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/* Copyright (C) 2007, 2009  Free Software Foundation, Inc.

This file is part of GCC.

GCC 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 3, or (at your option) any later

version.

GCC 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.

Under Section 7 of GPL version 3, you are granted additional

permissions described in the GCC Runtime Library Exception, version

3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and

a copy of the GCC Runtime Library Exception along with this program;

see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

<http://www.gnu.org/licenses/>.  */

#include "bid_internal.h"

#define MAX_FORMAT_DIGITS     16

#define DECIMAL_EXPONENT_BIAS 398

#if DECIMAL_CALL_BY_REFERENCE

void

bid64_logb (int * pres, UINT64 * px

            _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) {

  UINT64 x;

#else

int

bid64_logb (UINT64 x _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) {

#endif

  UINT64 sign_x, coefficient_x;

  int_double dx;

  int exponent_x, bin_expon_cx, digits;

#if DECIMAL_CALL_BY_REFERENCE

  x = *px;

#endif

  // unpack arguments, check for NaN or Infinity

  if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {

    // x is Inf. or NaN

#ifdef SET_STATUS_FLAGS

      __set_status_flags (pfpsf, INVALID_EXCEPTION);

#endif

      BID_RETURN (0x80000000);

  }

  // find number of digits in coefficient

  if (coefficient_x >= 1000000000000000ull) {

    digits = 16;

  } else {

    dx.d = (double)coefficient_x;   // exact conversion;

    bin_expon_cx = (int)(dx.i >> 52) - 1023;

    digits = estimate_decimal_digits[bin_expon_cx];

    if (coefficient_x >= power10_table_128[digits].w[0])

      digits++;

  }

  exponent_x = exponent_x - DECIMAL_EXPONENT_BIAS + digits - 1;

  BID_RETURN (exponent_x);

}