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  1. /* Copyright (C) 2007-2015 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. }
  106.