2017-12-07 Vladimir Makarov <vmakarov@redhat.com>
[official-gcc.git] / libdecnumber / decContext.c
blob93223bbee1431bf6b9324e6ddfd13d49ff2724fa
1 /* Decimal context module for the decNumber C Library.
2 Copyright (C) 2005-2017 Free Software Foundation, Inc.
3 Contributed by IBM Corporation. Author Mike Cowlishaw.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
26 /* ------------------------------------------------------------------ */
27 /* Decimal Context module */
28 /* ------------------------------------------------------------------ */
29 /* This module comprises the routines for handling arithmetic */
30 /* context structures. */
31 /* ------------------------------------------------------------------ */
33 #include <string.h> /* for strcmp */
34 #ifdef DECCHECK
35 #include <stdio.h> /* for printf if DECCHECK */
36 #endif
37 #include "dconfig.h" /* for GCC definitions */
38 #include "decContext.h" /* context and base types */
39 #include "decNumberLocal.h" /* decNumber local types, etc. */
41 /* compile-time endian tester [assumes sizeof(Int)>1] */
42 static const Int mfcone=1; /* constant 1 */
43 static const Flag *mfctop=(const Flag *)&mfcone; /* -> top byte */
44 #define LITEND *mfctop /* named flag; 1=little-endian */
46 /* ------------------------------------------------------------------ */
47 /* round-for-reround digits */
48 /* ------------------------------------------------------------------ */
49 const uByte DECSTICKYTAB[10]={1,1,2,3,4,6,6,7,8,9}; /* used if sticky */
51 /* ------------------------------------------------------------------ */
52 /* Powers of ten (powers[n]==10**n, 0<=n<=9) */
53 /* ------------------------------------------------------------------ */
54 const uInt DECPOWERS[10]={1, 10, 100, 1000, 10000, 100000, 1000000,
55 10000000, 100000000, 1000000000};
57 /* ------------------------------------------------------------------ */
58 /* decContextClearStatus -- clear bits in current status */
59 /* */
60 /* context is the context structure to be queried */
61 /* mask indicates the bits to be cleared (the status bit that */
62 /* corresponds to each 1 bit in the mask is cleared) */
63 /* returns context */
64 /* */
65 /* No error is possible. */
66 /* ------------------------------------------------------------------ */
67 decContext *decContextClearStatus(decContext *context, uInt mask) {
68 context->status&=~mask;
69 return context;
70 } /* decContextClearStatus */
72 /* ------------------------------------------------------------------ */
73 /* decContextDefault -- initialize a context structure */
74 /* */
75 /* context is the structure to be initialized */
76 /* kind selects the required set of default values, one of: */
77 /* DEC_INIT_BASE -- select ANSI X3-274 defaults */
78 /* DEC_INIT_DECIMAL32 -- select IEEE 754 defaults, 32-bit */
79 /* DEC_INIT_DECIMAL64 -- select IEEE 754 defaults, 64-bit */
80 /* DEC_INIT_DECIMAL128 -- select IEEE 754 defaults, 128-bit */
81 /* For any other value a valid context is returned, but with */
82 /* Invalid_operation set in the status field. */
83 /* returns a context structure with the appropriate initial values. */
84 /* ------------------------------------------------------------------ */
85 decContext * decContextDefault(decContext *context, Int kind) {
86 /* set defaults... */
87 context->digits=9; /* 9 digits */
88 context->emax=DEC_MAX_EMAX; /* 9-digit exponents */
89 context->emin=DEC_MIN_EMIN; /* .. balanced */
90 context->round=DEC_ROUND_HALF_UP; /* 0.5 rises */
91 context->traps=DEC_Errors; /* all but informational */
92 context->status=0; /* cleared */
93 context->clamp=0; /* no clamping */
94 #if DECSUBSET
95 context->extended=0; /* cleared */
96 #endif
97 switch (kind) {
98 case DEC_INIT_BASE:
99 /* [use defaults] */
100 break;
101 case DEC_INIT_DECIMAL32:
102 context->digits=7; /* digits */
103 context->emax=96; /* Emax */
104 context->emin=-95; /* Emin */
105 context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
106 context->traps=0; /* no traps set */
107 context->clamp=1; /* clamp exponents */
108 #if DECSUBSET
109 context->extended=1; /* set */
110 #endif
111 break;
112 case DEC_INIT_DECIMAL64:
113 context->digits=16; /* digits */
114 context->emax=384; /* Emax */
115 context->emin=-383; /* Emin */
116 context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
117 context->traps=0; /* no traps set */
118 context->clamp=1; /* clamp exponents */
119 #if DECSUBSET
120 context->extended=1; /* set */
121 #endif
122 break;
123 case DEC_INIT_DECIMAL128:
124 context->digits=34; /* digits */
125 context->emax=6144; /* Emax */
126 context->emin=-6143; /* Emin */
127 context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
128 context->traps=0; /* no traps set */
129 context->clamp=1; /* clamp exponents */
130 #if DECSUBSET
131 context->extended=1; /* set */
132 #endif
133 break;
135 default: /* invalid Kind */
136 /* use defaults, and .. */
137 decContextSetStatus(context, DEC_Invalid_operation); /* trap */
140 return context;} /* decContextDefault */
142 /* ------------------------------------------------------------------ */
143 /* decContextGetRounding -- return current rounding mode */
144 /* */
145 /* context is the context structure to be queried */
146 /* returns the rounding mode */
147 /* */
148 /* No error is possible. */
149 /* ------------------------------------------------------------------ */
150 enum rounding decContextGetRounding(decContext *context) {
151 return context->round;
152 } /* decContextGetRounding */
154 /* ------------------------------------------------------------------ */
155 /* decContextGetStatus -- return current status */
156 /* */
157 /* context is the context structure to be queried */
158 /* returns status */
159 /* */
160 /* No error is possible. */
161 /* ------------------------------------------------------------------ */
162 uInt decContextGetStatus(decContext *context) {
163 return context->status;
164 } /* decContextGetStatus */
166 /* ------------------------------------------------------------------ */
167 /* decContextRestoreStatus -- restore bits in current status */
168 /* */
169 /* context is the context structure to be updated */
170 /* newstatus is the source for the bits to be restored */
171 /* mask indicates the bits to be restored (the status bit that */
172 /* corresponds to each 1 bit in the mask is set to the value of */
173 /* the correspnding bit in newstatus) */
174 /* returns context */
175 /* */
176 /* No error is possible. */
177 /* ------------------------------------------------------------------ */
178 decContext *decContextRestoreStatus(decContext *context,
179 uInt newstatus, uInt mask) {
180 context->status&=~mask; /* clear the selected bits */
181 context->status|=(mask&newstatus); /* or in the new bits */
182 return context;
183 } /* decContextRestoreStatus */
185 /* ------------------------------------------------------------------ */
186 /* decContextSaveStatus -- save bits in current status */
187 /* */
188 /* context is the context structure to be queried */
189 /* mask indicates the bits to be saved (the status bits that */
190 /* correspond to each 1 bit in the mask are saved) */
191 /* returns the AND of the mask and the current status */
192 /* */
193 /* No error is possible. */
194 /* ------------------------------------------------------------------ */
195 uInt decContextSaveStatus(decContext *context, uInt mask) {
196 return context->status&mask;
197 } /* decContextSaveStatus */
199 /* ------------------------------------------------------------------ */
200 /* decContextSetRounding -- set current rounding mode */
201 /* */
202 /* context is the context structure to be updated */
203 /* newround is the value which will replace the current mode */
204 /* returns context */
205 /* */
206 /* No error is possible. */
207 /* ------------------------------------------------------------------ */
208 decContext *decContextSetRounding(decContext *context,
209 enum rounding newround) {
210 context->round=newround;
211 return context;
212 } /* decContextSetRounding */
214 /* ------------------------------------------------------------------ */
215 /* decContextSetStatus -- set status and raise trap if appropriate */
216 /* */
217 /* context is the context structure to be updated */
218 /* status is the DEC_ exception code */
219 /* returns the context structure */
220 /* */
221 /* Control may never return from this routine, if there is a signal */
222 /* handler and it takes a long jump. */
223 /* ------------------------------------------------------------------ */
224 decContext * decContextSetStatus(decContext *context, uInt status) {
225 context->status|=status;
226 if (status & context->traps) raise(SIGFPE);
227 return context;} /* decContextSetStatus */
229 /* ------------------------------------------------------------------ */
230 /* decContextSetStatusFromString -- set status from a string + trap */
231 /* */
232 /* context is the context structure to be updated */
233 /* string is a string exactly equal to one that might be returned */
234 /* by decContextStatusToString */
235 /* */
236 /* The status bit corresponding to the string is set, and a trap */
237 /* is raised if appropriate. */
238 /* */
239 /* returns the context structure, unless the string is equal to */
240 /* DEC_Condition_MU or is not recognized. In these cases NULL is */
241 /* returned. */
242 /* ------------------------------------------------------------------ */
243 decContext * decContextSetStatusFromString(decContext *context,
244 const char *string) {
245 if (strcmp(string, DEC_Condition_CS)==0)
246 return decContextSetStatus(context, DEC_Conversion_syntax);
247 if (strcmp(string, DEC_Condition_DZ)==0)
248 return decContextSetStatus(context, DEC_Division_by_zero);
249 if (strcmp(string, DEC_Condition_DI)==0)
250 return decContextSetStatus(context, DEC_Division_impossible);
251 if (strcmp(string, DEC_Condition_DU)==0)
252 return decContextSetStatus(context, DEC_Division_undefined);
253 if (strcmp(string, DEC_Condition_IE)==0)
254 return decContextSetStatus(context, DEC_Inexact);
255 if (strcmp(string, DEC_Condition_IS)==0)
256 return decContextSetStatus(context, DEC_Insufficient_storage);
257 if (strcmp(string, DEC_Condition_IC)==0)
258 return decContextSetStatus(context, DEC_Invalid_context);
259 if (strcmp(string, DEC_Condition_IO)==0)
260 return decContextSetStatus(context, DEC_Invalid_operation);
261 #if DECSUBSET
262 if (strcmp(string, DEC_Condition_LD)==0)
263 return decContextSetStatus(context, DEC_Lost_digits);
264 #endif
265 if (strcmp(string, DEC_Condition_OV)==0)
266 return decContextSetStatus(context, DEC_Overflow);
267 if (strcmp(string, DEC_Condition_PA)==0)
268 return decContextSetStatus(context, DEC_Clamped);
269 if (strcmp(string, DEC_Condition_RO)==0)
270 return decContextSetStatus(context, DEC_Rounded);
271 if (strcmp(string, DEC_Condition_SU)==0)
272 return decContextSetStatus(context, DEC_Subnormal);
273 if (strcmp(string, DEC_Condition_UN)==0)
274 return decContextSetStatus(context, DEC_Underflow);
275 if (strcmp(string, DEC_Condition_ZE)==0)
276 return context;
277 return NULL; /* Multiple status, or unknown */
278 } /* decContextSetStatusFromString */
280 /* ------------------------------------------------------------------ */
281 /* decContextSetStatusFromStringQuiet -- set status from a string */
282 /* */
283 /* context is the context structure to be updated */
284 /* string is a string exactly equal to one that might be returned */
285 /* by decContextStatusToString */
286 /* */
287 /* The status bit corresponding to the string is set; no trap is */
288 /* raised. */
289 /* */
290 /* returns the context structure, unless the string is equal to */
291 /* DEC_Condition_MU or is not recognized. In these cases NULL is */
292 /* returned. */
293 /* ------------------------------------------------------------------ */
294 decContext * decContextSetStatusFromStringQuiet(decContext *context,
295 const char *string) {
296 if (strcmp(string, DEC_Condition_CS)==0)
297 return decContextSetStatusQuiet(context, DEC_Conversion_syntax);
298 if (strcmp(string, DEC_Condition_DZ)==0)
299 return decContextSetStatusQuiet(context, DEC_Division_by_zero);
300 if (strcmp(string, DEC_Condition_DI)==0)
301 return decContextSetStatusQuiet(context, DEC_Division_impossible);
302 if (strcmp(string, DEC_Condition_DU)==0)
303 return decContextSetStatusQuiet(context, DEC_Division_undefined);
304 if (strcmp(string, DEC_Condition_IE)==0)
305 return decContextSetStatusQuiet(context, DEC_Inexact);
306 if (strcmp(string, DEC_Condition_IS)==0)
307 return decContextSetStatusQuiet(context, DEC_Insufficient_storage);
308 if (strcmp(string, DEC_Condition_IC)==0)
309 return decContextSetStatusQuiet(context, DEC_Invalid_context);
310 if (strcmp(string, DEC_Condition_IO)==0)
311 return decContextSetStatusQuiet(context, DEC_Invalid_operation);
312 #if DECSUBSET
313 if (strcmp(string, DEC_Condition_LD)==0)
314 return decContextSetStatusQuiet(context, DEC_Lost_digits);
315 #endif
316 if (strcmp(string, DEC_Condition_OV)==0)
317 return decContextSetStatusQuiet(context, DEC_Overflow);
318 if (strcmp(string, DEC_Condition_PA)==0)
319 return decContextSetStatusQuiet(context, DEC_Clamped);
320 if (strcmp(string, DEC_Condition_RO)==0)
321 return decContextSetStatusQuiet(context, DEC_Rounded);
322 if (strcmp(string, DEC_Condition_SU)==0)
323 return decContextSetStatusQuiet(context, DEC_Subnormal);
324 if (strcmp(string, DEC_Condition_UN)==0)
325 return decContextSetStatusQuiet(context, DEC_Underflow);
326 if (strcmp(string, DEC_Condition_ZE)==0)
327 return context;
328 return NULL; /* Multiple status, or unknown */
329 } /* decContextSetStatusFromStringQuiet */
331 /* ------------------------------------------------------------------ */
332 /* decContextSetStatusQuiet -- set status without trap */
333 /* */
334 /* context is the context structure to be updated */
335 /* status is the DEC_ exception code */
336 /* returns the context structure */
337 /* */
338 /* No error is possible. */
339 /* ------------------------------------------------------------------ */
340 decContext * decContextSetStatusQuiet(decContext *context, uInt status) {
341 context->status|=status;
342 return context;} /* decContextSetStatusQuiet */
344 /* ------------------------------------------------------------------ */
345 /* decContextStatusToString -- convert status flags to a string */
346 /* */
347 /* context is a context with valid status field */
348 /* */
349 /* returns a constant string describing the condition. If multiple */
350 /* (or no) flags are set, a generic constant message is returned. */
351 /* ------------------------------------------------------------------ */
352 const char *decContextStatusToString(const decContext *context) {
353 Int status=context->status;
355 /* test the five IEEE first, as some of the others are ambiguous when */
356 /* DECEXTFLAG=0 */
357 if (status==DEC_Invalid_operation ) return DEC_Condition_IO;
358 if (status==DEC_Division_by_zero ) return DEC_Condition_DZ;
359 if (status==DEC_Overflow ) return DEC_Condition_OV;
360 if (status==DEC_Underflow ) return DEC_Condition_UN;
361 if (status==DEC_Inexact ) return DEC_Condition_IE;
363 if (status==DEC_Division_impossible ) return DEC_Condition_DI;
364 if (status==DEC_Division_undefined ) return DEC_Condition_DU;
365 if (status==DEC_Rounded ) return DEC_Condition_RO;
366 if (status==DEC_Clamped ) return DEC_Condition_PA;
367 if (status==DEC_Subnormal ) return DEC_Condition_SU;
368 if (status==DEC_Conversion_syntax ) return DEC_Condition_CS;
369 if (status==DEC_Insufficient_storage ) return DEC_Condition_IS;
370 if (status==DEC_Invalid_context ) return DEC_Condition_IC;
371 #if DECSUBSET
372 if (status==DEC_Lost_digits ) return DEC_Condition_LD;
373 #endif
374 if (status==0 ) return DEC_Condition_ZE;
375 return DEC_Condition_MU; /* Multiple errors */
376 } /* decContextStatusToString */
378 /* ------------------------------------------------------------------ */
379 /* decContextTestEndian -- test whether DECLITEND is set correctly */
380 /* */
381 /* quiet is 1 to suppress message; 0 otherwise */
382 /* returns 0 if DECLITEND is correct */
383 /* 1 if DECLITEND is incorrect and should be 1 */
384 /* -1 if DECLITEND is incorrect and should be 0 */
385 /* */
386 /* A message is displayed if the return value is not 0 and quiet==0. */
387 /* */
388 /* No error is possible. */
389 /* ------------------------------------------------------------------ */
390 Int decContextTestEndian(Flag quiet) {
391 Int res=0; /* optimist */
392 uInt dle=(uInt)DECLITEND; /* unsign */
393 if (dle>1) dle=1; /* ensure 0 or 1 */
395 if (LITEND!=DECLITEND) {
396 if (!quiet) {
397 #if DECCHECK
398 const char *adj;
399 if (LITEND) adj="little";
400 else adj="big";
401 printf("Warning: DECLITEND is set to %d, but this computer appears to be %s-endian\n",
402 DECLITEND, adj);
403 #endif
405 res=(Int)LITEND-dle;
407 return res;
408 } /* decContextTestEndian */
410 /* ------------------------------------------------------------------ */
411 /* decContextTestSavedStatus -- test bits in saved status */
412 /* */
413 /* oldstatus is the status word to be tested */
414 /* mask indicates the bits to be tested (the oldstatus bits that */
415 /* correspond to each 1 bit in the mask are tested) */
416 /* returns 1 if any of the tested bits are 1, or 0 otherwise */
417 /* */
418 /* No error is possible. */
419 /* ------------------------------------------------------------------ */
420 uInt decContextTestSavedStatus(uInt oldstatus, uInt mask) {
421 return (oldstatus&mask)!=0;
422 } /* decContextTestSavedStatus */
424 /* ------------------------------------------------------------------ */
425 /* decContextTestStatus -- test bits in current status */
426 /* */
427 /* context is the context structure to be updated */
428 /* mask indicates the bits to be tested (the status bits that */
429 /* correspond to each 1 bit in the mask are tested) */
430 /* returns 1 if any of the tested bits are 1, or 0 otherwise */
431 /* */
432 /* No error is possible. */
433 /* ------------------------------------------------------------------ */
434 uInt decContextTestStatus(decContext *context, uInt mask) {
435 return (context->status&mask)!=0;
436 } /* decContextTestStatus */
438 /* ------------------------------------------------------------------ */
439 /* decContextZeroStatus -- clear all status bits */
440 /* */
441 /* context is the context structure to be updated */
442 /* returns context */
443 /* */
444 /* No error is possible. */
445 /* ------------------------------------------------------------------ */
446 decContext *decContextZeroStatus(decContext *context) {
447 context->status=0;
448 return context;
449 } /* decContextZeroStatus */