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 /* We need just a few things from here for op-4, if we ever need some
25 other macros, they can be added. */
26 #define _FP_FRAC_DECL_8(X) _FP_W_TYPE X##_f[8]
27 #define _FP_FRAC_HIGH_8(X) (X##_f[7])
28 #define _FP_FRAC_LOW_8(X) (X##_f[0])
29 #define _FP_FRAC_WORD_8(X,w) (X##_f[w])
30
31 #define _FP_FRAC_SLL_8(X,N) \
32 do { \
33 _FP_I_TYPE _up, _down, _skip, _i; \
34 _skip = (N) / _FP_W_TYPE_SIZE; \
35 _up = (N) % _FP_W_TYPE_SIZE; \
36 _down = _FP_W_TYPE_SIZE - _up; \
37 if (!_up) \
38 for (_i = 7; _i >= _skip; --_i) \
39 X##_f[_i] = X##_f[_i-_skip]; \
40 else \
41 { \
42 for (_i = 7; _i > _skip; --_i) \
43 X##_f[_i] = X##_f[_i-_skip] << _up \
44 | X##_f[_i-_skip-1] >> _down; \
45 X##_f[_i--] = X##_f[0] << _up; \
46 } \
47 for (; _i >= 0; --_i) \
48 X##_f[_i] = 0; \
49 } while (0)
50
51 #define _FP_FRAC_SRL_8(X,N) \
52 do { \
53 _FP_I_TYPE _up, _down, _skip, _i; \
54 _skip = (N) / _FP_W_TYPE_SIZE; \
55 _down = (N) % _FP_W_TYPE_SIZE; \
56 _up = _FP_W_TYPE_SIZE - _down; \
57 if (!_down) \
58 for (_i = 0; _i <= 7-_skip; ++_i) \
59 X##_f[_i] = X##_f[_i+_skip]; \
60 else \
61 { \
62 for (_i = 0; _i < 7-_skip; ++_i) \
63 X##_f[_i] = X##_f[_i+_skip] >> _down \
64 | X##_f[_i+_skip+1] << _up; \
65 X##_f[_i++] = X##_f[7] >> _down; \
66 } \
67 for (; _i < 8; ++_i) \
68 X##_f[_i] = 0; \
69 } while (0)
70
71
72 /* Right shift with sticky-lsb.
73 * What this actually means is that we do a standard right-shift,
74 * but that if any of the bits that fall off the right hand side
75 * were one then we always set the LSbit.
76 */
77 #define _FP_FRAC_SRS_8(X,N,size) \
78 do { \
79 _FP_I_TYPE _up, _down, _skip, _i; \
80 _FP_W_TYPE _s; \
81 _skip = (N) / _FP_W_TYPE_SIZE; \
82 _down = (N) % _FP_W_TYPE_SIZE; \
83 _up = _FP_W_TYPE_SIZE - _down; \
84 for (_s = _i = 0; _i < _skip; ++_i) \
85 _s |= X##_f[_i]; \
86 _s |= X##_f[_i] << _up; \
87 /* s is now != 0 if we want to set the LSbit */ \
88 if (!_down) \
89 for (_i = 0; _i <= 7-_skip; ++_i) \
90 X##_f[_i] = X##_f[_i+_skip]; \
91 else \
92 { \
93 for (_i = 0; _i < 7-_skip; ++_i) \
94 X##_f[_i] = X##_f[_i+_skip] >> _down \
95 | X##_f[_i+_skip+1] << _up; \
96 X##_f[_i++] = X##_f[7] >> _down; \
97 } \
98 for (; _i < 8; ++_i) \
99 X##_f[_i] = 0; \
100 /* don't fix the LSB until the very end when we're sure f[0] is stable */ \
101 X##_f[0] |= (_s != 0); \
102 } while (0)
103
104
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