LXR linux/include/math-emu/op-8.h

   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