1  /* Copyright (C) 2007-2023 Free Software Foundation, Inc.
       2  
       3  This file is part of GCC.
       4  
       5  GCC is free software; you can redistribute it and/or modify it under
       6  the terms of the GNU General Public License as published by the Free
       7  Software Foundation; either version 3, or (at your option) any later
       8  version.
       9  
      10  GCC is distributed in the hope that it will be useful, but WITHOUT ANY
      11  WARRANTY; without even the implied warranty of MERCHANTABILITY or
      12  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      13  for more details.
      14  
      15  Under Section 7 of GPL version 3, you are granted additional
      16  permissions described in the GCC Runtime Library Exception, version
      17  3.1, as published by the Free Software Foundation.
      18  
      19  You should have received a copy of the GNU General Public License and
      20  a copy of the GCC Runtime Library Exception along with this program;
      21  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      22  <http://www.gnu.org/licenses/>.  */
      23  
      24  #include "bid_internal.h"
      25  
      26  #define MAX_FORMAT_DIGITS     16
      27  #define DECIMAL_EXPONENT_BIAS 398
      28  #define MAX_DECIMAL_EXPONENT  767
      29  
      30  #if DECIMAL_CALL_BY_REFERENCE
      31  
      32  void
      33  bid64_scalb (UINT64 * pres, UINT64 * px,
      34  	     int *pn _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
      35  	     _EXC_INFO_PARAM) {
      36    UINT64 x;
      37    int n;
      38  #else
      39  
      40  UINT64
      41  bid64_scalb (UINT64 x,
      42  	     int n _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
      43  	     _EXC_INFO_PARAM) {
      44  #endif
      45    UINT64 sign_x, coefficient_x, res;
      46    SINT64 exp64;
      47    int exponent_x, rmode;
      48  
      49  #if DECIMAL_CALL_BY_REFERENCE
      50  #if !DECIMAL_GLOBAL_ROUNDING
      51    _IDEC_round rnd_mode = *prnd_mode;
      52  #endif
      53    x = *px;
      54    n = *pn;
      55  #endif
      56  
      57    // unpack arguments, check for NaN or Infinity
      58    if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {
      59      // x is Inf. or NaN or 0
      60  #ifdef SET_STATUS_FLAGS
      61      if ((x & SNAN_MASK64) == SNAN_MASK64)	// y is sNaN
      62        __set_status_flags (pfpsf, INVALID_EXCEPTION);
      63  #endif
      64      if (coefficient_x)
      65        res = coefficient_x & QUIET_MASK64;
      66  	else {
      67         exp64 = (SINT64) exponent_x + (SINT64) n;
      68  	   if(exp64<0) exp64=0;
      69  	   if(exp64>MAX_DECIMAL_EXPONENT) exp64=MAX_DECIMAL_EXPONENT;
      70         exponent_x = exp64;
      71        res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);	// 0
      72  	}
      73      BID_RETURN (res);
      74    }
      75  
      76    exp64 = (SINT64) exponent_x + (SINT64) n;
      77    exponent_x = exp64;
      78  
      79    if ((UINT32) exponent_x <= MAX_DECIMAL_EXPONENT) {
      80      res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);
      81      BID_RETURN (res);
      82    }
      83    // check for overflow
      84    if (exp64 > MAX_DECIMAL_EXPONENT) {
      85      // try to normalize coefficient
      86      while ((coefficient_x < 1000000000000000ull)
      87  	   && (exp64 > MAX_DECIMAL_EXPONENT)) {
      88        // coefficient_x < 10^15, scale by 10
      89        coefficient_x = (coefficient_x << 1) + (coefficient_x << 3);
      90        exponent_x--;
      91        exp64--;
      92      }
      93      if (exp64 <= MAX_DECIMAL_EXPONENT) {
      94        res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);
      95        BID_RETURN (res);
      96      } else
      97        exponent_x = 0x7fffffff;	// overflow
      98    }
      99    // exponent < 0
     100    // the BID pack routine will round the coefficient
     101    rmode = rnd_mode;
     102    res = get_BID64 (sign_x, exponent_x, coefficient_x, rmode, pfpsf);
     103    BID_RETURN (res);
     104  
     105  }