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  1. /* Software floating-point emulation.
  2.    Basic eight-word fraction declaration and manipulation.
  3.    Copyright (C) 1997,1998,1999 Free Software Foundation, Inc.
  4.    This file is part of the GNU C Library.
  5.    Contributed by Richard Henderson (rth@cygnus.com),
  6.           Jakub Jelinek (jj@ultra.linux.cz) and
  7.           Peter Maydell (pmaydell@chiark.greenend.org.uk).
  8.                                                          
  9.    The GNU C Library is free software; you can redistribute it and/or
  10.    modify it under the terms of the GNU Library General Public License as
  11.    published by the Free Software Foundation; either version 2 of the
  12.    License, or (at your option) any later version.
  13.  
  14.    The GNU C Library is distributed in the hope that it will be useful,
  15.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17.    Library General Public License for more details.
  18.  
  19.    You should have received a copy of the GNU Library General Public
  20.    License along with the GNU C Library; see the file COPYING.LIB.  If
  21.    not, write to the Free Software Foundation, Inc.,
  22.    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  23.  
  24. #ifndef __MATH_EMU_OP_8_H__
  25. #define __MATH_EMU_OP_8_H__
  26.  
  27. /* We need just a few things from here for op-4, if we ever need some
  28.    other macros, they can be added. */
  29. #define _FP_FRAC_DECL_8(X)    _FP_W_TYPE X##_f[8]
  30. #define _FP_FRAC_HIGH_8(X)    (X##_f[7])
  31. #define _FP_FRAC_LOW_8(X)    (X##_f[0])
  32. #define _FP_FRAC_WORD_8(X,w)    (X##_f[w])
  33.  
  34. #define _FP_FRAC_SLL_8(X,N)                        \
  35.   do {                                    \
  36.     _FP_I_TYPE _up, _down, _skip, _i;                    \
  37.     _skip = (N) / _FP_W_TYPE_SIZE;                    \
  38.     _up = (N) % _FP_W_TYPE_SIZE;                    \
  39.     _down = _FP_W_TYPE_SIZE - _up;                    \
  40.     if (!_up)                                \
  41.       for (_i = 7; _i >= _skip; --_i)                    \
  42.     X##_f[_i] = X##_f[_i-_skip];                    \
  43.     else                                \
  44.       {                                    \
  45.     for (_i = 7; _i > _skip; --_i)                    \
  46.       X##_f[_i] = X##_f[_i-_skip] << _up                \
  47.               | X##_f[_i-_skip-1] >> _down;            \
  48.     X##_f[_i--] = X##_f[0] << _up;                     \
  49.       }                                    \
  50.     for (; _i >= 0; --_i)                        \
  51.       X##_f[_i] = 0;                            \
  52.   } while (0)
  53.  
  54. #define _FP_FRAC_SRL_8(X,N)                        \
  55.   do {                                    \
  56.     _FP_I_TYPE _up, _down, _skip, _i;                    \
  57.     _skip = (N) / _FP_W_TYPE_SIZE;                    \
  58.     _down = (N) % _FP_W_TYPE_SIZE;                    \
  59.     _up = _FP_W_TYPE_SIZE - _down;                    \
  60.     if (!_down)                                \
  61.       for (_i = 0; _i <= 7-_skip; ++_i)                    \
  62.     X##_f[_i] = X##_f[_i+_skip];                    \
  63.     else                                \
  64.       {                                    \
  65.     for (_i = 0; _i < 7-_skip; ++_i)                \
  66.       X##_f[_i] = X##_f[_i+_skip] >> _down                \
  67.               | X##_f[_i+_skip+1] << _up;            \
  68.     X##_f[_i++] = X##_f[7] >> _down;                \
  69.       }                                    \
  70.     for (; _i < 8; ++_i)                        \
  71.       X##_f[_i] = 0;                            \
  72.   } while (0)
  73.  
  74.  
  75. /* Right shift with sticky-lsb. 
  76.  * What this actually means is that we do a standard right-shift,
  77.  * but that if any of the bits that fall off the right hand side
  78.  * were one then we always set the LSbit.
  79.  */
  80. #define _FP_FRAC_SRS_8(X,N,size)                    \
  81.   do {                                    \
  82.     _FP_I_TYPE _up, _down, _skip, _i;                    \
  83.     _FP_W_TYPE _s;                            \
  84.     _skip = (N) / _FP_W_TYPE_SIZE;                    \
  85.     _down = (N) % _FP_W_TYPE_SIZE;                    \
  86.     _up = _FP_W_TYPE_SIZE - _down;                    \
  87.     for (_s = _i = 0; _i < _skip; ++_i)                    \
  88.       _s |= X##_f[_i];                            \
  89.     _s |= X##_f[_i] << _up;                        \
  90. /* s is now != 0 if we want to set the LSbit */                \
  91.     if (!_down)                                \
  92.       for (_i = 0; _i <= 7-_skip; ++_i)                    \
  93.     X##_f[_i] = X##_f[_i+_skip];                    \
  94.     else                                \
  95.       {                                    \
  96.     for (_i = 0; _i < 7-_skip; ++_i)                \
  97.       X##_f[_i] = X##_f[_i+_skip] >> _down                \
  98.               | X##_f[_i+_skip+1] << _up;            \
  99.     X##_f[_i++] = X##_f[7] >> _down;                \
  100.       }                                    \
  101.     for (; _i < 8; ++_i)                        \
  102.       X##_f[_i] = 0;                            \
  103.     /* don't fix the LSB until the very end when we're sure f[0] is stable */    \
  104.     X##_f[0] |= (_s != 0);                        \
  105.   } while (0)
  106.  
  107. #endif
  108.