1/* Decimal 32-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 32-bit format module */
28/* ------------------------------------------------------------------ */
29/* This module comprises the routines for decimal32 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 7 /* make decNumbers with space for 7 */
42#include "decNumber.h" /* base number library */
43#include "decNumberLocal.h" /* decNumber local types, etc. */
44#include "decimal32.h" /* our primary include */
45
46/* Utility tables and routines [in decimal64.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 decDigitsToDPD(const decNumber *, uInt *, Int);
53extern void decDigitsFromDPD(decNumber *, const uInt *, Int);
54
55#if DECTRACE || DECCHECK
56void decimal32Show(const decimal32 *); /* 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/* ------------------------------------------------------------------ */
65/* decimal32FromNumber -- convert decNumber to decimal32 */
66/* */
67/* ds is the target decimal32 */
68/* dn is the source number (assumed valid) */
69/* set is the context, used only for reporting errors */
70/* */
71/* The set argument is used only for status reporting and for the */
72/* rounding mode (used if the coefficient is more than DECIMAL32_Pmax */
73/* digits or an overflow is detected). If the exponent is out of the */
74/* valid range then Overflow or Underflow will be raised. */
75/* After Underflow a subnormal result is possible. */
76/* */
77/* DEC_Clamped is set if the number has to be 'folded down' to fit, */
78/* by reducing its exponent and multiplying the coefficient by a */
79/* power of ten, or if the exponent on a zero had to be clamped. */
80/* ------------------------------------------------------------------ */
81decimal32 * decimal32FromNumber(decimal32 *d32, const decNumber *dn,
82 decContext *set) {
83 uInt status=0; /* status accumulator */
84 Int ae; /* adjusted exponent */
85 decNumber dw; /* work */
86 decContext dc; /* .. */
87 uInt comb, exp; /* .. */
88 uInt uiwork; /* for macros */
89 uInt targ=0; /* target 32-bit */
90
91 /* If the number has too many digits, or the exponent could be */
92 /* out of range then reduce the number under the appropriate */
93 /* constraints. This could push the number to Infinity or zero, */
94 /* so this check and rounding must be done before generating the */
95 /* decimal32] */
96 ae=dn->exponent+dn->digits-1; /* [0 if special] */
97 if (dn->digits>DECIMAL32_Pmax /* too many digits */
98 || ae>DECIMAL32_Emax /* likely overflow */
99 || ae<DECIMAL32_Emin) { /* likely underflow */
100 decContextDefault(&dc, DEC_INIT_DECIMAL32); /* [no traps] */
101 dc.round=set->round; /* use supplied rounding */
102 decNumberPlus(&dw, dn, &dc); /* (round and check) */
103 /* [this changes -0 to 0, so enforce the sign...] */
104 dw.bits|=dn->bits&DECNEG;
105 status=dc.status; /* save status */
106 dn=&dw; /* use the work number */
107 } /* maybe out of range */
108
109 if (dn->bits&DECSPECIAL) { /* a special value */
110 if (dn->bits&DECINF) targ=DECIMAL_Inf<<24;
111 else { /* sNaN or qNaN */
112 if ((*dn->lsu!=0 || dn->digits>1) /* non-zero coefficient */
113 && (dn->digits<DECIMAL32_Pmax)) { /* coefficient fits */
114 decDigitsToDPD(dn, &targ, 0);
115 }
116 if (dn->bits&DECNAN) targ|=DECIMAL_NaN<<24;
117 else targ|=DECIMAL_sNaN<<24;
118 } /* a NaN */
119 } /* special */
120
121 else { /* is finite */
122 if (decNumberIsZero(dn)) { /* is a zero */
123 /* set and clamp exponent */
124 if (dn->exponent<-DECIMAL32_Bias) {
125 exp=0; /* low clamp */
126 status|=DEC_Clamped;
127 }
128 else {
129 exp=dn->exponent+DECIMAL32_Bias; /* bias exponent */
130 if (exp>DECIMAL32_Ehigh) { /* top clamp */
131 exp=DECIMAL32_Ehigh;
132 status|=DEC_Clamped;
133 }
134 }
135 comb=(exp>>3) & 0x18; /* msd=0, exp top 2 bits .. */
136 }
137 else { /* non-zero finite number */
138 uInt msd; /* work */
139 Int pad=0; /* coefficient pad digits */
140
141 /* the dn is known to fit, but it may need to be padded */
142 exp=(uInt)(dn->exponent+DECIMAL32_Bias); /* bias exponent */
143 if (exp>DECIMAL32_Ehigh) { /* fold-down case */
144 pad=exp-DECIMAL32_Ehigh;
145 exp=DECIMAL32_Ehigh; /* [to maximum] */
146 status|=DEC_Clamped;
147 }
148
149 /* fastpath common case */
150 if (DECDPUN==3 && pad==0) {
151 targ=BIN2DPD[dn->lsu[0]];
152 if (dn->digits>3) targ|=(uInt)(BIN2DPD[dn->lsu[1]])<<10;
153 msd=(dn->digits==7 ? dn->lsu[2] : 0);
154 }
155 else { /* general case */
156 decDigitsToDPD(dn, &targ, pad);
157 /* save and clear the top digit */
158 msd=targ>>20;
159 targ&=0x000fffff;
160 }
161
162 /* create the combination field */
163 if (msd>=8) comb=0x18 | ((exp>>5) & 0x06) | (msd & 0x01);
164 else comb=((exp>>3) & 0x18) | msd;
165 }
166 targ|=comb<<26; /* add combination field .. */
167 targ|=(exp&0x3f)<<20; /* .. and exponent continuation */
168 } /* finite */
169
170 if (dn->bits&DECNEG) targ|=0x80000000; /* add sign bit */
171
172 /* now write to storage; this is endian */
173 UBFROMUI(d32->bytes, targ); /* directly store the int */
174
175 if (status!=0) decContextSetStatus(set, status); /* pass on status */
176 /* decimal32Show(d32); */
177 return d32;
178 } /* decimal32FromNumber */
179
180/* ------------------------------------------------------------------ */
181/* decimal32ToNumber -- convert decimal32 to decNumber */
182/* d32 is the source decimal32 */
183/* dn is the target number, with appropriate space */
184/* No error is possible. */
185/* ------------------------------------------------------------------ */
186decNumber * decimal32ToNumber(const decimal32 *d32, decNumber *dn) {
187 uInt msd; /* coefficient MSD */
188 uInt exp; /* exponent top two bits */
189 uInt comb; /* combination field */
190 uInt sour; /* source 32-bit */
191 uInt uiwork; /* for macros */
192
193 /* load source from storage; this is endian */
194 sour=UBTOUI(d32->bytes); /* directly load the int */
195
196 comb=(sour>>26)&0x1f; /* combination field */
197
198 decNumberZero(dn); /* clean number */
199 if (sour&0x80000000) dn->bits=DECNEG; /* set sign if negative */
200
201 msd=COMBMSD[comb]; /* decode the combination field */
202 exp=COMBEXP[comb]; /* .. */
203
204 if (exp==3) { /* is a special */
205 if (msd==0) {
206 dn->bits|=DECINF;
207 return dn; /* no coefficient needed */
208 }
209 else if (sour&0x02000000) dn->bits|=DECSNAN;
210 else dn->bits|=DECNAN;
211 msd=0; /* no top digit */
212 }
213 else { /* is a finite number */
214 dn->exponent=(exp<<6)+((sour>>20)&0x3f)-DECIMAL32_Bias; /* unbiased */
215 }
216
217 /* get the coefficient */
218 sour&=0x000fffff; /* clean coefficient continuation */
219 if (msd) { /* non-zero msd */
220 sour|=msd<<20; /* prefix to coefficient */
221 decDigitsFromDPD(dn, &sour, 3); /* process 3 declets */
222 return dn;
223 }
224 /* msd=0 */
225 if (!sour) return dn; /* easy: coefficient is 0 */
226 if (sour&0x000ffc00) /* need 2 declets? */
227 decDigitsFromDPD(dn, &sour, 2); /* process 2 declets */
228 else
229 decDigitsFromDPD(dn, &sour, 1); /* process 1 declet */
230 return dn;
231 } /* decimal32ToNumber */
232
233/* ------------------------------------------------------------------ */
234/* to-scientific-string -- conversion to numeric string */
235/* to-engineering-string -- conversion to numeric string */
236/* */
237/* decimal32ToString(d32, string); */
238/* decimal32ToEngString(d32, string); */
239/* */
240/* d32 is the decimal32 format number to convert */
241/* string is the string where the result will be laid out */
242/* */
243/* string must be at least 24 characters */
244/* */
245/* No error is possible, and no status can be set. */
246/* ------------------------------------------------------------------ */
247char * decimal32ToEngString(const decimal32 *d32, char *string){
248 decNumber dn; /* work */
249 decimal32ToNumber(d32, dn: &dn);
250 decNumberToEngString(&dn, string);
251 return string;
252 } /* decimal32ToEngString */
253
254char * decimal32ToString(const decimal32 *d32, char *string){
255 uInt msd; /* coefficient MSD */
256 Int exp; /* exponent top two bits or full */
257 uInt comb; /* combination field */
258 char *cstart; /* coefficient start */
259 char *c; /* output pointer in string */
260 const uByte *u; /* work */
261 char *s, *t; /* .. (source, target) */
262 Int dpd; /* .. */
263 Int pre, e; /* .. */
264 uInt uiwork; /* for macros */
265 uInt sour; /* source 32-bit */
266
267 /* load source from storage; this is endian */
268 sour=UBTOUI(d32->bytes); /* directly load the int */
269
270 c=string; /* where result will go */
271 if (((Int)sour)<0) *c++='-'; /* handle sign */
272
273 comb=(sour>>26)&0x1f; /* combination field */
274 msd=COMBMSD[comb]; /* decode the combination field */
275 exp=COMBEXP[comb]; /* .. */
276
277 if (exp==3) {
278 if (msd==0) { /* infinity */
279 strcpy(dest: c, src: "Inf");
280 strcpy(dest: c+3, src: "inity");
281 return string; /* easy */
282 }
283 if (sour&0x02000000) *c++='s'; /* sNaN */
284 strcpy(dest: c, src: "NaN"); /* complete word */
285 c+=3; /* step past */
286 if ((sour&0x000fffff)==0) return string; /* zero payload */
287 /* otherwise drop through to add integer; set correct exp */
288 exp=0; msd=0; /* setup for following code */
289 }
290 else exp=(exp<<6)+((sour>>20)&0x3f)-DECIMAL32_Bias; /* unbiased */
291
292 /* convert 7 digits of significand to characters */
293 cstart=c; /* save start of coefficient */
294 if (msd) *c++='0'+(char)msd; /* non-zero most significant digit */
295
296 /* Now decode the declets. After extracting each one, it is */
297 /* decoded to binary and then to a 4-char sequence by table lookup; */
298 /* the 4-chars are a 1-char length (significant digits, except 000 */
299 /* has length 0). This allows us to left-align the first declet */
300 /* with non-zero content, then remaining ones are full 3-char */
301 /* length. We use fixed-length memcpys because variable-length */
302 /* causes a subroutine call in GCC. (These are length 4 for speed */
303 /* and are safe because the array has an extra terminator byte.) */
304 #define dpd2char u=&BIN2CHAR[DPD2BIN[dpd]*4]; \
305 if (c!=cstart) {memcpy(c, u+1, 4); c+=3;} \
306 else if (*u) {memcpy(c, u+4-*u, 4); c+=*u;}
307
308 dpd=(sour>>10)&0x3ff; /* declet 1 */
309 dpd2char;
310 dpd=(sour)&0x3ff; /* declet 2 */
311 dpd2char;
312
313 if (c==cstart) *c++='0'; /* all zeros -- make 0 */
314
315 if (exp==0) { /* integer or NaN case -- easy */
316 *c='\0'; /* terminate */
317 return string;
318 }
319
320 /* non-0 exponent */
321 e=0; /* assume no E */
322 pre=c-cstart+exp;
323 /* [here, pre-exp is the digits count (==1 for zero)] */
324 if (exp>0 || pre<-5) { /* need exponential form */
325 e=pre-1; /* calculate E value */
326 pre=1; /* assume one digit before '.' */
327 } /* exponential form */
328
329 /* modify the coefficient, adding 0s, '.', and E+nn as needed */
330 s=c-1; /* source (LSD) */
331 if (pre>0) { /* ddd.ddd (plain), perhaps with E */
332 char *dotat=cstart+pre;
333 if (dotat<c) { /* if embedded dot needed... */
334 t=c; /* target */
335 for (; s>=dotat; s--, t--) *t=*s; /* open the gap; leave t at gap */
336 *t='.'; /* insert the dot */
337 c++; /* length increased by one */
338 }
339
340 /* finally add the E-part, if needed; it will never be 0, and has */
341 /* a maximum length of 3 digits (E-101 case) */
342 if (e!=0) {
343 *c++='E'; /* starts with E */
344 *c++='+'; /* assume positive */
345 if (e<0) {
346 *(c-1)='-'; /* oops, need '-' */
347 e=-e; /* uInt, please */
348 }
349 u=&BIN2CHAR[e*4]; /* -> length byte */
350 memcpy(dest: c, src: u+4-*u, n: 4); /* copy fixed 4 characters [is safe] */
351 c+=*u; /* bump pointer appropriately */
352 }
353 *c='\0'; /* add terminator */
354 /*printf("res %s\n", string); */
355 return string;
356 } /* pre>0 */
357
358 /* -5<=pre<=0: here for plain 0.ddd or 0.000ddd forms (can never have E) */
359 t=c+1-pre;
360 *(t+1)='\0'; /* can add terminator now */
361 for (; s>=cstart; s--, t--) *t=*s; /* shift whole coefficient right */
362 c=cstart;
363 *c++='0'; /* always starts with 0. */
364 *c++='.';
365 for (; pre<0; pre++) *c++='0'; /* add any 0's after '.' */
366 /*printf("res %s\n", string); */
367 return string;
368 } /* decimal32ToString */
369
370/* ------------------------------------------------------------------ */
371/* to-number -- conversion from numeric string */
372/* */
373/* decimal32FromString(result, string, set); */
374/* */
375/* result is the decimal32 format number which gets the result of */
376/* the conversion */
377/* *string is the character string which should contain a valid */
378/* number (which may be a special value) */
379/* set is the context */
380/* */
381/* The context is supplied to this routine is used for error handling */
382/* (setting of status and traps) and for the rounding mode, only. */
383/* If an error occurs, the result will be a valid decimal32 NaN. */
384/* ------------------------------------------------------------------ */
385decimal32 * decimal32FromString(decimal32 *result, const char *string,
386 decContext *set) {
387 decContext dc; /* work */
388 decNumber dn; /* .. */
389
390 decContextDefault(&dc, DEC_INIT_DECIMAL32); /* no traps, please */
391 dc.round=set->round; /* use supplied rounding */
392
393 decNumberFromString(&dn, string, &dc); /* will round if needed */
394 decimal32FromNumber(d32: result, dn: &dn, set: &dc);
395 if (dc.status!=0) { /* something happened */
396 decContextSetStatus(set, dc.status); /* .. pass it on */
397 }
398 return result;
399 } /* decimal32FromString */
400
401/* ------------------------------------------------------------------ */
402/* decimal32IsCanonical -- test whether encoding is canonical */
403/* d32 is the source decimal32 */
404/* returns 1 if the encoding of d32 is canonical, 0 otherwise */
405/* No error is possible. */
406/* ------------------------------------------------------------------ */
407uInt decimal32IsCanonical(const decimal32 *d32) {
408 decNumber dn; /* work */
409 decimal32 canon; /* .. */
410 decContext dc; /* .. */
411 decContextDefault(&dc, DEC_INIT_DECIMAL32);
412 decimal32ToNumber(d32, dn: &dn);
413 decimal32FromNumber(d32: &canon, dn: &dn, set: &dc);/* canon will now be canonical */
414 return memcmp(s1: d32, s2: &canon, DECIMAL32_Bytes)==0;
415 } /* decimal32IsCanonical */
416
417/* ------------------------------------------------------------------ */
418/* decimal32Canonical -- copy an encoding, ensuring it is canonical */
419/* d32 is the source decimal32 */
420/* result is the target (may be the same decimal32) */
421/* returns result */
422/* No error is possible. */
423/* ------------------------------------------------------------------ */
424decimal32 * decimal32Canonical(decimal32 *result, const decimal32 *d32) {
425 decNumber dn; /* work */
426 decContext dc; /* .. */
427 decContextDefault(&dc, DEC_INIT_DECIMAL32);
428 decimal32ToNumber(d32, dn: &dn);
429 decimal32FromNumber(d32: result, dn: &dn, set: &dc);/* result will now be canonical */
430 return result;
431 } /* decimal32Canonical */
432
433#if DECTRACE || DECCHECK
434/* Macros for accessing decimal32 fields. These assume the argument
435 is a reference (pointer) to the decimal32 structure, and the
436 decimal32 is in network byte order (big-endian) */
437/* Get sign */
438#define decimal32Sign(d) ((unsigned)(d)->bytes[0]>>7)
439
440/* Get combination field */
441#define decimal32Comb(d) (((d)->bytes[0] & 0x7c)>>2)
442
443/* Get exponent continuation [does not remove bias] */
444#define decimal32ExpCon(d) ((((d)->bytes[0] & 0x03)<<4) \
445 | ((unsigned)(d)->bytes[1]>>4))
446
447/* Set sign [this assumes sign previously 0] */
448#define decimal32SetSign(d, b) { \
449 (d)->bytes[0]|=((unsigned)(b)<<7);}
450
451/* Set exponent continuation [does not apply bias] */
452/* This assumes range has been checked and exponent previously 0; */
453/* type of exponent must be unsigned */
454#define decimal32SetExpCon(d, e) { \
455 (d)->bytes[0]|=(uByte)((e)>>4); \
456 (d)->bytes[1]|=(uByte)(((e)&0x0F)<<4);}
457
458/* ------------------------------------------------------------------ */
459/* decimal32Show -- display a decimal32 in hexadecimal [debug aid] */
460/* d32 -- the number to show */
461/* ------------------------------------------------------------------ */
462/* Also shows sign/cob/expconfields extracted - valid bigendian only */
463void decimal32Show(const decimal32 *d32) {
464 char buf[DECIMAL32_Bytes*2+1];
465 Int i, j=0;
466
467 if (DECLITEND) {
468 for (i=0; i<DECIMAL32_Bytes; i++, j+=2) {
469 sprintf(&buf[j], "%02x", d32->bytes[3-i]);
470 }
471 printf(" D32> %s [S:%d Cb:%02x Ec:%02x] LittleEndian\n", buf,
472 d32->bytes[3]>>7, (d32->bytes[3]>>2)&0x1f,
473 ((d32->bytes[3]&0x3)<<4)| (d32->bytes[2]>>4));
474 }
475 else {
476 for (i=0; i<DECIMAL32_Bytes; i++, j+=2) {
477 sprintf(&buf[j], "%02x", d32->bytes[i]);
478 }
479 printf(" D32> %s [S:%d Cb:%02x Ec:%02x] BigEndian\n", buf,
480 decimal32Sign(d32), decimal32Comb(d32), decimal32ExpCon(d32));
481 }
482 } /* decimal32Show */
483#endif
484

source code of libdecnumber/dpd/decimal32.c