1/* Decimal context module for the decNumber C Library.
2 Copyright (C) 2005-2024 Free Software Foundation, Inc.
3 Contributed by IBM Corporation. Author Mike Cowlishaw.
4
5 This file is part of GCC.
6
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.
11
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.
16
17Under Section 7 of GPL version 3, you are granted additional
18permissions described in the GCC Runtime Library Exception, version
193.1, as published by the Free Software Foundation.
20
21You should have received a copy of the GNU General Public License and
22a copy of the GCC Runtime Library Exception along with this program;
23see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24<http://www.gnu.org/licenses/>. */
25
26/* ------------------------------------------------------------------ */
27/* Decimal Context module */
28/* ------------------------------------------------------------------ */
29/* This module comprises the routines for handling arithmetic */
30/* context structures. */
31/* ------------------------------------------------------------------ */
32
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. */
40
41/* compile-time endian tester [assumes sizeof(Int)>1] */
42static const Int mfcone=1; /* constant 1 */
43static const Flag *mfctop=(const Flag *)&mfcone; /* -> top byte */
44#define LITEND *mfctop /* named flag; 1=little-endian */
45
46/* ------------------------------------------------------------------ */
47/* round-for-reround digits */
48/* ------------------------------------------------------------------ */
49const uByte DECSTICKYTAB[10]={1,1,2,3,4,6,6,7,8,9}; /* used if sticky */
50
51/* ------------------------------------------------------------------ */
52/* Powers of ten (powers[n]==10**n, 0<=n<=9) */
53/* ------------------------------------------------------------------ */
54const uInt DECPOWERS[10]={1, 10, 100, 1000, 10000, 100000, 1000000,
55 10000000, 100000000, 1000000000};
56
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/* ------------------------------------------------------------------ */
67decContext *decContextClearStatus(decContext *context, uInt mask) {
68 context->status&=~mask;
69 return context;
70 } /* decContextClearStatus */
71
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/* ------------------------------------------------------------------ */
85decContext * 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;
134
135 default: /* invalid Kind */
136 /* use defaults, and .. */
137 decContextSetStatus(context, DEC_Invalid_operation); /* trap */
138 }
139
140 return context;} /* decContextDefault */
141
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/* ------------------------------------------------------------------ */
150enum rounding decContextGetRounding(decContext *context) {
151 return context->round;
152 } /* decContextGetRounding */
153
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/* ------------------------------------------------------------------ */
162uInt decContextGetStatus(decContext *context) {
163 return context->status;
164 } /* decContextGetStatus */
165
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/* ------------------------------------------------------------------ */
178decContext *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 */
184
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/* ------------------------------------------------------------------ */
195uInt decContextSaveStatus(decContext *context, uInt mask) {
196 return context->status&mask;
197 } /* decContextSaveStatus */
198
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/* ------------------------------------------------------------------ */
208decContext *decContextSetRounding(decContext *context,
209 enum rounding newround) {
210 context->round=newround;
211 return context;
212 } /* decContextSetRounding */
213
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/* ------------------------------------------------------------------ */
224decContext * decContextSetStatus(decContext *context, uInt status) {
225 context->status|=status;
226 if (status & context->traps) raise(SIGFPE);
227 return context;} /* decContextSetStatus */
228
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/* ------------------------------------------------------------------ */
243decContext * decContextSetStatusFromString(decContext *context,
244 const char *string) {
245 if (strcmp(s1: string, DEC_Condition_CS)==0)
246 return decContextSetStatus(context, DEC_Conversion_syntax);
247 if (strcmp(s1: string, DEC_Condition_DZ)==0)
248 return decContextSetStatus(context, DEC_Division_by_zero);
249 if (strcmp(s1: string, DEC_Condition_DI)==0)
250 return decContextSetStatus(context, DEC_Division_impossible);
251 if (strcmp(s1: string, DEC_Condition_DU)==0)
252 return decContextSetStatus(context, DEC_Division_undefined);
253 if (strcmp(s1: string, DEC_Condition_IE)==0)
254 return decContextSetStatus(context, DEC_Inexact);
255 if (strcmp(s1: string, DEC_Condition_IS)==0)
256 return decContextSetStatus(context, DEC_Insufficient_storage);
257 if (strcmp(s1: string, DEC_Condition_IC)==0)
258 return decContextSetStatus(context, DEC_Invalid_context);
259 if (strcmp(s1: 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(s1: string, DEC_Condition_OV)==0)
266 return decContextSetStatus(context, DEC_Overflow);
267 if (strcmp(s1: string, DEC_Condition_PA)==0)
268 return decContextSetStatus(context, DEC_Clamped);
269 if (strcmp(s1: string, DEC_Condition_RO)==0)
270 return decContextSetStatus(context, DEC_Rounded);
271 if (strcmp(s1: string, DEC_Condition_SU)==0)
272 return decContextSetStatus(context, DEC_Subnormal);
273 if (strcmp(s1: string, DEC_Condition_UN)==0)
274 return decContextSetStatus(context, DEC_Underflow);
275 if (strcmp(s1: string, DEC_Condition_ZE)==0)
276 return context;
277 return NULL; /* Multiple status, or unknown */
278 } /* decContextSetStatusFromString */
279
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/* ------------------------------------------------------------------ */
294decContext * decContextSetStatusFromStringQuiet(decContext *context,
295 const char *string) {
296 if (strcmp(s1: string, DEC_Condition_CS)==0)
297 return decContextSetStatusQuiet(context, DEC_Conversion_syntax);
298 if (strcmp(s1: string, DEC_Condition_DZ)==0)
299 return decContextSetStatusQuiet(context, DEC_Division_by_zero);
300 if (strcmp(s1: string, DEC_Condition_DI)==0)
301 return decContextSetStatusQuiet(context, DEC_Division_impossible);
302 if (strcmp(s1: string, DEC_Condition_DU)==0)
303 return decContextSetStatusQuiet(context, DEC_Division_undefined);
304 if (strcmp(s1: string, DEC_Condition_IE)==0)
305 return decContextSetStatusQuiet(context, DEC_Inexact);
306 if (strcmp(s1: string, DEC_Condition_IS)==0)
307 return decContextSetStatusQuiet(context, DEC_Insufficient_storage);
308 if (strcmp(s1: string, DEC_Condition_IC)==0)
309 return decContextSetStatusQuiet(context, DEC_Invalid_context);
310 if (strcmp(s1: 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(s1: string, DEC_Condition_OV)==0)
317 return decContextSetStatusQuiet(context, DEC_Overflow);
318 if (strcmp(s1: string, DEC_Condition_PA)==0)
319 return decContextSetStatusQuiet(context, DEC_Clamped);
320 if (strcmp(s1: string, DEC_Condition_RO)==0)
321 return decContextSetStatusQuiet(context, DEC_Rounded);
322 if (strcmp(s1: string, DEC_Condition_SU)==0)
323 return decContextSetStatusQuiet(context, DEC_Subnormal);
324 if (strcmp(s1: string, DEC_Condition_UN)==0)
325 return decContextSetStatusQuiet(context, DEC_Underflow);
326 if (strcmp(s1: string, DEC_Condition_ZE)==0)
327 return context;
328 return NULL; /* Multiple status, or unknown */
329 } /* decContextSetStatusFromStringQuiet */
330
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/* ------------------------------------------------------------------ */
340decContext * decContextSetStatusQuiet(decContext *context, uInt status) {
341 context->status|=status;
342 return context;} /* decContextSetStatusQuiet */
343
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/* ------------------------------------------------------------------ */
352const char *decContextStatusToString(const decContext *context) {
353 Int status=context->status;
354
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;
362
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 */
377
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/* ------------------------------------------------------------------ */
390Int decContextTestEndian(Flag quiet) {
391 Int res=0; /* optimist */
392 uInt dle=(uInt)DECLITEND; /* unsign */
393 if (dle>1) dle=1; /* ensure 0 or 1 */
394
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
404 }
405 res=(Int)LITEND-dle;
406 }
407 return res;
408 } /* decContextTestEndian */
409
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/* ------------------------------------------------------------------ */
420uInt decContextTestSavedStatus(uInt oldstatus, uInt mask) {
421 return (oldstatus&mask)!=0;
422 } /* decContextTestSavedStatus */
423
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/* ------------------------------------------------------------------ */
434uInt decContextTestStatus(decContext *context, uInt mask) {
435 return (context->status&mask)!=0;
436 } /* decContextTestStatus */
437
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/* ------------------------------------------------------------------ */
446decContext *decContextZeroStatus(decContext *context) {
447 context->status=0;
448 return context;
449 } /* decContextZeroStatus */
450
451

source code of libdecnumber/decContext.c