Linux-2.6.12-rc2
[linux-2.6.git] / 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