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[glibc/history.git] / soft-fp / op-1.h
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1 /* Software floating-point emulation.
2 Basic one-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),
7 David S. Miller (davem@redhat.com) and
8 Peter Maydell (pmaydell@chiark.greenend.org.uk).
9
10 The GNU C Library is free software; you can redistribute it and/or
11 modify it under the terms of the GNU Lesser General Public
12 License as published by the Free Software Foundation; either
13 version 2.1 of the License, or (at your option) any later version.
14
15 The GNU C Library is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
19
20 You should have received a copy of the GNU Lesser General Public
21 License along with the GNU C Library; if not, write to the Free
22 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
23 02111-1307 USA. */
24
25 #define _FP_FRAC_DECL_1(X) _FP_W_TYPE X##_f
26 #define _FP_FRAC_COPY_1(D,S) (D##_f = S##_f)
27 #define _FP_FRAC_SET_1(X,I) (X##_f = I)
28 #define _FP_FRAC_HIGH_1(X) (X##_f)
29 #define _FP_FRAC_LOW_1(X) (X##_f)
30 #define _FP_FRAC_WORD_1(X,w) (X##_f)
31
32 #define _FP_FRAC_ADDI_1(X,I) (X##_f += I)
33 #define _FP_FRAC_SLL_1(X,N) \
34 do { \
35 if (__builtin_constant_p(N) && (N) == 1) \
36 X##_f += X##_f; \
37 else \
38 X##_f <<= (N); \
39 } while (0)
40 #define _FP_FRAC_SRL_1(X,N) (X##_f >>= N)
41
42 /* Right shift with sticky-lsb. */
43 #define _FP_FRAC_SRS_1(X,N,sz) __FP_FRAC_SRS_1(X##_f, N, sz)
44
45 #define __FP_FRAC_SRS_1(X,N,sz) \
46 (X = (X >> (N) | (__builtin_constant_p(N) && (N) == 1 \
47 ? X & 1 : (X << (_FP_W_TYPE_SIZE - (N))) != 0)))
48
49 #define _FP_FRAC_ADD_1(R,X,Y) (R##_f = X##_f + Y##_f)
50 #define _FP_FRAC_SUB_1(R,X,Y) (R##_f = X##_f - Y##_f)
51 #define _FP_FRAC_DEC_1(X,Y) (X##_f -= Y##_f)
52 #define _FP_FRAC_CLZ_1(z, X) __FP_CLZ(z, X##_f)
53
54 /* Predicates */
55 #define _FP_FRAC_NEGP_1(X) ((_FP_WS_TYPE)X##_f < 0)
56 #define _FP_FRAC_ZEROP_1(X) (X##_f == 0)
57 #define _FP_FRAC_OVERP_1(fs,X) (X##_f & _FP_OVERFLOW_##fs)
58 #define _FP_FRAC_CLEAR_OVERP_1(fs,X) (X##_f &= ~_FP_OVERFLOW_##fs)
59 #define _FP_FRAC_EQ_1(X, Y) (X##_f == Y##_f)
60 #define _FP_FRAC_GE_1(X, Y) (X##_f >= Y##_f)
61 #define _FP_FRAC_GT_1(X, Y) (X##_f > Y##_f)
62
63 #define _FP_ZEROFRAC_1 0
64 #define _FP_MINFRAC_1 1
65 #define _FP_MAXFRAC_1 (~(_FP_WS_TYPE)0)
66
67 /*
68 * Unpack the raw bits of a native fp value. Do not classify or
69 * normalize the data.
70 */
71
72 #define _FP_UNPACK_RAW_1(fs, X, val) \
73 do { \
74 union _FP_UNION_##fs _flo; _flo.flt = (val); \
75 \
76 X##_f = _flo.bits.frac; \
77 X##_e = _flo.bits.exp; \
78 X##_s = _flo.bits.sign; \
79 } while (0)
80
81 #define _FP_UNPACK_RAW_1_P(fs, X, val) \
82 do { \
83 union _FP_UNION_##fs *_flo = \
84 (union _FP_UNION_##fs *)(val); \
85 \
86 X##_f = _flo->bits.frac; \
87 X##_e = _flo->bits.exp; \
88 X##_s = _flo->bits.sign; \
89 } while (0)
90
91 /*
92 * Repack the raw bits of a native fp value.
93 */
94
95 #define _FP_PACK_RAW_1(fs, val, X) \
96 do { \
97 union _FP_UNION_##fs _flo; \
98 \
99 _flo.bits.frac = X##_f; \
100 _flo.bits.exp = X##_e; \
101 _flo.bits.sign = X##_s; \
102 \
103 (val) = _flo.flt; \
104 } while (0)
105
106 #define _FP_PACK_RAW_1_P(fs, val, X) \
107 do { \
108 union _FP_UNION_##fs *_flo = \
109 (union _FP_UNION_##fs *)(val); \
110 \
111 _flo->bits.frac = X##_f; \
112 _flo->bits.exp = X##_e; \
113 _flo->bits.sign = X##_s; \
114 } while (0)
115
116
117 /*
118 * Multiplication algorithms:
119 */
120
121 /* Basic. Assuming the host word size is >= 2*FRACBITS, we can do the
122 multiplication immediately. */
123
124 #define _FP_MUL_MEAT_1_imm(wfracbits, R, X, Y) \
125 do { \
126 R##_f = X##_f * Y##_f; \
127 /* Normalize since we know where the msb of the multiplicands \
128 were (bit B), we know that the msb of the of the product is \
129 at either 2B or 2B-1. */ \
130 _FP_FRAC_SRS_1(R, wfracbits-1, 2*wfracbits); \
131 } while (0)
132
133 /* Given a 1W * 1W => 2W primitive, do the extended multiplication. */
134
135 #define _FP_MUL_MEAT_1_wide(wfracbits, R, X, Y, doit) \
136 do { \
137 _FP_W_TYPE _Z_f0, _Z_f1; \
138 doit(_Z_f1, _Z_f0, X##_f, Y##_f); \
139 /* Normalize since we know where the msb of the multiplicands \
140 were (bit B), we know that the msb of the of the product is \
141 at either 2B or 2B-1. */ \
142 _FP_FRAC_SRS_2(_Z, wfracbits-1, 2*wfracbits); \
143 R##_f = _Z_f0; \
144 } while (0)
145
146 /* Finally, a simple widening multiply algorithm. What fun! */
147
148 #define _FP_MUL_MEAT_1_hard(wfracbits, R, X, Y) \
149 do { \
150 _FP_W_TYPE _xh, _xl, _yh, _yl, _z_f0, _z_f1, _a_f0, _a_f1; \
151 \
152 /* split the words in half */ \
153 _xh = X##_f >> (_FP_W_TYPE_SIZE/2); \
154 _xl = X##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1); \
155 _yh = Y##_f >> (_FP_W_TYPE_SIZE/2); \
156 _yl = Y##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1); \
157 \
158 /* multiply the pieces */ \
159 _z_f0 = _xl * _yl; \
160 _a_f0 = _xh * _yl; \
161 _a_f1 = _xl * _yh; \
162 _z_f1 = _xh * _yh; \
163 \
164 /* reassemble into two full words */ \
165 if ((_a_f0 += _a_f1) < _a_f1) \
166 _z_f1 += (_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2); \
167 _a_f1 = _a_f0 >> (_FP_W_TYPE_SIZE/2); \
168 _a_f0 = _a_f0 << (_FP_W_TYPE_SIZE/2); \
169 _FP_FRAC_ADD_2(_z, _z, _a); \
170 \
171 /* normalize */ \
172 _FP_FRAC_SRS_2(_z, wfracbits - 1, 2*wfracbits); \
173 R##_f = _z_f0; \
174 } while (0)
175
176
177 /*
178 * Division algorithms:
179 */
180
181 /* Basic. Assuming the host word size is >= 2*FRACBITS, we can do the
182 division immediately. Give this macro either _FP_DIV_HELP_imm for
183 C primitives or _FP_DIV_HELP_ldiv for the ISO function. Which you
184 choose will depend on what the compiler does with divrem4. */
185
186 #define _FP_DIV_MEAT_1_imm(fs, R, X, Y, doit) \
187 do { \
188 _FP_W_TYPE _q, _r; \
189 X##_f <<= (X##_f < Y##_f \
190 ? R##_e--, _FP_WFRACBITS_##fs \
191 : _FP_WFRACBITS_##fs - 1); \
192 doit(_q, _r, X##_f, Y##_f); \
193 R##_f = _q | (_r != 0); \
194 } while (0)
195
196 /* GCC's longlong.h defines a 2W / 1W => (1W,1W) primitive udiv_qrnnd
197 that may be useful in this situation. This first is for a primitive
198 that requires normalization, the second for one that does not. Look
199 for UDIV_NEEDS_NORMALIZATION to tell which your machine needs. */
200
201 #define _FP_DIV_MEAT_1_udiv_norm(fs, R, X, Y) \
202 do { \
203 _FP_W_TYPE _nh, _nl, _q, _r, _y; \
204 \
205 /* Normalize Y -- i.e. make the most significant bit set. */ \
206 _y = Y##_f << _FP_WFRACXBITS_##fs; \
207 \
208 /* Shift X op correspondingly high, that is, up one full word. */ \
209 if (X##_f < Y##_f) \
210 { \
211 R##_e--; \
212 _nl = 0; \
213 _nh = X##_f; \
214 } \
215 else \
216 { \
217 _nl = X##_f << (_FP_W_TYPE_SIZE - 1); \
218 _nh = X##_f >> 1; \
219 } \
220 \
221 udiv_qrnnd(_q, _r, _nh, _nl, _y); \
222 R##_f = _q | (_r != 0); \
223 } while (0)
224
225 #define _FP_DIV_MEAT_1_udiv(fs, R, X, Y) \
226 do { \
227 _FP_W_TYPE _nh, _nl, _q, _r; \
228 if (X##_f < Y##_f) \
229 { \
230 R##_e--; \
231 _nl = X##_f << _FP_WFRACBITS_##fs; \
232 _nh = X##_f >> _FP_WFRACXBITS_##fs; \
233 } \
234 else \
235 { \
236 _nl = X##_f << (_FP_WFRACBITS_##fs - 1); \
237 _nh = X##_f >> (_FP_WFRACXBITS_##fs + 1); \
238 } \
239 udiv_qrnnd(_q, _r, _nh, _nl, Y##_f); \
240 R##_f = _q | (_r != 0); \
241 } while (0)
242
243
244 /*
245 * Square root algorithms:
246 * We have just one right now, maybe Newton approximation
247 * should be added for those machines where division is fast.
248 */
249
250 #define _FP_SQRT_MEAT_1(R, S, T, X, q) \
251 do { \
252 while (q != _FP_WORK_ROUND) \
253 { \
254 T##_f = S##_f + q; \
255 if (T##_f <= X##_f) \
256 { \
257 S##_f = T##_f + q; \
258 X##_f -= T##_f; \
259 R##_f += q; \
260 } \
261 _FP_FRAC_SLL_1(X, 1); \
262 q >>= 1; \
263 } \
264 if (X##_f) \
265 { \
266 if (S##_f < X##_f) \
267 R##_f |= _FP_WORK_ROUND; \
268 R##_f |= _FP_WORK_STICKY; \
269 } \
270 } while (0)
271
272 /*
273 * Assembly/disassembly for converting to/from integral types.
274 * No shifting or overflow handled here.
275 */
276
277 #define _FP_FRAC_ASSEMBLE_1(r, X, rsize) (r = X##_f)
278 #define _FP_FRAC_DISASSEMBLE_1(X, r, rsize) (X##_f = r)
279
280
281 /*
282 * Convert FP values between word sizes
283 */
284
285 #define _FP_FRAC_CONV_1_1(dfs, sfs, D, S) \
286 do { \
287 D##_f = S##_f; \
288 if (_FP_WFRACBITS_##sfs > _FP_WFRACBITS_##dfs) \
289 { \
290 if (S##_c != FP_CLS_NAN) \
291 _FP_FRAC_SRS_1(D, (_FP_WFRACBITS_##sfs-_FP_WFRACBITS_##dfs), \
292 _FP_WFRACBITS_##sfs); \
293 else \
294 _FP_FRAC_SRL_1(D, (_FP_WFRACBITS_##sfs-_FP_WFRACBITS_##dfs)); \
295 } \
296 else \
297 D##_f <<= _FP_WFRACBITS_##dfs - _FP_WFRACBITS_##sfs; \
298 } while (0)
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