1/* Decimal 64-bit format 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 64-bit format module */
28/* ------------------------------------------------------------------ */
29/* This module comprises the routines for decimal64 format numbers. */
30/* Conversions are supplied to and from decNumber and String. */
31/* */
32/* This is used when decNumber provides operations, either for all */
33/* operations or as a proxy between decNumber and decSingle. */
34/* */
35/* Error handling is the same as decNumber (qv.). */
36/* ------------------------------------------------------------------ */
37#include <string.h> /* [for memset/memcpy] */
38#include <stdio.h> /* [for printf] */
39
40#include "dconfig.h" /* GCC definitions */
41#define DECNUMDIGITS 16 /* make decNumbers with space for 16 */
42#include "decNumber.h" /* base number library */
43#include "decNumberLocal.h" /* decNumber local types, etc. */
44#include "decimal64.h" /* our primary include */
45
46/* Utility routines and tables [in decimal64.c]; externs for C++ */
47extern const uInt COMBEXP[32], COMBMSD[32];
48extern const uShort DPD2BIN[1024];
49extern const uShort BIN2DPD[1000];
50extern const uByte BIN2CHAR[4001];
51
52extern void decDigitsFromDPD(decNumber *, const uInt *, Int);
53extern void decDigitsToDPD(const decNumber *, uInt *, Int);
54
55#if DECTRACE || DECCHECK
56void decimal64Show(const decimal64 *); /* for debug */
57extern void decNumberShow(const decNumber *); /* .. */
58#endif
59
60/* Useful macro */
61/* Clear a structure (e.g., a decNumber) */
62#define DEC_clear(d) memset(d, 0, sizeof(*d))
63
64/* define and include the tables to use for conversions */
65#define DEC_BIN2CHAR 1
66#define DEC_DPD2BIN 1
67#define DEC_BIN2DPD 1 /* used for all sizes */
68#include "decDPD.h" /* lookup tables */
69
70/* ------------------------------------------------------------------ */
71/* decimal64FromNumber -- convert decNumber to decimal64 */
72/* */
73/* ds is the target decimal64 */
74/* dn is the source number (assumed valid) */
75/* set is the context, used only for reporting errors */
76/* */
77/* The set argument is used only for status reporting and for the */
78/* rounding mode (used if the coefficient is more than DECIMAL64_Pmax */
79/* digits or an overflow is detected). If the exponent is out of the */
80/* valid range then Overflow or Underflow will be raised. */
81/* After Underflow a subnormal result is possible. */
82/* */
83/* DEC_Clamped is set if the number has to be 'folded down' to fit, */
84/* by reducing its exponent and multiplying the coefficient by a */
85/* power of ten, or if the exponent on a zero had to be clamped. */
86/* ------------------------------------------------------------------ */
87decimal64 * decimal64FromNumber(decimal64 *d64, const decNumber *dn,
88 decContext *set) {
89 uInt status=0; /* status accumulator */
90 Int ae; /* adjusted exponent */
91 decNumber dw; /* work */
92 decContext dc; /* .. */
93 uInt comb, exp; /* .. */
94 uInt uiwork; /* for macros */
95 uInt targar[2]={0, 0}; /* target 64-bit */
96 #define targhi targar[1] /* name the word with the sign */
97 #define targlo targar[0] /* and the other */
98
99 /* If the number has too many digits, or the exponent could be */
100 /* out of range then reduce the number under the appropriate */
101 /* constraints. This could push the number to Infinity or zero, */
102 /* so this check and rounding must be done before generating the */
103 /* decimal64] */
104 ae=dn->exponent+dn->digits-1; /* [0 if special] */
105 if (dn->digits>DECIMAL64_Pmax /* too many digits */
106 || ae>DECIMAL64_Emax /* likely overflow */
107 || ae<DECIMAL64_Emin) { /* likely underflow */
108 decContextDefault(&dc, DEC_INIT_DECIMAL64); /* [no traps] */
109 dc.round=set->round; /* use supplied rounding */
110 decNumberPlus(&dw, dn, &dc); /* (round and check) */
111 /* [this changes -0 to 0, so enforce the sign...] */
112 dw.bits|=dn->bits&DECNEG;
113 status=dc.status; /* save status */
114 dn=&dw; /* use the work number */
115 } /* maybe out of range */
116
117 if (dn->bits&DECSPECIAL) { /* a special value */
118 if (dn->bits&DECINF) targhi=DECIMAL_Inf<<24;
119 else { /* sNaN or qNaN */
120 if ((*dn->lsu!=0 || dn->digits>1) /* non-zero coefficient */
121 && (dn->digits<DECIMAL64_Pmax)) { /* coefficient fits */
122 decDigitsToDPD(dn, targar, 0);
123 }
124 if (dn->bits&DECNAN) targhi|=DECIMAL_NaN<<24;
125 else targhi|=DECIMAL_sNaN<<24;
126 } /* a NaN */
127 } /* special */
128
129 else { /* is finite */
130 if (decNumberIsZero(dn)) { /* is a zero */
131 /* set and clamp exponent */
132 if (dn->exponent<-DECIMAL64_Bias) {
133 exp=0; /* low clamp */
134 status|=DEC_Clamped;
135 }
136 else {
137 exp=dn->exponent+DECIMAL64_Bias; /* bias exponent */
138 if (exp>DECIMAL64_Ehigh) { /* top clamp */
139 exp=DECIMAL64_Ehigh;
140 status|=DEC_Clamped;
141 }
142 }
143 comb=(exp>>5) & 0x18; /* msd=0, exp top 2 bits .. */
144 }
145 else { /* non-zero finite number */
146 uInt msd; /* work */
147 Int pad=0; /* coefficient pad digits */
148
149 /* the dn is known to fit, but it may need to be padded */
150 exp=(uInt)(dn->exponent+DECIMAL64_Bias); /* bias exponent */
151 if (exp>DECIMAL64_Ehigh) { /* fold-down case */
152 pad=exp-DECIMAL64_Ehigh;
153 exp=DECIMAL64_Ehigh; /* [to maximum] */
154 status|=DEC_Clamped;
155 }
156
157 /* fastpath common case */
158 if (DECDPUN==3 && pad==0) {
159 uInt dpd[6]={0,0,0,0,0,0};
160 uInt i;
161 Int d=dn->digits;
162 for (i=0; d>0; i++, d-=3) dpd[i]=BIN2DPD[dn->lsu[i]];
163 targlo =dpd[0];
164 targlo|=dpd[1]<<10;
165 targlo|=dpd[2]<<20;
166 if (dn->digits>6) {
167 targlo|=dpd[3]<<30;
168 targhi =dpd[3]>>2;
169 targhi|=dpd[4]<<8;
170 }
171 msd=dpd[5]; /* [did not really need conversion] */
172 }
173 else { /* general case */
174 decDigitsToDPD(dn, targar, pad);
175 /* save and clear the top digit */
176 msd=targhi>>18;
177 targhi&=0x0003ffff;
178 }
179
180 /* create the combination field */
181 if (msd>=8) comb=0x18 | ((exp>>7) & 0x06) | (msd & 0x01);
182 else comb=((exp>>5) & 0x18) | msd;
183 }
184 targhi|=comb<<26; /* add combination field .. */
185 targhi|=(exp&0xff)<<18; /* .. and exponent continuation */
186 } /* finite */
187
188 if (dn->bits&DECNEG) targhi|=0x80000000; /* add sign bit */
189
190 /* now write to storage; this is now always endian */
191 if (DECLITEND) {
192 /* lo int then hi */
193 UBFROMUI(d64->bytes, targar[0]);
194 UBFROMUI(d64->bytes+4, targar[1]);
195 }
196 else {
197 /* hi int then lo */
198 UBFROMUI(d64->bytes, targar[1]);
199 UBFROMUI(d64->bytes+4, targar[0]);
200 }
201
202 if (status!=0) decContextSetStatus(set, status); /* pass on status */
203 /* decimal64Show(d64); */
204 return d64;
205 } /* decimal64FromNumber */
206
207/* ------------------------------------------------------------------ */
208/* decimal64ToNumber -- convert decimal64 to decNumber */
209/* d64 is the source decimal64 */
210/* dn is the target number, with appropriate space */
211/* No error is possible. */
212/* ------------------------------------------------------------------ */
213decNumber * decimal64ToNumber(const decimal64 *d64, decNumber *dn) {
214 uInt msd; /* coefficient MSD */
215 uInt exp; /* exponent top two bits */
216 uInt comb; /* combination field */
217 Int need; /* work */
218 uInt uiwork; /* for macros */
219 uInt sourar[2]; /* source 64-bit */
220 #define sourhi sourar[1] /* name the word with the sign */
221 #define sourlo sourar[0] /* and the lower word */
222
223 /* load source from storage; this is endian */
224 if (DECLITEND) {
225 sourlo=UBTOUI(d64->bytes ); /* directly load the low int */
226 sourhi=UBTOUI(d64->bytes+4); /* then the high int */
227 }
228 else {
229 sourhi=UBTOUI(d64->bytes ); /* directly load the high int */
230 sourlo=UBTOUI(d64->bytes+4); /* then the low int */
231 }
232
233 comb=(sourhi>>26)&0x1f; /* combination field */
234
235 decNumberZero(dn); /* clean number */
236 if (sourhi&0x80000000) dn->bits=DECNEG; /* set sign if negative */
237
238 msd=COMBMSD[comb]; /* decode the combination field */
239 exp=COMBEXP[comb]; /* .. */
240
241 if (exp==3) { /* is a special */
242 if (msd==0) {
243 dn->bits|=DECINF;
244 return dn; /* no coefficient needed */
245 }
246 else if (sourhi&0x02000000) dn->bits|=DECSNAN;
247 else dn->bits|=DECNAN;
248 msd=0; /* no top digit */
249 }
250 else { /* is a finite number */
251 dn->exponent=(exp<<8)+((sourhi>>18)&0xff)-DECIMAL64_Bias; /* unbiased */
252 }
253
254 /* get the coefficient */
255 sourhi&=0x0003ffff; /* clean coefficient continuation */
256 if (msd) { /* non-zero msd */
257 sourhi|=msd<<18; /* prefix to coefficient */
258 need=6; /* process 6 declets */
259 }
260 else { /* msd=0 */
261 if (!sourhi) { /* top word 0 */
262 if (!sourlo) return dn; /* easy: coefficient is 0 */
263 need=3; /* process at least 3 declets */
264 if (sourlo&0xc0000000) need++; /* process 4 declets */
265 /* [could reduce some more, here] */
266 }
267 else { /* some bits in top word, msd=0 */
268 need=4; /* process at least 4 declets */
269 if (sourhi&0x0003ff00) need++; /* top declet!=0, process 5 */
270 }
271 } /*msd=0 */
272
273 decDigitsFromDPD(dn, sourar, need); /* process declets */
274 return dn;
275 } /* decimal64ToNumber */
276
277
278/* ------------------------------------------------------------------ */
279/* to-scientific-string -- conversion to numeric string */
280/* to-engineering-string -- conversion to numeric string */
281/* */
282/* decimal64ToString(d64, string); */
283/* decimal64ToEngString(d64, string); */
284/* */
285/* d64 is the decimal64 format number to convert */
286/* string is the string where the result will be laid out */
287/* */
288/* string must be at least 24 characters */
289/* */
290/* No error is possible, and no status can be set. */
291/* ------------------------------------------------------------------ */
292char * decimal64ToEngString(const decimal64 *d64, char *string){
293 decNumber dn; /* work */
294 decimal64ToNumber(d64, dn: &dn);
295 decNumberToEngString(&dn, string);
296 return string;
297 } /* decimal64ToEngString */
298
299char * decimal64ToString(const decimal64 *d64, char *string){
300 uInt msd; /* coefficient MSD */
301 Int exp; /* exponent top two bits or full */
302 uInt comb; /* combination field */
303 char *cstart; /* coefficient start */
304 char *c; /* output pointer in string */
305 const uByte *u; /* work */
306 char *s, *t; /* .. (source, target) */
307 Int dpd; /* .. */
308 Int pre, e; /* .. */
309 uInt uiwork; /* for macros */
310
311 uInt sourar[2]; /* source 64-bit */
312 #define sourhi sourar[1] /* name the word with the sign */
313 #define sourlo sourar[0] /* and the lower word */
314
315 /* load source from storage; this is endian */
316 if (DECLITEND) {
317 sourlo=UBTOUI(d64->bytes ); /* directly load the low int */
318 sourhi=UBTOUI(d64->bytes+4); /* then the high int */
319 }
320 else {
321 sourhi=UBTOUI(d64->bytes ); /* directly load the high int */
322 sourlo=UBTOUI(d64->bytes+4); /* then the low int */
323 }
324
325 c=string; /* where result will go */
326 if (((Int)sourhi)<0) *c++='-'; /* handle sign */
327
328 comb=(sourhi>>26)&0x1f; /* combination field */
329 msd=COMBMSD[comb]; /* decode the combination field */
330 exp=COMBEXP[comb]; /* .. */
331
332 if (exp==3) {
333 if (msd==0) { /* infinity */
334 strcpy(dest: c, src: "Inf");
335 strcpy(dest: c+3, src: "inity");
336 return string; /* easy */
337 }
338 if (sourhi&0x02000000) *c++='s'; /* sNaN */
339 strcpy(dest: c, src: "NaN"); /* complete word */
340 c+=3; /* step past */
341 if (sourlo==0 && (sourhi&0x0003ffff)==0) return string; /* zero payload */
342 /* otherwise drop through to add integer; set correct exp */
343 exp=0; msd=0; /* setup for following code */
344 }
345 else exp=(exp<<8)+((sourhi>>18)&0xff)-DECIMAL64_Bias;
346
347 /* convert 16 digits of significand to characters */
348 cstart=c; /* save start of coefficient */
349 if (msd) *c++='0'+(char)msd; /* non-zero most significant digit */
350
351 /* Now decode the declets. After extracting each one, it is */
352 /* decoded to binary and then to a 4-char sequence by table lookup; */
353 /* the 4-chars are a 1-char length (significant digits, except 000 */
354 /* has length 0). This allows us to left-align the first declet */
355 /* with non-zero content, then remaining ones are full 3-char */
356 /* length. We use fixed-length memcpys because variable-length */
357 /* causes a subroutine call in GCC. (These are length 4 for speed */
358 /* and are safe because the array has an extra terminator byte.) */
359 #define dpd2char u=&BIN2CHAR[DPD2BIN[dpd]*4]; \
360 if (c!=cstart) {memcpy(c, u+1, 4); c+=3;} \
361 else if (*u) {memcpy(c, u+4-*u, 4); c+=*u;}
362
363 dpd=(sourhi>>8)&0x3ff; /* declet 1 */
364 dpd2char;
365 dpd=((sourhi&0xff)<<2) | (sourlo>>30); /* declet 2 */
366 dpd2char;
367 dpd=(sourlo>>20)&0x3ff; /* declet 3 */
368 dpd2char;
369 dpd=(sourlo>>10)&0x3ff; /* declet 4 */
370 dpd2char;
371 dpd=(sourlo)&0x3ff; /* declet 5 */
372 dpd2char;
373
374 if (c==cstart) *c++='0'; /* all zeros -- make 0 */
375
376 if (exp==0) { /* integer or NaN case -- easy */
377 *c='\0'; /* terminate */
378 return string;
379 }
380
381 /* non-0 exponent */
382 e=0; /* assume no E */
383 pre=c-cstart+exp;
384 /* [here, pre-exp is the digits count (==1 for zero)] */
385 if (exp>0 || pre<-5) { /* need exponential form */
386 e=pre-1; /* calculate E value */
387 pre=1; /* assume one digit before '.' */
388 } /* exponential form */
389
390 /* modify the coefficient, adding 0s, '.', and E+nn as needed */
391 s=c-1; /* source (LSD) */
392 if (pre>0) { /* ddd.ddd (plain), perhaps with E */
393 char *dotat=cstart+pre;
394 if (dotat<c) { /* if embedded dot needed... */
395 t=c; /* target */
396 for (; s>=dotat; s--, t--) *t=*s; /* open the gap; leave t at gap */
397 *t='.'; /* insert the dot */
398 c++; /* length increased by one */
399 }
400
401 /* finally add the E-part, if needed; it will never be 0, and has */
402 /* a maximum length of 3 digits */
403 if (e!=0) {
404 *c++='E'; /* starts with E */
405 *c++='+'; /* assume positive */
406 if (e<0) {
407 *(c-1)='-'; /* oops, need '-' */
408 e=-e; /* uInt, please */
409 }
410 u=&BIN2CHAR[e*4]; /* -> length byte */
411 memcpy(dest: c, src: u+4-*u, n: 4); /* copy fixed 4 characters [is safe] */
412 c+=*u; /* bump pointer appropriately */
413 }
414 *c='\0'; /* add terminator */
415 /*printf("res %s\n", string); */
416 return string;
417 } /* pre>0 */
418
419 /* -5<=pre<=0: here for plain 0.ddd or 0.000ddd forms (can never have E) */
420 t=c+1-pre;
421 *(t+1)='\0'; /* can add terminator now */
422 for (; s>=cstart; s--, t--) *t=*s; /* shift whole coefficient right */
423 c=cstart;
424 *c++='0'; /* always starts with 0. */
425 *c++='.';
426 for (; pre<0; pre++) *c++='0'; /* add any 0's after '.' */
427 /*printf("res %s\n", string); */
428 return string;
429 } /* decimal64ToString */
430
431/* ------------------------------------------------------------------ */
432/* to-number -- conversion from numeric string */
433/* */
434/* decimal64FromString(result, string, set); */
435/* */
436/* result is the decimal64 format number which gets the result of */
437/* the conversion */
438/* *string is the character string which should contain a valid */
439/* number (which may be a special value) */
440/* set is the context */
441/* */
442/* The context is supplied to this routine is used for error handling */
443/* (setting of status and traps) and for the rounding mode, only. */
444/* If an error occurs, the result will be a valid decimal64 NaN. */
445/* ------------------------------------------------------------------ */
446decimal64 * decimal64FromString(decimal64 *result, const char *string,
447 decContext *set) {
448 decContext dc; /* work */
449 decNumber dn; /* .. */
450
451 decContextDefault(&dc, DEC_INIT_DECIMAL64); /* no traps, please */
452 dc.round=set->round; /* use supplied rounding */
453
454 decNumberFromString(&dn, string, &dc); /* will round if needed */
455
456 decimal64FromNumber(d64: result, dn: &dn, set: &dc);
457 if (dc.status!=0) { /* something happened */
458 decContextSetStatus(set, dc.status); /* .. pass it on */
459 }
460 return result;
461 } /* decimal64FromString */
462
463/* ------------------------------------------------------------------ */
464/* decimal64IsCanonical -- test whether encoding is canonical */
465/* d64 is the source decimal64 */
466/* returns 1 if the encoding of d64 is canonical, 0 otherwise */
467/* No error is possible. */
468/* ------------------------------------------------------------------ */
469uInt decimal64IsCanonical(const decimal64 *d64) {
470 decNumber dn; /* work */
471 decimal64 canon; /* .. */
472 decContext dc; /* .. */
473 decContextDefault(&dc, DEC_INIT_DECIMAL64);
474 decimal64ToNumber(d64, dn: &dn);
475 decimal64FromNumber(d64: &canon, dn: &dn, set: &dc);/* canon will now be canonical */
476 return memcmp(s1: d64, s2: &canon, DECIMAL64_Bytes)==0;
477 } /* decimal64IsCanonical */
478
479/* ------------------------------------------------------------------ */
480/* decimal64Canonical -- copy an encoding, ensuring it is canonical */
481/* d64 is the source decimal64 */
482/* result is the target (may be the same decimal64) */
483/* returns result */
484/* No error is possible. */
485/* ------------------------------------------------------------------ */
486decimal64 * decimal64Canonical(decimal64 *result, const decimal64 *d64) {
487 decNumber dn; /* work */
488 decContext dc; /* .. */
489 decContextDefault(&dc, DEC_INIT_DECIMAL64);
490 decimal64ToNumber(d64, dn: &dn);
491 decimal64FromNumber(d64: result, dn: &dn, set: &dc);/* result will now be canonical */
492 return result;
493 } /* decimal64Canonical */
494
495#if DECTRACE || DECCHECK
496/* Macros for accessing decimal64 fields. These assume the
497 argument is a reference (pointer) to the decimal64 structure,
498 and the decimal64 is in network byte order (big-endian) */
499/* Get sign */
500#define decimal64Sign(d) ((unsigned)(d)->bytes[0]>>7)
501
502/* Get combination field */
503#define decimal64Comb(d) (((d)->bytes[0] & 0x7c)>>2)
504
505/* Get exponent continuation [does not remove bias] */
506#define decimal64ExpCon(d) ((((d)->bytes[0] & 0x03)<<6) \
507 | ((unsigned)(d)->bytes[1]>>2))
508
509/* Set sign [this assumes sign previously 0] */
510#define decimal64SetSign(d, b) { \
511 (d)->bytes[0]|=((unsigned)(b)<<7);}
512
513/* Set exponent continuation [does not apply bias] */
514/* This assumes range has been checked and exponent previously 0; */
515/* type of exponent must be unsigned */
516#define decimal64SetExpCon(d, e) { \
517 (d)->bytes[0]|=(uByte)((e)>>6); \
518 (d)->bytes[1]|=(uByte)(((e)&0x3F)<<2);}
519
520/* ------------------------------------------------------------------ */
521/* decimal64Show -- display a decimal64 in hexadecimal [debug aid] */
522/* d64 -- the number to show */
523/* ------------------------------------------------------------------ */
524/* Also shows sign/cob/expconfields extracted */
525void decimal64Show(const decimal64 *d64) {
526 char buf[DECIMAL64_Bytes*2+1];
527 Int i, j=0;
528
529 if (DECLITEND) {
530 for (i=0; i<DECIMAL64_Bytes; i++, j+=2) {
531 sprintf(&buf[j], "%02x", d64->bytes[7-i]);
532 }
533 printf(" D64> %s [S:%d Cb:%02x Ec:%02x] LittleEndian\n", buf,
534 d64->bytes[7]>>7, (d64->bytes[7]>>2)&0x1f,
535 ((d64->bytes[7]&0x3)<<6)| (d64->bytes[6]>>2));
536 }
537 else { /* big-endian */
538 for (i=0; i<DECIMAL64_Bytes; i++, j+=2) {
539 sprintf(&buf[j], "%02x", d64->bytes[i]);
540 }
541 printf(" D64> %s [S:%d Cb:%02x Ec:%02x] BigEndian\n", buf,
542 decimal64Sign(d64), decimal64Comb(d64), decimal64ExpCon(d64));
543 }
544 } /* decimal64Show */
545#endif
546
547/* ================================================================== */
548/* Shared utility routines and tables */
549/* ================================================================== */
550/* define and include the conversion tables to use for shared code */
551#if DECDPUN==3
552 #define DEC_DPD2BIN 1
553#else
554 #define DEC_DPD2BCD 1
555#endif
556#include "decDPD.h" /* lookup tables */
557
558/* The maximum number of decNumberUnits needed for a working copy of */
559/* the units array is the ceiling of digits/DECDPUN, where digits is */
560/* the maximum number of digits in any of the formats for which this */
561/* is used. decimal128.h must not be included in this module, so, as */
562/* a very special case, that number is defined as a literal here. */
563#define DECMAX754 34
564#define DECMAXUNITS ((DECMAX754+DECDPUN-1)/DECDPUN)
565
566/* ------------------------------------------------------------------ */
567/* Combination field lookup tables (uInts to save measurable work) */
568/* */
569/* COMBEXP - 2-bit most-significant-bits of exponent */
570/* [11 if an Infinity or NaN] */
571/* COMBMSD - 4-bit most-significant-digit */
572/* [0=Infinity, 1=NaN if COMBEXP=11] */
573/* */
574/* Both are indexed by the 5-bit combination field (0-31) */
575/* ------------------------------------------------------------------ */
576const uInt COMBEXP[32]={0, 0, 0, 0, 0, 0, 0, 0,
577 1, 1, 1, 1, 1, 1, 1, 1,
578 2, 2, 2, 2, 2, 2, 2, 2,
579 0, 0, 1, 1, 2, 2, 3, 3};
580const uInt COMBMSD[32]={0, 1, 2, 3, 4, 5, 6, 7,
581 0, 1, 2, 3, 4, 5, 6, 7,
582 0, 1, 2, 3, 4, 5, 6, 7,
583 8, 9, 8, 9, 8, 9, 0, 1};
584
585/* ------------------------------------------------------------------ */
586/* decDigitsToDPD -- pack coefficient into DPD form */
587/* */
588/* dn is the source number (assumed valid, max DECMAX754 digits) */
589/* targ is 1, 2, or 4-element uInt array, which the caller must */
590/* have cleared to zeros */
591/* shift is the number of 0 digits to add on the right (normally 0) */
592/* */
593/* The coefficient must be known small enough to fit. The full */
594/* coefficient is copied, including the leading 'odd' digit. This */
595/* digit is retrieved and packed into the combination field by the */
596/* caller. */
597/* */
598/* The target uInts are altered only as necessary to receive the */
599/* digits of the decNumber. When more than one uInt is needed, they */
600/* are filled from left to right (that is, the uInt at offset 0 will */
601/* end up with the least-significant digits). */
602/* */
603/* shift is used for 'fold-down' padding. */
604/* */
605/* No error is possible. */
606/* ------------------------------------------------------------------ */
607#if DECDPUN<=4
608/* Constant multipliers for divide-by-power-of five using reciprocal */
609/* multiply, after removing powers of 2 by shifting, and final shift */
610/* of 17 [we only need up to **4] */
611static const uInt multies[]={131073, 26215, 5243, 1049, 210};
612/* QUOT10 -- macro to return the quotient of unit u divided by 10**n */
613#define QUOT10(u, n) ((((uInt)(u)>>(n))*multies[n])>>17)
614#endif
615void decDigitsToDPD(const decNumber *dn, uInt *targ, Int shift) {
616 Int cut; /* work */
617 Int digits=dn->digits; /* digit countdown */
618 uInt dpd; /* densely packed decimal value */
619 uInt bin; /* binary value 0-999 */
620 uInt *uout=targ; /* -> current output uInt */
621 uInt uoff=0; /* -> current output offset [from right] */
622 const Unit *inu=dn->lsu; /* -> current input unit */
623 Unit uar[DECMAXUNITS]; /* working copy of units, iff shifted */
624 #if DECDPUN!=3 /* not fast path */
625 Unit in; /* current unit */
626 #endif
627
628 if (shift!=0) { /* shift towards most significant required */
629 /* shift the units array to the left by pad digits and copy */
630 /* [this code is a special case of decShiftToMost, which could */
631 /* be used instead if exposed and the array were copied first] */
632 const Unit *source; /* .. */
633 Unit *target, *first; /* .. */
634 uInt next=0; /* work */
635
636 source=dn->lsu+D2U(digits)-1; /* where msu comes from */
637 target=uar+D2U(digits)-1+D2U(shift);/* where upper part of first cut goes */
638 cut=DECDPUN-MSUDIGITS(shift); /* where to slice */
639 if (cut==0) { /* unit-boundary case */
640 for (; source>=dn->lsu; source--, target--) *target=*source;
641 }
642 else {
643 first=uar+D2U(digits+shift)-1; /* where msu will end up */
644 for (; source>=dn->lsu; source--, target--) {
645 /* split the source Unit and accumulate remainder for next */
646 #if DECDPUN<=4
647 uInt quot=QUOT10(*source, cut);
648 uInt rem=*source-quot*DECPOWERS[cut];
649 next+=quot;
650 #else
651 uInt rem=*source%DECPOWERS[cut];
652 next+=*source/DECPOWERS[cut];
653 #endif
654 if (target<=first) *target=(Unit)next; /* write to target iff valid */
655 next=rem*DECPOWERS[DECDPUN-cut]; /* save remainder for next Unit */
656 }
657 } /* shift-move */
658 /* propagate remainder to one below and clear the rest */
659 for (; target>=uar; target--) {
660 *target=(Unit)next;
661 next=0;
662 }
663 digits+=shift; /* add count (shift) of zeros added */
664 inu=uar; /* use units in working array */
665 }
666
667 /* now densely pack the coefficient into DPD declets */
668
669 #if DECDPUN!=3 /* not fast path */
670 in=*inu; /* current unit */
671 cut=0; /* at lowest digit */
672 bin=0; /* [keep compiler quiet] */
673 #endif
674
675 for(; digits>0;) { /* each output bunch */
676 #if DECDPUN==3 /* fast path, 3-at-a-time */
677 bin=*inu; /* 3 digits ready for convert */
678 digits-=3; /* [may go negative] */
679 inu++; /* may need another */
680
681 #else /* must collect digit-by-digit */
682 Unit dig; /* current digit */
683 Int j; /* digit-in-declet count */
684 for (j=0; j<3; j++) {
685 #if DECDPUN<=4
686 Unit temp=(Unit)((uInt)(in*6554)>>16);
687 dig=(Unit)(in-X10(temp));
688 in=temp;
689 #else
690 dig=in%10;
691 in=in/10;
692 #endif
693 if (j==0) bin=dig;
694 else if (j==1) bin+=X10(dig);
695 else /* j==2 */ bin+=X100(dig);
696 digits--;
697 if (digits==0) break; /* [also protects *inu below] */
698 cut++;
699 if (cut==DECDPUN) {inu++; in=*inu; cut=0;}
700 }
701 #endif
702 /* here there are 3 digits in bin, or have used all input digits */
703
704 dpd=BIN2DPD[bin];
705
706 /* write declet to uInt array */
707 *uout|=dpd<<uoff;
708 uoff+=10;
709 if (uoff<32) continue; /* no uInt boundary cross */
710 uout++;
711 uoff-=32;
712 *uout|=dpd>>(10-uoff); /* collect top bits */
713 } /* n declets */
714 return;
715 } /* decDigitsToDPD */
716
717/* ------------------------------------------------------------------ */
718/* decDigitsFromDPD -- unpack a format's coefficient */
719/* */
720/* dn is the target number, with 7, 16, or 34-digit space. */
721/* sour is a 1, 2, or 4-element uInt array containing only declets */
722/* declets is the number of (right-aligned) declets in sour to */
723/* be processed. This may be 1 more than the obvious number in */
724/* a format, as any top digit is prefixed to the coefficient */
725/* continuation field. It also may be as small as 1, as the */
726/* caller may pre-process leading zero declets. */
727/* */
728/* When doing the 'extra declet' case care is taken to avoid writing */
729/* extra digits when there are leading zeros, as these could overflow */
730/* the units array when DECDPUN is not 3. */
731/* */
732/* The target uInts are used only as necessary to process declets */
733/* declets into the decNumber. When more than one uInt is needed, */
734/* they are used from left to right (that is, the uInt at offset 0 */
735/* provides the least-significant digits). */
736/* */
737/* dn->digits is set, but not the sign or exponent. */
738/* No error is possible [the redundant 888 codes are allowed]. */
739/* ------------------------------------------------------------------ */
740void decDigitsFromDPD(decNumber *dn, const uInt *sour, Int declets) {
741
742 uInt dpd; /* collector for 10 bits */
743 Int n; /* counter */
744 Unit *uout=dn->lsu; /* -> current output unit */
745 Unit *last=uout; /* will be unit containing msd */
746 const uInt *uin=sour; /* -> current input uInt */
747 uInt uoff=0; /* -> current input offset [from right] */
748
749 #if DECDPUN!=3
750 uInt bcd; /* BCD result */
751 uInt nibble; /* work */
752 Unit out=0; /* accumulator */
753 Int cut=0; /* power of ten in current unit */
754 #endif
755 #if DECDPUN>4
756 uInt const *pow; /* work */
757 #endif
758
759 /* Expand the densely-packed integer, right to left */
760 for (n=declets-1; n>=0; n--) { /* count down declets of 10 bits */
761 dpd=*uin>>uoff;
762 uoff+=10;
763 if (uoff>32) { /* crossed uInt boundary */
764 uin++;
765 uoff-=32;
766 dpd|=*uin<<(10-uoff); /* get waiting bits */
767 }
768 dpd&=0x3ff; /* clear uninteresting bits */
769
770 #if DECDPUN==3
771 if (dpd==0) *uout=0;
772 else {
773 *uout=DPD2BIN[dpd]; /* convert 10 bits to binary 0-999 */
774 last=uout; /* record most significant unit */
775 }
776 uout++;
777 } /* n */
778
779 #else /* DECDPUN!=3 */
780 if (dpd==0) { /* fastpath [e.g., leading zeros] */
781 /* write out three 0 digits (nibbles); out may have digit(s) */
782 cut++;
783 if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;}
784 if (n==0) break; /* [as below, works even if MSD=0] */
785 cut++;
786 if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;}
787 cut++;
788 if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;}
789 continue;
790 }
791
792 bcd=DPD2BCD[dpd]; /* convert 10 bits to 12 bits BCD */
793
794 /* now accumulate the 3 BCD nibbles into units */
795 nibble=bcd & 0x00f;
796 if (nibble) out=(Unit)(out+nibble*DECPOWERS[cut]);
797 cut++;
798 if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;}
799 bcd>>=4;
800
801 /* if this is the last declet and the remaining nibbles in bcd */
802 /* are 00 then process no more nibbles, because this could be */
803 /* the 'odd' MSD declet and writing any more Units would then */
804 /* overflow the unit array */
805 if (n==0 && !bcd) break;
806
807 nibble=bcd & 0x00f;
808 if (nibble) out=(Unit)(out+nibble*DECPOWERS[cut]);
809 cut++;
810 if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;}
811 bcd>>=4;
812
813 nibble=bcd & 0x00f;
814 if (nibble) out=(Unit)(out+nibble*DECPOWERS[cut]);
815 cut++;
816 if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;}
817 } /* n */
818 if (cut!=0) { /* some more left over */
819 *uout=out; /* write out final unit */
820 if (out) last=uout; /* and note if non-zero */
821 }
822 #endif
823
824 /* here, last points to the most significant unit with digits; */
825 /* inspect it to get the final digits count -- this is essentially */
826 /* the same code as decGetDigits in decNumber.c */
827 dn->digits=(last-dn->lsu)*DECDPUN+1; /* floor of digits, plus */
828 /* must be at least 1 digit */
829 #if DECDPUN>1
830 if (*last<10) return; /* common odd digit or 0 */
831 dn->digits++; /* must be 2 at least */
832 #if DECDPUN>2
833 if (*last<100) return; /* 10-99 */
834 dn->digits++; /* must be 3 at least */
835 #if DECDPUN>3
836 if (*last<1000) return; /* 100-999 */
837 dn->digits++; /* must be 4 at least */
838 #if DECDPUN>4
839 for (pow=&DECPOWERS[4]; *last>=*pow; pow++) dn->digits++;
840 #endif
841 #endif
842 #endif
843 #endif
844 return;
845 } /*decDigitsFromDPD */
846

source code of libdecnumber/dpd/decimal64.c