errors);
    from= (uchar*) tmp.ptr();
    len=  tmp.length();
  }

  const uchar *end= from+len;
  /* The pointer where the field value starts (i.e., "where to write") */
  uchar *to= ptr;
  uint tmp_dec, tmp_uint;
  /*
    The sign of the number : will be 0 (means positive but sign not
    specified), '+' or '-'
  */
  uchar sign_char=0;
  /* The pointers where prezeros start and stop */
  const uchar *pre_zeros_from, *pre_zeros_end;
  /* The pointers where digits at the left of '.' start and stop */
  const uchar *int_digits_from, *int_digits_end;
  /* The pointers where digits at the right of '.' start and stop */
  const uchar *frac_digits_from, *frac_digits_end;
  /* The sign of the exponent : will be 0 (means no exponent), '+' or '-' */
  char expo_sign_char=0;
  uint exponent=0;                                // value of the exponent
  /*
    Pointers used when digits move from the left of the '.' to the
    right of the '.' (explained below)
  */
  const uchar *UNINIT_VAR(int_digits_tail_from);
  /* Number of 0 that need to be added at the left of the '.' (1E3: 3 zeros) */
  uint UNINIT_VAR(int_digits_added_zeros);
  /*
    Pointer used when digits move from the right of the '.' to the left
    of the '.'
  */
  const uchar *UNINIT_VAR(frac_digits_head_end);
  /* Number of 0 that need to be added at the right of the '.' (for 1E-3) */
  uint UNINIT_VAR(frac_digits_added_zeros);
  uchar *pos,*tmp_left_pos,*tmp_right_pos;
  /* Pointers that are used as limits (begin and end of the field buffer) */
  uchar *left_wall,*right_wall;
  uchar tmp_char;
  /*
    To remember if get_thd()->cuted_fields has already been incremented,
    to do that only once
  */
  bool is_cuted_fields_incr=0;

  /*
    There are three steps in this function :
    - parse the input string
    - modify the position of digits around the decimal dot '.' 
      according to the exponent value (if specified)
    - write the formatted number
  */

  if ((tmp_dec=dec))
    tmp_dec++;

  /* skip pre-space */
  while (from != end && my_isspace(&my_charset_bin,*from))
    from++;
  if (from == end)
  {
    set_warning(WARN_DATA_TRUNCATED, 1);
    is_cuted_fields_incr=1;
  }
  else if (*from == '+' || *from == '-')	// Found some sign ?
  {
    sign_char= *from++;
    /*
      We allow "+" for unsigned decimal unless defined different
      Both options allowed as one may wish not to have "+" for unsigned numbers
      because of data processing issues
    */ 
    if (unsigned_flag)  
    { 
      if (sign_char=='-')
      {
        Field_decimal::overflow(1);
        return 1;
      }
      /* 
	 Defining this will not store "+" for unsigned decimal type even if
	 it is passed in numeric string. This will make some tests to fail
      */	 
#ifdef DONT_ALLOW_UNSIGNED_PLUS      
      else 
        sign_char=0;
#endif 	
    }
  }

  pre_zeros_from= from;
  for (; from!=end && *from == '0'; from++) ;	// Read prezeros
  pre_zeros_end=int_digits_from=from;      
  /* Read non zero digits at the left of '.'*/
  for (; from != end && my_isdigit(&my_charset_bin, *from) ; from++) ;
  int_digits_end=from;
  if (from!=end && *from == '.')		// Some '.' ?
    from++;
  frac_digits_from= from;
  /* Read digits at the right of '.' */
  for (;from!=end && my_isdigit(&my_charset_bin, *from); from++) ;
  frac_digits_end=from;
  // Some exponentiation symbol ?
  if (from != end && (*from == 'e' || *from == 'E'))
  {   
    from++;
    if (from != end && (*from == '+' || *from == '-'))  // Some exponent sign ?
      expo_sign_char= *from++;
    else
      expo_sign_char= '+';
    /*
      Read digits of the exponent and compute its value.  We must care about
      'exponent' overflow, because as unsigned arithmetic is "modulo", big 
      exponents will become small (e.g. 1e4294967296 will become 1e0, and the 
      field will finally contain 1 instead of its max possible value).
    */
    for (;from!=end && my_isdigit(&my_charset_bin, *from); from++)
    {
      exponent=10*exponent+(*from-'0');
      if (exponent>MAX_EXPONENT)
        break;
    }
  }
  
  /*
    We only have to generate warnings if count_cuted_fields is set.
    This is to avoid extra checks of the number when they are not needed.
    Even if this flag is not set, it's OK to increment warnings, if
    it makes the code easier to read.
  */

  if (get_thd()->count_cuted_fields)
  {
    // Skip end spaces
    for (;from != end && my_isspace(&my_charset_bin, *from); from++) ;
    if (from != end)                     // If still something left, warn
    {
      set_warning(WARN_DATA_TRUNCATED, 1);
      is_cuted_fields_incr=1;
    }
  }
  
  /*
    Now "move" digits around the decimal dot according to the exponent value,
    and add necessary zeros.
    Examples :
    - 1E+3 : needs 3 more zeros at the left of '.' (int_digits_added_zeros=3)
    - 1E-3 : '1' moves at the right of '.', and 2 more zeros are needed
    between '.' and '1'
    - 1234.5E-3 : '234' moves at the right of '.'
    These moves are implemented with pointers which point at the begin
    and end of each moved segment. Examples :
    - 1234.5E-3 : before the code below is executed, the int_digits part is
    from '1' to '4' and the frac_digits part from '5' to '5'. After the code
    below, the int_digits part is from '1' to '1', the frac_digits_head
    part is from '2' to '4', and the frac_digits part from '5' to '5'.
    - 1234.5E3 : before the code below is executed, the int_digits part is
    from '1' to '4' and the frac_digits part from '5' to '5'. After the code
    below, the int_digits part is from '1' to '4', the int_digits_tail
    part is from '5' to '5', the frac_digits part is empty, and
    int_digits_added_zeros=2 (to make 1234500).
  */
  
  /* 
     Below tmp_uint cannot overflow with small enough MAX_EXPONENT setting,
     as int_digits_added_zeros<=exponent<4G and 
     (int_digits_end-int_digits_from)<=max_allowed_packet<=2G and
     (frac_digits_from-int_digits_tail_from)<=max_allowed_packet<=2G
  */

  if (!expo_sign_char)
    tmp_uint=tmp_dec+(uint)(int_digits_end-int_digits_from);
  else if (expo_sign_char == '-') 
  {
    tmp_uint=MY_MIN(exponent,(uint)(int_digits_end-int_digits_from));
    frac_digits_added_zeros=exponent-tmp_uint;
    int_digits_end -= tmp_uint;
    frac_digits_head_end=int_digits_end+tmp_uint;
    tmp_uint=tmp_dec+(uint)(int_digits_end-int_digits_from);     
  }
  else // (expo_sign_char=='+') 
  {
    tmp_uint=MY_MIN(exponent,(uint)(frac_digits_end-frac_digits_from));
    int_digits_added_zeros=exponent-tmp_uint;
    int_digits_tail_from=frac_digits_from;
    frac_digits_from=frac_digits_from+tmp_uint;
    /*
      We "eat" the heading zeros of the 
      int_digits.int_digits_tail.int_digits_added_zeros concatenation
      (for example 0.003e3 must become 3 and not 0003)
    */
    if (int_digits_from == int_digits_end) 
    {
      /*
	There was nothing in the int_digits part, so continue
	eating int_digits_tail zeros
      */
      for (; int_digits_tail_from != frac_digits_from &&
	     *int_digits_tail_from == '0'; int_digits_tail_from++) ;
      if (int_digits_tail_from == frac_digits_from) 
      {
	// there were only zeros in int_digits_tail too
	int_digits_added_zeros=0;
      }
    }
    tmp_uint= (uint) (tmp_dec+(int_digits_end-int_digits_from)+
               (uint)(frac_digits_from-int_digits_tail_from)+
               int_digits_added_zeros);
  }
  
  /*
    Now write the formatted number
    
    First the digits of the int_% parts.
    Do we have enough room to write these digits ?
    If the sign is defined and '-', we need one position for it
  */

  if (field_length < tmp_uint + (int) (sign_char == '-')) 
  {
    // too big number, change to max or min number
    Field_decimal::overflow(sign_char == '-');
    return 1;
  }
 
  /*
    Tmp_left_pos is the position where the leftmost digit of
    the int_% parts will be written
  */
  tmp_left_pos=pos=to+(uint)(field_length-tmp_uint);
  
  // Write all digits of the int_% parts
  while (int_digits_from != int_digits_end)
    *pos++ = *int_digits_from++ ;

  if (expo_sign_char == '+')
  {    
    while (int_digits_tail_from != frac_digits_from)
      *pos++= *int_digits_tail_from++;
    while (int_digits_added_zeros-- >0)
      *pos++= '0';  
  }
  /*
    Note the position where the rightmost digit of the int_% parts has been
    written (this is to later check if the int_% parts contained nothing,
    meaning an extra 0 is needed).
  */
  tmp_right_pos=pos;

  /*
    Step back to the position of the leftmost digit of the int_% parts,
    to write sign and fill with zeros or blanks or prezeros.
  */
  pos=tmp_left_pos-1;
  if (zerofill)
  {
    left_wall=to-1;
    while (pos > left_wall)			// Fill with zeros
      *pos--='0';
  }
  else
  {
    left_wall=to+(sign_char != 0)-1;
    if (!expo_sign_char)	// If exponent was specified, ignore prezeros
    {
      for (;pos > left_wall && pre_zeros_from !=pre_zeros_end;
	   pre_zeros_from++)
	*pos--= '0';
    }
    if (pos == tmp_right_pos-1)
      *pos--= '0';		// no 0 has ever been written, so write one
    left_wall= to-1;
    if (sign_char && pos != left_wall)
    {
      /* Write sign if possible (it is if sign is '-') */
      *pos--= sign_char;
    }
    while (pos != left_wall)
      *pos--=' ';  //fill with blanks
  }
  
  /*
    Write digits of the frac_% parts ;
    Depending on get_thd()->count_cuted_fields, we may also want
    to know if some non-zero tail of these parts will
    be truncated (for example, 0.002->0.00 will generate a warning,
    while 0.000->0.00 will not)
    (and 0E1000000000 will not, while 1E-1000000000 will)
  */
      
  pos=to+(uint)(field_length-tmp_dec);	// Calculate post to '.'
  right_wall=to+field_length;
  if (pos != right_wall) 
    *pos++='.';

  if (expo_sign_char == '-')
  {
    while (frac_digits_added_zeros-- > 0)
    {
      if (pos == right_wall) 
      {
        if (get_thd()->count_cuted_fields && !is_cuted_fields_incr) 
          break; // Go on below to see if we lose non zero digits
        return 0;
      }
      *pos++='0';
    }
    while (int_digits_end != frac_digits_head_end)
    {
      tmp_char= *int_digits_end++;
      if (pos == right_wall)
      {
        if (tmp_char != '0')			// Losing a non zero digit ?
        {
          if (!is_cuted_fields_incr)
            set_warning(WARN_DATA_TRUNCATED, 1);
          return 0;
        }
        continue;
      }
      *pos++= tmp_char;
    }
  }

  for (;frac_digits_from!=frac_digits_end;) 
  {
    tmp_char= *frac_digits_from++;
    if (pos == right_wall)
    {
      if (tmp_char != '0')			// Losing a non zero digit ?
      {
        if (!is_cuted_fields_incr)
        {
          /*
            This is a note, not a warning, as we don't want to abort
            when we cut decimals in strict mode
          */
	  set_note(WARN_DATA_TRUNCATED, 1);
        }
        return 0;
      }
      continue;
    }
    *pos++= tmp_char;
  }
      
  while (pos != right_wall)
   *pos++='0';			// Fill with zeros at right of '.'
  return 0;
}