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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

#define MAX_DECIMAL_EXPONENT  767

#if DECIMAL_CALL_BY_REFERENCE

void

bid64_scalb (UINT64 * pres, UINT64 * px,

             int *pn _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM

             _EXC_INFO_PARAM) {

  UINT64 x;

  int n;

#else

UINT64

bid64_scalb (UINT64 x,

             int n _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM

             _EXC_INFO_PARAM) {

#endif

  UINT64 sign_x, coefficient_x, res;

  SINT64 exp64;

  int exponent_x, rmode;

#if DECIMAL_CALL_BY_REFERENCE

#if !DECIMAL_GLOBAL_ROUNDING

  _IDEC_round rnd_mode = *prnd_mode;

#endif

  x = *px;

  n = *pn;

#endif

  // unpack arguments, check for NaN or Infinity

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

    // x is Inf. or NaN or 0

#ifdef SET_STATUS_FLAGS

    if ((x & SNAN_MASK64) == SNAN_MASK64)       // y is sNaN

      __set_status_flags (pfpsf, INVALID_EXCEPTION);

#endif

    if (coefficient_x)

      res = coefficient_x & QUIET_MASK64;

        else {

       exp64 = (SINT64) exponent_x + (SINT64) n;

           if(exp64<0) exp64=0;

           if(exp64>MAX_DECIMAL_EXPONENT) exp64=MAX_DECIMAL_EXPONENT;

       exponent_x = exp64;

      res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);    // 0

        }

    BID_RETURN (res);

  }

  exp64 = (SINT64) exponent_x + (SINT64) n;

  exponent_x = exp64;

  if ((UINT32) exponent_x <= MAX_DECIMAL_EXPONENT) {

    res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);

    BID_RETURN (res);

  }

  // check for overflow

  if (exp64 > MAX_DECIMAL_EXPONENT) {

    // try to normalize coefficient

    while ((coefficient_x < 1000000000000000ull)

           && (exp64 > MAX_DECIMAL_EXPONENT)) {

      // coefficient_x < 10^15, scale by 10

      coefficient_x = (coefficient_x << 1) + (coefficient_x << 3);

      exponent_x--;

      exp64--;

    }

    if (exp64 <= MAX_DECIMAL_EXPONENT) {

      res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);

      BID_RETURN (res);

    } else

      exponent_x = 0x7fffffff;  // overflow

  }

  // exponent < 0

  // the BID pack routine will round the coefficient

  rmode = rnd_mode;

  res = get_BID64 (sign_x, exponent_x, coefficient_x, rmode, pfpsf);

  BID_RETURN (res);

}