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*/
1 // vim: filetype=c:tabstop=4:ai:expandtab
2 // SPDX-License-Identifier: ICU
3 // scspell-id: a0c30a33-f62c-11ec-a4e6-80ee73e9b8e7
4 /* ------------------------------------------------------------------ */
5 /* Decimal Context module */
6 /* ------------------------------------------------------------------ */
7 /* Copyright (c) IBM Corporation, 2000, 2009. All rights reserved. */
8 /* */
9 /* This software is made available under the terms of the */
10 /* ICU License -- ICU 1.8.1 and later. */
11 /* */
12 /* The description and User's Guide ("The decNumber C Library") for */
13 /* this software is called decNumber.pdf. This document is */
14 /* available, together with arithmetic and format specifications, */
15 /* testcases, and Web links, on the General Decimal Arithmetic page. */
16 /* */
17 /* Please send comments, suggestions, and corrections to the author: */
18 /* mfc@uk.ibm.com */
19 /* Mike Cowlishaw, IBM Fellow */
20 /* IBM UK, PO Box 31, Birmingham Road, Warwick CV34 5JL, UK */
21 /* ------------------------------------------------------------------ */
22 /* This module comprises the routines for handling arithmetic */
23 /* context structures. */
24 /* ------------------------------------------------------------------ */
25
26 #include <string.h> // for strcmp
27 #include <stdio.h>
28 #include "decContext.h" // context and base types
29 #include "decNumberLocal.h" // decNumber local types, etc.
30
31 /* compile-time endian tester [assumes sizeof(Int)>1] */
32 static const Int mfcone=1; // constant 1
33 static const Flag *mfctop=(const Flag *)&mfcone; // -> top byte
34 #define LITEND *mfctop // named flag; 1=little-endian
35
36 /* ------------------------------------------------------------------ */
37 /* round-for-reround digits */
38 /* ------------------------------------------------------------------ */
39 const uByte DECSTICKYTAB[10]={1,1,2,3,4,6,6,7,8,9}; /* used if sticky */
40
41 /* ------------------------------------------------------------------ */
42 /* Powers of ten (powers[n]==10**n, 0<=n<=9) */
43 /* ------------------------------------------------------------------ */
44 const uInt DECPOWERS[10]={1, 10, 100, 1000, 10000, 100000, 1000000,
45 10000000, 100000000, 1000000000};
46
47 /* ------------------------------------------------------------------ */
48 /* decContextClearStatus -- clear bits in current status */
49 /* */
50 /* context is the context structure to be queried */
51 /* mask indicates the bits to be cleared (the status bit that */
52 /* corresponds to each 1 bit in the mask is cleared) */
53 /* returns context */
54 /* */
55 /* No error is possible. */
56 /* ------------------------------------------------------------------ */
57 decContext *decContextClearStatus(decContext *context, uInt mask) {
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58 context->status&=~mask;
59 return context;
60 } // decContextClearStatus
61
62 /* ------------------------------------------------------------------ */
63 /* decContextDefault -- initialize a context structure */
64 /* */
65 /* context is the structure to be initialized */
66 /* kind selects the required set of default values, one of: */
67 /* DEC_INIT_BASE -- select ANSI X3-274 defaults */
68 /* DEC_INIT_DECIMAL32 -- select IEEE 754 defaults, 32-bit */
69 /* DEC_INIT_DECIMAL64 -- select IEEE 754 defaults, 64-bit */
70 /* DEC_INIT_DECIMAL128 -- select IEEE 754 defaults, 128-bit */
71 /* For any other value a valid context is returned, but with */
72 /* Invalid_operation set in the status field. */
73 /* returns a context structure with the appropriate initial values. */
74 /* ------------------------------------------------------------------ */
75 decContext * decContextDefault(decContext *context, Int kind) {
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76 // set defaults...
77 context->digits=9; // 9 digits
78 context->emax=DEC_MAX_EMAX; // 9-digit exponents
79 context->emin=DEC_MIN_EMIN; // .. balanced
80 context->round=DEC_ROUND_HALF_UP; // 0.5 rises
81 context->traps=DEC_Errors; // all but informational
82 context->status=0; // cleared
83 context->clamp=0; // no clamping
84 #if DECSUBSET
85 context->extended=0; // cleared
86 #endif
87 switch (kind) {
88 case DEC_INIT_BASE:
89 // [use defaults]
90 break;
91 case DEC_INIT_DECIMAL32:
92 context->digits=7; // digits
93 context->emax=96; // Emax
94 context->emin=-95; // Emin
95 context->round=DEC_ROUND_HALF_EVEN; // 0.5 to nearest even
96 context->traps=0; // no traps set
97 context->clamp=1; // clamp exponents
98 #if DECSUBSET
99 context->extended=1; // set
100 #endif
101 break;
102 case DEC_INIT_DECIMAL64:
103 context->digits=16; // digits
104 context->emax=384; // Emax
105 context->emin=-383; // Emin
106 context->round=DEC_ROUND_HALF_EVEN; // 0.5 to nearest even
107 context->traps=0; // no traps set
108 context->clamp=1; // clamp exponents
109 #if DECSUBSET
110 context->extended=1; // set
111 #endif
112 break;
113 case DEC_INIT_DECIMAL128:
114 context->digits=34; // digits
115 context->emax=6144; // Emax
116 context->emin=-6143; // Emin
117 context->round=DEC_ROUND_HALF_EVEN; // 0.5 to nearest even
118 context->traps=0; // no traps set
119 context->clamp=1; // clamp exponents
120 #if DECSUBSET
121 context->extended=1; // set
122 #endif
123 break;
124
125 default: // invalid Kind
126 // use defaults, and trap
127 (void)decContextSetStatus(context, DEC_Invalid_operation);
128 }
129
130 return context;} // decContextDefault
131
132 /* ------------------------------------------------------------------ */
133 /* decContextGetRounding -- return current rounding mode */
134 /* */
135 /* context is the context structure to be queried */
136 /* returns the rounding mode */
137 /* */
138 /* No error is possible. */
139 /* ------------------------------------------------------------------ */
140 enum rounding decContextGetRounding(decContext *context) {
/* */
141 return context->round;
142 } // decContextGetRounding
143
144 /* ------------------------------------------------------------------ */
145 /* decContextGetStatus -- return current status */
146 /* */
147 /* context is the context structure to be queried */
148 /* returns status */
149 /* */
150 /* No error is possible. */
151 /* ------------------------------------------------------------------ */
152 uInt decContextGetStatus(decContext *context) {
/* */
153 return context->status;
154 } // decContextGetStatus
155
156 /* ------------------------------------------------------------------ */
157 /* decContextRestoreStatus -- restore bits in current status */
158 /* */
159 /* context is the context structure to be updated */
160 /* newstatus is the source for the bits to be restored */
161 /* mask indicates the bits to be restored (the status bit that */
162 /* corresponds to each 1 bit in the mask is set to the value of */
163 /* the corresponding bit in newstatus) */
164 /* returns context */
165 /* */
166 /* No error is possible. */
167 /* ------------------------------------------------------------------ */
168 decContext *decContextRestoreStatus(decContext *context,
/* */
169 uInt newstatus, uInt mask) {
170 context->status&=~mask; // clear the selected bits
171 context->status|=(mask&newstatus); // or in the new bits
172 return context;
173 } // decContextRestoreStatus
174
175 /* ------------------------------------------------------------------ */
176 /* decContextSaveStatus -- save bits in current status */
177 /* */
178 /* context is the context structure to be queried */
179 /* mask indicates the bits to be saved (the status bits that */
180 /* correspond to each 1 bit in the mask are saved) */
181 /* returns the AND of the mask and the current status */
182 /* */
183 /* No error is possible. */
184 /* ------------------------------------------------------------------ */
185 uInt decContextSaveStatus(decContext *context, uInt mask) {
/* */
186 return context->status&mask;
187 } // decContextSaveStatus
188
189 /* ------------------------------------------------------------------ */
190 /* decContextSetRounding -- set current rounding mode */
191 /* */
192 /* context is the context structure to be updated */
193 /* newround is the value which will replace the current mode */
194 /* returns context */
195 /* */
196 /* No error is possible. */
197 /* ------------------------------------------------------------------ */
198 decContext *decContextSetRounding(decContext *context,
/* */
199 enum rounding newround) {
200 context->round=newround;
201 return context;
202 } // decContextSetRounding
203
204 /* ------------------------------------------------------------------ */
205 /* decContextSetStatus -- set status and raise trap if appropriate */
206 /* */
207 /* context is the context structure to be updated */
208 /* status is the DEC_ exception code */
209 /* returns the context structure */
210 /* */
211 /* Control may never return from this routine, if there is a signal */
212 /* handler and it takes a long jump. */
213 /* ------------------------------------------------------------------ */
214 decContext * decContextSetStatus(decContext *context, uInt status) {
/* */
215 context->status|=status;
216 if (status & context->traps) raise(SIGFPE);
217 return context;} // decContextSetStatus
218
219 /* ------------------------------------------------------------------ */
220 /* decContextSetStatusFromString -- set status from a string + trap */
221 /* */
222 /* context is the context structure to be updated */
223 /* string is a string exactly equal to one that might be returned */
224 /* by decContextStatusToString */
225 /* */
226 /* The status bit corresponding to the string is set, and a trap */
227 /* is raised if appropriate. */
228 /* */
229 /* returns the context structure, unless the string is equal to */
230 /* DEC_Condition_MU or is not recognized. In these cases NULL is */
231 /* returned. */
232 /* ------------------------------------------------------------------ */
233 decContext * decContextSetStatusFromString(decContext *context,
/* */
234 const char *string) {
235 if (strcmp(string, DEC_Condition_CS)==0)
236 return decContextSetStatus(context, DEC_Conversion_syntax);
237 if (strcmp(string, DEC_Condition_DZ)==0)
238 return decContextSetStatus(context, DEC_Division_by_zero);
239 if (strcmp(string, DEC_Condition_DI)==0)
240 return decContextSetStatus(context, DEC_Division_impossible);
241 if (strcmp(string, DEC_Condition_DU)==0)
242 return decContextSetStatus(context, DEC_Division_undefined);
243 if (strcmp(string, DEC_Condition_IE)==0)
244 return decContextSetStatus(context, DEC_Inexact);
245 if (strcmp(string, DEC_Condition_IS)==0)
246 return decContextSetStatus(context, DEC_Insufficient_storage);
247 if (strcmp(string, DEC_Condition_IC)==0)
248 return decContextSetStatus(context, DEC_Invalid_context);
249 if (strcmp(string, DEC_Condition_IO)==0)
250 return decContextSetStatus(context, DEC_Invalid_operation);
251 #if DECSUBSET
252 if (strcmp(string, DEC_Condition_LD)==0)
253 return decContextSetStatus(context, DEC_Lost_digits);
254 #endif
255 if (strcmp(string, DEC_Condition_OV)==0)
256 return decContextSetStatus(context, DEC_Overflow);
257 if (strcmp(string, DEC_Condition_PA)==0)
258 return decContextSetStatus(context, DEC_Clamped);
259 if (strcmp(string, DEC_Condition_RO)==0)
260 return decContextSetStatus(context, DEC_Rounded);
261 if (strcmp(string, DEC_Condition_SU)==0)
262 return decContextSetStatus(context, DEC_Subnormal);
263 if (strcmp(string, DEC_Condition_UN)==0)
264 return decContextSetStatus(context, DEC_Underflow);
265 if (strcmp(string, DEC_Condition_ZE)==0)
266 return context;
267 return NULL; // Multiple status, or unknown
268 } // decContextSetStatusFromString
269
270 /* ------------------------------------------------------------------ */
271 /* decContextSetStatusFromStringQuiet -- set status from a string */
272 /* */
273 /* context is the context structure to be updated */
274 /* string is a string exactly equal to one that might be returned */
275 /* by decContextStatusToString */
276 /* */
277 /* The status bit corresponding to the string is set; no trap is */
278 /* raised. */
279 /* */
280 /* returns the context structure, unless the string is equal to */
281 /* DEC_Condition_MU or is not recognized. In these cases NULL is */
282 /* returned. */
283 /* ------------------------------------------------------------------ */
284 decContext * decContextSetStatusFromStringQuiet(decContext *context,
/* */
285 const char *string) {
286 if (strcmp(string, DEC_Condition_CS)==0)
287 return decContextSetStatusQuiet(context, DEC_Conversion_syntax);
288 if (strcmp(string, DEC_Condition_DZ)==0)
289 return decContextSetStatusQuiet(context, DEC_Division_by_zero);
290 if (strcmp(string, DEC_Condition_DI)==0)
291 return decContextSetStatusQuiet(context, DEC_Division_impossible);
292 if (strcmp(string, DEC_Condition_DU)==0)
293 return decContextSetStatusQuiet(context, DEC_Division_undefined);
294 if (strcmp(string, DEC_Condition_IE)==0)
295 return decContextSetStatusQuiet(context, DEC_Inexact);
296 if (strcmp(string, DEC_Condition_IS)==0)
297 return decContextSetStatusQuiet(context, DEC_Insufficient_storage);
298 if (strcmp(string, DEC_Condition_IC)==0)
299 return decContextSetStatusQuiet(context, DEC_Invalid_context);
300 if (strcmp(string, DEC_Condition_IO)==0)
301 return decContextSetStatusQuiet(context, DEC_Invalid_operation);
302 #if DECSUBSET
303 if (strcmp(string, DEC_Condition_LD)==0)
304 return decContextSetStatusQuiet(context, DEC_Lost_digits);
305 #endif
306 if (strcmp(string, DEC_Condition_OV)==0)
307 return decContextSetStatusQuiet(context, DEC_Overflow);
308 if (strcmp(string, DEC_Condition_PA)==0)
309 return decContextSetStatusQuiet(context, DEC_Clamped);
310 if (strcmp(string, DEC_Condition_RO)==0)
311 return decContextSetStatusQuiet(context, DEC_Rounded);
312 if (strcmp(string, DEC_Condition_SU)==0)
313 return decContextSetStatusQuiet(context, DEC_Subnormal);
314 if (strcmp(string, DEC_Condition_UN)==0)
315 return decContextSetStatusQuiet(context, DEC_Underflow);
316 if (strcmp(string, DEC_Condition_ZE)==0)
317 return context;
318 return NULL; // Multiple status, or unknown
319 } // decContextSetStatusFromStringQuiet
320
321 /* ------------------------------------------------------------------ */
322 /* decContextSetStatusQuiet -- set status without trap */
323 /* */
324 /* context is the context structure to be updated */
325 /* status is the DEC_ exception code */
326 /* returns the context structure */
327 /* */
328 /* No error is possible. */
329 /* ------------------------------------------------------------------ */
330 decContext * decContextSetStatusQuiet(decContext *context, uInt status) {
/* */
331 context->status|=status;
332 return context;} // decContextSetStatusQuiet
333
334 /* ------------------------------------------------------------------ */
335 /* decContextStatusToString -- convert status flags to a string */
336 /* */
337 /* context is a context with valid status field */
338 /* */
339 /* returns a constant string describing the condition. If multiple */
340 /* (or no) flags are set, a generic constant message is returned. */
341 /* ------------------------------------------------------------------ */
342 const char *decContextStatusToString(const decContext *context) {
/* */
343 Int status=context->status;
344
345 // test the five IEEE first, as some of the others are ambiguous when
346 // DECEXTFLAG=0
347 if (status==DEC_Invalid_operation ) return DEC_Condition_IO;
348 if (status==DEC_Division_by_zero ) return DEC_Condition_DZ;
349 if (status==DEC_Overflow ) return DEC_Condition_OV;
350 if (status==DEC_Underflow ) return DEC_Condition_UN;
351 if (status==DEC_Inexact ) return DEC_Condition_IE;
352
353 if (status==DEC_Division_impossible ) return DEC_Condition_DI;
354 if (status==DEC_Division_undefined ) return DEC_Condition_DU;
355 if (status==DEC_Rounded ) return DEC_Condition_RO;
356 if (status==DEC_Clamped ) return DEC_Condition_PA;
357 if (status==DEC_Subnormal ) return DEC_Condition_SU;
358 if (status==DEC_Conversion_syntax ) return DEC_Condition_CS;
359 if (status==DEC_Insufficient_storage ) return DEC_Condition_IS;
360 if (status==DEC_Invalid_context ) return DEC_Condition_IC;
361 #if DECSUBSET
362 if (status==DEC_Lost_digits ) return DEC_Condition_LD;
363 #endif
364 if (status==0 ) return DEC_Condition_ZE;
365 return DEC_Condition_MU; // Multiple errors
366 } // decContextStatusToString
367
368 /* ------------------------------------------------------------------ */
369 /* decContextTestEndian -- test whether DECLITEND is set correctly */
370 /* */
371 /* quiet is 1 to suppress message; 0 otherwise */
372 /* returns 0 if DECLITEND is correct */
373 /* 1 if DECLITEND is incorrect and should be 1 */
374 /* -1 if DECLITEND is incorrect and should be 0 */
375 /* */
376 /* A message is displayed if the return value is not 0 and quiet==0. */
377 /* */
378 /* No error is possible. */
379 /* ------------------------------------------------------------------ */
380 Int decContextTestEndian(void) {
/* */
381 Int res=0; // optimist
382 uInt dle=(uInt)DECLITEND; // unsign
383 /* cppcheck-suppress knownConditionTrueFalse */
384 if (dle>1) dle=1; //-V547
385
386 if (LITEND!=DECLITEND) {
387 res=(Int)LITEND-dle;
388 }
389 return res;
390 } // decContextTestEndian
391
392 /* ------------------------------------------------------------------ */
393 /* decContextTestSavedStatus -- test bits in saved status */
394 /* */
395 /* oldstatus is the status word to be tested */
396 /* mask indicates the bits to be tested (the oldstatus bits that */
397 /* correspond to each 1 bit in the mask are tested) */
398 /* returns 1 if any of the tested bits are 1, or 0 otherwise */
399 /* */
400 /* No error is possible. */
401 /* ------------------------------------------------------------------ */
402 uInt decContextTestSavedStatus(uInt oldstatus, uInt mask) {
/* */
403 return (oldstatus&mask)!=0;
404 } // decContextTestSavedStatus
405
406 /* ------------------------------------------------------------------ */
407 /* decContextTestStatus -- test bits in current status */
408 /* */
409 /* context is the context structure to be updated */
410 /* mask indicates the bits to be tested (the status bits that */
411 /* correspond to each 1 bit in the mask are tested) */
412 /* returns 1 if any of the tested bits are 1, or 0 otherwise */
413 /* */
414 /* No error is possible. */
415 /* ------------------------------------------------------------------ */
416 uInt decContextTestStatus(decContext *context, uInt mask) {
/* */
417 return (context->status&mask)!=0;
418 } // decContextTestStatus
419
420 /* ------------------------------------------------------------------ */
421 /* decContextZeroStatus -- clear all status bits */
422 /* */
423 /* context is the context structure to be updated */
424 /* returns context */
425 /* */
426 /* No error is possible. */
427 /* ------------------------------------------------------------------ */
428 decContext *decContextZeroStatus(decContext *context) {
/* ![[last]](../icons/n_last.png)
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429 context->status=0;
430 return context;
431 } // decContextZeroStatus
432
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*/