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[glibc.git] / stdio-common / printf_fp.c
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1 /* Floating point output for `printf'.
2 Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Library General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Library General Public License for more details.
16 You should have received a copy of the GNU Library General Public
17 License along with the GNU C Library; see the file COPYING.LIB. If not,
18 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
21 /* The gmp headers need some configuration frobs. */
22 #define HAVE_ALLOCA 1
24 #ifdef USE_IN_LIBIO
25 # include <libioP.h>
26 #else
27 # include <stdio.h>
28 #endif
29 #include <alloca.h>
30 #include <ctype.h>
31 #include <float.h>
32 #include <gmp-mparam.h>
33 #include <stdlib/gmp.h>
34 #include <stdlib/gmp-impl.h>
35 #include <stdlib/longlong.h>
36 #include <stdlib/fpioconst.h>
37 #include <locale/localeinfo.h>
38 #include <limits.h>
39 #include <math.h>
40 #include <printf.h>
41 #include <string.h>
42 #include <unistd.h>
43 #include <stdlib.h>
45 #ifndef NDEBUG
46 # define NDEBUG /* Undefine this for debugging assertions. */
47 #endif
48 #include <assert.h>
50 /* This defines make it possible to use the same code for GNU C library and
51 the GNU I/O library. */
52 #ifdef USE_IN_LIBIO
53 # define PUT(f, s, n) _IO_sputn (f, s, n)
54 # define PAD(f, c, n) _IO_padn (f, c, n)
55 /* We use this file GNU C library and GNU I/O library. So make
56 names equal. */
57 # undef putc
58 # define putc(c, f) _IO_putc_unlocked (c, f)
59 # define size_t _IO_size_t
60 # define FILE _IO_FILE
61 #else /* ! USE_IN_LIBIO */
62 # define PUT(f, s, n) fwrite (s, 1, n, f)
63 # define PAD(f, c, n) __printf_pad (f, c, n)
64 ssize_t __printf_pad __P ((FILE *, char pad, int n)); /* In vfprintf.c. */
65 #endif /* USE_IN_LIBIO */
67 /* Macros for doing the actual output. */
69 #define outchar(ch) \
70 do \
71 { \
72 register const int outc = (ch); \
73 if (putc (outc, fp) == EOF) \
74 return -1; \
75 ++done; \
76 } while (0)
78 #define PRINT(ptr, len) \
79 do \
80 { \
81 register size_t outlen = (len); \
82 if (len > 20) \
83 { \
84 if (PUT (fp, ptr, outlen) != outlen) \
85 return -1; \
86 ptr += outlen; \
87 done += outlen; \
88 } \
89 else \
90 { \
91 while (outlen-- > 0) \
92 outchar (*ptr++); \
93 } \
94 } while (0)
96 #define PADN(ch, len) \
97 do \
98 { \
99 if (PAD (fp, ch, len) != len) \
100 return -1; \
101 done += len; \
103 while (0)
105 /* We use the GNU MP library to handle large numbers.
107 An MP variable occupies a varying number of entries in its array. We keep
108 track of this number for efficiency reasons. Otherwise we would always
109 have to process the whole array. */
110 #define MPN_VAR(name) mp_limb_t *name; mp_size_t name##size
112 #define MPN_ASSIGN(dst,src) \
113 memcpy (dst, src, (dst##size = src##size) * sizeof (mp_limb_t))
114 #define MPN_GE(u,v) \
115 (u##size > v##size || (u##size == v##size && __mpn_cmp (u, v, u##size) >= 0))
117 extern int __isinfl (long double), __isnanl (long double);
119 extern mp_size_t __mpn_extract_double (mp_ptr res_ptr, mp_size_t size,
120 int *expt, int *is_neg,
121 double value);
122 extern mp_size_t __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
123 int *expt, int *is_neg,
124 long double value);
125 extern unsigned int __guess_grouping (unsigned int intdig_max,
126 const char *grouping, wchar_t sepchar);
129 static char *group_number (char *buf, char *bufend, unsigned int intdig_no,
130 const char *grouping, wchar_t thousands_sep)
131 internal_function;
135 __printf_fp (FILE *fp,
136 const struct printf_info *info,
137 const void *const *args)
139 /* The floating-point value to output. */
140 union
142 double dbl;
143 __long_double_t ldbl;
145 fpnum;
147 /* Locale-dependent representation of decimal point. */
148 wchar_t decimal;
150 /* Locale-dependent thousands separator and grouping specification. */
151 wchar_t thousands_sep;
152 const char *grouping;
154 /* "NaN" or "Inf" for the special cases. */
155 const char *special = NULL;
157 /* We need just a few limbs for the input before shifting to the right
158 position. */
159 mp_limb_t fp_input[(LDBL_MANT_DIG + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB];
160 /* We need to shift the contents of fp_input by this amount of bits. */
161 int to_shift = 0;
163 /* The fraction of the floting-point value in question */
164 MPN_VAR(frac);
165 /* and the exponent. */
166 int exponent;
167 /* Sign of the exponent. */
168 int expsign = 0;
169 /* Sign of float number. */
170 int is_neg = 0;
172 /* Scaling factor. */
173 MPN_VAR(scale);
175 /* Temporary bignum value. */
176 MPN_VAR(tmp);
178 /* Digit which is result of last hack_digit() call. */
179 int digit;
181 /* The type of output format that will be used: 'e'/'E' or 'f'. */
182 int type;
184 /* Counter for number of written characters. */
185 int done = 0;
187 /* General helper (carry limb). */
188 mp_limb_t cy;
190 char hack_digit (void)
192 mp_limb_t hi;
194 if (expsign != 0 && type == 'f' && exponent-- > 0)
195 hi = 0;
196 else if (scalesize == 0)
198 hi = frac[fracsize - 1];
199 cy = __mpn_mul_1 (frac, frac, fracsize - 1, 10);
200 frac[fracsize - 1] = cy;
202 else
204 if (fracsize < scalesize)
205 hi = 0;
206 else
208 hi = mpn_divmod (tmp, frac, fracsize, scale, scalesize);
209 tmp[fracsize - scalesize] = hi;
210 hi = tmp[0];
212 fracsize = scalesize;
213 while (fracsize != 0 && frac[fracsize - 1] == 0)
214 --fracsize;
215 if (fracsize == 0)
217 /* We're not prepared for an mpn variable with zero
218 limbs. */
219 fracsize = 1;
220 return '0' + hi;
224 cy = __mpn_mul_1 (frac, frac, fracsize, 10);
225 if (cy != 0)
226 frac[fracsize++] = cy;
229 return '0' + hi;
233 /* Figure out the decimal point character. */
234 if (info->extra == 0)
236 if (mbtowc (&decimal, _NL_CURRENT (LC_NUMERIC, DECIMAL_POINT),
237 strlen (_NL_CURRENT (LC_NUMERIC, DECIMAL_POINT))) <= 0)
238 decimal = (wchar_t) *_NL_CURRENT (LC_NUMERIC, DECIMAL_POINT);
240 else
242 if (mbtowc (&decimal, _NL_CURRENT (LC_MONETARY, MON_DECIMAL_POINT),
243 strlen (_NL_CURRENT (LC_MONETARY, MON_DECIMAL_POINT))) <= 0)
244 decimal = (wchar_t) *_NL_CURRENT (LC_MONETARY, MON_DECIMAL_POINT);
246 /* Give default value. */
247 if (decimal == L'\0')
248 decimal = L'.';
251 if (info->group)
253 if (info->extra == 0)
254 grouping = _NL_CURRENT (LC_NUMERIC, GROUPING);
255 else
256 grouping = _NL_CURRENT (LC_MONETARY, MON_GROUPING);
258 if (*grouping <= 0 || *grouping == CHAR_MAX)
259 grouping = NULL;
260 else
262 /* Figure out the thousands separator character. */
263 if (info->extra == 0)
265 if (mbtowc (&thousands_sep, _NL_CURRENT (LC_NUMERIC,
266 THOUSANDS_SEP),
267 strlen (_NL_CURRENT (LC_NUMERIC, THOUSANDS_SEP)))
268 <= 0)
269 thousands_sep = (wchar_t) *_NL_CURRENT (LC_NUMERIC,
270 THOUSANDS_SEP);
272 else
274 if (mbtowc (&thousands_sep, _NL_CURRENT (LC_MONETARY,
275 MON_THOUSANDS_SEP),
276 strlen (_NL_CURRENT (LC_MONETARY,
277 MON_THOUSANDS_SEP))) <= 0)
278 thousands_sep = (wchar_t) *_NL_CURRENT (LC_MONETARY,
279 MON_THOUSANDS_SEP);
282 if (thousands_sep == L'\0')
283 grouping = NULL;
286 else
287 grouping = NULL;
289 /* Fetch the argument value. */
290 if (info->is_long_double && sizeof (long double) > sizeof (double))
292 fpnum.ldbl = *(const long double *) args[0];
294 /* Check for special values: not a number or infinity. */
295 if (__isnanl (fpnum.ldbl))
297 special = isupper (info->spec) ? "NAN" : "nan";
298 is_neg = 0;
300 else if (__isinfl (fpnum.ldbl))
302 special = isupper (info->spec) ? "INF" : "inf";
303 is_neg = fpnum.ldbl < 0;
305 else
307 fracsize = __mpn_extract_long_double (fp_input,
308 (sizeof (fp_input) /
309 sizeof (fp_input[0])),
310 &exponent, &is_neg,
311 fpnum.ldbl);
312 to_shift = 1 + fracsize * BITS_PER_MP_LIMB - LDBL_MANT_DIG;
315 else
317 fpnum.dbl = *(const double *) args[0];
319 /* Check for special values: not a number or infinity. */
320 if (__isnan (fpnum.dbl))
322 special = isupper (info->spec) ? "NAN" : "nan";
323 is_neg = 0;
325 else if (__isinf (fpnum.dbl))
327 special = isupper (info->spec) ? "INF" : "inf";
328 is_neg = fpnum.dbl < 0;
330 else
332 fracsize = __mpn_extract_double (fp_input,
333 (sizeof (fp_input)
334 / sizeof (fp_input[0])),
335 &exponent, &is_neg, fpnum.dbl);
336 to_shift = 1 + fracsize * BITS_PER_MP_LIMB - DBL_MANT_DIG;
340 if (special)
342 int width = info->width;
344 if (is_neg || info->showsign || info->space)
345 --width;
346 width -= 3;
348 if (!info->left && width > 0)
349 PADN (' ', width);
351 if (is_neg)
352 outchar ('-');
353 else if (info->showsign)
354 outchar ('+');
355 else if (info->space)
356 outchar (' ');
358 PRINT (special, 3);
360 if (info->left && width > 0)
361 PADN (' ', width);
363 return done;
367 /* We need three multiprecision variables. Now that we have the exponent
368 of the number we can allocate the needed memory. It would be more
369 efficient to use variables of the fixed maximum size but because this
370 would be really big it could lead to memory problems. */
372 mp_size_t bignum_size = ((ABS (exponent) + BITS_PER_MP_LIMB - 1)
373 / BITS_PER_MP_LIMB + 4) * sizeof (mp_limb_t);
374 frac = (mp_limb_t *) alloca (bignum_size);
375 tmp = (mp_limb_t *) alloca (bignum_size);
376 scale = (mp_limb_t *) alloca (bignum_size);
379 /* We now have to distinguish between numbers with positive and negative
380 exponents because the method used for the one is not applicable/efficient
381 for the other. */
382 scalesize = 0;
383 if (exponent > 2)
385 /* |FP| >= 8.0. */
386 int scaleexpo = 0;
387 int explog = LDBL_MAX_10_EXP_LOG;
388 int exp10 = 0;
389 const struct mp_power *tens = &_fpioconst_pow10[explog + 1];
390 int cnt_h, cnt_l, i;
392 if ((exponent + to_shift) % BITS_PER_MP_LIMB == 0)
394 MPN_COPY_DECR (frac + (exponent + to_shift) / BITS_PER_MP_LIMB,
395 fp_input, fracsize);
396 fracsize += (exponent + to_shift) / BITS_PER_MP_LIMB;
398 else
400 cy = __mpn_lshift (frac + (exponent + to_shift) / BITS_PER_MP_LIMB,
401 fp_input, fracsize,
402 (exponent + to_shift) % BITS_PER_MP_LIMB);
403 fracsize += (exponent + to_shift) / BITS_PER_MP_LIMB;
404 if (cy)
405 frac[fracsize++] = cy;
407 MPN_ZERO (frac, (exponent + to_shift) / BITS_PER_MP_LIMB);
409 assert (tens > &_fpioconst_pow10[0]);
412 --tens;
414 /* The number of the product of two binary numbers with n and m
415 bits respectively has m+n or m+n-1 bits. */
416 if (exponent >= scaleexpo + tens->p_expo - 1)
418 if (scalesize == 0)
419 MPN_ASSIGN (tmp, tens->array);
420 else
422 cy = __mpn_mul (tmp, scale, scalesize,
423 &tens->array[_FPIO_CONST_OFFSET],
424 tens->arraysize - _FPIO_CONST_OFFSET);
425 tmpsize = scalesize + tens->arraysize - _FPIO_CONST_OFFSET;
426 if (cy == 0)
427 --tmpsize;
430 if (MPN_GE (frac, tmp))
432 int cnt;
433 MPN_ASSIGN (scale, tmp);
434 count_leading_zeros (cnt, scale[scalesize - 1]);
435 scaleexpo = (scalesize - 2) * BITS_PER_MP_LIMB - cnt - 1;
436 exp10 |= 1 << explog;
439 --explog;
441 while (tens > &_fpioconst_pow10[0]);
442 exponent = exp10;
444 /* Optimize number representations. We want to represent the numbers
445 with the lowest number of bytes possible without losing any
446 bytes. Also the highest bit in the scaling factor has to be set
447 (this is a requirement of the MPN division routines). */
448 if (scalesize > 0)
450 /* Determine minimum number of zero bits at the end of
451 both numbers. */
452 for (i = 0; scale[i] == 0 && frac[i] == 0; i++)
455 /* Determine number of bits the scaling factor is misplaced. */
456 count_leading_zeros (cnt_h, scale[scalesize - 1]);
458 if (cnt_h == 0)
460 /* The highest bit of the scaling factor is already set. So
461 we only have to remove the trailing empty limbs. */
462 if (i > 0)
464 MPN_COPY_INCR (scale, scale + i, scalesize - i);
465 scalesize -= i;
466 MPN_COPY_INCR (frac, frac + i, fracsize - i);
467 fracsize -= i;
470 else
472 if (scale[i] != 0)
474 count_trailing_zeros (cnt_l, scale[i]);
475 if (frac[i] != 0)
477 int cnt_l2;
478 count_trailing_zeros (cnt_l2, frac[i]);
479 if (cnt_l2 < cnt_l)
480 cnt_l = cnt_l2;
483 else
484 count_trailing_zeros (cnt_l, frac[i]);
486 /* Now shift the numbers to their optimal position. */
487 if (i == 0 && BITS_PER_MP_LIMB - cnt_h > cnt_l)
489 /* We cannot save any memory. So just roll both numbers
490 so that the scaling factor has its highest bit set. */
492 (void) __mpn_lshift (scale, scale, scalesize, cnt_h);
493 cy = __mpn_lshift (frac, frac, fracsize, cnt_h);
494 if (cy != 0)
495 frac[fracsize++] = cy;
497 else if (BITS_PER_MP_LIMB - cnt_h <= cnt_l)
499 /* We can save memory by removing the trailing zero limbs
500 and by packing the non-zero limbs which gain another
501 free one. */
503 (void) __mpn_rshift (scale, scale + i, scalesize - i,
504 BITS_PER_MP_LIMB - cnt_h);
505 scalesize -= i + 1;
506 (void) __mpn_rshift (frac, frac + i, fracsize - i,
507 BITS_PER_MP_LIMB - cnt_h);
508 fracsize -= frac[fracsize - i - 1] == 0 ? i + 1 : i;
510 else
512 /* We can only save the memory of the limbs which are zero.
513 The non-zero parts occupy the same number of limbs. */
515 (void) __mpn_rshift (scale, scale + (i - 1),
516 scalesize - (i - 1),
517 BITS_PER_MP_LIMB - cnt_h);
518 scalesize -= i;
519 (void) __mpn_rshift (frac, frac + (i - 1),
520 fracsize - (i - 1),
521 BITS_PER_MP_LIMB - cnt_h);
522 fracsize -= frac[fracsize - (i - 1) - 1] == 0 ? i : i - 1;
527 else if (exponent < 0)
529 /* |FP| < 1.0. */
530 int exp10 = 0;
531 int explog = LDBL_MAX_10_EXP_LOG;
532 const struct mp_power *tens = &_fpioconst_pow10[explog + 1];
533 mp_size_t used_limbs = fracsize - 1;
535 /* Now shift the input value to its right place. */
536 cy = __mpn_lshift (frac, fp_input, fracsize, to_shift);
537 frac[fracsize++] = cy;
538 assert (cy == 1 || (frac[fracsize - 2] == 0 && frac[0] == 0));
540 expsign = 1;
541 exponent = -exponent;
543 assert (tens != &_fpioconst_pow10[0]);
546 --tens;
548 if (exponent >= tens->m_expo)
550 int i, incr, cnt_h, cnt_l;
551 mp_limb_t topval[2];
553 /* The __mpn_mul function expects the first argument to be
554 bigger than the second. */
555 if (fracsize < tens->arraysize - _FPIO_CONST_OFFSET)
556 cy = __mpn_mul (tmp, &tens->array[_FPIO_CONST_OFFSET],
557 tens->arraysize - _FPIO_CONST_OFFSET,
558 frac, fracsize);
559 else
560 cy = __mpn_mul (tmp, frac, fracsize,
561 &tens->array[_FPIO_CONST_OFFSET],
562 tens->arraysize - _FPIO_CONST_OFFSET);
563 tmpsize = fracsize + tens->arraysize - _FPIO_CONST_OFFSET;
564 if (cy == 0)
565 --tmpsize;
567 count_leading_zeros (cnt_h, tmp[tmpsize - 1]);
568 incr = (tmpsize - fracsize) * BITS_PER_MP_LIMB
569 + BITS_PER_MP_LIMB - 1 - cnt_h;
571 assert (incr <= tens->p_expo);
573 /* If we increased the exponent by exactly 3 we have to test
574 for overflow. This is done by comparing with 10 shifted
575 to the right position. */
576 if (incr == exponent + 3)
577 if (cnt_h <= BITS_PER_MP_LIMB - 4)
579 topval[0] = 0;
580 topval[1]
581 = ((mp_limb_t) 10) << (BITS_PER_MP_LIMB - 4 - cnt_h);
583 else
585 topval[0] = ((mp_limb_t) 10) << (BITS_PER_MP_LIMB - 4);
586 topval[1] = 0;
587 (void) __mpn_lshift (topval, topval, 2,
588 BITS_PER_MP_LIMB - cnt_h);
591 /* We have to be careful when multiplying the last factor.
592 If the result is greater than 1.0 be have to test it
593 against 10.0. If it is greater or equal to 10.0 the
594 multiplication was not valid. This is because we cannot
595 determine the number of bits in the result in advance. */
596 if (incr < exponent + 3
597 || (incr == exponent + 3 &&
598 (tmp[tmpsize - 1] < topval[1]
599 || (tmp[tmpsize - 1] == topval[1]
600 && tmp[tmpsize - 2] < topval[0]))))
602 /* The factor is right. Adapt binary and decimal
603 exponents. */
604 exponent -= incr;
605 exp10 |= 1 << explog;
607 /* If this factor yields a number greater or equal to
608 1.0, we must not shift the non-fractional digits down. */
609 if (exponent < 0)
610 cnt_h += -exponent;
612 /* Now we optimize the number representation. */
613 for (i = 0; tmp[i] == 0; ++i);
614 if (cnt_h == BITS_PER_MP_LIMB - 1)
616 MPN_COPY (frac, tmp + i, tmpsize - i);
617 fracsize = tmpsize - i;
619 else
621 count_trailing_zeros (cnt_l, tmp[i]);
623 /* Now shift the numbers to their optimal position. */
624 if (i == 0 && BITS_PER_MP_LIMB - 1 - cnt_h > cnt_l)
626 /* We cannot save any memory. Just roll the
627 number so that the leading digit is in a
628 separate limb. */
630 cy = __mpn_lshift (frac, tmp, tmpsize, cnt_h + 1);
631 fracsize = tmpsize + 1;
632 frac[fracsize - 1] = cy;
634 else if (BITS_PER_MP_LIMB - 1 - cnt_h <= cnt_l)
636 (void) __mpn_rshift (frac, tmp + i, tmpsize - i,
637 BITS_PER_MP_LIMB - 1 - cnt_h);
638 fracsize = tmpsize - i;
640 else
642 /* We can only save the memory of the limbs which
643 are zero. The non-zero parts occupy the same
644 number of limbs. */
646 (void) __mpn_rshift (frac, tmp + (i - 1),
647 tmpsize - (i - 1),
648 BITS_PER_MP_LIMB - 1 - cnt_h);
649 fracsize = tmpsize - (i - 1);
652 used_limbs = fracsize - 1;
655 --explog;
657 while (tens != &_fpioconst_pow10[1] && exponent > 0);
658 /* All factors but 10^-1 are tested now. */
659 if (exponent > 0)
661 int cnt_l;
663 cy = __mpn_mul_1 (tmp, frac, fracsize, 10);
664 tmpsize = fracsize;
665 assert (cy == 0 || tmp[tmpsize - 1] < 20);
667 count_trailing_zeros (cnt_l, tmp[0]);
668 if (cnt_l < MIN (4, exponent))
670 cy = __mpn_lshift (frac, tmp, tmpsize,
671 BITS_PER_MP_LIMB - MIN (4, exponent));
672 if (cy != 0)
673 frac[tmpsize++] = cy;
675 else
676 (void) __mpn_rshift (frac, tmp, tmpsize, MIN (4, exponent));
677 fracsize = tmpsize;
678 exp10 |= 1;
679 assert (frac[fracsize - 1] < 10);
681 exponent = exp10;
683 else
685 /* This is a special case. We don't need a factor because the
686 numbers are in the range of 0.0 <= fp < 8.0. We simply
687 shift it to the right place and divide it by 1.0 to get the
688 leading digit. (Of course this division is not really made.) */
689 assert (0 <= exponent && exponent < 3 &&
690 exponent + to_shift < BITS_PER_MP_LIMB);
692 /* Now shift the input value to its right place. */
693 cy = __mpn_lshift (frac, fp_input, fracsize, (exponent + to_shift));
694 frac[fracsize++] = cy;
695 exponent = 0;
699 int width = info->width;
700 char *buffer, *startp, *cp;
701 int chars_needed;
702 int expscale;
703 int intdig_max, intdig_no = 0;
704 int fracdig_min, fracdig_max, fracdig_no = 0;
705 int dig_max;
706 int significant;
708 if (tolower (info->spec) == 'e')
710 type = info->spec;
711 intdig_max = 1;
712 fracdig_min = fracdig_max = info->prec < 0 ? 6 : info->prec;
713 chars_needed = 1 + 1 + fracdig_max + 1 + 1 + 4;
714 /* d . ddd e +- ddd */
715 dig_max = INT_MAX; /* Unlimited. */
716 significant = 1; /* Does not matter here. */
718 else if (info->spec == 'f')
720 type = 'f';
721 fracdig_min = fracdig_max = info->prec < 0 ? 6 : info->prec;
722 if (expsign == 0)
724 intdig_max = exponent + 1;
725 /* This can be really big! */ /* XXX Maybe malloc if too big? */
726 chars_needed = exponent + 1 + 1 + fracdig_max;
728 else
730 intdig_max = 1;
731 chars_needed = 1 + 1 + fracdig_max;
733 dig_max = INT_MAX; /* Unlimited. */
734 significant = 1; /* Does not matter here. */
736 else
738 dig_max = info->prec < 0 ? 6 : (info->prec == 0 ? 1 : info->prec);
739 if ((expsign == 0 && exponent >= dig_max)
740 || (expsign != 0 && exponent > 4))
742 type = isupper (info->spec) ? 'E' : 'e';
743 fracdig_max = dig_max - 1;
744 intdig_max = 1;
745 chars_needed = 1 + 1 + fracdig_max + 1 + 1 + 4;
747 else
749 type = 'f';
750 intdig_max = expsign == 0 ? exponent + 1 : 0;
751 fracdig_max = dig_max - intdig_max;
752 /* We need space for the significant digits and perhaps for
753 leading zeros when < 1.0. Pessimistic guess: dig_max. */
754 chars_needed = dig_max + dig_max + 1;
756 fracdig_min = info->alt ? fracdig_max : 0;
757 significant = 0; /* We count significant digits. */
760 if (grouping)
761 /* Guess the number of groups we will make, and thus how
762 many spaces we need for separator characters. */
763 chars_needed += __guess_grouping (intdig_max, grouping, thousands_sep);
765 /* Allocate buffer for output. We need two more because while rounding
766 it is possible that we need two more characters in front of all the
767 other output. */
768 buffer = alloca (2 + chars_needed);
769 cp = startp = buffer + 2; /* Let room for rounding. */
771 /* Do the real work: put digits in allocated buffer. */
772 if (expsign == 0 || type != 'f')
774 assert (expsign == 0 || intdig_max == 1);
775 while (intdig_no < intdig_max)
777 ++intdig_no;
778 *cp++ = hack_digit ();
780 significant = 1;
781 if (info->alt
782 || fracdig_min > 0
783 || (fracdig_max > 0 && (fracsize > 1 || frac[0] != 0)))
784 *cp++ = decimal;
786 else
788 /* |fp| < 1.0 and the selected type is 'f', so put "0."
789 in the buffer. */
790 *cp++ = '0';
791 --exponent;
792 *cp++ = decimal;
795 /* Generate the needed number of fractional digits. */
796 while (fracdig_no < fracdig_min
797 || (fracdig_no < fracdig_max && (fracsize > 1 || frac[0] != 0)))
799 ++fracdig_no;
800 *cp = hack_digit ();
801 if (*cp != '0')
802 significant = 1;
803 else if (significant == 0)
805 ++fracdig_max;
806 if (fracdig_min > 0)
807 ++fracdig_min;
809 ++cp;
812 /* Do rounding. */
813 digit = hack_digit ();
814 if (digit > '4')
816 char *tp = cp;
818 if (digit == '5' && (*(cp - 1) & 1) == 0)
819 /* This is the critical case. */
820 if (fracsize == 1 && frac[0] == 0)
821 /* Rest of the number is zero -> round to even.
822 (IEEE 754-1985 4.1 says this is the default rounding.) */
823 goto do_expo;
824 else if (scalesize == 0)
826 /* Here we have to see whether all limbs are zero since no
827 normalization happened. */
828 size_t lcnt = fracsize;
829 while (lcnt >= 1 && frac[lcnt - 1] == 0)
830 --lcnt;
831 if (lcnt == 0)
832 /* Rest of the number is zero -> round to even.
833 (IEEE 754-1985 4.1 says this is the default rounding.) */
834 goto do_expo;
837 if (fracdig_no > 0)
839 /* Process fractional digits. Terminate if not rounded or
840 radix character is reached. */
841 while (*--tp != decimal && *tp == '9')
842 *tp = '0';
843 if (*tp != decimal)
844 /* Round up. */
845 (*tp)++;
848 if (fracdig_no == 0 || *tp == decimal)
850 /* Round the integer digits. */
851 if (*(tp - 1) == decimal)
852 --tp;
854 while (--tp >= startp && *tp == '9')
855 *tp = '0';
857 if (tp >= startp)
858 /* Round up. */
859 (*tp)++;
860 else
861 /* It is more critical. All digits were 9's. */
863 if (type != 'f')
865 *startp = '1';
866 exponent += expsign == 0 ? 1 : -1;
868 else if (intdig_no == dig_max)
870 /* This is the case where for type %g the number fits
871 really in the range for %f output but after rounding
872 the number of digits is too big. */
873 *--startp = decimal;
874 *--startp = '1';
876 if (info->alt || fracdig_no > 0)
878 /* Overwrite the old radix character. */
879 startp[intdig_no + 2] = '0';
880 ++fracdig_no;
883 fracdig_no += intdig_no;
884 intdig_no = 1;
885 fracdig_max = intdig_max - intdig_no;
886 ++exponent;
887 /* Now we must print the exponent. */
888 type = isupper (info->spec) ? 'E' : 'e';
890 else
892 /* We can simply add another another digit before the
893 radix. */
894 *--startp = '1';
895 ++intdig_no;
898 /* While rounding the number of digits can change.
899 If the number now exceeds the limits remove some
900 fractional digits. */
901 if (intdig_no + fracdig_no > dig_max)
903 cp -= intdig_no + fracdig_no - dig_max;
904 fracdig_no -= intdig_no + fracdig_no - dig_max;
910 do_expo:
911 /* Now remove unnecessary '0' at the end of the string. */
912 while (fracdig_no > fracdig_min && *(cp - 1) == '0')
914 --cp;
915 --fracdig_no;
917 /* If we eliminate all fractional digits we perhaps also can remove
918 the radix character. */
919 if (fracdig_no == 0 && !info->alt && *(cp - 1) == decimal)
920 --cp;
922 if (grouping)
923 /* Add in separator characters, overwriting the same buffer. */
924 cp = group_number (startp, cp, intdig_no, grouping, thousands_sep);
926 /* Write the exponent if it is needed. */
927 if (type != 'f')
929 *cp++ = type;
930 *cp++ = expsign ? '-' : '+';
932 /* Find the magnitude of the exponent. */
933 expscale = 10;
934 while (expscale <= exponent)
935 expscale *= 10;
937 if (exponent < 10)
938 /* Exponent always has at least two digits. */
939 *cp++ = '0';
940 else
943 expscale /= 10;
944 *cp++ = '0' + (exponent / expscale);
945 exponent %= expscale;
947 while (expscale > 10);
948 *cp++ = '0' + exponent;
951 /* Compute number of characters which must be filled with the padding
952 character. */
953 if (is_neg || info->showsign || info->space)
954 --width;
955 width -= cp - startp;
957 if (!info->left && info->pad != '0' && width > 0)
958 PADN (info->pad, width);
960 if (is_neg)
961 outchar ('-');
962 else if (info->showsign)
963 outchar ('+');
964 else if (info->space)
965 outchar (' ');
967 if (!info->left && info->pad == '0' && width > 0)
968 PADN ('0', width);
970 PRINT (startp, cp - startp);
972 if (info->left && width > 0)
973 PADN (info->pad, width);
975 return done;
978 /* Return the number of extra grouping characters that will be inserted
979 into a number with INTDIG_MAX integer digits. */
981 unsigned int
982 __guess_grouping (unsigned int intdig_max, const char *grouping,
983 wchar_t sepchar)
985 unsigned int groups;
987 /* We treat all negative values like CHAR_MAX. */
989 if (*grouping == CHAR_MAX || *grouping <= 0)
990 /* No grouping should be done. */
991 return 0;
993 groups = 0;
994 while (intdig_max > (unsigned int) *grouping)
996 ++groups;
997 intdig_max -= *grouping++;
999 if (*grouping == CHAR_MAX
1000 #if CHAR_MIN < 0
1001 || *grouping < 0
1002 #endif
1004 /* No more grouping should be done. */
1005 break;
1006 else if (*grouping == 0)
1008 /* Same grouping repeats. */
1009 groups += (intdig_max - 1) / grouping[-1];
1010 break;
1014 return groups;
1017 /* Group the INTDIG_NO integer digits of the number in [BUF,BUFEND).
1018 There is guaranteed enough space past BUFEND to extend it.
1019 Return the new end of buffer. */
1021 static char *
1022 internal_function
1023 group_number (char *buf, char *bufend, unsigned int intdig_no,
1024 const char *grouping, wchar_t thousands_sep)
1026 unsigned int groups = __guess_grouping (intdig_no, grouping, thousands_sep);
1027 char *p;
1029 if (groups == 0)
1030 return bufend;
1032 /* Move the fractional part down. */
1033 memmove (buf + intdig_no + groups, buf + intdig_no,
1034 bufend - (buf + intdig_no));
1036 p = buf + intdig_no + groups - 1;
1039 unsigned int len = *grouping++;
1041 *p-- = buf[--intdig_no];
1042 while (--len > 0);
1043 *p-- = thousands_sep;
1045 if (*grouping == CHAR_MAX
1046 #if CHAR_MIN < 0
1047 || *grouping < 0
1048 #endif
1050 /* No more grouping should be done. */
1051 break;
1052 else if (*grouping == 0)
1053 /* Same grouping repeats. */
1054 --grouping;
1055 } while (intdig_no > (unsigned int) *grouping);
1057 /* Copy the remaining ungrouped digits. */
1059 *p-- = buf[--intdig_no];
1060 while (p > buf);
1062 return bufend + groups;