~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008 Sun Microsystems

 *

 *  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; version 2 of the License.

 *

 *  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

#include <drizzled/server_includes.h>

#include <drizzled/function/math/round.h>

#include <limits>

#include <algorithm>

using namespace std;

void Item_func_round::fix_length_and_dec()

{

  int      decimals_to_set;

  int64_t val1;

  bool     val1_unsigned;

  unsigned_flag= args[0]->unsigned_flag;

  if (!args[1]->const_item())

  {

    max_length= args[0]->max_length;

    decimals= args[0]->decimals;

    if (args[0]->result_type() == DECIMAL_RESULT)

    {

      max_length++;

      hybrid_type= DECIMAL_RESULT;

    }

    else

      hybrid_type= REAL_RESULT;

    return;

  }

  val1= args[1]->val_int();

  val1_unsigned= args[1]->unsigned_flag;

  if (val1 < 0)

    decimals_to_set= val1_unsigned ? INT_MAX : 0;

  else

    decimals_to_set= (val1 > INT_MAX) ? INT_MAX : (int) val1;

  if (args[0]->decimals == NOT_FIXED_DEC)

  {

    max_length= args[0]->max_length;

    decimals= min(decimals_to_set, (int)NOT_FIXED_DEC);

    hybrid_type= REAL_RESULT;

    return;

  }

  switch (args[0]->result_type()) {

  case REAL_RESULT:

  case STRING_RESULT:

    hybrid_type= REAL_RESULT;

    decimals= min(decimals_to_set, (int)NOT_FIXED_DEC);

    max_length= float_length(decimals);

    break;

  case INT_RESULT:

    if ((!decimals_to_set && truncate) || (args[0]->decimal_precision() < DECIMAL_LONGLONG_DIGITS))

    {

      int length_can_increase= test(!truncate && (val1 < 0) && !val1_unsigned);

      max_length= args[0]->max_length + length_can_increase;

      /* Here we can keep INT_RESULT */

      hybrid_type= INT_RESULT;

      decimals= 0;

      break;

    }

    /* fall through */

  case DECIMAL_RESULT:

  {

    hybrid_type= DECIMAL_RESULT;

    decimals_to_set= min(DECIMAL_MAX_SCALE, decimals_to_set);

    int decimals_delta= args[0]->decimals - decimals_to_set;

    int precision= args[0]->decimal_precision();

    int length_increase= ((decimals_delta <= 0) || truncate) ? 0:1;

    precision-= decimals_delta - length_increase;

    decimals= min(decimals_to_set, DECIMAL_MAX_SCALE);

    max_length= my_decimal_precision_to_length(precision, decimals,

                                               unsigned_flag);

    break;

  }

  default:

    assert(0); /* This result type isn't handled */

  }

}

double my_double_round(double value, int64_t dec, bool dec_unsigned,

                       bool truncate)

{

  double tmp;

  bool dec_negative= (dec < 0) && !dec_unsigned;

  uint64_t abs_dec= dec_negative ? -dec : dec;

  /*

    tmp2 is here to avoid return the value with 80 bit precision

    This will fix that the test round(0.1,1) = round(0.1,1) is true

  */

  double tmp2;

  tmp=(abs_dec < array_elements(log_10) ?

       log_10[abs_dec] : pow(10.0,(double) abs_dec));

  double value_times_tmp= value * tmp;

  /*

    NOTE: This is a workaround for a gcc 4.3 bug on Intel x86 32bit

    See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39228

    See http://bugs.mysql.com/bug.php?id=42965

    This forces the compiler to store/load the value as 64bit and avoids

    an optimisation that *could* have the infinite check be done on the 80bit

    representation.

   */

  if(sizeof(double) < sizeof(double_t))

  {

    volatile double t= value_times_tmp;

    value_times_tmp= t;

  }

  double infinity= numeric_limits<double>::infinity();

  if (dec_negative && (tmp == infinity))

    tmp2= 0;

  else if (!dec_negative && (value_times_tmp == infinity))

    tmp2= value;

  else if (truncate)

  {

    if (value >= 0)

      tmp2= dec < 0 ? floor(value/tmp)*tmp : floor(value*tmp)/tmp;

    else

      tmp2= dec < 0 ? ceil(value/tmp)*tmp : ceil(value*tmp)/tmp;

  }

  else

    tmp2=dec < 0 ? rint(value/tmp)*tmp : rint(value*tmp)/tmp;

  return tmp2;

}

double Item_func_round::real_op()

{

  double value= args[0]->val_real();

  if (!(null_value= args[0]->null_value || args[1]->null_value))

    return my_double_round(value, args[1]->val_int(), args[1]->unsigned_flag,

                           truncate);

  return 0.0;

}

/*

  Rounds a given value to a power of 10 specified as the 'to' argument,

  avoiding overflows when the value is close to the uint64_t range boundary.

*/

static inline uint64_t my_unsigned_round(uint64_t value, uint64_t to)

{

  uint64_t tmp= value / to * to;

  return (value - tmp < (to >> 1)) ? tmp : tmp + to;

}

int64_t Item_func_round::int_op()

{

  int64_t value= args[0]->val_int();

  int64_t dec= args[1]->val_int();

  decimals= 0;

  uint64_t abs_dec;

  if ((null_value= args[0]->null_value || args[1]->null_value))

    return 0;

  if ((dec >= 0) || args[1]->unsigned_flag)

    return value; // integer have not digits after point

  abs_dec= -dec;

  int64_t tmp;

  if(abs_dec >= array_elements(log_10_int))

    return 0;

  tmp= log_10_int[abs_dec];

  if (truncate)

    value= (unsigned_flag) ?

      ((uint64_t) value / tmp) * tmp : (value / tmp) * tmp;

  else

    value= (unsigned_flag || value >= 0) ?

      my_unsigned_round((uint64_t) value, tmp) :

      -(int64_t) my_unsigned_round((uint64_t) -value, tmp);

  return value;

}

my_decimal *Item_func_round::decimal_op(my_decimal *decimal_value)

{

  my_decimal val, *value= args[0]->val_decimal(&val);

  int64_t dec= args[1]->val_int();

  if (dec >= 0 || args[1]->unsigned_flag)

    dec= min(dec, (int64_t) decimals);

  else if (dec < INT_MIN)

    dec= INT_MIN;

  if (!(null_value= (args[0]->null_value || args[1]->null_value ||

                     my_decimal_round(E_DEC_FATAL_ERROR, value, (int) dec,

                                      truncate, decimal_value) > 1)))

  {

    decimal_value->frac= decimals;

    return decimal_value;

  }

  return 0;

}