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1 | /* Copyright (C) 2007 Free Software Foundation, Inc. |
2 | ||
3 | This file is part of GCC. | |
4 | ||
5 | GCC is free software; you can redistribute it and/or modify it under | |
6 | the terms of the GNU General Public License as published by the Free | |
7 | Software Foundation; either version 2, or (at your option) any later | |
8 | version. | |
9 | ||
10 | In addition to the permissions in the GNU General Public License, the | |
11 | Free Software Foundation gives you unlimited permission to link the | |
12 | compiled version of this file into combinations with other programs, | |
13 | and to distribute those combinations without any restriction coming | |
14 | from the use of this file. (The General Public License restrictions | |
15 | do apply in other respects; for example, they cover modification of | |
16 | the file, and distribution when not linked into a combine | |
17 | executable.) | |
18 | ||
19 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
20 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
21 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
22 | for more details. | |
23 | ||
24 | You should have received a copy of the GNU General Public License | |
25 | along with GCC; see the file COPYING. If not, write to the Free | |
26 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA | |
27 | 02110-1301, USA. */ | |
28 | ||
29 | #define BID_128RES | |
30 | ||
31 | #include "bid_internal.h" | |
32 | ||
33 | /***************************************************************************** | |
34 | * BID128_round_integral_exact | |
35 | ****************************************************************************/ | |
36 | ||
37 | BID128_FUNCTION_ARG1(__bid128_round_integral_exact, x) | |
38 | ||
39 | UINT128 res = {{ 0xbaddbaddbaddbaddull, 0xbaddbaddbaddbaddull }}; | |
40 | UINT64 x_sign; | |
41 | UINT64 x_exp; | |
42 | int exp; // unbiased exponent | |
43 | // Note: C1.w[1], C1.w[0] represent x_signif_hi, x_signif_lo (all are UINT64) | |
44 | UINT64 tmp64; | |
45 | BID_UI64DOUBLE tmp1; | |
46 | unsigned int x_nr_bits; | |
47 | int q, ind, shift; | |
48 | UINT128 C1; | |
49 | UINT256 fstar; | |
50 | UINT256 P256; | |
51 | ||
52 | // check for NaN or Infinity | |
53 | if ((x.w[1] & MASK_SPECIAL) == MASK_SPECIAL) { | |
54 | // x is special | |
55 | if ((x.w[1] & MASK_NAN) == MASK_NAN) { // x is NAN | |
56 | if ((x.w[1] & MASK_SNAN) == MASK_SNAN) { // x is SNAN | |
57 | // set invalid flag | |
58 | *pfpsf |= INVALID_EXCEPTION; | |
59 | // return Quiet (SNaN) | |
60 | res.w[1] = x.w[1] & 0xfdffffffffffffffull; | |
61 | res.w[0] = x.w[0]; | |
62 | } else { // x is QNaN | |
63 | // return the input QNaN | |
64 | res.w[1] = x.w[1]; | |
65 | res.w[0] = x.w[0]; | |
66 | } | |
67 | BID_RETURN (res); | |
68 | } else { // x is not a NaN, so it must be infinity | |
69 | if ((x.w[1] & MASK_SIGN) == 0x0ull) { // x is +inf | |
70 | // return +inf | |
71 | res.w[1] = 0x7800000000000000ull; | |
72 | res.w[0] = 0x0000000000000000ull; | |
73 | } else { // x is -inf | |
74 | // return -inf | |
75 | res.w[1] = 0xf800000000000000ull; | |
76 | res.w[0] = 0x0000000000000000ull; | |
77 | } | |
78 | BID_RETURN (res); | |
79 | } | |
80 | } | |
81 | // unpack x | |
82 | x_sign = x.w[1] & MASK_SIGN; // 0 for positive, MASK_SIGN for negative | |
83 | x_exp = x.w[1] & MASK_EXP; // biased and shifted left 49 bit positions | |
84 | C1.w[1] = x.w[1] & MASK_COEFF; | |
85 | C1.w[0] = x.w[0]; | |
86 | ||
87 | // test for non-canonical values: | |
88 | // - values whose encoding begins with x00, x01, or x10 and whose | |
89 | // coefficient is larger than 10^34 -1, or | |
90 | // - values whose encoding begins with x1100, x1101, x1110 (if NaNs | |
91 | // and infinitis were eliminated already this test is reduced to | |
92 | // checking for x10x) | |
93 | ||
94 | // test for non-canonical values of the argument x | |
95 | if ((((C1.w[1] > 0x0001ed09bead87c0ull) || | |
96 | ((C1.w[1] == 0x0001ed09bead87c0ull) && | |
97 | (C1.w[0] > 0x378d8e63ffffffffull))) && | |
98 | ((x.w[1] & 0x6000000000000000ull) != 0x6000000000000000ull)) || | |
99 | ((x.w[1] & 0x6000000000000000ull) == 0x6000000000000000ull)) { | |
100 | x.w[1] = x.w[1] & 0x8000000000000000ull; // preserve the sign bit | |
101 | x.w[0] = 0; | |
102 | x_exp = 0x1820ull << 49; | |
103 | C1.w[1] = 0; | |
104 | C1.w[0] = 0; | |
105 | } | |
106 | // test for input equal to zero | |
107 | if ((C1.w[1] == 0x0ull) && (C1.w[0] == 0x0ull)) { | |
108 | // x is 0 | |
109 | // return 0 preserving the sign bit and the preferred exponent | |
110 | // of MAX(Q(x), 0) | |
111 | if (x_exp <= (0x1820ull << 49)) { | |
112 | res.w[1] = | |
113 | (x.w[1] & 0x8000000000000000ull) | 0x3040000000000000ull; | |
114 | } else { | |
115 | res.w[1] = x.w[1] & 0xfffe000000000000ull; | |
116 | } | |
117 | res.w[0] = 0x0000000000000000ull; | |
118 | BID_RETURN (res); | |
119 | } | |
120 | // x is not special and is not zero | |
121 | ||
122 | switch (rnd_mode) { | |
123 | case ROUNDING_TO_NEAREST: | |
124 | case ROUNDING_TIES_AWAY: | |
125 | // if (exp <= -(p+1)) return 0.0 | |
126 | if (x_exp <= 0x2ffa000000000000ull) { // 0x2ffa000000000000ull == -35 | |
127 | res.w[1] = x_sign | 0x3040000000000000ull; | |
128 | res.w[0] = 0x0000000000000000ull; | |
129 | *pfpsf |= INEXACT_EXCEPTION; | |
130 | BID_RETURN (res); | |
131 | } | |
132 | break; | |
133 | case ROUNDING_DOWN: | |
134 | // if (exp <= -p) return -1.0 or +0.0 | |
135 | if (x_exp <= 0x2ffc000000000000ull) { // 0x2ffa000000000000ull == -34 | |
136 | if (x_sign) { | |
137 | // if negative, return negative 1, because we know coefficient | |
138 | // is non-zero (would have been caught above) | |
139 | res.w[1] = 0xb040000000000000ull; | |
140 | res.w[0] = 0x0000000000000001ull; | |
141 | } else { | |
142 | // if positive, return positive 0, because we know coefficient is | |
143 | // non-zero (would have been caught above) | |
144 | res.w[1] = 0x3040000000000000ull; | |
145 | res.w[0] = 0x0000000000000000ull; | |
146 | } | |
147 | *pfpsf |= INEXACT_EXCEPTION; | |
148 | BID_RETURN (res); | |
149 | } | |
150 | break; | |
151 | case ROUNDING_UP: | |
152 | // if (exp <= -p) return -0.0 or +1.0 | |
153 | if (x_exp <= 0x2ffc000000000000ull) { // 0x2ffc000000000000ull == -34 | |
154 | if (x_sign) { | |
155 | // if negative, return negative 0, because we know the coefficient | |
156 | // is non-zero (would have been caught above) | |
157 | res.w[1] = 0xb040000000000000ull; | |
158 | res.w[0] = 0x0000000000000000ull; | |
159 | } else { | |
160 | // if positive, return positive 1, because we know coefficient is | |
161 | // non-zero (would have been caught above) | |
162 | res.w[1] = 0x3040000000000000ull; | |
163 | res.w[0] = 0x0000000000000001ull; | |
164 | } | |
165 | *pfpsf |= INEXACT_EXCEPTION; | |
166 | BID_RETURN (res); | |
167 | } | |
168 | break; | |
169 | case ROUNDING_TO_ZERO: | |
170 | // if (exp <= -p) return -0.0 or +0.0 | |
171 | if (x_exp <= 0x2ffc000000000000ull) { // 0x2ffc000000000000ull == -34 | |
172 | res.w[1] = x_sign | 0x3040000000000000ull; | |
173 | res.w[0] = 0x0000000000000000ull; | |
174 | *pfpsf |= INEXACT_EXCEPTION; | |
175 | BID_RETURN (res); | |
176 | } | |
177 | break; | |
178 | } | |
179 | ||
180 | // q = nr. of decimal digits in x | |
181 | // determine first the nr. of bits in x | |
182 | if (C1.w[1] == 0) { | |
183 | if (C1.w[0] >= 0x0020000000000000ull) { // x >= 2^53 | |
184 | // split the 64-bit value in two 32-bit halves to avoid rounding errors | |
185 | if (C1.w[0] >= 0x0000000100000000ull) { // x >= 2^32 | |
186 | tmp1.d = (double) (C1.w[0] >> 32); // exact conversion | |
187 | x_nr_bits = | |
188 | 33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
189 | } else { // x < 2^32 | |
190 | tmp1.d = (double) (C1.w[0]); // exact conversion | |
191 | x_nr_bits = | |
192 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
193 | } | |
194 | } else { // if x < 2^53 | |
195 | tmp1.d = (double) C1.w[0]; // exact conversion | |
196 | x_nr_bits = | |
197 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
198 | } | |
199 | } else { // C1.w[1] != 0 => nr. bits = 64 + nr_bits (C1.w[1]) | |
200 | tmp1.d = (double) C1.w[1]; // exact conversion | |
201 | x_nr_bits = | |
202 | 65 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
203 | } | |
204 | q = __bid_nr_digits[x_nr_bits - 1].digits; | |
205 | if (q == 0) { | |
206 | q = __bid_nr_digits[x_nr_bits - 1].digits1; | |
207 | if (C1.w[1] > __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
208 | || (C1.w[1] == __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
209 | && C1.w[0] >= __bid_nr_digits[x_nr_bits - 1].threshold_lo)) | |
210 | q++; | |
211 | } | |
212 | exp = (x_exp >> 49) - 6176; | |
213 | if (exp >= 0) { // -exp <= 0 | |
214 | // the argument is an integer already | |
215 | res.w[1] = x.w[1]; | |
216 | res.w[0] = x.w[0]; | |
217 | BID_RETURN (res); | |
218 | } | |
219 | // exp < 0 | |
220 | switch (rnd_mode) { | |
221 | case ROUNDING_TO_NEAREST: | |
222 | if ((q + exp) >= 0) { // exp < 0 and 1 <= -exp <= q | |
223 | // need to shift right -exp digits from the coefficient; exp will be 0 | |
224 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
225 | // chop off ind digits from the lower part of C1 | |
226 | // C1 = C1 + 1/2 * 10^x where the result C1 fits in 127 bits | |
227 | tmp64 = C1.w[0]; | |
228 | if (ind <= 19) { | |
229 | C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
230 | } else { | |
231 | C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
232 | C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
233 | } | |
234 | if (C1.w[0] < tmp64) | |
235 | C1.w[1]++; | |
236 | // calculate C* and f* | |
237 | // C* is actually floor(C*) in this case | |
238 | // C* and f* need shifting and masking, as shown by | |
239 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
240 | // 1 <= x <= 34 | |
241 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
242 | // C* = (C1 + 1/2 * 10^x) * 10^(-x) | |
243 | // the approximation of 10^(-x) was rounded up to 118 bits | |
244 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
245 | // determine the value of res and fstar | |
246 | ||
247 | // determine inexactness of the rounding of C* | |
248 | // if (0 < f* - 1/2 < 10^(-x)) then | |
249 | // the result is exact | |
250 | // else // if (f* - 1/2 > T*) then | |
251 | // the result is inexact | |
252 | // Note: we are going to use __bid_ten2mk128[] instead of __bid_ten2mk128trunc[] | |
253 | ||
254 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
255 | // redundant shift = __bid_shiftright128[ind - 1]; // shift = 0 | |
256 | res.w[1] = P256.w[3]; | |
257 | res.w[0] = P256.w[2]; | |
258 | // redundant fstar.w[3] = 0; | |
259 | // redundant fstar.w[2] = 0; | |
260 | fstar.w[1] = P256.w[1]; | |
261 | fstar.w[0] = P256.w[0]; | |
262 | // fraction f* < 10^(-x) <=> midpoint | |
263 | // f* is in the right position to be compared with | |
264 | // 10^(-x) from __bid_ten2mk128[] | |
265 | // if 0 < fstar < 10^(-x), subtract 1 if odd (for rounding to even) | |
266 | if ((res.w[0] & 0x0000000000000001ull) && // is result odd? | |
267 | ((fstar.w[1] < (__bid_ten2mk128[ind - 1].w[1])) | |
268 | || ((fstar.w[1] == __bid_ten2mk128[ind - 1].w[1]) | |
269 | && (fstar.w[0] < __bid_ten2mk128[ind - 1].w[0])))) { | |
270 | // subract 1 to make even | |
271 | if (res.w[0]-- == 0) { | |
272 | res.w[1]--; | |
273 | } | |
274 | } | |
275 | if (fstar.w[1] > 0x8000000000000000ull || | |
276 | (fstar.w[1] == 0x8000000000000000ull && fstar.w[0] > 0x0ull)) { | |
277 | // f* > 1/2 and the result may be exact | |
278 | tmp64 = fstar.w[1] - 0x8000000000000000ull; // f* - 1/2 | |
279 | if ((tmp64 > __bid_ten2mk128[ind - 1].w[1] | |
280 | || (tmp64 == __bid_ten2mk128[ind - 1].w[1] | |
281 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0]))) { | |
282 | // set the inexact flag | |
283 | *pfpsf |= INEXACT_EXCEPTION; | |
284 | } // else the result is exact | |
285 | } else { // the result is inexact; f2* <= 1/2 | |
286 | // set the inexact flag | |
287 | *pfpsf |= INEXACT_EXCEPTION; | |
288 | } | |
289 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
290 | shift = __bid_shiftright128[ind - 1]; // 3 <= shift <= 63 | |
291 | res.w[1] = (P256.w[3] >> shift); | |
292 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
293 | // redundant fstar.w[3] = 0; | |
294 | fstar.w[2] = P256.w[2] & __bid_maskhigh128[ind - 1]; | |
295 | fstar.w[1] = P256.w[1]; | |
296 | fstar.w[0] = P256.w[0]; | |
297 | // fraction f* < 10^(-x) <=> midpoint | |
298 | // f* is in the right position to be compared with | |
299 | // 10^(-x) from __bid_ten2mk128[] | |
300 | if ((res.w[0] & 0x0000000000000001ull) && // is result odd? | |
301 | fstar.w[2] == 0 && (fstar.w[1] < __bid_ten2mk128[ind - 1].w[1] | |
302 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
303 | && fstar.w[0] < __bid_ten2mk128[ind - 1].w[0]))) { | |
304 | // subract 1 to make even | |
305 | if (res.w[0]-- == 0) { | |
306 | res.w[1]--; | |
307 | } | |
308 | } | |
309 | if (fstar.w[2] > __bid_one_half128[ind - 1] | |
310 | || (fstar.w[2] == __bid_one_half128[ind - 1] | |
311 | && (fstar.w[1] || fstar.w[0]))) { | |
312 | // f2* > 1/2 and the result may be exact | |
313 | // Calculate f2* - 1/2 | |
314 | tmp64 = fstar.w[2] - __bid_one_half128[ind - 1]; | |
315 | if (tmp64 || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
316 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
317 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
318 | // set the inexact flag | |
319 | *pfpsf |= INEXACT_EXCEPTION; | |
320 | } // else the result is exact | |
321 | } else { // the result is inexact; f2* <= 1/2 | |
322 | // set the inexact flag | |
323 | *pfpsf |= INEXACT_EXCEPTION; | |
324 | } | |
325 | } else { // 22 <= ind - 1 <= 33 | |
326 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
327 | res.w[1] = 0; | |
328 | res.w[0] = P256.w[3] >> shift; | |
329 | fstar.w[3] = P256.w[3] & __bid_maskhigh128[ind - 1]; | |
330 | fstar.w[2] = P256.w[2]; | |
331 | fstar.w[1] = P256.w[1]; | |
332 | fstar.w[0] = P256.w[0]; | |
333 | // fraction f* < 10^(-x) <=> midpoint | |
334 | // f* is in the right position to be compared with | |
335 | // 10^(-x) from __bid_ten2mk128[] | |
336 | if ((res.w[0] & 0x0000000000000001ull) && // is result odd? | |
337 | fstar.w[3] == 0 && fstar.w[2] == 0 | |
338 | && (fstar.w[1] < __bid_ten2mk128[ind - 1].w[1] | |
339 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
340 | && fstar.w[0] < __bid_ten2mk128[ind - 1].w[0]))) { | |
341 | // subract 1 to make even | |
342 | if (res.w[0]-- == 0) { | |
343 | res.w[1]--; | |
344 | } | |
345 | } | |
346 | if (fstar.w[3] > __bid_one_half128[ind - 1] | |
347 | || (fstar.w[3] == __bid_one_half128[ind - 1] | |
348 | && (fstar.w[2] || fstar.w[1] || fstar.w[0]))) { | |
349 | // f2* > 1/2 and the result may be exact | |
350 | // Calculate f2* - 1/2 | |
351 | tmp64 = fstar.w[3] - __bid_one_half128[ind - 1]; | |
352 | if (tmp64 || fstar.w[2] | |
353 | || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
354 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
355 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
356 | // set the inexact flag | |
357 | *pfpsf |= INEXACT_EXCEPTION; | |
358 | } // else the result is exact | |
359 | } else { // the result is inexact; f2* <= 1/2 | |
360 | // set the inexact flag | |
361 | *pfpsf |= INEXACT_EXCEPTION; | |
362 | } | |
363 | } | |
364 | res.w[1] = x_sign | 0x3040000000000000ull | res.w[1]; | |
365 | BID_RETURN (res); | |
366 | } else { // if ((q + exp) < 0) <=> q < -exp | |
367 | // the result is +0 or -0 | |
368 | res.w[1] = x_sign | 0x3040000000000000ull; | |
369 | res.w[0] = 0x0000000000000000ull; | |
370 | *pfpsf |= INEXACT_EXCEPTION; | |
371 | BID_RETURN (res); | |
372 | } | |
373 | break; | |
374 | case ROUNDING_TIES_AWAY: | |
375 | if ((q + exp) >= 0) { // exp < 0 and 1 <= -exp <= q | |
376 | // need to shift right -exp digits from the coefficient; exp will be 0 | |
377 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
378 | // chop off ind digits from the lower part of C1 | |
379 | // C1 = C1 + 1/2 * 10^x where the result C1 fits in 127 bits | |
380 | tmp64 = C1.w[0]; | |
381 | if (ind <= 19) { | |
382 | C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
383 | } else { | |
384 | C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
385 | C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
386 | } | |
387 | if (C1.w[0] < tmp64) | |
388 | C1.w[1]++; | |
389 | // calculate C* and f* | |
390 | // C* is actually floor(C*) in this case | |
391 | // C* and f* need shifting and masking, as shown by | |
392 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
393 | // 1 <= x <= 34 | |
394 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
395 | // C* = (C1 + 1/2 * 10^x) * 10^(-x) | |
396 | // the approximation of 10^(-x) was rounded up to 118 bits | |
397 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
398 | // the top Ex bits of 10^(-x) are T* = __bid_ten2mk128trunc[ind], e.g. | |
399 | // if x=1, T*=__bid_ten2mk128trunc[0]=0x19999999999999999999999999999999 | |
400 | // if (0 < f* < 10^(-x)) then the result is a midpoint | |
401 | // if floor(C*) is even then C* = floor(C*) - logical right | |
402 | // shift; C* has p decimal digits, correct by Prop. 1) | |
403 | // else if floor(C*) is odd C* = floor(C*)-1 (logical right | |
404 | // shift; C* has p decimal digits, correct by Pr. 1) | |
405 | // else | |
406 | // C* = floor(C*) (logical right shift; C has p decimal digits, | |
407 | // correct by Property 1) | |
408 | // n = C* * 10^(e+x) | |
409 | ||
410 | // determine also the inexactness of the rounding of C* | |
411 | // if (0 < f* - 1/2 < 10^(-x)) then | |
412 | // the result is exact | |
413 | // else // if (f* - 1/2 > T*) then | |
414 | // the result is inexact | |
415 | // Note: we are going to use __bid_ten2mk128[] instead of __bid_ten2mk128trunc[] | |
416 | // shift right C* by Ex-128 = __bid_shiftright128[ind] | |
417 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
418 | // redundant shift = __bid_shiftright128[ind - 1]; // shift = 0 | |
419 | res.w[1] = P256.w[3]; | |
420 | res.w[0] = P256.w[2]; | |
421 | // redundant fstar.w[3] = 0; | |
422 | // redundant fstar.w[2] = 0; | |
423 | fstar.w[1] = P256.w[1]; | |
424 | fstar.w[0] = P256.w[0]; | |
425 | if (fstar.w[1] > 0x8000000000000000ull || | |
426 | (fstar.w[1] == 0x8000000000000000ull && fstar.w[0] > 0x0ull)) { | |
427 | // f* > 1/2 and the result may be exact | |
428 | tmp64 = fstar.w[1] - 0x8000000000000000ull; // f* - 1/2 | |
429 | if ((tmp64 > __bid_ten2mk128[ind - 1].w[1] | |
430 | || (tmp64 == __bid_ten2mk128[ind - 1].w[1] | |
431 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0]))) { | |
432 | // set the inexact flag | |
433 | *pfpsf |= INEXACT_EXCEPTION; | |
434 | } // else the result is exact | |
435 | } else { // the result is inexact; f2* <= 1/2 | |
436 | // set the inexact flag | |
437 | *pfpsf |= INEXACT_EXCEPTION; | |
438 | } | |
439 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
440 | shift = __bid_shiftright128[ind - 1]; // 3 <= shift <= 63 | |
441 | res.w[1] = (P256.w[3] >> shift); | |
442 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
443 | // redundant fstar.w[3] = 0; | |
444 | fstar.w[2] = P256.w[2] & __bid_maskhigh128[ind - 1]; | |
445 | fstar.w[1] = P256.w[1]; | |
446 | fstar.w[0] = P256.w[0]; | |
447 | if (fstar.w[2] > __bid_one_half128[ind - 1] | |
448 | || (fstar.w[2] == __bid_one_half128[ind - 1] | |
449 | && (fstar.w[1] || fstar.w[0]))) { | |
450 | // f2* > 1/2 and the result may be exact | |
451 | // Calculate f2* - 1/2 | |
452 | tmp64 = fstar.w[2] - __bid_one_half128[ind - 1]; | |
453 | if (tmp64 || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
454 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
455 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
456 | // set the inexact flag | |
457 | *pfpsf |= INEXACT_EXCEPTION; | |
458 | } // else the result is exact | |
459 | } else { // the result is inexact; f2* <= 1/2 | |
460 | // set the inexact flag | |
461 | *pfpsf |= INEXACT_EXCEPTION; | |
462 | } | |
463 | } else { // 22 <= ind - 1 <= 33 | |
464 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
465 | res.w[1] = 0; | |
466 | res.w[0] = P256.w[3] >> shift; | |
467 | fstar.w[3] = P256.w[3] & __bid_maskhigh128[ind - 1]; | |
468 | fstar.w[2] = P256.w[2]; | |
469 | fstar.w[1] = P256.w[1]; | |
470 | fstar.w[0] = P256.w[0]; | |
471 | if (fstar.w[3] > __bid_one_half128[ind - 1] | |
472 | || (fstar.w[3] == __bid_one_half128[ind - 1] | |
473 | && (fstar.w[2] || fstar.w[1] || fstar.w[0]))) { | |
474 | // f2* > 1/2 and the result may be exact | |
475 | // Calculate f2* - 1/2 | |
476 | tmp64 = fstar.w[3] - __bid_one_half128[ind - 1]; | |
477 | if (tmp64 || fstar.w[2] | |
478 | || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
479 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
480 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
481 | // set the inexact flag | |
482 | *pfpsf |= INEXACT_EXCEPTION; | |
483 | } // else the result is exact | |
484 | } else { // the result is inexact; f2* <= 1/2 | |
485 | // set the inexact flag | |
486 | *pfpsf |= INEXACT_EXCEPTION; | |
487 | } | |
488 | } | |
489 | // if the result was a midpoint, it was already rounded away from zero | |
490 | res.w[1] |= x_sign | 0x3040000000000000ull; | |
491 | BID_RETURN (res); | |
492 | } else { // if ((q + exp) < 0) <=> q < -exp | |
493 | // the result is +0 or -0 | |
494 | res.w[1] = x_sign | 0x3040000000000000ull; | |
495 | res.w[0] = 0x0000000000000000ull; | |
496 | *pfpsf |= INEXACT_EXCEPTION; | |
497 | BID_RETURN (res); | |
498 | } | |
499 | break; | |
500 | case ROUNDING_DOWN: | |
501 | if ((q + exp) > 0) { // exp < 0 and 1 <= -exp < q | |
502 | // need to shift right -exp digits from the coefficient; exp will be 0 | |
503 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
504 | // (number of digits to be chopped off) | |
505 | // chop off ind digits from the lower part of C1 | |
506 | // FOR ROUND_TO_NEAREST, WE ADD 1/2 ULP(y) then truncate | |
507 | // FOR ROUND_TO_ZERO, WE DON'T NEED TO ADD 1/2 ULP | |
508 | // FOR ROUND_TO_POSITIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF POSITIVE | |
509 | // FOR ROUND_TO_NEGATIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF NEGATIVE | |
510 | // tmp64 = C1.w[0]; | |
511 | // if (ind <= 19) { | |
512 | // C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
513 | // } else { | |
514 | // C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
515 | // C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
516 | // } | |
517 | // if (C1.w[0] < tmp64) C1.w[1]++; | |
518 | // if carry-out from C1.w[0], increment C1.w[1] | |
519 | // calculate C* and f* | |
520 | // C* is actually floor(C*) in this case | |
521 | // C* and f* need shifting and masking, as shown by | |
522 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
523 | // 1 <= x <= 34 | |
524 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
525 | // C* = (C1 + 1/2 * 10^x) * 10^(-x) | |
526 | // the approximation of 10^(-x) was rounded up to 118 bits | |
527 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
528 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
529 | res.w[1] = P256.w[3]; | |
530 | res.w[0] = P256.w[2]; | |
531 | // redundant fstar.w[3] = 0; | |
532 | // redundant fstar.w[2] = 0; | |
533 | // redundant fstar.w[1] = P256.w[1]; | |
534 | // redundant fstar.w[0] = P256.w[0]; | |
535 | // fraction f* > 10^(-x) <=> inexact | |
536 | // f* is in the right position to be compared with | |
537 | // 10^(-x) from __bid_ten2mk128[] | |
538 | if ((P256.w[1] > __bid_ten2mk128[ind - 1].w[1]) | |
539 | || (P256.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
540 | && (P256.w[0] >= __bid_ten2mk128[ind - 1].w[0]))) { | |
541 | *pfpsf |= INEXACT_EXCEPTION; | |
542 | // if positive, the truncated value is already the correct result | |
543 | if (x_sign) { // if negative | |
544 | if (++res.w[0] == 0) { | |
545 | res.w[1]++; | |
546 | } | |
547 | } | |
548 | } | |
549 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
550 | shift = __bid_shiftright128[ind - 1]; // 0 <= shift <= 102 | |
551 | res.w[1] = (P256.w[3] >> shift); | |
552 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
553 | // redundant fstar.w[3] = 0; | |
554 | fstar.w[2] = P256.w[2] & __bid_maskhigh128[ind - 1]; | |
555 | fstar.w[1] = P256.w[1]; | |
556 | fstar.w[0] = P256.w[0]; | |
557 | // fraction f* > 10^(-x) <=> inexact | |
558 | // f* is in the right position to be compared with | |
559 | // 10^(-x) from __bid_ten2mk128[] | |
560 | if (fstar.w[2] || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
561 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
562 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
563 | *pfpsf |= INEXACT_EXCEPTION; | |
564 | // if positive, the truncated value is already the correct result | |
565 | if (x_sign) { // if negative | |
566 | if (++res.w[0] == 0) { | |
567 | res.w[1]++; | |
568 | } | |
569 | } | |
570 | } | |
571 | } else { // 22 <= ind - 1 <= 33 | |
572 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
573 | res.w[1] = 0; | |
574 | res.w[0] = P256.w[3] >> shift; | |
575 | fstar.w[3] = P256.w[3] & __bid_maskhigh128[ind - 1]; | |
576 | fstar.w[2] = P256.w[2]; | |
577 | fstar.w[1] = P256.w[1]; | |
578 | fstar.w[0] = P256.w[0]; | |
579 | // fraction f* > 10^(-x) <=> inexact | |
580 | // f* is in the right position to be compared with | |
581 | // 10^(-x) from __bid_ten2mk128[] | |
582 | if (fstar.w[3] || fstar.w[2] | |
583 | || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
584 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
585 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
586 | *pfpsf |= INEXACT_EXCEPTION; | |
587 | // if positive, the truncated value is already the correct result | |
588 | if (x_sign) { // if negative | |
589 | if (++res.w[0] == 0) { | |
590 | res.w[1]++; | |
591 | } | |
592 | } | |
593 | } | |
594 | } | |
595 | res.w[1] = x_sign | 0x3040000000000000ull | res.w[1]; | |
596 | BID_RETURN (res); | |
597 | } else { // if exp < 0 and q + exp <= 0 | |
598 | if (x_sign) { // negative rounds down to -1.0 | |
599 | res.w[1] = 0xb040000000000000ull; | |
600 | res.w[0] = 0x0000000000000001ull; | |
601 | } else { // positive rpunds down to +0.0 | |
602 | res.w[1] = 0x3040000000000000ull; | |
603 | res.w[0] = 0x0000000000000000ull; | |
604 | } | |
605 | *pfpsf |= INEXACT_EXCEPTION; | |
606 | BID_RETURN (res); | |
607 | } | |
608 | break; | |
609 | case ROUNDING_UP: | |
610 | if ((q + exp) > 0) { // exp < 0 and 1 <= -exp < q | |
611 | // need to shift right -exp digits from the coefficient; exp will be 0 | |
612 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
613 | // (number of digits to be chopped off) | |
614 | // chop off ind digits from the lower part of C1 | |
615 | // FOR ROUND_TO_NEAREST, WE ADD 1/2 ULP(y) then truncate | |
616 | // FOR ROUND_TO_ZERO, WE DON'T NEED TO ADD 1/2 ULP | |
617 | // FOR ROUND_TO_POSITIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF POSITIVE | |
618 | // FOR ROUND_TO_NEGATIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF NEGATIVE | |
619 | // tmp64 = C1.w[0]; | |
620 | // if (ind <= 19) { | |
621 | // C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
622 | // } else { | |
623 | // C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
624 | // C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
625 | // } | |
626 | // if (C1.w[0] < tmp64) C1.w[1]++; | |
627 | // if carry-out from C1.w[0], increment C1.w[1] | |
628 | // calculate C* and f* | |
629 | // C* is actually floor(C*) in this case | |
630 | // C* and f* need shifting and masking, as shown by | |
631 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
632 | // 1 <= x <= 34 | |
633 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
634 | // C* = C1 * 10^(-x) | |
635 | // the approximation of 10^(-x) was rounded up to 118 bits | |
636 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
637 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
638 | res.w[1] = P256.w[3]; | |
639 | res.w[0] = P256.w[2]; | |
640 | // redundant fstar.w[3] = 0; | |
641 | // redundant fstar.w[2] = 0; | |
642 | // redundant fstar.w[1] = P256.w[1]; | |
643 | // redundant fstar.w[0] = P256.w[0]; | |
644 | // fraction f* > 10^(-x) <=> inexact | |
645 | // f* is in the right position to be compared with | |
646 | // 10^(-x) from __bid_ten2mk128[] | |
647 | if ((P256.w[1] > __bid_ten2mk128[ind - 1].w[1]) | |
648 | || (P256.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
649 | && (P256.w[0] >= __bid_ten2mk128[ind - 1].w[0]))) { | |
650 | *pfpsf |= INEXACT_EXCEPTION; | |
651 | // if negative, the truncated value is already the correct result | |
652 | if (!x_sign) { // if positive | |
653 | if (++res.w[0] == 0) { | |
654 | res.w[1]++; | |
655 | } | |
656 | } | |
657 | } | |
658 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
659 | shift = __bid_shiftright128[ind - 1]; // 3 <= shift <= 63 | |
660 | res.w[1] = (P256.w[3] >> shift); | |
661 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
662 | // redundant fstar.w[3] = 0; | |
663 | fstar.w[2] = P256.w[2] & __bid_maskhigh128[ind - 1]; | |
664 | fstar.w[1] = P256.w[1]; | |
665 | fstar.w[0] = P256.w[0]; | |
666 | // fraction f* > 10^(-x) <=> inexact | |
667 | // f* is in the right position to be compared with | |
668 | // 10^(-x) from __bid_ten2mk128[] | |
669 | if (fstar.w[2] || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
670 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
671 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
672 | *pfpsf |= INEXACT_EXCEPTION; | |
673 | // if negative, the truncated value is already the correct result | |
674 | if (!x_sign) { // if positive | |
675 | if (++res.w[0] == 0) { | |
676 | res.w[1]++; | |
677 | } | |
678 | } | |
679 | } | |
680 | } else { // 22 <= ind - 1 <= 33 | |
681 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
682 | res.w[1] = 0; | |
683 | res.w[0] = P256.w[3] >> shift; | |
684 | fstar.w[3] = P256.w[3] & __bid_maskhigh128[ind - 1]; | |
685 | fstar.w[2] = P256.w[2]; | |
686 | fstar.w[1] = P256.w[1]; | |
687 | fstar.w[0] = P256.w[0]; | |
688 | // fraction f* > 10^(-x) <=> inexact | |
689 | // f* is in the right position to be compared with | |
690 | // 10^(-x) from __bid_ten2mk128[] | |
691 | if (fstar.w[3] || fstar.w[2] | |
692 | || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
693 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
694 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
695 | *pfpsf |= INEXACT_EXCEPTION; | |
696 | // if negative, the truncated value is already the correct result | |
697 | if (!x_sign) { // if positive | |
698 | if (++res.w[0] == 0) { | |
699 | res.w[1]++; | |
700 | } | |
701 | } | |
702 | } | |
703 | } | |
704 | res.w[1] = x_sign | 0x3040000000000000ull | res.w[1]; | |
705 | BID_RETURN (res); | |
706 | } else { // if exp < 0 and q + exp <= 0 | |
707 | if (x_sign) { // negative rounds up to -0.0 | |
708 | res.w[1] = 0xb040000000000000ull; | |
709 | res.w[0] = 0x0000000000000000ull; | |
710 | } else { // positive rpunds up to +1.0 | |
711 | res.w[1] = 0x3040000000000000ull; | |
712 | res.w[0] = 0x0000000000000001ull; | |
713 | } | |
714 | *pfpsf |= INEXACT_EXCEPTION; | |
715 | BID_RETURN (res); | |
716 | } | |
717 | break; | |
718 | case ROUNDING_TO_ZERO: | |
719 | if ((q + exp) > 0) { // exp < 0 and 1 <= -exp < q | |
720 | // need to shift right -exp digits from the coefficient; exp will be 0 | |
721 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
722 | // (number of digits to be chopped off) | |
723 | // chop off ind digits from the lower part of C1 | |
724 | // FOR ROUND_TO_NEAREST, WE ADD 1/2 ULP(y) then truncate | |
725 | // FOR ROUND_TO_ZERO, WE DON'T NEED TO ADD 1/2 ULP | |
726 | // FOR ROUND_TO_POSITIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF POSITIVE | |
727 | // FOR ROUND_TO_NEGATIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF NEGATIVE | |
728 | //tmp64 = C1.w[0]; | |
729 | // if (ind <= 19) { | |
730 | // C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
731 | // } else { | |
732 | // C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
733 | // C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
734 | // } | |
735 | // if (C1.w[0] < tmp64) C1.w[1]++; | |
736 | // if carry-out from C1.w[0], increment C1.w[1] | |
737 | // calculate C* and f* | |
738 | // C* is actually floor(C*) in this case | |
739 | // C* and f* need shifting and masking, as shown by | |
740 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
741 | // 1 <= x <= 34 | |
742 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
743 | // C* = (C1 + 1/2 * 10^x) * 10^(-x) | |
744 | // the approximation of 10^(-x) was rounded up to 118 bits | |
745 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
746 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
747 | res.w[1] = P256.w[3]; | |
748 | res.w[0] = P256.w[2]; | |
749 | // redundant fstar.w[3] = 0; | |
750 | // redundant fstar.w[2] = 0; | |
751 | // redundant fstar.w[1] = P256.w[1]; | |
752 | // redundant fstar.w[0] = P256.w[0]; | |
753 | // fraction f* > 10^(-x) <=> inexact | |
754 | // f* is in the right position to be compared with | |
755 | // 10^(-x) from __bid_ten2mk128[] | |
756 | if ((P256.w[1] > __bid_ten2mk128[ind - 1].w[1]) | |
757 | || (P256.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
758 | && (P256.w[0] >= __bid_ten2mk128[ind - 1].w[0]))) { | |
759 | *pfpsf |= INEXACT_EXCEPTION; | |
760 | } | |
761 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
762 | shift = __bid_shiftright128[ind - 1]; // 3 <= shift <= 63 | |
763 | res.w[1] = (P256.w[3] >> shift); | |
764 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
765 | // redundant fstar.w[3] = 0; | |
766 | fstar.w[2] = P256.w[2] & __bid_maskhigh128[ind - 1]; | |
767 | fstar.w[1] = P256.w[1]; | |
768 | fstar.w[0] = P256.w[0]; | |
769 | // fraction f* > 10^(-x) <=> inexact | |
770 | // f* is in the right position to be compared with | |
771 | // 10^(-x) from __bid_ten2mk128[] | |
772 | if (fstar.w[2] || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
773 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
774 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
775 | *pfpsf |= INEXACT_EXCEPTION; | |
776 | } | |
777 | } else { // 22 <= ind - 1 <= 33 | |
778 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
779 | res.w[1] = 0; | |
780 | res.w[0] = P256.w[3] >> shift; | |
781 | fstar.w[3] = P256.w[3] & __bid_maskhigh128[ind - 1]; | |
782 | fstar.w[2] = P256.w[2]; | |
783 | fstar.w[1] = P256.w[1]; | |
784 | fstar.w[0] = P256.w[0]; | |
785 | // fraction f* > 10^(-x) <=> inexact | |
786 | // f* is in the right position to be compared with | |
787 | // 10^(-x) from __bid_ten2mk128[] | |
788 | if (fstar.w[3] || fstar.w[2] | |
789 | || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
790 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
791 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
792 | *pfpsf |= INEXACT_EXCEPTION; | |
793 | } | |
794 | } | |
795 | res.w[1] = x_sign | 0x3040000000000000ull | res.w[1]; | |
796 | BID_RETURN (res); | |
797 | } else { // if exp < 0 and q + exp <= 0 the result is +0 or -0 | |
798 | res.w[1] = x_sign | 0x3040000000000000ull; | |
799 | res.w[0] = 0x0000000000000000ull; | |
800 | *pfpsf |= INEXACT_EXCEPTION; | |
801 | BID_RETURN (res); | |
802 | } | |
803 | break; | |
804 | } | |
805 | BID_RETURN (res); | |
806 | } | |
807 | ||
808 | /***************************************************************************** | |
809 | * BID128_round_integral_nearest_even | |
810 | ****************************************************************************/ | |
811 | ||
812 | BID128_FUNCTION_ARG1_NORND(__bid128_round_integral_nearest_even, x) | |
813 | ||
814 | UINT128 res; | |
815 | UINT64 x_sign; | |
816 | UINT64 x_exp; | |
817 | int exp; // unbiased exponent | |
818 | // Note: C1.w[1], C1.w[0] represent x_signif_hi, x_signif_lo (all are UINT64) | |
819 | UINT64 tmp64; | |
820 | BID_UI64DOUBLE tmp1; | |
821 | unsigned int x_nr_bits; | |
822 | int q, ind, shift; | |
823 | UINT128 C1; | |
824 | // UINT128 res is C* at first - represents up to 34 decimal digits ~ 113 bits | |
825 | UINT256 fstar; | |
826 | UINT256 P256; | |
827 | ||
828 | // check for NaN or Infinity | |
829 | if ((x.w[1] & MASK_SPECIAL) == MASK_SPECIAL) { | |
830 | // x is special | |
831 | if ((x.w[1] & MASK_NAN) == MASK_NAN) { // x is NAN | |
832 | if ((x.w[1] & MASK_SNAN) == MASK_SNAN) { // x is SNAN | |
833 | // set invalid flag | |
834 | *pfpsf |= INVALID_EXCEPTION; | |
835 | // return Quiet (SNaN) | |
836 | res.w[1] = x.w[1] & 0xfdffffffffffffffull; | |
837 | res.w[0] = x.w[0]; | |
838 | } else { // x is QNaN | |
839 | // return the input QNaN | |
840 | res.w[1] = x.w[1]; | |
841 | res.w[0] = x.w[0]; | |
842 | } | |
843 | BID_RETURN (res); | |
844 | } else { // x is not a NaN, so it must be infinity | |
845 | if ((x.w[1] & MASK_SIGN) == 0x0ull) { // x is +inf | |
846 | // return +inf | |
847 | res.w[1] = 0x7800000000000000ull; | |
848 | res.w[0] = 0x0000000000000000ull; | |
849 | } else { // x is -inf | |
850 | // return -inf | |
851 | res.w[1] = 0xf800000000000000ull; | |
852 | res.w[0] = 0x0000000000000000ull; | |
853 | } | |
854 | BID_RETURN (res); | |
855 | } | |
856 | } | |
857 | // unpack x | |
858 | x_sign = x.w[1] & MASK_SIGN; // 0 for positive, MASK_SIGN for negative | |
859 | x_exp = x.w[1] & MASK_EXP; // biased and shifted left 49 bit positions | |
860 | C1.w[1] = x.w[1] & MASK_COEFF; | |
861 | C1.w[0] = x.w[0]; | |
862 | ||
863 | // test for non-canonical values: | |
864 | // - values whose encoding begins with x00, x01, or x10 and whose | |
865 | // coefficient is larger than 10^34 -1, or | |
866 | // - values whose encoding begins with x1100, x1101, x1110 (if NaNs | |
867 | // and infinitis were eliminated already this test is reduced to | |
868 | // checking for x10x) | |
869 | ||
870 | // test for non-canonical values of the argument x | |
871 | if ((((C1.w[1] > 0x0001ed09bead87c0ull) | |
872 | || ((C1.w[1] == 0x0001ed09bead87c0ull) | |
873 | && (C1.w[0] > 0x378d8e63ffffffffull))) | |
874 | && ((x.w[1] & 0x6000000000000000ull) != 0x6000000000000000ull)) | |
875 | || ((x.w[1] & 0x6000000000000000ull) == 0x6000000000000000ull)) { | |
876 | x.w[1] = x.w[1] & 0x8000000000000000ull; // preserve the sign bit | |
877 | x.w[0] = 0; | |
878 | x_exp = 0x1820ull << 49; | |
879 | C1.w[1] = 0; | |
880 | C1.w[0] = 0; | |
881 | } | |
882 | // test for input equal to zero | |
883 | if ((C1.w[1] == 0x0ull) && (C1.w[0] == 0x0ull)) { | |
884 | // x is 0 | |
885 | // return 0 preserving the sign bit and the preferred exponent | |
886 | // of MAX(Q(x), 0) | |
887 | if (x_exp <= (0x1820ull << 49)) { | |
888 | res.w[1] = | |
889 | (x.w[1] & 0x8000000000000000ull) | 0x3040000000000000ull; | |
890 | } else { | |
891 | res.w[1] = x.w[1] & 0xfffe000000000000ull; | |
892 | } | |
893 | res.w[0] = 0x0000000000000000ull; | |
894 | BID_RETURN (res); | |
895 | } | |
896 | // x is not special and is not zero | |
897 | ||
898 | // if (exp <= -(p+1)) return 0 | |
899 | if (x_exp <= 0x2ffa000000000000ull) { // 0x2ffa000000000000ull == -35 | |
900 | res.w[1] = x_sign | 0x3040000000000000ull; | |
901 | res.w[0] = 0x0000000000000000ull; | |
902 | BID_RETURN (res); | |
903 | } | |
904 | // q = nr. of decimal digits in x | |
905 | // determine first the nr. of bits in x | |
906 | if (C1.w[1] == 0) { | |
907 | if (C1.w[0] >= 0x0020000000000000ull) { // x >= 2^53 | |
908 | // split the 64-bit value in two 32-bit halves to avoid rounding errors | |
909 | if (C1.w[0] >= 0x0000000100000000ull) { // x >= 2^32 | |
910 | tmp1.d = (double) (C1.w[0] >> 32); // exact conversion | |
911 | x_nr_bits = | |
912 | 33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
913 | } else { // x < 2^32 | |
914 | tmp1.d = (double) (C1.w[0]); // exact conversion | |
915 | x_nr_bits = | |
916 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
917 | } | |
918 | } else { // if x < 2^53 | |
919 | tmp1.d = (double) C1.w[0]; // exact conversion | |
920 | x_nr_bits = | |
921 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
922 | } | |
923 | } else { // C1.w[1] != 0 => nr. bits = 64 + nr_bits (C1.w[1]) | |
924 | tmp1.d = (double) C1.w[1]; // exact conversion | |
925 | x_nr_bits = | |
926 | 65 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
927 | } | |
928 | q = __bid_nr_digits[x_nr_bits - 1].digits; | |
929 | if (q == 0) { | |
930 | q = __bid_nr_digits[x_nr_bits - 1].digits1; | |
931 | if (C1.w[1] > __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
932 | || (C1.w[1] == __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
933 | && C1.w[0] >= __bid_nr_digits[x_nr_bits - 1].threshold_lo)) | |
934 | q++; | |
935 | } | |
936 | exp = (x_exp >> 49) - 6176; | |
937 | if (exp >= 0) { // -exp <= 0 | |
938 | // the argument is an integer already | |
939 | res.w[1] = x.w[1]; | |
940 | res.w[0] = x.w[0]; | |
941 | BID_RETURN (res); | |
942 | } else if ((q + exp) >= 0) { // exp < 0 and 1 <= -exp <= q | |
943 | // need to shift right -exp digits from the coefficient; the exp will be 0 | |
944 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
945 | // chop off ind digits from the lower part of C1 | |
946 | // C1 = C1 + 1/2 * 10^x where the result C1 fits in 127 bits | |
947 | tmp64 = C1.w[0]; | |
948 | if (ind <= 19) { | |
949 | C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
950 | } else { | |
951 | C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
952 | C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
953 | } | |
954 | if (C1.w[0] < tmp64) | |
955 | C1.w[1]++; | |
956 | // calculate C* and f* | |
957 | // C* is actually floor(C*) in this case | |
958 | // C* and f* need shifting and masking, as shown by | |
959 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
960 | // 1 <= x <= 34 | |
961 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
962 | // C* = (C1 + 1/2 * 10^x) * 10^(-x) | |
963 | // the approximation of 10^(-x) was rounded up to 118 bits | |
964 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
965 | // determine the value of res and fstar | |
966 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
967 | // redundant shift = __bid_shiftright128[ind - 1]; // shift = 0 | |
968 | res.w[1] = P256.w[3]; | |
969 | res.w[0] = P256.w[2]; | |
970 | // redundant fstar.w[3] = 0; | |
971 | // redundant fstar.w[2] = 0; | |
972 | // redundant fstar.w[1] = P256.w[1]; | |
973 | // redundant fstar.w[0] = P256.w[0]; | |
974 | // fraction f* < 10^(-x) <=> midpoint | |
975 | // f* is in the right position to be compared with | |
976 | // 10^(-x) from __bid_ten2mk128[] | |
977 | // if 0 < fstar < 10^(-x), subtract 1 if odd (for rounding to even) | |
978 | if ((res.w[0] & 0x0000000000000001ull) && // is result odd? | |
979 | ((P256.w[1] < (__bid_ten2mk128[ind - 1].w[1])) | |
980 | || ((P256.w[1] == __bid_ten2mk128[ind - 1].w[1]) | |
981 | && (P256.w[0] < __bid_ten2mk128[ind - 1].w[0])))) { | |
982 | // subract 1 to make even | |
983 | if (res.w[0]-- == 0) { | |
984 | res.w[1]--; | |
985 | } | |
986 | } | |
987 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
988 | shift = __bid_shiftright128[ind - 1]; // 3 <= shift <= 63 | |
989 | res.w[1] = (P256.w[3] >> shift); | |
990 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
991 | // redundant fstar.w[3] = 0; | |
992 | fstar.w[2] = P256.w[2] & __bid_maskhigh128[ind - 1]; | |
993 | fstar.w[1] = P256.w[1]; | |
994 | fstar.w[0] = P256.w[0]; | |
995 | // fraction f* < 10^(-x) <=> midpoint | |
996 | // f* is in the right position to be compared with | |
997 | // 10^(-x) from __bid_ten2mk128[] | |
998 | if ((res.w[0] & 0x0000000000000001ull) && // is result odd? | |
999 | fstar.w[2] == 0 && (fstar.w[1] < __bid_ten2mk128[ind - 1].w[1] | |
1000 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
1001 | && fstar.w[0] < __bid_ten2mk128[ind - 1].w[0]))) { | |
1002 | // subract 1 to make even | |
1003 | if (res.w[0]-- == 0) { | |
1004 | res.w[1]--; | |
1005 | } | |
1006 | } | |
1007 | } else { // 22 <= ind - 1 <= 33 | |
1008 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
1009 | res.w[1] = 0; | |
1010 | res.w[0] = P256.w[3] >> shift; | |
1011 | fstar.w[3] = P256.w[3] & __bid_maskhigh128[ind - 1]; | |
1012 | fstar.w[2] = P256.w[2]; | |
1013 | fstar.w[1] = P256.w[1]; | |
1014 | fstar.w[0] = P256.w[0]; | |
1015 | // fraction f* < 10^(-x) <=> midpoint | |
1016 | // f* is in the right position to be compared with | |
1017 | // 10^(-x) from __bid_ten2mk128[] | |
1018 | if ((res.w[0] & 0x0000000000000001ull) && // is result odd? | |
1019 | fstar.w[3] == 0 && fstar.w[2] == 0 | |
1020 | && (fstar.w[1] < __bid_ten2mk128[ind - 1].w[1] | |
1021 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
1022 | && fstar.w[0] < __bid_ten2mk128[ind - 1].w[0]))) { | |
1023 | // subract 1 to make even | |
1024 | if (res.w[0]-- == 0) { | |
1025 | res.w[1]--; | |
1026 | } | |
1027 | } | |
1028 | } | |
1029 | res.w[1] = x_sign | 0x3040000000000000ull | res.w[1]; | |
1030 | BID_RETURN (res); | |
1031 | } else { // if ((q + exp) < 0) <=> q < -exp | |
1032 | // the result is +0 or -0 | |
1033 | res.w[1] = x_sign | 0x3040000000000000ull; | |
1034 | res.w[0] = 0x0000000000000000ull; | |
1035 | BID_RETURN (res); | |
1036 | } | |
1037 | } | |
1038 | ||
1039 | /***************************************************************************** | |
1040 | * BID128_round_integral_negative | |
1041 | ****************************************************************************/ | |
1042 | ||
1043 | BID128_FUNCTION_ARG1_NORND(__bid128_round_integral_negative, x) | |
1044 | ||
1045 | UINT128 res; | |
1046 | UINT64 x_sign; | |
1047 | UINT64 x_exp; | |
1048 | int exp; // unbiased exponent | |
1049 | // Note: C1.w[1], C1.w[0] represent x_signif_hi, x_signif_lo | |
1050 | // (all are UINT64) | |
1051 | BID_UI64DOUBLE tmp1; | |
1052 | unsigned int x_nr_bits; | |
1053 | int q, ind, shift; | |
1054 | UINT128 C1; | |
1055 | // UINT128 res is C* at first - represents up to 34 decimal digits ~ | |
1056 | // 113 bits | |
1057 | UINT256 fstar; | |
1058 | UINT256 P256; | |
1059 | ||
1060 | // check for NaN or Infinity | |
1061 | if ((x.w[1] & MASK_SPECIAL) == MASK_SPECIAL) { | |
1062 | // x is special | |
1063 | if ((x.w[1] & MASK_NAN) == MASK_NAN) { // x is NAN | |
1064 | if ((x.w[1] & MASK_SNAN) == MASK_SNAN) { // x is SNAN | |
1065 | // set invalid flag | |
1066 | *pfpsf |= INVALID_EXCEPTION; | |
1067 | // return Quiet (SNaN) | |
1068 | res.w[1] = x.w[1] & 0xfdffffffffffffffull; | |
1069 | res.w[0] = x.w[0]; | |
1070 | } else { // x is QNaN | |
1071 | // return the input QNaN | |
1072 | res.w[1] = x.w[1]; | |
1073 | res.w[0] = x.w[0]; | |
1074 | } | |
1075 | BID_RETURN (res); | |
1076 | } else { // x is not a NaN, so it must be infinity | |
1077 | if ((x.w[1] & MASK_SIGN) == 0x0ull) { // x is +inf | |
1078 | // return +inf | |
1079 | res.w[1] = 0x7800000000000000ull; | |
1080 | res.w[0] = 0x0000000000000000ull; | |
1081 | } else { // x is -inf | |
1082 | // return -inf | |
1083 | res.w[1] = 0xf800000000000000ull; | |
1084 | res.w[0] = 0x0000000000000000ull; | |
1085 | } | |
1086 | BID_RETURN (res); | |
1087 | } | |
1088 | } | |
1089 | // unpack x | |
1090 | x_sign = x.w[1] & MASK_SIGN; // 0 for positive, MASK_SIGN for negative | |
1091 | x_exp = x.w[1] & MASK_EXP; // biased and shifted left 49 bit positions | |
1092 | C1.w[1] = x.w[1] & MASK_COEFF; | |
1093 | C1.w[0] = x.w[0]; | |
1094 | ||
1095 | // test for non-canonical values: | |
1096 | // - values whose encoding begins with x00, x01, or x10 and whose | |
1097 | // coefficient is larger than 10^34 -1, or | |
1098 | // - values whose encoding begins with x1100, x1101, x1110 (if NaNs | |
1099 | // and infinitis were eliminated already this test is reduced to | |
1100 | // checking for x10x) | |
1101 | ||
1102 | // test for non-canonical values of the argument x | |
1103 | if ((((C1.w[1] > 0x0001ed09bead87c0ull) | |
1104 | || ((C1.w[1] == 0x0001ed09bead87c0ull) | |
1105 | && (C1.w[0] > 0x378d8e63ffffffffull))) | |
1106 | && ((x.w[1] & 0x6000000000000000ull) != 0x6000000000000000ull)) | |
1107 | || ((x.w[1] & 0x6000000000000000ull) == 0x6000000000000000ull)) { | |
1108 | x.w[1] = x.w[1] & 0x8000000000000000ull; // preserve the sign bit | |
1109 | x.w[0] = 0; | |
1110 | x_exp = 0x1820ull << 49; | |
1111 | C1.w[1] = 0; | |
1112 | C1.w[0] = 0; | |
1113 | } | |
1114 | // test for input equal to zero | |
1115 | if ((C1.w[1] == 0x0ull) && (C1.w[0] == 0x0ull)) { | |
1116 | // x is 0 | |
1117 | // return 0 preserving the sign bit and the preferred exponent | |
1118 | // of MAX(Q(x), 0) | |
1119 | if (x_exp <= (0x1820ull << 49)) { | |
1120 | res.w[1] = | |
1121 | (x.w[1] & 0x8000000000000000ull) | 0x3040000000000000ull; | |
1122 | } else { | |
1123 | res.w[1] = x.w[1] & 0xfffe000000000000ull; | |
1124 | } | |
1125 | res.w[0] = 0x0000000000000000ull; | |
1126 | BID_RETURN (res); | |
1127 | } | |
1128 | // x is not special and is not zero | |
1129 | ||
1130 | // if (exp <= -p) return -1.0 or +0.0 | |
1131 | if (x_exp <= 0x2ffc000000000000ull) { // 0x2ffc000000000000ull == -34 | |
1132 | if (x_sign) { | |
1133 | // if negative, return negative 1, because we know the coefficient | |
1134 | // is non-zero (would have been caught above) | |
1135 | res.w[1] = 0xb040000000000000ull; | |
1136 | res.w[0] = 0x0000000000000001ull; | |
1137 | } else { | |
1138 | // if positive, return positive 0, because we know coefficient is | |
1139 | // non-zero (would have been caught above) | |
1140 | res.w[1] = 0x3040000000000000ull; | |
1141 | res.w[0] = 0x0000000000000000ull; | |
1142 | } | |
1143 | BID_RETURN (res); | |
1144 | } | |
1145 | // q = nr. of decimal digits in x | |
1146 | // determine first the nr. of bits in x | |
1147 | if (C1.w[1] == 0) { | |
1148 | if (C1.w[0] >= 0x0020000000000000ull) { // x >= 2^53 | |
1149 | // split the 64-bit value in two 32-bit halves to avoid rounding errors | |
1150 | if (C1.w[0] >= 0x0000000100000000ull) { // x >= 2^32 | |
1151 | tmp1.d = (double) (C1.w[0] >> 32); // exact conversion | |
1152 | x_nr_bits = | |
1153 | 33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1154 | } else { // x < 2^32 | |
1155 | tmp1.d = (double) (C1.w[0]); // exact conversion | |
1156 | x_nr_bits = | |
1157 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1158 | } | |
1159 | } else { // if x < 2^53 | |
1160 | tmp1.d = (double) C1.w[0]; // exact conversion | |
1161 | x_nr_bits = | |
1162 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1163 | } | |
1164 | } else { // C1.w[1] != 0 => nr. bits = 64 + nr_bits (C1.w[1]) | |
1165 | tmp1.d = (double) C1.w[1]; // exact conversion | |
1166 | x_nr_bits = | |
1167 | 65 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1168 | } | |
1169 | q = __bid_nr_digits[x_nr_bits - 1].digits; | |
1170 | if (q == 0) { | |
1171 | q = __bid_nr_digits[x_nr_bits - 1].digits1; | |
1172 | if (C1.w[1] > __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
1173 | || (C1.w[1] == __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
1174 | && C1.w[0] >= __bid_nr_digits[x_nr_bits - 1].threshold_lo)) | |
1175 | q++; | |
1176 | } | |
1177 | exp = (x_exp >> 49) - 6176; | |
1178 | if (exp >= 0) { // -exp <= 0 | |
1179 | // the argument is an integer already | |
1180 | res.w[1] = x.w[1]; | |
1181 | res.w[0] = x.w[0]; | |
1182 | BID_RETURN (res); | |
1183 | } else if ((q + exp) > 0) { // exp < 0 and 1 <= -exp < q | |
1184 | // need to shift right -exp digits from the coefficient; the exp will be 0 | |
1185 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
1186 | // (number of digits to be chopped off) | |
1187 | // chop off ind digits from the lower part of C1 | |
1188 | // FOR ROUND_TO_NEAREST, WE ADD 1/2 ULP(y) then truncate | |
1189 | // FOR ROUND_TO_ZERO, WE DON'T NEED TO ADD 1/2 ULP | |
1190 | // FOR ROUND_TO_POSITIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF POSITIVE | |
1191 | // FOR ROUND_TO_NEGATIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF NEGATIVE | |
1192 | //tmp64 = C1.w[0]; | |
1193 | // if (ind <= 19) { | |
1194 | // C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
1195 | // } else { | |
1196 | // C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
1197 | // C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
1198 | // } | |
1199 | // if (C1.w[0] < tmp64) C1.w[1]++; | |
1200 | // if carry-out from C1.w[0], increment C1.w[1] | |
1201 | // calculate C* and f* | |
1202 | // C* is actually floor(C*) in this case | |
1203 | // C* and f* need shifting and masking, as shown by | |
1204 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
1205 | // 1 <= x <= 34 | |
1206 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
1207 | // C* = (C1 + 1/2 * 10^x) * 10^(-x) | |
1208 | // the approximation of 10^(-x) was rounded up to 118 bits | |
1209 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
1210 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
1211 | res.w[1] = P256.w[3]; | |
1212 | res.w[0] = P256.w[2]; | |
1213 | // if positive, the truncated value is already the correct result | |
1214 | if (x_sign) { // if negative | |
1215 | // redundant fstar.w[3] = 0; | |
1216 | // redundant fstar.w[2] = 0; | |
1217 | // redundant fstar.w[1] = P256.w[1]; | |
1218 | // redundant fstar.w[0] = P256.w[0]; | |
1219 | // fraction f* > 10^(-x) <=> inexact | |
1220 | // f* is in the right position to be compared with | |
1221 | // 10^(-x) from __bid_ten2mk128[] | |
1222 | if ((P256.w[1] > __bid_ten2mk128[ind - 1].w[1]) | |
1223 | || (P256.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
1224 | && (P256.w[0] >= __bid_ten2mk128[ind - 1].w[0]))) { | |
1225 | if (++res.w[0] == 0) { | |
1226 | res.w[1]++; | |
1227 | } | |
1228 | } | |
1229 | } | |
1230 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
1231 | shift = __bid_shiftright128[ind - 1]; // 0 <= shift <= 102 | |
1232 | res.w[1] = (P256.w[3] >> shift); | |
1233 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
1234 | // if positive, the truncated value is already the correct result | |
1235 | if (x_sign) { // if negative | |
1236 | // redundant fstar.w[3] = 0; | |
1237 | fstar.w[2] = P256.w[2] & __bid_maskhigh128[ind - 1]; | |
1238 | fstar.w[1] = P256.w[1]; | |
1239 | fstar.w[0] = P256.w[0]; | |
1240 | // fraction f* > 10^(-x) <=> inexact | |
1241 | // f* is in the right position to be compared with | |
1242 | // 10^(-x) from __bid_ten2mk128[] | |
1243 | if (fstar.w[2] || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
1244 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
1245 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
1246 | if (++res.w[0] == 0) { | |
1247 | res.w[1]++; | |
1248 | } | |
1249 | } | |
1250 | } | |
1251 | } else { // 22 <= ind - 1 <= 33 | |
1252 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
1253 | res.w[1] = 0; | |
1254 | res.w[0] = P256.w[3] >> shift; | |
1255 | // if positive, the truncated value is already the correct result | |
1256 | if (x_sign) { // if negative | |
1257 | fstar.w[3] = P256.w[3] & __bid_maskhigh128[ind - 1]; | |
1258 | fstar.w[2] = P256.w[2]; | |
1259 | fstar.w[1] = P256.w[1]; | |
1260 | fstar.w[0] = P256.w[0]; | |
1261 | // fraction f* > 10^(-x) <=> inexact | |
1262 | // f* is in the right position to be compared with | |
1263 | // 10^(-x) from __bid_ten2mk128[] | |
1264 | if (fstar.w[3] || fstar.w[2] | |
1265 | || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
1266 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
1267 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
1268 | if (++res.w[0] == 0) { | |
1269 | res.w[1]++; | |
1270 | } | |
1271 | } | |
1272 | } | |
1273 | } | |
1274 | res.w[1] = x_sign | 0x3040000000000000ull | res.w[1]; | |
1275 | BID_RETURN (res); | |
1276 | } else { // if exp < 0 and q + exp <= 0 | |
1277 | if (x_sign) { // negative rounds down to -1.0 | |
1278 | res.w[1] = 0xb040000000000000ull; | |
1279 | res.w[0] = 0x0000000000000001ull; | |
1280 | } else { // positive rpunds down to +0.0 | |
1281 | res.w[1] = 0x3040000000000000ull; | |
1282 | res.w[0] = 0x0000000000000000ull; | |
1283 | } | |
1284 | BID_RETURN (res); | |
1285 | } | |
1286 | } | |
1287 | ||
1288 | /***************************************************************************** | |
1289 | * BID128_round_integral_positive | |
1290 | ****************************************************************************/ | |
1291 | ||
1292 | BID128_FUNCTION_ARG1_NORND(__bid128_round_integral_positive, x) | |
1293 | ||
1294 | UINT128 res; | |
1295 | UINT64 x_sign; | |
1296 | UINT64 x_exp; | |
1297 | int exp; // unbiased exponent | |
1298 | // Note: C1.w[1], C1.w[0] represent x_signif_hi, x_signif_lo | |
1299 | // (all are UINT64) | |
1300 | BID_UI64DOUBLE tmp1; | |
1301 | unsigned int x_nr_bits; | |
1302 | int q, ind, shift; | |
1303 | UINT128 C1; | |
1304 | // UINT128 res is C* at first - represents up to 34 decimal digits ~ | |
1305 | // 113 bits | |
1306 | UINT256 fstar; | |
1307 | UINT256 P256; | |
1308 | ||
1309 | // check for NaN or Infinity | |
1310 | if ((x.w[1] & MASK_SPECIAL) == MASK_SPECIAL) { | |
1311 | // x is special | |
1312 | if ((x.w[1] & MASK_NAN) == MASK_NAN) { // x is NAN | |
1313 | if ((x.w[1] & MASK_SNAN) == MASK_SNAN) { // x is SNAN | |
1314 | // set invalid flag | |
1315 | *pfpsf |= INVALID_EXCEPTION; | |
1316 | // return Quiet (SNaN) | |
1317 | res.w[1] = x.w[1] & 0xfdffffffffffffffull; | |
1318 | res.w[0] = x.w[0]; | |
1319 | } else { // x is QNaN | |
1320 | // return the input QNaN | |
1321 | res.w[1] = x.w[1]; | |
1322 | res.w[0] = x.w[0]; | |
1323 | } | |
1324 | BID_RETURN (res); | |
1325 | } else { // x is not a NaN, so it must be infinity | |
1326 | if ((x.w[1] & MASK_SIGN) == 0x0ull) { // x is +inf | |
1327 | // return +inf | |
1328 | res.w[1] = 0x7800000000000000ull; | |
1329 | res.w[0] = 0x0000000000000000ull; | |
1330 | } else { // x is -inf | |
1331 | // return -inf | |
1332 | res.w[1] = 0xf800000000000000ull; | |
1333 | res.w[0] = 0x0000000000000000ull; | |
1334 | } | |
1335 | BID_RETURN (res); | |
1336 | } | |
1337 | } | |
1338 | // unpack x | |
1339 | x_sign = x.w[1] & MASK_SIGN; // 0 for positive, MASK_SIGN for negative | |
1340 | x_exp = x.w[1] & MASK_EXP; // biased and shifted left 49 bit positions | |
1341 | C1.w[1] = x.w[1] & MASK_COEFF; | |
1342 | C1.w[0] = x.w[0]; | |
1343 | ||
1344 | // test for non-canonical values: | |
1345 | // - values whose encoding begins with x00, x01, or x10 and whose | |
1346 | // coefficient is larger than 10^34 -1, or | |
1347 | // - values whose encoding begins with x1100, x1101, x1110 (if NaNs | |
1348 | // and infinitis were eliminated already this test is reduced to | |
1349 | // checking for x10x) | |
1350 | ||
1351 | // test for non-canonical values of the argument x | |
1352 | if ((((C1.w[1] > 0x0001ed09bead87c0ull) | |
1353 | || ((C1.w[1] == 0x0001ed09bead87c0ull) | |
1354 | && (C1.w[0] > 0x378d8e63ffffffffull))) | |
1355 | && ((x.w[1] & 0x6000000000000000ull) != 0x6000000000000000ull)) | |
1356 | || ((x.w[1] & 0x6000000000000000ull) == 0x6000000000000000ull)) { | |
1357 | x.w[1] = x.w[1] & 0x8000000000000000ull; // preserve the sign bit | |
1358 | x.w[0] = 0; | |
1359 | x_exp = 0x1820ull << 49; | |
1360 | C1.w[1] = 0; | |
1361 | C1.w[0] = 0; | |
1362 | } | |
1363 | // test for input equal to zero | |
1364 | if ((C1.w[1] == 0x0ull) && (C1.w[0] == 0x0ull)) { | |
1365 | // x is 0 | |
1366 | // return 0 preserving the sign bit and the preferred exponent | |
1367 | // of MAX(Q(x), 0) | |
1368 | if (x_exp <= (0x1820ull << 49)) { | |
1369 | res.w[1] = | |
1370 | (x.w[1] & 0x8000000000000000ull) | 0x3040000000000000ull; | |
1371 | } else { | |
1372 | res.w[1] = x.w[1] & 0xfffe000000000000ull; | |
1373 | } | |
1374 | res.w[0] = 0x0000000000000000ull; | |
1375 | BID_RETURN (res); | |
1376 | } | |
1377 | // x is not special and is not zero | |
1378 | ||
1379 | // if (exp <= -p) return -0.0 or +1.0 | |
1380 | if (x_exp <= 0x2ffc000000000000ull) { // 0x2ffc000000000000ull == -34 | |
1381 | if (x_sign) { | |
1382 | // if negative, return negative 0, because we know the coefficient | |
1383 | // is non-zero (would have been caught above) | |
1384 | res.w[1] = 0xb040000000000000ull; | |
1385 | res.w[0] = 0x0000000000000000ull; | |
1386 | } else { | |
1387 | // if positive, return positive 1, because we know coefficient is | |
1388 | // non-zero (would have been caught above) | |
1389 | res.w[1] = 0x3040000000000000ull; | |
1390 | res.w[0] = 0x0000000000000001ull; | |
1391 | } | |
1392 | BID_RETURN (res); | |
1393 | } | |
1394 | // q = nr. of decimal digits in x | |
1395 | // determine first the nr. of bits in x | |
1396 | if (C1.w[1] == 0) { | |
1397 | if (C1.w[0] >= 0x0020000000000000ull) { // x >= 2^53 | |
1398 | // split 64-bit value in two 32-bit halves to avoid rounding errors | |
1399 | if (C1.w[0] >= 0x0000000100000000ull) { // x >= 2^32 | |
1400 | tmp1.d = (double) (C1.w[0] >> 32); // exact conversion | |
1401 | x_nr_bits = | |
1402 | 33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1403 | } else { // x < 2^32 | |
1404 | tmp1.d = (double) (C1.w[0]); // exact conversion | |
1405 | x_nr_bits = | |
1406 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1407 | } | |
1408 | } else { // if x < 2^53 | |
1409 | tmp1.d = (double) C1.w[0]; // exact conversion | |
1410 | x_nr_bits = | |
1411 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1412 | } | |
1413 | } else { // C1.w[1] != 0 => nr. bits = 64 + nr_bits (C1.w[1]) | |
1414 | tmp1.d = (double) C1.w[1]; // exact conversion | |
1415 | x_nr_bits = | |
1416 | 65 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1417 | } | |
1418 | q = __bid_nr_digits[x_nr_bits - 1].digits; | |
1419 | if (q == 0) { | |
1420 | q = __bid_nr_digits[x_nr_bits - 1].digits1; | |
1421 | if (C1.w[1] > __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
1422 | || (C1.w[1] == __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
1423 | && C1.w[0] >= __bid_nr_digits[x_nr_bits - 1].threshold_lo)) | |
1424 | q++; | |
1425 | } | |
1426 | exp = (x_exp >> 49) - 6176; | |
1427 | if (exp >= 0) { // -exp <= 0 | |
1428 | // the argument is an integer already | |
1429 | res.w[1] = x.w[1]; | |
1430 | res.w[0] = x.w[0]; | |
1431 | BID_RETURN (res); | |
1432 | } else if ((q + exp) > 0) { // exp < 0 and 1 <= -exp < q | |
1433 | // need to shift right -exp digits from the coefficient; exp will be 0 | |
1434 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
1435 | // (number of digits to be chopped off) | |
1436 | // chop off ind digits from the lower part of C1 | |
1437 | // FOR ROUND_TO_NEAREST, WE ADD 1/2 ULP(y) then truncate | |
1438 | // FOR ROUND_TO_ZERO, WE DON'T NEED TO ADD 1/2 ULP | |
1439 | // FOR ROUND_TO_POSITIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF POSITIVE | |
1440 | // FOR ROUND_TO_NEGATIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF NEGATIVE | |
1441 | // tmp64 = C1.w[0]; | |
1442 | // if (ind <= 19) { | |
1443 | // C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
1444 | // } else { | |
1445 | // C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
1446 | // C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
1447 | // } | |
1448 | // if (C1.w[0] < tmp64) C1.w[1]++; | |
1449 | // if carry-out from C1.w[0], increment C1.w[1] | |
1450 | // calculate C* and f* | |
1451 | // C* is actually floor(C*) in this case | |
1452 | // C* and f* need shifting and masking, as shown by | |
1453 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
1454 | // 1 <= x <= 34 | |
1455 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
1456 | // C* = C1 * 10^(-x) | |
1457 | // the approximation of 10^(-x) was rounded up to 118 bits | |
1458 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
1459 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
1460 | res.w[1] = P256.w[3]; | |
1461 | res.w[0] = P256.w[2]; | |
1462 | // if negative, the truncated value is already the correct result | |
1463 | if (!x_sign) { // if positive | |
1464 | // redundant fstar.w[3] = 0; | |
1465 | // redundant fstar.w[2] = 0; | |
1466 | // redundant fstar.w[1] = P256.w[1]; | |
1467 | // redundant fstar.w[0] = P256.w[0]; | |
1468 | // fraction f* > 10^(-x) <=> inexact | |
1469 | // f* is in the right position to be compared with | |
1470 | // 10^(-x) from __bid_ten2mk128[] | |
1471 | if ((P256.w[1] > __bid_ten2mk128[ind - 1].w[1]) | |
1472 | || (P256.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
1473 | && (P256.w[0] >= __bid_ten2mk128[ind - 1].w[0]))) { | |
1474 | if (++res.w[0] == 0) { | |
1475 | res.w[1]++; | |
1476 | } | |
1477 | } | |
1478 | } | |
1479 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
1480 | shift = __bid_shiftright128[ind - 1]; // 3 <= shift <= 63 | |
1481 | res.w[1] = (P256.w[3] >> shift); | |
1482 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
1483 | // if negative, the truncated value is already the correct result | |
1484 | if (!x_sign) { // if positive | |
1485 | // redundant fstar.w[3] = 0; | |
1486 | fstar.w[2] = P256.w[2] & __bid_maskhigh128[ind - 1]; | |
1487 | fstar.w[1] = P256.w[1]; | |
1488 | fstar.w[0] = P256.w[0]; | |
1489 | // fraction f* > 10^(-x) <=> inexact | |
1490 | // f* is in the right position to be compared with | |
1491 | // 10^(-x) from __bid_ten2mk128[] | |
1492 | if (fstar.w[2] || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
1493 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
1494 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
1495 | if (++res.w[0] == 0) { | |
1496 | res.w[1]++; | |
1497 | } | |
1498 | } | |
1499 | } | |
1500 | } else { // 22 <= ind - 1 <= 33 | |
1501 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
1502 | res.w[1] = 0; | |
1503 | res.w[0] = P256.w[3] >> shift; | |
1504 | // if negative, the truncated value is already the correct result | |
1505 | if (!x_sign) { // if positive | |
1506 | fstar.w[3] = P256.w[3] & __bid_maskhigh128[ind - 1]; | |
1507 | fstar.w[2] = P256.w[2]; | |
1508 | fstar.w[1] = P256.w[1]; | |
1509 | fstar.w[0] = P256.w[0]; | |
1510 | // fraction f* > 10^(-x) <=> inexact | |
1511 | // f* is in the right position to be compared with | |
1512 | // 10^(-x) from __bid_ten2mk128[] | |
1513 | if (fstar.w[3] || fstar.w[2] | |
1514 | || fstar.w[1] > __bid_ten2mk128[ind - 1].w[1] | |
1515 | || (fstar.w[1] == __bid_ten2mk128[ind - 1].w[1] | |
1516 | && fstar.w[0] >= __bid_ten2mk128[ind - 1].w[0])) { | |
1517 | if (++res.w[0] == 0) { | |
1518 | res.w[1]++; | |
1519 | } | |
1520 | } | |
1521 | } | |
1522 | } | |
1523 | res.w[1] = x_sign | 0x3040000000000000ull | res.w[1]; | |
1524 | BID_RETURN (res); | |
1525 | } else { // if exp < 0 and q + exp <= 0 | |
1526 | if (x_sign) { // negative rounds up to -0.0 | |
1527 | res.w[1] = 0xb040000000000000ull; | |
1528 | res.w[0] = 0x0000000000000000ull; | |
1529 | } else { // positive rpunds up to +1.0 | |
1530 | res.w[1] = 0x3040000000000000ull; | |
1531 | res.w[0] = 0x0000000000000001ull; | |
1532 | } | |
1533 | BID_RETURN (res); | |
1534 | } | |
1535 | } | |
1536 | ||
1537 | /***************************************************************************** | |
1538 | * BID128_round_integral_zero | |
1539 | ****************************************************************************/ | |
1540 | ||
1541 | BID128_FUNCTION_ARG1_NORND(__bid128_round_integral_zero, x) | |
1542 | ||
1543 | UINT128 res; | |
1544 | UINT64 x_sign; | |
1545 | UINT64 x_exp; | |
1546 | int exp; // unbiased exponent | |
1547 | // Note: C1.w[1], C1.w[0] represent x_signif_hi, x_signif_lo | |
1548 | // (all are UINT64) | |
1549 | BID_UI64DOUBLE tmp1; | |
1550 | unsigned int x_nr_bits; | |
1551 | int q, ind, shift; | |
1552 | UINT128 C1; | |
1553 | // UINT128 res is C* at first - represents up to 34 decimal digits ~ | |
1554 | // 113 bits | |
1555 | UINT256 P256; | |
1556 | ||
1557 | // check for NaN or Infinity | |
1558 | if ((x.w[1] & MASK_SPECIAL) == MASK_SPECIAL) { | |
1559 | // x is special | |
1560 | if ((x.w[1] & MASK_NAN) == MASK_NAN) { // x is NAN | |
1561 | if ((x.w[1] & MASK_SNAN) == MASK_SNAN) { // x is SNAN | |
1562 | // set invalid flag | |
1563 | *pfpsf |= INVALID_EXCEPTION; | |
1564 | // return Quiet (SNaN) | |
1565 | res.w[1] = x.w[1] & 0xfdffffffffffffffull; | |
1566 | res.w[0] = x.w[0]; | |
1567 | } else { // x is QNaN | |
1568 | // return the input QNaN | |
1569 | res.w[1] = x.w[1]; | |
1570 | res.w[0] = x.w[0]; | |
1571 | } | |
1572 | BID_RETURN (res); | |
1573 | } else { // x is not a NaN, so it must be infinity | |
1574 | if ((x.w[1] & MASK_SIGN) == 0x0ull) { // x is +inf | |
1575 | // return +inf | |
1576 | res.w[1] = 0x7800000000000000ull; | |
1577 | res.w[0] = 0x0000000000000000ull; | |
1578 | } else { // x is -inf | |
1579 | // return -inf | |
1580 | res.w[1] = 0xf800000000000000ull; | |
1581 | res.w[0] = 0x0000000000000000ull; | |
1582 | } | |
1583 | BID_RETURN (res); | |
1584 | } | |
1585 | } | |
1586 | // unpack x | |
1587 | x_sign = x.w[1] & MASK_SIGN; // 0 for positive, MASK_SIGN for negative | |
1588 | x_exp = x.w[1] & MASK_EXP; // biased and shifted left 49 bit positions | |
1589 | C1.w[1] = x.w[1] & MASK_COEFF; | |
1590 | C1.w[0] = x.w[0]; | |
1591 | ||
1592 | // test for non-canonical values: | |
1593 | // - values whose encoding begins with x00, x01, or x10 and whose | |
1594 | // coefficient is larger than 10^34 -1, or | |
1595 | // - values whose encoding begins with x1100, x1101, x1110 (if NaNs | |
1596 | // and infinitis were eliminated already this test is reduced to | |
1597 | // checking for x10x) | |
1598 | ||
1599 | // test for non-canonical values of the argument x | |
1600 | if ((((C1.w[1] > 0x0001ed09bead87c0ull) | |
1601 | || ((C1.w[1] == 0x0001ed09bead87c0ull) | |
1602 | && (C1.w[0] > 0x378d8e63ffffffffull))) | |
1603 | && ((x.w[1] & 0x6000000000000000ull) != 0x6000000000000000ull)) | |
1604 | || ((x.w[1] & 0x6000000000000000ull) == 0x6000000000000000ull)) { | |
1605 | x.w[1] = x.w[1] & 0x8000000000000000ull; // preserve the sign bit | |
1606 | x.w[0] = 0; | |
1607 | x_exp = 0x1820ull << 49; | |
1608 | C1.w[1] = 0; | |
1609 | C1.w[0] = 0; | |
1610 | } | |
1611 | // test for input equal to zero | |
1612 | if ((C1.w[1] == 0x0ull) && (C1.w[0] == 0x0ull)) { | |
1613 | // x is 0 | |
1614 | // return 0 preserving the sign bit and the preferred exponent | |
1615 | // of MAX(Q(x), 0) | |
1616 | if (x_exp <= (0x1820ull << 49)) { | |
1617 | res.w[1] = | |
1618 | (x.w[1] & 0x8000000000000000ull) | 0x3040000000000000ull; | |
1619 | } else { | |
1620 | res.w[1] = x.w[1] & 0xfffe000000000000ull; | |
1621 | } | |
1622 | res.w[0] = 0x0000000000000000ull; | |
1623 | BID_RETURN (res); | |
1624 | } | |
1625 | // x is not special and is not zero | |
1626 | ||
1627 | // if (exp <= -p) return -0.0 or +0.0 | |
1628 | if (x_exp <= 0x2ffc000000000000ull) { // 0x2ffc000000000000ull == -34 | |
1629 | res.w[1] = x_sign | 0x3040000000000000ull; | |
1630 | res.w[0] = 0x0000000000000000ull; | |
1631 | BID_RETURN (res); | |
1632 | } | |
1633 | // q = nr. of decimal digits in x | |
1634 | // determine first the nr. of bits in x | |
1635 | if (C1.w[1] == 0) { | |
1636 | if (C1.w[0] >= 0x0020000000000000ull) { // x >= 2^53 | |
1637 | // split the 64-bit value in two 32-bit halves to avoid rounding errors | |
1638 | if (C1.w[0] >= 0x0000000100000000ull) { // x >= 2^32 | |
1639 | tmp1.d = (double) (C1.w[0] >> 32); // exact conversion | |
1640 | x_nr_bits = | |
1641 | 33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1642 | } else { // x < 2^32 | |
1643 | tmp1.d = (double) (C1.w[0]); // exact conversion | |
1644 | x_nr_bits = | |
1645 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1646 | } | |
1647 | } else { // if x < 2^53 | |
1648 | tmp1.d = (double) C1.w[0]; // exact conversion | |
1649 | x_nr_bits = | |
1650 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1651 | } | |
1652 | } else { // C1.w[1] != 0 => nr. bits = 64 + nr_bits (C1.w[1]) | |
1653 | tmp1.d = (double) C1.w[1]; // exact conversion | |
1654 | x_nr_bits = | |
1655 | 65 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1656 | } | |
1657 | q = __bid_nr_digits[x_nr_bits - 1].digits; | |
1658 | if (q == 0) { | |
1659 | q = __bid_nr_digits[x_nr_bits - 1].digits1; | |
1660 | if (C1.w[1] > __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
1661 | || (C1.w[1] == __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
1662 | && C1.w[0] >= __bid_nr_digits[x_nr_bits - 1].threshold_lo)) | |
1663 | q++; | |
1664 | } | |
1665 | exp = (x_exp >> 49) - 6176; | |
1666 | if (exp >= 0) { // -exp <= 0 | |
1667 | // the argument is an integer already | |
1668 | res.w[1] = x.w[1]; | |
1669 | res.w[0] = x.w[0]; | |
1670 | BID_RETURN (res); | |
1671 | } else if ((q + exp) > 0) { // exp < 0 and 1 <= -exp < q | |
1672 | // need to shift right -exp digits from the coefficient; the exp will be 0 | |
1673 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
1674 | // (number of digits to be chopped off) | |
1675 | // chop off ind digits from the lower part of C1 | |
1676 | // FOR ROUND_TO_NEAREST, WE ADD 1/2 ULP(y) then truncate | |
1677 | // FOR ROUND_TO_ZERO, WE DON'T NEED TO ADD 1/2 ULP | |
1678 | // FOR ROUND_TO_POSITIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF POSITIVE | |
1679 | // FOR ROUND_TO_NEGATIVE_INFINITY, WE TRUNCATE, THEN ADD 1 IF NEGATIVE | |
1680 | //tmp64 = C1.w[0]; | |
1681 | // if (ind <= 19) { | |
1682 | // C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
1683 | // } else { | |
1684 | // C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
1685 | // C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
1686 | // } | |
1687 | // if (C1.w[0] < tmp64) C1.w[1]++; | |
1688 | // if carry-out from C1.w[0], increment C1.w[1] | |
1689 | // calculate C* and f* | |
1690 | // C* is actually floor(C*) in this case | |
1691 | // C* and f* need shifting and masking, as shown by | |
1692 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
1693 | // 1 <= x <= 34 | |
1694 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
1695 | // C* = (C1 + 1/2 * 10^x) * 10^(-x) | |
1696 | // the approximation of 10^(-x) was rounded up to 118 bits | |
1697 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
1698 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
1699 | res.w[1] = P256.w[3]; | |
1700 | res.w[0] = P256.w[2]; | |
1701 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
1702 | shift = __bid_shiftright128[ind - 1]; // 3 <= shift <= 63 | |
1703 | res.w[1] = (P256.w[3] >> shift); | |
1704 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
1705 | } else { // 22 <= ind - 1 <= 33 | |
1706 | shift = __bid_shiftright128[ind - 1] - 64; // 2 <= shift <= 38 | |
1707 | res.w[1] = 0; | |
1708 | res.w[0] = P256.w[3] >> shift; | |
1709 | } | |
1710 | res.w[1] = x_sign | 0x3040000000000000ull | res.w[1]; | |
1711 | BID_RETURN (res); | |
1712 | } else { // if exp < 0 and q + exp <= 0 the result is +0 or -0 | |
1713 | res.w[1] = x_sign | 0x3040000000000000ull; | |
1714 | res.w[0] = 0x0000000000000000ull; | |
1715 | BID_RETURN (res); | |
1716 | } | |
1717 | } | |
1718 | ||
1719 | /***************************************************************************** | |
1720 | * BID128_round_integral_nearest_away | |
1721 | ****************************************************************************/ | |
1722 | ||
1723 | BID128_FUNCTION_ARG1_NORND(__bid128_round_integral_nearest_away, x) | |
1724 | ||
1725 | UINT128 res; | |
1726 | UINT64 x_sign; | |
1727 | UINT64 x_exp; | |
1728 | int exp; // unbiased exponent | |
1729 | // Note: C1.w[1], C1.w[0] represent x_signif_hi, x_signif_lo | |
1730 | // (all are UINT64) | |
1731 | UINT64 tmp64; | |
1732 | BID_UI64DOUBLE tmp1; | |
1733 | unsigned int x_nr_bits; | |
1734 | int q, ind, shift; | |
1735 | UINT128 C1; | |
1736 | // UINT128 res is C* at first - represents up to 34 decimal digits ~ | |
1737 | // 113 bits | |
1738 | // UINT256 fstar; | |
1739 | UINT256 P256; | |
1740 | ||
1741 | // check for NaN or Infinity | |
1742 | if ((x.w[1] & MASK_SPECIAL) == MASK_SPECIAL) { | |
1743 | // x is special | |
1744 | if ((x.w[1] & MASK_NAN) == MASK_NAN) { // x is NAN | |
1745 | if ((x.w[1] & MASK_SNAN) == MASK_SNAN) { // x is SNAN | |
1746 | // set invalid flag | |
1747 | *pfpsf |= INVALID_EXCEPTION; | |
1748 | // return Quiet (SNaN) | |
1749 | res.w[1] = x.w[1] & 0xfdffffffffffffffull; | |
1750 | res.w[0] = x.w[0]; | |
1751 | } else { // x is QNaN | |
1752 | // return the input QNaN | |
1753 | res.w[1] = x.w[1]; | |
1754 | res.w[0] = x.w[0]; | |
1755 | } | |
1756 | BID_RETURN (res); | |
1757 | } else { // x is not a NaN, so it must be infinity | |
1758 | if ((x.w[1] & MASK_SIGN) == 0x0ull) { // x is +inf | |
1759 | // return +inf | |
1760 | res.w[1] = 0x7800000000000000ull; | |
1761 | res.w[0] = 0x0000000000000000ull; | |
1762 | } else { // x is -inf | |
1763 | // return -inf | |
1764 | res.w[1] = 0xf800000000000000ull; | |
1765 | res.w[0] = 0x0000000000000000ull; | |
1766 | } | |
1767 | BID_RETURN (res); | |
1768 | } | |
1769 | } | |
1770 | // unpack x | |
1771 | x_sign = x.w[1] & MASK_SIGN; // 0 for positive, MASK_SIGN for negative | |
1772 | x_exp = x.w[1] & MASK_EXP; // biased and shifted left 49 bit positions | |
1773 | C1.w[1] = x.w[1] & MASK_COEFF; | |
1774 | C1.w[0] = x.w[0]; | |
1775 | ||
1776 | // test for non-canonical values: | |
1777 | // - values whose encoding begins with x00, x01, or x10 and whose | |
1778 | // coefficient is larger than 10^34 -1, or | |
1779 | // - values whose encoding begins with x1100, x1101, x1110 (if NaNs | |
1780 | // and infinitis were eliminated already this test is reduced to | |
1781 | // checking for x10x) | |
1782 | ||
1783 | // test for non-canonical values of the argument x | |
1784 | if ((((C1.w[1] > 0x0001ed09bead87c0ull) | |
1785 | || ((C1.w[1] == 0x0001ed09bead87c0ull) | |
1786 | && (C1.w[0] > 0x378d8e63ffffffffull))) | |
1787 | && ((x.w[1] & 0x6000000000000000ull) != 0x6000000000000000ull)) | |
1788 | || ((x.w[1] & 0x6000000000000000ull) == 0x6000000000000000ull)) { | |
1789 | x.w[1] = x.w[1] & 0x8000000000000000ull; // preserve the sign bit | |
1790 | x.w[0] = 0; | |
1791 | x_exp = 0x1820ull << 49; | |
1792 | C1.w[1] = 0; | |
1793 | C1.w[0] = 0; | |
1794 | } | |
1795 | // test for input equal to zero | |
1796 | if ((C1.w[1] == 0x0ull) && (C1.w[0] == 0x0ull)) { | |
1797 | // x is 0 | |
1798 | // return 0 preserving the sign bit and the preferred exponent | |
1799 | // of MAX(Q(x), 0) | |
1800 | if (x_exp <= (0x1820ull << 49)) { | |
1801 | res.w[1] = | |
1802 | (x.w[1] & 0x8000000000000000ull) | 0x3040000000000000ull; | |
1803 | } else { | |
1804 | res.w[1] = x.w[1] & 0xfffe000000000000ull; | |
1805 | } | |
1806 | res.w[0] = 0x0000000000000000ull; | |
1807 | BID_RETURN (res); | |
1808 | } | |
1809 | // x is not special and is not zero | |
1810 | ||
1811 | // if (exp <= -(p+1)) return 0.0 | |
1812 | if (x_exp <= 0x2ffa000000000000ull) { // 0x2ffa000000000000ull == -35 | |
1813 | res.w[1] = x_sign | 0x3040000000000000ull; | |
1814 | res.w[0] = 0x0000000000000000ull; | |
1815 | BID_RETURN (res); | |
1816 | } | |
1817 | // q = nr. of decimal digits in x | |
1818 | // determine first the nr. of bits in x | |
1819 | if (C1.w[1] == 0) { | |
1820 | if (C1.w[0] >= 0x0020000000000000ull) { // x >= 2^53 | |
1821 | // split the 64-bit value in two 32-bit halves to avoid rounding errors | |
1822 | if (C1.w[0] >= 0x0000000100000000ull) { // x >= 2^32 | |
1823 | tmp1.d = (double) (C1.w[0] >> 32); // exact conversion | |
1824 | x_nr_bits = | |
1825 | 33 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1826 | } else { // x < 2^32 | |
1827 | tmp1.d = (double) (C1.w[0]); // exact conversion | |
1828 | x_nr_bits = | |
1829 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1830 | } | |
1831 | } else { // if x < 2^53 | |
1832 | tmp1.d = (double) C1.w[0]; // exact conversion | |
1833 | x_nr_bits = | |
1834 | 1 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1835 | } | |
1836 | } else { // C1.w[1] != 0 => nr. bits = 64 + nr_bits (C1.w[1]) | |
1837 | tmp1.d = (double) C1.w[1]; // exact conversion | |
1838 | x_nr_bits = | |
1839 | 65 + ((((unsigned int) (tmp1.ui64 >> 52)) & 0x7ff) - 0x3ff); | |
1840 | } | |
1841 | q = __bid_nr_digits[x_nr_bits - 1].digits; | |
1842 | if (q == 0) { | |
1843 | q = __bid_nr_digits[x_nr_bits - 1].digits1; | |
1844 | if (C1.w[1] > __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
1845 | || (C1.w[1] == __bid_nr_digits[x_nr_bits - 1].threshold_hi | |
1846 | && C1.w[0] >= __bid_nr_digits[x_nr_bits - 1].threshold_lo)) | |
1847 | q++; | |
1848 | } | |
1849 | exp = (x_exp >> 49) - 6176; | |
1850 | if (exp >= 0) { // -exp <= 0 | |
1851 | // the argument is an integer already | |
1852 | res.w[1] = x.w[1]; | |
1853 | res.w[0] = x.w[0]; | |
1854 | BID_RETURN (res); | |
1855 | } else if ((q + exp) >= 0) { // exp < 0 and 1 <= -exp <= q | |
1856 | // need to shift right -exp digits from the coefficient; the exp will be 0 | |
1857 | ind = -exp; // 1 <= ind <= 34; ind is a synonym for 'x' | |
1858 | // chop off ind digits from the lower part of C1 | |
1859 | // C1 = C1 + 1/2 * 10^x where the result C1 fits in 127 bits | |
1860 | tmp64 = C1.w[0]; | |
1861 | if (ind <= 19) { | |
1862 | C1.w[0] = C1.w[0] + __bid_midpoint64[ind - 1]; | |
1863 | } else { | |
1864 | C1.w[0] = C1.w[0] + __bid_midpoint128[ind - 20].w[0]; | |
1865 | C1.w[1] = C1.w[1] + __bid_midpoint128[ind - 20].w[1]; | |
1866 | } | |
1867 | if (C1.w[0] < tmp64) | |
1868 | C1.w[1]++; | |
1869 | // calculate C* and f* | |
1870 | // C* is actually floor(C*) in this case | |
1871 | // C* and f* need shifting and masking, as shown by | |
1872 | // __bid_shiftright128[] and __bid_maskhigh128[] | |
1873 | // 1 <= x <= 34 | |
1874 | // kx = 10^(-x) = __bid_ten2mk128[ind - 1] | |
1875 | // C* = (C1 + 1/2 * 10^x) * 10^(-x) | |
1876 | // the approximation of 10^(-x) was rounded up to 118 bits | |
1877 | __mul_128x128_to_256 (P256, C1, __bid_ten2mk128[ind - 1]); | |
1878 | // the top Ex bits of 10^(-x) are T* = __bid_ten2mk128trunc[ind], e.g. | |
1879 | // if x=1, T*=__bid_ten2mk128trunc[0]=0x19999999999999999999999999999999 | |
1880 | // if (0 < f* < 10^(-x)) then the result is a midpoint | |
1881 | // if floor(C*) is even then C* = floor(C*) - logical right | |
1882 | // shift; C* has p decimal digits, correct by Prop. 1) | |
1883 | // else if floor(C*) is odd C* = floor(C*)-1 (logical right | |
1884 | // shift; C* has p decimal digits, correct by Pr. 1) | |
1885 | // else | |
1886 | // C* = floor(C*) (logical right shift; C has p decimal digits, | |
1887 | // correct by Property 1) | |
1888 | // n = C* * 10^(e+x) | |
1889 | ||
1890 | // shift right C* by Ex-128 = __bid_shiftright128[ind] | |
1891 | if (ind - 1 <= 2) { // 0 <= ind - 1 <= 2 => shift = 0 | |
1892 | res.w[1] = P256.w[3]; | |
1893 | res.w[0] = P256.w[2]; | |
1894 | } else if (ind - 1 <= 21) { // 3 <= ind - 1 <= 21 => 3 <= shift <= 63 | |
1895 | shift = __bid_shiftright128[ind - 1]; // 3 <= shift <= 63 | |
1896 | res.w[0] = (P256.w[3] << (64 - shift)) | (P256.w[2] >> shift); | |
1897 | res.w[1] = (P256.w[3] >> shift); | |
1898 | } else { // 22 <= ind - 1 <= 33 | |
1899 | shift = __bid_shiftright128[ind - 1]; // 2 <= shift <= 38 | |
1900 | res.w[1] = 0; | |
1901 | res.w[0] = (P256.w[3] >> (shift - 64)); // 2 <= shift - 64 <= 38 | |
1902 | } | |
1903 | // if the result was a midpoint, it was already rounded away from zero | |
1904 | res.w[1] |= x_sign | 0x3040000000000000ull; | |
1905 | BID_RETURN (res); | |
1906 | } else { // if ((q + exp) < 0) <=> q < -exp | |
1907 | // the result is +0 or -0 | |
1908 | res.w[1] = x_sign | 0x3040000000000000ull; | |
1909 | res.w[0] = 0x0000000000000000ull; | |
1910 | BID_RETURN (res); | |
1911 | } | |
1912 | } |