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[thirdparty/glibc.git] / soft-fp / op-1.h
1 /* Software floating-point emulation.
2 Basic one-word fraction declaration and manipulation.
3 Copyright (C) 1997-2013 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 In addition to the permissions in the GNU Lesser General Public
16 License, the Free Software Foundation gives you unlimited
17 permission to link the compiled version of this file into
18 combinations with other programs, and to distribute those
19 combinations without any restriction coming from the use of this
20 file. (The Lesser General Public License restrictions do apply in
21 other respects; for example, they cover modification of the file,
22 and distribution when not linked into a combine executable.)
23
24 The GNU C Library is distributed in the hope that it will be useful,
25 but WITHOUT ANY WARRANTY; without even the implied warranty of
26 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
27 Lesser General Public License for more details.
28
29 You should have received a copy of the GNU Lesser General Public
30 License along with the GNU C Library; if not, see
31 <http://www.gnu.org/licenses/>. */
32
33 #define _FP_FRAC_DECL_1(X) _FP_W_TYPE X##_f
34 #define _FP_FRAC_COPY_1(D,S) (D##_f = S##_f)
35 #define _FP_FRAC_SET_1(X,I) (X##_f = I)
36 #define _FP_FRAC_HIGH_1(X) (X##_f)
37 #define _FP_FRAC_LOW_1(X) (X##_f)
38 #define _FP_FRAC_WORD_1(X,w) (X##_f)
39
40 #define _FP_FRAC_ADDI_1(X,I) (X##_f += I)
41 #define _FP_FRAC_SLL_1(X,N) \
42 do { \
43 if (__builtin_constant_p(N) && (N) == 1) \
44 X##_f += X##_f; \
45 else \
46 X##_f <<= (N); \
47 } while (0)
48 #define _FP_FRAC_SRL_1(X,N) (X##_f >>= N)
49
50 /* Right shift with sticky-lsb. */
51 #define _FP_FRAC_SRST_1(X,S,N,sz) __FP_FRAC_SRST_1(X##_f, S, N, sz)
52 #define _FP_FRAC_SRS_1(X,N,sz) __FP_FRAC_SRS_1(X##_f, N, sz)
53
54 #define __FP_FRAC_SRST_1(X,S,N,sz) \
55 do { \
56 S = (__builtin_constant_p(N) && (N) == 1 \
57 ? X & 1 : (X << (_FP_W_TYPE_SIZE - (N))) != 0); \
58 X = X >> (N); \
59 } while (0)
60
61 #define __FP_FRAC_SRS_1(X,N,sz) \
62 (X = (X >> (N) | (__builtin_constant_p(N) && (N) == 1 \
63 ? X & 1 : (X << (_FP_W_TYPE_SIZE - (N))) != 0)))
64
65 #define _FP_FRAC_ADD_1(R,X,Y) (R##_f = X##_f + Y##_f)
66 #define _FP_FRAC_SUB_1(R,X,Y) (R##_f = X##_f - Y##_f)
67 #define _FP_FRAC_DEC_1(X,Y) (X##_f -= Y##_f)
68 #define _FP_FRAC_CLZ_1(z, X) __FP_CLZ(z, X##_f)
69
70 /* Predicates */
71 #define _FP_FRAC_NEGP_1(X) ((_FP_WS_TYPE)X##_f < 0)
72 #define _FP_FRAC_ZEROP_1(X) (X##_f == 0)
73 #define _FP_FRAC_OVERP_1(fs,X) (X##_f & _FP_OVERFLOW_##fs)
74 #define _FP_FRAC_CLEAR_OVERP_1(fs,X) (X##_f &= ~_FP_OVERFLOW_##fs)
75 #define _FP_FRAC_EQ_1(X, Y) (X##_f == Y##_f)
76 #define _FP_FRAC_GE_1(X, Y) (X##_f >= Y##_f)
77 #define _FP_FRAC_GT_1(X, Y) (X##_f > Y##_f)
78
79 #define _FP_ZEROFRAC_1 0
80 #define _FP_MINFRAC_1 1
81 #define _FP_MAXFRAC_1 (~(_FP_WS_TYPE)0)
82
83 /*
84 * Unpack the raw bits of a native fp value. Do not classify or
85 * normalize the data.
86 */
87
88 #define _FP_UNPACK_RAW_1(fs, X, val) \
89 do { \
90 union _FP_UNION_##fs _flo; _flo.flt = (val); \
91 \
92 X##_f = _flo.bits.frac; \
93 X##_e = _flo.bits.exp; \
94 X##_s = _flo.bits.sign; \
95 } while (0)
96
97 #define _FP_UNPACK_RAW_1_P(fs, X, val) \
98 do { \
99 union _FP_UNION_##fs *_flo = \
100 (union _FP_UNION_##fs *)(val); \
101 \
102 X##_f = _flo->bits.frac; \
103 X##_e = _flo->bits.exp; \
104 X##_s = _flo->bits.sign; \
105 } while (0)
106
107 /*
108 * Repack the raw bits of a native fp value.
109 */
110
111 #define _FP_PACK_RAW_1(fs, val, X) \
112 do { \
113 union _FP_UNION_##fs _flo; \
114 \
115 _flo.bits.frac = X##_f; \
116 _flo.bits.exp = X##_e; \
117 _flo.bits.sign = X##_s; \
118 \
119 (val) = _flo.flt; \
120 } while (0)
121
122 #define _FP_PACK_RAW_1_P(fs, val, X) \
123 do { \
124 union _FP_UNION_##fs *_flo = \
125 (union _FP_UNION_##fs *)(val); \
126 \
127 _flo->bits.frac = X##_f; \
128 _flo->bits.exp = X##_e; \
129 _flo->bits.sign = X##_s; \
130 } while (0)
131
132
133 /*
134 * Multiplication algorithms:
135 */
136
137 /* Basic. Assuming the host word size is >= 2*FRACBITS, we can do the
138 multiplication immediately. */
139
140 #define _FP_MUL_MEAT_1_imm(wfracbits, R, X, Y) \
141 do { \
142 R##_f = X##_f * Y##_f; \
143 /* Normalize since we know where the msb of the multiplicands \
144 were (bit B), we know that the msb of the of the product is \
145 at either 2B or 2B-1. */ \
146 _FP_FRAC_SRS_1(R, wfracbits-1, 2*wfracbits); \
147 } while (0)
148
149 /* Given a 1W * 1W => 2W primitive, do the extended multiplication. */
150
151 #define _FP_MUL_MEAT_1_wide(wfracbits, R, X, Y, doit) \
152 do { \
153 _FP_W_TYPE _Z_f0, _Z_f1; \
154 doit(_Z_f1, _Z_f0, X##_f, Y##_f); \
155 /* Normalize since we know where the msb of the multiplicands \
156 were (bit B), we know that the msb of the of the product is \
157 at either 2B or 2B-1. */ \
158 _FP_FRAC_SRS_2(_Z, wfracbits-1, 2*wfracbits); \
159 R##_f = _Z_f0; \
160 } while (0)
161
162 /* Finally, a simple widening multiply algorithm. What fun! */
163
164 #define _FP_MUL_MEAT_1_hard(wfracbits, R, X, Y) \
165 do { \
166 _FP_W_TYPE _xh, _xl, _yh, _yl, _z_f0, _z_f1, _a_f0, _a_f1; \
167 \
168 /* split the words in half */ \
169 _xh = X##_f >> (_FP_W_TYPE_SIZE/2); \
170 _xl = X##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1); \
171 _yh = Y##_f >> (_FP_W_TYPE_SIZE/2); \
172 _yl = Y##_f & (((_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2)) - 1); \
173 \
174 /* multiply the pieces */ \
175 _z_f0 = _xl * _yl; \
176 _a_f0 = _xh * _yl; \
177 _a_f1 = _xl * _yh; \
178 _z_f1 = _xh * _yh; \
179 \
180 /* reassemble into two full words */ \
181 if ((_a_f0 += _a_f1) < _a_f1) \
182 _z_f1 += (_FP_W_TYPE)1 << (_FP_W_TYPE_SIZE/2); \
183 _a_f1 = _a_f0 >> (_FP_W_TYPE_SIZE/2); \
184 _a_f0 = _a_f0 << (_FP_W_TYPE_SIZE/2); \
185 _FP_FRAC_ADD_2(_z, _z, _a); \
186 \
187 /* normalize */ \
188 _FP_FRAC_SRS_2(_z, wfracbits - 1, 2*wfracbits); \
189 R##_f = _z_f0; \
190 } while (0)
191
192
193 /*
194 * Division algorithms:
195 */
196
197 /* Basic. Assuming the host word size is >= 2*FRACBITS, we can do the
198 division immediately. Give this macro either _FP_DIV_HELP_imm for
199 C primitives or _FP_DIV_HELP_ldiv for the ISO function. Which you
200 choose will depend on what the compiler does with divrem4. */
201
202 #define _FP_DIV_MEAT_1_imm(fs, R, X, Y, doit) \
203 do { \
204 _FP_W_TYPE _q, _r; \
205 X##_f <<= (X##_f < Y##_f \
206 ? R##_e--, _FP_WFRACBITS_##fs \
207 : _FP_WFRACBITS_##fs - 1); \
208 doit(_q, _r, X##_f, Y##_f); \
209 R##_f = _q | (_r != 0); \
210 } while (0)
211
212 /* GCC's longlong.h defines a 2W / 1W => (1W,1W) primitive udiv_qrnnd
213 that may be useful in this situation. This first is for a primitive
214 that requires normalization, the second for one that does not. Look
215 for UDIV_NEEDS_NORMALIZATION to tell which your machine needs. */
216
217 #define _FP_DIV_MEAT_1_udiv_norm(fs, R, X, Y) \
218 do { \
219 _FP_W_TYPE _nh, _nl, _q, _r, _y; \
220 \
221 /* Normalize Y -- i.e. make the most significant bit set. */ \
222 _y = Y##_f << _FP_WFRACXBITS_##fs; \
223 \
224 /* Shift X op correspondingly high, that is, up one full word. */ \
225 if (X##_f < Y##_f) \
226 { \
227 R##_e--; \
228 _nl = 0; \
229 _nh = X##_f; \
230 } \
231 else \
232 { \
233 _nl = X##_f << (_FP_W_TYPE_SIZE - 1); \
234 _nh = X##_f >> 1; \
235 } \
236 \
237 udiv_qrnnd(_q, _r, _nh, _nl, _y); \
238 R##_f = _q | (_r != 0); \
239 } while (0)
240
241 #define _FP_DIV_MEAT_1_udiv(fs, R, X, Y) \
242 do { \
243 _FP_W_TYPE _nh, _nl, _q, _r; \
244 if (X##_f < Y##_f) \
245 { \
246 R##_e--; \
247 _nl = X##_f << _FP_WFRACBITS_##fs; \
248 _nh = X##_f >> _FP_WFRACXBITS_##fs; \
249 } \
250 else \
251 { \
252 _nl = X##_f << (_FP_WFRACBITS_##fs - 1); \
253 _nh = X##_f >> (_FP_WFRACXBITS_##fs + 1); \
254 } \
255 udiv_qrnnd(_q, _r, _nh, _nl, Y##_f); \
256 R##_f = _q | (_r != 0); \
257 } while (0)
258
259
260 /*
261 * Square root algorithms:
262 * We have just one right now, maybe Newton approximation
263 * should be added for those machines where division is fast.
264 */
265
266 #define _FP_SQRT_MEAT_1(R, S, T, X, q) \
267 do { \
268 while (q != _FP_WORK_ROUND) \
269 { \
270 T##_f = S##_f + q; \
271 if (T##_f <= X##_f) \
272 { \
273 S##_f = T##_f + q; \
274 X##_f -= T##_f; \
275 R##_f += q; \
276 } \
277 _FP_FRAC_SLL_1(X, 1); \
278 q >>= 1; \
279 } \
280 if (X##_f) \
281 { \
282 if (S##_f < X##_f) \
283 R##_f |= _FP_WORK_ROUND; \
284 R##_f |= _FP_WORK_STICKY; \
285 } \
286 } while (0)
287
288 /*
289 * Assembly/disassembly for converting to/from integral types.
290 * No shifting or overflow handled here.
291 */
292
293 #define _FP_FRAC_ASSEMBLE_1(r, X, rsize) (r = X##_f)
294 #define _FP_FRAC_DISASSEMBLE_1(X, r, rsize) (X##_f = r)
295
296
297 /*
298 * Convert FP values between word sizes
299 */
300
301 #define _FP_FRAC_COPY_1_1(D, S) (D##_f = S##_f)
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