xref: /freebsd/lib/libc/stdio/xprintf_float.c (revision 5b9c547c)
1 /*-
2  * Copyright (c) 2005 Poul-Henning Kamp
3  * Copyright (c) 1990, 1993
4  *	The Regents of the University of California.  All rights reserved.
5  *
6  * This code is derived from software contributed to Berkeley by
7  * Chris Torek.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * $FreeBSD$
34  */
35 
36 #include <namespace.h>
37 #include <stdio.h>
38 #include <wchar.h>
39 #include <assert.h>
40 #include <locale.h>
41 #include <limits.h>
42 
43 #define	dtoa		__dtoa
44 #define	freedtoa	__freedtoa
45 
46 #include <float.h>
47 #include <math.h>
48 #include "gdtoa.h"
49 #include "floatio.h"
50 #include "printf.h"
51 #include <un-namespace.h>
52 
53 /*
54  * The size of the buffer we use as scratch space for integer
55  * conversions, among other things.  Technically, we would need the
56  * most space for base 10 conversions with thousands' grouping
57  * characters between each pair of digits.  100 bytes is a
58  * conservative overestimate even for a 128-bit uintmax_t.
59  */
60 #define	BUF	100
61 
62 #define	DEFPREC		6	/* Default FP precision */
63 
64 
65 /* various globals ---------------------------------------------------*/
66 
67 
68 /* padding function---------------------------------------------------*/
69 
70 #define	PRINTANDPAD(p, ep, len, with) do {		\
71 	n2 = (ep) - (p);       				\
72 	if (n2 > (len))					\
73 		n2 = (len);				\
74 	if (n2 > 0)					\
75 		ret += __printf_puts(io, (p), n2);		\
76 	ret += __printf_pad(io, (len) - (n2 > 0 ? n2 : 0), (with));	\
77 } while(0)
78 
79 /* misc --------------------------------------------------------------*/
80 
81 #define	to_char(n)	((n) + '0')
82 
83 static int
84 exponent(char *p0, int expo, int fmtch)
85 {
86 	char *p, *t;
87 	char expbuf[MAXEXPDIG];
88 
89 	p = p0;
90 	*p++ = fmtch;
91 	if (expo < 0) {
92 		expo = -expo;
93 		*p++ = '-';
94 	}
95 	else
96 		*p++ = '+';
97 	t = expbuf + MAXEXPDIG;
98 	if (expo > 9) {
99 		do {
100 			*--t = to_char(expo % 10);
101 		} while ((expo /= 10) > 9);
102 		*--t = to_char(expo);
103 		for (; t < expbuf + MAXEXPDIG; *p++ = *t++)
104 			;
105 	}
106 	else {
107 		/*
108 		 * Exponents for decimal floating point conversions
109 		 * (%[eEgG]) must be at least two characters long,
110 		 * whereas exponents for hexadecimal conversions can
111 		 * be only one character long.
112 		 */
113 		if (fmtch == 'e' || fmtch == 'E')
114 			*p++ = '0';
115 		*p++ = to_char(expo);
116 	}
117 	return (p - p0);
118 }
119 
120 /* 'f' ---------------------------------------------------------------*/
121 
122 int
123 __printf_arginfo_float(const struct printf_info *pi, size_t n, int *argt)
124 {
125 	assert (n > 0);
126 	argt[0] = PA_DOUBLE;
127 	if (pi->is_long_double)
128 		argt[0] |= PA_FLAG_LONG_DOUBLE;
129 	return (1);
130 }
131 
132 /*
133  * We can decompose the printed representation of floating
134  * point numbers into several parts, some of which may be empty:
135  *
136  * [+|-| ] [0x|0X] MMM . NNN [e|E|p|P] [+|-] ZZ
137  *    A       B     ---C---      D       E   F
138  *
139  * A:	'sign' holds this value if present; '\0' otherwise
140  * B:	ox[1] holds the 'x' or 'X'; '\0' if not hexadecimal
141  * C:	cp points to the string MMMNNN.  Leading and trailing
142  *	zeros are not in the string and must be added.
143  * D:	expchar holds this character; '\0' if no exponent, e.g. %f
144  * F:	at least two digits for decimal, at least one digit for hex
145  */
146 
147 int
148 __printf_render_float(struct __printf_io *io, const struct printf_info *pi, const void *const *arg)
149 {
150 	int prec;		/* precision from format; <0 for N/A */
151 	char *dtoaresult;	/* buffer allocated by dtoa */
152 	char expchar;		/* exponent character: [eEpP\0] */
153 	char *cp;
154 	int expt;		/* integer value of exponent */
155 	int signflag;		/* true if float is negative */
156 	char *dtoaend;		/* pointer to end of converted digits */
157 	char sign;		/* sign prefix (' ', '+', '-', or \0) */
158 	int size;		/* size of converted field or string */
159 	int ndig;		/* actual number of digits returned by dtoa */
160 	int expsize;		/* character count for expstr */
161 	char expstr[MAXEXPDIG+2];	/* buffer for exponent string: e+ZZZ */
162 	int nseps;		/* number of group separators with ' */
163 	int nrepeats;		/* number of repeats of the last group */
164 	const char *grouping;	/* locale specific numeric grouping rules */
165 	int lead;		/* sig figs before decimal or group sep */
166 	long double ld;
167 	double d;
168 	int realsz;		/* field size expanded by dprec, sign, etc */
169 	int dprec;		/* a copy of prec if [diouxX], 0 otherwise */
170 	char ox[2];		/* space for 0x; ox[1] is either x, X, or \0 */
171 	int ret;		/* return value accumulator */
172 	char *decimal_point;	/* locale specific decimal point */
173 	int n2;			/* XXX: for PRINTANDPAD */
174 	char thousands_sep;	/* locale specific thousands separator */
175 	char buf[BUF];		/* buffer with space for digits of uintmax_t */
176 	const char *xdigs;
177 	int flag;
178 
179 	prec = pi->prec;
180 	ox[1] = '\0';
181 	sign = pi->showsign;
182 	flag = 0;
183 	ret = 0;
184 
185 	thousands_sep = *(localeconv()->thousands_sep);
186 	grouping = NULL;
187 	if (pi->alt)
188 		grouping = localeconv()->grouping;
189 	decimal_point = localeconv()->decimal_point;
190 	dprec = -1;
191 
192 	switch(pi->spec) {
193 	case 'a':
194 	case 'A':
195 		if (pi->spec == 'a') {
196 			ox[1] = 'x';
197 			xdigs = __lowercase_hex;
198 			expchar = 'p';
199 		} else {
200 			ox[1] = 'X';
201 			xdigs = __uppercase_hex;
202 			expchar = 'P';
203 		}
204 		if (prec >= 0)
205 			prec++;
206 		if (pi->is_long_double) {
207 			ld = *((long double *)arg[0]);
208 			dtoaresult = cp =
209 			    __hldtoa(ld, xdigs, prec,
210 			    &expt, &signflag, &dtoaend);
211 		} else {
212 			d = *((double *)arg[0]);
213 			dtoaresult = cp =
214 			    __hdtoa(d, xdigs, prec,
215 			    &expt, &signflag, &dtoaend);
216 		}
217 		if (prec < 0)
218 			prec = dtoaend - cp;
219 		if (expt == INT_MAX)
220 			ox[1] = '\0';
221 		goto fp_common;
222 	case 'e':
223 	case 'E':
224 		expchar = pi->spec;
225 		if (prec < 0)	/* account for digit before decpt */
226 			prec = DEFPREC + 1;
227 		else
228 			prec++;
229 		break;
230 	case 'f':
231 	case 'F':
232 		expchar = '\0';
233 		break;
234 	case 'g':
235 	case 'G':
236 		expchar = pi->spec - ('g' - 'e');
237 		if (prec == 0)
238 			prec = 1;
239 		break;
240 	default:
241 		assert(pi->spec == 'f');
242 	}
243 
244 	if (prec < 0)
245 		prec = DEFPREC;
246 	if (pi->is_long_double) {
247 		ld = *((long double *)arg[0]);
248 		dtoaresult = cp =
249 		    __ldtoa(&ld, expchar ? 2 : 3, prec,
250 		    &expt, &signflag, &dtoaend);
251 	} else {
252 		d = *((double *)arg[0]);
253 		dtoaresult = cp =
254 		    dtoa(d, expchar ? 2 : 3, prec,
255 		    &expt, &signflag, &dtoaend);
256 		if (expt == 9999)
257 			expt = INT_MAX;
258 	}
259 fp_common:
260 	if (signflag)
261 		sign = '-';
262 	if (expt == INT_MAX) {	/* inf or nan */
263 		if (*cp == 'N') {
264 			cp = (pi->spec >= 'a') ? "nan" : "NAN";
265 			sign = '\0';
266 		} else
267 			cp = (pi->spec >= 'a') ? "inf" : "INF";
268 		size = 3;
269 		flag = 1;
270 		goto here;
271 	}
272 	ndig = dtoaend - cp;
273 	if (pi->spec == 'g' || pi->spec == 'G') {
274 		if (expt > -4 && expt <= prec) {
275 			/* Make %[gG] smell like %[fF] */
276 			expchar = '\0';
277 			if (pi->alt)
278 				prec -= expt;
279 			else
280 				prec = ndig - expt;
281 			if (prec < 0)
282 				prec = 0;
283 		} else {
284 			/*
285 			 * Make %[gG] smell like %[eE], but
286 			 * trim trailing zeroes if no # flag.
287 			 */
288 			if (!pi->alt)
289 				prec = ndig;
290 		}
291 	}
292 	if (expchar) {
293 		expsize = exponent(expstr, expt - 1, expchar);
294 		size = expsize + prec;
295 		if (prec > 1 || pi->alt)
296 			++size;
297 	} else {
298 		/* space for digits before decimal point */
299 		if (expt > 0)
300 			size = expt;
301 		else	/* "0" */
302 			size = 1;
303 		/* space for decimal pt and following digits */
304 		if (prec || pi->alt)
305 			size += prec + 1;
306 		if (grouping && expt > 0) {
307 			/* space for thousands' grouping */
308 			nseps = nrepeats = 0;
309 			lead = expt;
310 			while (*grouping != CHAR_MAX) {
311 				if (lead <= *grouping)
312 					break;
313 				lead -= *grouping;
314 				if (*(grouping+1)) {
315 					nseps++;
316 					grouping++;
317 				} else
318 					nrepeats++;
319 			}
320 			size += nseps + nrepeats;
321 		} else
322 			lead = expt;
323 	}
324 
325 here:
326 	/*
327 	 * All reasonable formats wind up here.  At this point, `cp'
328 	 * points to a string which (if not flags&LADJUST) should be
329 	 * padded out to `width' places.  If flags&ZEROPAD, it should
330 	 * first be prefixed by any sign or other prefix; otherwise,
331 	 * it should be blank padded before the prefix is emitted.
332 	 * After any left-hand padding and prefixing, emit zeroes
333 	 * required by a decimal [diouxX] precision, then print the
334 	 * string proper, then emit zeroes required by any leftover
335 	 * floating precision; finally, if LADJUST, pad with blanks.
336 	 *
337 	 * Compute actual size, so we know how much to pad.
338 	 * size excludes decimal prec; realsz includes it.
339 	 */
340 	realsz = dprec > size ? dprec : size;
341 	if (sign)
342 		realsz++;
343 	if (ox[1])
344 		realsz += 2;
345 
346 	/* right-adjusting blank padding */
347 	if (pi->pad != '0' && pi->left == 0)
348 		ret += __printf_pad(io, pi->width - realsz, 0);
349 
350 	/* prefix */
351 	if (sign)
352 		ret += __printf_puts(io, &sign, 1);
353 
354 	if (ox[1]) {	/* ox[1] is either x, X, or \0 */
355 		ox[0] = '0';
356 		ret += __printf_puts(io, ox, 2);
357 	}
358 
359 	/* right-adjusting zero padding */
360 	if (pi->pad == '0' && pi->left == 0)
361 		ret += __printf_pad(io, pi->width - realsz, 1);
362 
363 	/* leading zeroes from decimal precision */
364 	ret += __printf_pad(io, dprec - size, 1);
365 
366 	if (flag)
367 		ret += __printf_puts(io, cp, size);
368 	else {
369 		/* glue together f_p fragments */
370 		if (!expchar) {	/* %[fF] or sufficiently short %[gG] */
371 			if (expt <= 0) {
372 				ret += __printf_puts(io, "0", 1);
373 				if (prec || pi->alt)
374 					ret += __printf_puts(io, decimal_point, 1);
375 				ret += __printf_pad(io, -expt, 1);
376 				/* already handled initial 0's */
377 				prec += expt;
378 			} else {
379 				PRINTANDPAD(cp, dtoaend, lead, 1);
380 				cp += lead;
381 				if (grouping) {
382 					while (nseps>0 || nrepeats>0) {
383 						if (nrepeats > 0)
384 							nrepeats--;
385 						else {
386 							grouping--;
387 							nseps--;
388 						}
389 						ret += __printf_puts(io, &thousands_sep, 1);
390 						PRINTANDPAD(cp,dtoaend,
391 						    *grouping, 1);
392 						cp += *grouping;
393 					}
394 					if (cp > dtoaend)
395 						cp = dtoaend;
396 				}
397 				if (prec || pi->alt)
398 					ret += __printf_puts(io, decimal_point,1);
399 			}
400 			PRINTANDPAD(cp, dtoaend, prec, 1);
401 		} else {	/* %[eE] or sufficiently long %[gG] */
402 			if (prec > 1 || pi->alt) {
403 				buf[0] = *cp++;
404 				buf[1] = *decimal_point;
405 				ret += __printf_puts(io, buf, 2);
406 				ret += __printf_puts(io, cp, ndig-1);
407 				ret += __printf_pad(io, prec - ndig, 1);
408 			} else	/* XeYYY */
409 				ret += __printf_puts(io, cp, 1);
410 			ret += __printf_puts(io, expstr, expsize);
411 		}
412 	}
413 	/* left-adjusting padding (always blank) */
414 	if (pi->left)
415 		ret += __printf_pad(io, pi->width - realsz, 0);
416 
417 	__printf_flush(io);
418 	if (dtoaresult != NULL)
419 		freedtoa(dtoaresult);
420 
421 	return (ret);
422 }
423