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