1 /*
2 * The authors of this software are Rob Pike and Ken Thompson.
3 * Copyright (c) 2002 by Lucent Technologies.
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose without fee is hereby granted, provided that this entire notice
6 * is included in all copies of any software which is or includes a copy
7 * or modification of this software and in all copies of the supporting
8 * documentation for such software.
9 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
10 * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
11 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
12 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
13 */
14 #include <stdio.h>
15 #include <math.h>
16 #include <float.h>
17 #include <string.h>
18 #include <stdlib.h>
19 #include <errno.h>
20 #include <stdarg.h>
21 #include "fmt.h"
22 #include "fmtdef.h"
23 #include "nan.h"
24
25 enum
26 {
27 FDEFLT = 6,
28 NSIGNIF = 17
29 };
30
31 /*
32 * first few powers of 10, enough for about 1/2 of the
33 * total space for doubles.
34 */
35 static double pows10[] =
36 {
37 1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
38 1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
39 1e20, 1e21, 1e22, 1e23, 1e24, 1e25, 1e26, 1e27, 1e28, 1e29,
40 1e30, 1e31, 1e32, 1e33, 1e34, 1e35, 1e36, 1e37, 1e38, 1e39,
41 1e40, 1e41, 1e42, 1e43, 1e44, 1e45, 1e46, 1e47, 1e48, 1e49,
42 1e50, 1e51, 1e52, 1e53, 1e54, 1e55, 1e56, 1e57, 1e58, 1e59,
43 1e60, 1e61, 1e62, 1e63, 1e64, 1e65, 1e66, 1e67, 1e68, 1e69,
44 1e70, 1e71, 1e72, 1e73, 1e74, 1e75, 1e76, 1e77, 1e78, 1e79,
45 1e80, 1e81, 1e82, 1e83, 1e84, 1e85, 1e86, 1e87, 1e88, 1e89,
46 1e90, 1e91, 1e92, 1e93, 1e94, 1e95, 1e96, 1e97, 1e98, 1e99,
47 1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109,
48 1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119,
49 1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129,
50 1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139,
51 1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149,
52 1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159,
53 };
54
55 static double
pow10(int n)56 pow10(int n)
57 {
58 double d;
59 int neg;
60
61 neg = 0;
62 if(n < 0){
63 if(n < DBL_MIN_10_EXP){
64 return 0.;
65 }
66 neg = 1;
67 n = -n;
68 }else if(n > DBL_MAX_10_EXP){
69 return HUGE_VAL;
70 }
71 if(n < (int)(sizeof(pows10)/sizeof(pows10[0])))
72 d = pows10[n];
73 else{
74 d = pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
75 for(;;){
76 n -= sizeof(pows10)/sizeof(pows10[0]) - 1;
77 if(n < (int)(sizeof(pows10)/sizeof(pows10[0]))){
78 d *= pows10[n];
79 break;
80 }
81 d *= pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
82 }
83 }
84 if(neg){
85 return 1./d;
86 }
87 return d;
88 }
89
90 static int
xadd(char * a,int n,int v)91 xadd(char *a, int n, int v)
92 {
93 char *b;
94 int c;
95
96 if(n < 0 || n >= NSIGNIF)
97 return 0;
98 for(b = a+n; b >= a; b--) {
99 c = *b + v;
100 if(c <= '9') {
101 *b = c;
102 return 0;
103 }
104 *b = '0';
105 v = 1;
106 }
107 *a = '1'; /* overflow adding */
108 return 1;
109 }
110
111 static int
xsub(char * a,int n,int v)112 xsub(char *a, int n, int v)
113 {
114 char *b;
115 int c;
116
117 for(b = a+n; b >= a; b--) {
118 c = *b - v;
119 if(c >= '0') {
120 *b = c;
121 return 0;
122 }
123 *b = '9';
124 v = 1;
125 }
126 *a = '9'; /* underflow subtracting */
127 return 1;
128 }
129
130 static void
xaddexp(char * p,int e)131 xaddexp(char *p, int e)
132 {
133 char se[9];
134 int i;
135
136 *p++ = 'e';
137 if(e < 0) {
138 *p++ = '-';
139 e = -e;
140 }
141 i = 0;
142 while(e) {
143 se[i++] = e % 10 + '0';
144 e /= 10;
145 }
146 if(i == 0) {
147 *p++ = '0';
148 } else {
149 while(i > 0)
150 *p++ = se[--i];
151 }
152 *p = '\0';
153 }
154
155 static char*
xdodtoa(char * s1,double f,int chr,int prec,int * decpt,int * rsign)156 xdodtoa(char *s1, double f, int chr, int prec, int *decpt, int *rsign)
157 {
158 char s2[NSIGNIF+10];
159 double g, h;
160 int e, d, i;
161 int c2, sign, oerr;
162
163 if(chr == 'F')
164 chr = 'f';
165 if(prec > NSIGNIF)
166 prec = NSIGNIF;
167 if(prec < 0)
168 prec = 0;
169 if(__isNaN(f)) {
170 *decpt = 9999;
171 *rsign = 0;
172 strcpy(s1, "nan");
173 return &s1[3];
174 }
175 sign = 0;
176 if(f < 0) {
177 f = -f;
178 sign++;
179 }
180 *rsign = sign;
181 if(__isInf(f, 1) || __isInf(f, -1)) {
182 *decpt = 9999;
183 strcpy(s1, "inf");
184 return &s1[3];
185 }
186
187 e = 0;
188 g = f;
189 if(g != 0) {
190 frexp(f, &e);
191 e = (int)(e * .301029995664);
192 if(e >= -150 && e <= +150) {
193 d = 0;
194 h = f;
195 } else {
196 d = e/2;
197 h = f * pow10(-d);
198 }
199 g = h * pow10(d-e);
200 while(g < 1) {
201 e--;
202 g = h * pow10(d-e);
203 }
204 while(g >= 10) {
205 e++;
206 g = h * pow10(d-e);
207 }
208 }
209
210 /*
211 * convert NSIGNIF digits and convert
212 * back to get accuracy.
213 */
214 for(i=0; i<NSIGNIF; i++) {
215 d = (int)g;
216 s1[i] = d + '0';
217 g = (g - d) * 10;
218 }
219 s1[i] = 0;
220
221 /*
222 * try decimal rounding to eliminate 9s
223 */
224 c2 = prec + 1;
225 if(chr == 'f')
226 c2 += e;
227 oerr = errno;
228 if(c2 >= NSIGNIF-2) {
229 strcpy(s2, s1);
230 d = e;
231 s1[NSIGNIF-2] = '0';
232 s1[NSIGNIF-1] = '0';
233 xaddexp(s1+NSIGNIF, e-NSIGNIF+1);
234 g = fmtstrtod(s1, nil);
235 if(g == f)
236 goto found;
237 if(xadd(s1, NSIGNIF-3, 1)) {
238 e++;
239 xaddexp(s1+NSIGNIF, e-NSIGNIF+1);
240 }
241 g = fmtstrtod(s1, nil);
242 if(g == f)
243 goto found;
244 strcpy(s1, s2);
245 e = d;
246 }
247
248 /*
249 * convert back so s1 gets exact answer
250 */
251 for(d = 0; d < 10; d++) {
252 xaddexp(s1+NSIGNIF, e-NSIGNIF+1);
253 g = fmtstrtod(s1, nil);
254 if(f > g) {
255 if(xadd(s1, NSIGNIF-1, 1))
256 e--;
257 continue;
258 }
259 if(f < g) {
260 if(xsub(s1, NSIGNIF-1, 1))
261 e++;
262 continue;
263 }
264 break;
265 }
266
267 found:
268 errno = oerr;
269
270 /*
271 * round & adjust 'f' digits
272 */
273 c2 = prec + 1;
274 if(chr == 'f'){
275 if(xadd(s1, c2+e, 5))
276 e++;
277 c2 += e;
278 if(c2 < 0){
279 c2 = 0;
280 e = -prec - 1;
281 }
282 }else{
283 if(xadd(s1, c2, 5))
284 e++;
285 }
286 if(c2 > NSIGNIF){
287 c2 = NSIGNIF;
288 }
289
290 *decpt = e + 1;
291
292 /*
293 * terminate the converted digits
294 */
295 s1[c2] = '\0';
296 return &s1[c2];
297 }
298
299 /*
300 * this function works like the standard dtoa, if you want it.
301 */
302 #if 0
303 static char*
304 __dtoa(double f, int mode, int ndigits, int *decpt, int *rsign, char **rve)
305 {
306 static char s2[NSIGNIF + 10];
307 char *es;
308 int chr, prec;
309
310 switch(mode) {
311 /* like 'e' */
312 case 2:
313 case 4:
314 case 6:
315 case 8:
316 chr = 'e';
317 break;
318 /* like 'g' */
319 case 0:
320 case 1:
321 default:
322 chr = 'g';
323 break;
324 /* like 'f' */
325 case 3:
326 case 5:
327 case 7:
328 case 9:
329 chr = 'f';
330 break;
331 }
332
333 if(chr != 'f' && ndigits){
334 ndigits--;
335 }
336 prec = ndigits;
337 if(prec > NSIGNIF)
338 prec = NSIGNIF;
339 if(ndigits == 0)
340 prec = NSIGNIF;
341 es = xdodtoa(s2, f, chr, prec, decpt, rsign);
342
343 /*
344 * strip trailing 0
345 */
346 for(; es > s2 + 1; es--){
347 if(es[-1] != '0'){
348 break;
349 }
350 }
351 *es = '\0';
352 if(rve != NULL)
353 *rve = es;
354 return s2;
355 }
356 #endif
357
358 static int
fmtzdotpad(Fmt * f,int n,int pt)359 fmtzdotpad(Fmt *f, int n, int pt)
360 {
361 char *t, *s;
362 int i;
363 Rune *rt, *rs;
364
365 if(f->runes){
366 rt = (Rune*)f->to;
367 rs = (Rune*)f->stop;
368 for(i = 0; i < n; i++){
369 if(i == pt){
370 FMTRCHAR(f, rt, rs, '.');
371 }
372 FMTRCHAR(f, rt, rs, '0');
373 }
374 f->nfmt += rt - (Rune*)f->to;
375 f->to = rt;
376 }else{
377 t = (char*)f->to;
378 s = (char*)f->stop;
379 for(i = 0; i < n; i++){
380 if(i == pt){
381 FMTCHAR(f, t, s, '.');
382 }
383 FMTCHAR(f, t, s, '0');
384 }
385 f->nfmt += t - (char *)f->to;
386 f->to = t;
387 }
388 return 0;
389 }
390
391 int
__efgfmt(Fmt * fmt)392 __efgfmt(Fmt *fmt)
393 {
394 double f;
395 char s1[NSIGNIF+10];
396 int e, d, n;
397 int c1, c2, c3, c4, ucase, sign, chr, prec, fl;
398
399 f = va_arg(fmt->args, double);
400 prec = FDEFLT;
401 fl = fmt->flags;
402 fmt->flags = 0;
403 if(fl & FmtPrec)
404 prec = fmt->prec;
405 chr = fmt->r;
406 ucase = 0;
407 if(chr == 'E'){
408 chr = 'e';
409 ucase = 1;
410 }else if(chr == 'F'){
411 chr = 'f';
412 ucase = 1;
413 }else if(chr == 'G'){
414 chr = 'g';
415 ucase = 1;
416 }
417 if(prec > 0 && chr == 'g')
418 prec--;
419 if(prec < 0)
420 prec = 0;
421
422 xdodtoa(s1, f, chr, prec, &e, &sign);
423 e--;
424 if(*s1 == 'i' || *s1 == 'n'){
425 if(ucase){
426 if(*s1 == 'i'){
427 strcpy(s1, "INF");
428 }else{
429 strcpy(s1, "NAN");
430 }
431 }
432 fmt->flags = fl & (FmtWidth|FmtLeft);
433 return __fmtcpy(fmt, (const void*)s1, 3, 3);
434 }
435
436 /*
437 * copy into final place
438 * c1 digits of leading '0'
439 * c2 digits from conversion
440 * c3 digits of trailing '0'
441 * c4 digits after '.'
442 */
443 c1 = 0;
444 c2 = prec + 1;
445 c3 = 0;
446 c4 = prec;
447 switch(chr) {
448 default:
449 chr = 'e';
450 break;
451 case 'g':
452 /*
453 * decide on 'e' of 'f' style convers
454 */
455 if(e >= -4 && e <= prec) {
456 c1 = -e;
457 c4 = prec - e;
458 chr = 'h'; /* flag for 'f' style */
459 }
460 break;
461 case 'f':
462 c1 = -e;
463 if(c1 > prec)
464 c1 = prec + 1;
465 c2 += e;
466 break;
467 }
468
469 /*
470 * clean up c1 c2 and c3
471 */
472 if(c1 < 0)
473 c1 = 0;
474 if(c2 < 0)
475 c2 = 0;
476 if(c2 > NSIGNIF) {
477 c3 = c2-NSIGNIF;
478 c2 = NSIGNIF;
479 }
480
481 /*
482 * trim trailing zeros for %g
483 */
484 if(!(fl & FmtSharp)
485 && (chr == 'g' || chr == 'h')){
486 if(c4 >= c3){
487 c4 -= c3;
488 c3 = 0;
489 }else{
490 c3 -= c4;
491 c4 = 0;
492 }
493 while(c4 && c2 > 1 && s1[c2 - 1] == '0'){
494 c4--;
495 c2--;
496 }
497 }
498
499 /*
500 * calculate the total length
501 */
502 n = c1 + c2 + c3;
503 if(sign || (fl & (FmtSign|FmtSpace)))
504 n++;
505 if(c4 || (fl & FmtSharp)){
506 n++;
507 }
508 if(chr == 'e' || chr == 'g'){
509 n += 4;
510 if(e >= 100)
511 n++;
512 }
513
514 /*
515 * pad to width if right justified
516 */
517 if((fl & (FmtWidth|FmtLeft)) == FmtWidth && n < fmt->width){
518 if(fl & FmtZero){
519 c1 += fmt->width - n;
520 }else{
521 if(__fmtpad(fmt, fmt->width - n) < 0){
522 return -1;
523 }
524 }
525 }
526
527 /*
528 * sign
529 */
530 d = 0;
531 if(sign)
532 d = '-';
533 else if(fl & FmtSign)
534 d = '+';
535 else if(fl & FmtSpace)
536 d = ' ';
537 if(d && fmtrune(fmt, d) < 0){
538 return -1;
539 }
540
541 /*
542 * copy digits
543 */
544 c4 = c1 + c2 + c3 - c4;
545 if(c1 > 0){
546 if(fmtzdotpad(fmt, c1, c4) < 0){
547 return -1;
548 }
549 c4 -= c1;
550 }
551 d = 0;
552 if(c4 >= 0 && c4 < c2){
553 if(__fmtcpy(fmt, s1, c4, c4) < 0 || fmtrune(fmt, '.') < 0)
554 return -1;
555 d = c4;
556 c2 -= c4;
557 c4 = -1;
558 }
559 if(__fmtcpy(fmt, (const void*)(s1 + d), c2, c2) < 0){
560 return -1;
561 }
562 c4 -= c2;
563 if(c3 > 0){
564 if(fmtzdotpad(fmt, c3, c4) < 0){
565 return -1;
566 }
567 c4 -= c3;
568 }
569
570 /*
571 * strip trailing '0' on g conv
572 */
573 if((fl & FmtSharp) && c4 == 0 && fmtrune(fmt, '.') < 0){
574 return -1;
575 }
576 if(chr == 'e' || chr == 'g') {
577 d = 0;
578 if(ucase)
579 s1[d++] = 'E';
580 else
581 s1[d++] = 'e';
582 c1 = e;
583 if(c1 < 0) {
584 s1[d++] = '-';
585 c1 = -c1;
586 } else
587 s1[d++] = '+';
588 if(c1 >= 100) {
589 s1[d++] = c1/100 + '0';
590 c1 = c1%100;
591 }
592 s1[d++] = c1/10 + '0';
593 s1[d++] = c1%10 + '0';
594 if(__fmtcpy(fmt, s1, d, d) < 0){
595 return -1;
596 }
597 }
598 if((fl & (FmtWidth|FmtLeft)) == (FmtWidth|FmtLeft) && n < fmt->width){
599 if(__fmtpad(fmt, fmt->width - n) < 0){
600 return -1;
601 }
602 }
603 return 0;
604 }
605