1 /* $NetBSD: vfprintf.c,v 1.30 1998/11/15 17:19:05 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1990 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char *sccsid = "@(#)vfprintf.c 5.50 (Berkeley) 12/16/92"; 43 #else 44 __RCSID("$NetBSD: vfprintf.c,v 1.30 1998/11/15 17:19:05 christos Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 /* 49 * Actual printf innards. 50 * 51 * This code is large and complicated... 52 */ 53 54 #include "namespace.h" 55 #include <sys/types.h> 56 #include <errno.h> 57 #include <stdio.h> 58 #include <stdlib.h> 59 #include <string.h> 60 61 #if __STDC__ 62 #include <stdarg.h> 63 #else 64 #include <varargs.h> 65 #endif 66 67 #include "local.h" 68 #include "fvwrite.h" 69 #include "extern.h" 70 #include "reentrant.h" 71 72 static int __sprint __P((FILE *, struct __suio *)); 73 static int __sbprintf __P((FILE *, const char *, va_list)); 74 75 /* 76 * Flush out all the vectors defined by the given uio, 77 * then reset it so that it can be reused. 78 */ 79 static int 80 __sprint(fp, uio) 81 FILE *fp; 82 struct __suio *uio; 83 { 84 int err; 85 86 if (uio->uio_resid == 0) { 87 uio->uio_iovcnt = 0; 88 return (0); 89 } 90 err = __sfvwrite(fp, uio); 91 uio->uio_resid = 0; 92 uio->uio_iovcnt = 0; 93 return (err); 94 } 95 96 /* 97 * Helper function for `fprintf to unbuffered unix file': creates a 98 * temporary buffer. We only work on write-only files; this avoids 99 * worries about ungetc buffers and so forth. 100 */ 101 static int 102 __sbprintf(fp, fmt, ap) 103 FILE *fp; 104 const char *fmt; 105 va_list ap; 106 { 107 int ret; 108 FILE fake; 109 unsigned char buf[BUFSIZ]; 110 111 /* copy the important variables */ 112 fake._flags = fp->_flags & ~__SNBF; 113 fake._file = fp->_file; 114 fake._cookie = fp->_cookie; 115 fake._write = fp->_write; 116 117 /* set up the buffer */ 118 fake._bf._base = fake._p = buf; 119 fake._bf._size = fake._w = sizeof(buf); 120 fake._lbfsize = 0; /* not actually used, but Just In Case */ 121 122 /* do the work, then copy any error status */ 123 ret = vfprintf(&fake, fmt, ap); 124 if (ret >= 0 && fflush(&fake)) 125 ret = -1; 126 if (fake._flags & __SERR) 127 fp->_flags |= __SERR; 128 return (ret); 129 } 130 131 132 #ifdef FLOATING_POINT 133 #include <locale.h> 134 #include <math.h> 135 #include "floatio.h" 136 137 #define BUF (MAXEXP+MAXFRACT+1) /* + decimal point */ 138 #define DEFPREC 6 139 140 static char *cvt __P((double, int, int, char *, int *, int, int *)); 141 static int exponent __P((char *, int, int)); 142 143 #else /* no FLOATING_POINT */ 144 145 #define BUF 40 146 147 #endif /* FLOATING_POINT */ 148 149 #ifdef lint 150 static __inline void *__UNCONST __P((const void *)); 151 static __inline void * 152 __UNCONST(v) 153 const void *v; 154 { 155 /* LINTED */ 156 return (void *) v; 157 } 158 #else 159 #define __UNCONST(v) (void *)(v) 160 #endif 161 162 /* 163 * Macros for converting digits to letters and vice versa 164 */ 165 #define to_digit(c) ((c) - '0') 166 #define is_digit(c) ((unsigned)to_digit(c) <= 9) 167 #define to_char(n) ((char)((n) + '0')) 168 169 /* 170 * Flags used during conversion. 171 */ 172 #define ALT 0x001 /* alternate form */ 173 #define HEXPREFIX 0x002 /* add 0x or 0X prefix */ 174 #define LADJUST 0x004 /* left adjustment */ 175 #define LONGDBL 0x008 /* long double; unimplemented */ 176 #define LONGINT 0x010 /* long integer */ 177 #define QUADINT 0x020 /* quad integer */ 178 #define SHORTINT 0x040 /* short integer */ 179 #define ZEROPAD 0x080 /* zero (as opposed to blank) pad */ 180 #define FPT 0x100 /* Floating point number */ 181 int 182 vfprintf(fp, fmt0, ap) 183 FILE *fp; 184 const char *fmt0; 185 _BSD_VA_LIST_ ap; 186 { 187 const char *fmt;/* format string */ 188 int ch; /* character from fmt */ 189 int n, m; /* handy integers (short term usage) */ 190 const char *cp; /* handy char pointer (short term usage) */ 191 char *bp; /* handy char pointer (short term usage) */ 192 struct __siov *iovp;/* for PRINT macro */ 193 int flags; /* flags as above */ 194 int ret; /* return value accumulator */ 195 int width; /* width from format (%8d), or 0 */ 196 int prec; /* precision from format (%.3d), or -1 */ 197 char sign; /* sign prefix (' ', '+', '-', or \0) */ 198 wchar_t wc; 199 #ifdef FLOATING_POINT 200 char *decimal_point = localeconv()->decimal_point; 201 char softsign; /* temporary negative sign for floats */ 202 double _double = 0; /* double precision arguments %[eEfgG] */ 203 int expt; /* integer value of exponent */ 204 int expsize = 0; /* character count for expstr */ 205 int ndig; /* actual number of digits returned by cvt */ 206 char expstr[7]; /* buffer for exponent string */ 207 #endif 208 209 #ifdef __GNUC__ /* gcc has builtin quad type (long long) SOS */ 210 #define quad_t long long 211 #define u_quad_t unsigned long long 212 #endif 213 214 u_quad_t _uquad; /* integer arguments %[diouxX] */ 215 enum { OCT, DEC, HEX } base;/* base for [diouxX] conversion */ 216 int dprec; /* a copy of prec if [diouxX], 0 otherwise */ 217 int realsz; /* field size expanded by dprec */ 218 int size; /* size of converted field or string */ 219 char *xdigs = NULL; /* digits for [xX] conversion */ 220 #define NIOV 8 221 struct __suio uio; /* output information: summary */ 222 struct __siov iov[NIOV];/* ... and individual io vectors */ 223 char buf[BUF]; /* space for %c, %[diouxX], %[eEfgG] */ 224 char ox[2]; /* space for 0x hex-prefix */ 225 226 /* 227 * Choose PADSIZE to trade efficiency vs. size. If larger printf 228 * fields occur frequently, increase PADSIZE and make the initialisers 229 * below longer. 230 */ 231 #define PADSIZE 16 /* pad chunk size */ 232 static const char blanks[PADSIZE] = 233 {' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' '}; 234 static const char zeroes[PADSIZE] = 235 {'0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'}; 236 237 /* 238 * BEWARE, these `goto error' on error, and PAD uses `n'. 239 */ 240 #define PRINT(ptr, len) { \ 241 iovp->iov_base = __UNCONST(ptr); \ 242 iovp->iov_len = (len); \ 243 uio.uio_resid += (len); \ 244 iovp++; \ 245 if (++uio.uio_iovcnt >= NIOV) { \ 246 if (__sprint(fp, &uio)) \ 247 goto error; \ 248 iovp = iov; \ 249 } \ 250 } 251 #define PAD(howmany, with) { \ 252 if ((n = (howmany)) > 0) { \ 253 while (n > PADSIZE) { \ 254 PRINT(with, PADSIZE); \ 255 n -= PADSIZE; \ 256 } \ 257 PRINT(with, n); \ 258 } \ 259 } 260 #define FLUSH() { \ 261 if (uio.uio_resid && __sprint(fp, &uio)) \ 262 goto error; \ 263 uio.uio_iovcnt = 0; \ 264 iovp = iov; \ 265 } 266 267 /* 268 * To extend shorts properly, we need both signed and unsigned 269 * argument extraction methods. 270 */ 271 #define SARG() \ 272 (flags&QUADINT ? va_arg(ap, quad_t) : \ 273 flags&LONGINT ? va_arg(ap, long) : \ 274 flags&SHORTINT ? (long)(short)va_arg(ap, int) : \ 275 (long)va_arg(ap, int)) 276 #define UARG() \ 277 (flags&QUADINT ? va_arg(ap, u_quad_t) : \ 278 flags&LONGINT ? va_arg(ap, u_long) : \ 279 flags&SHORTINT ? (u_long)(u_short)va_arg(ap, int) : \ 280 (u_long)va_arg(ap, u_int)) 281 282 FLOCKFILE(fp); 283 284 /* sorry, fprintf(read_only_file, "") returns -1, not 0 */ 285 if (cantwrite(fp)) { 286 errno = EBADF; 287 FUNLOCKFILE(fp); 288 return (-1); 289 } 290 291 /* optimise fprintf(stderr) (and other unbuffered Unix files) */ 292 if ((fp->_flags & (__SNBF|__SWR|__SRW)) == (__SNBF|__SWR) && 293 fp->_file >= 0) { 294 ret = __sbprintf(fp, fmt0, ap); 295 FUNLOCKFILE(fp); 296 return (ret); 297 } 298 299 fmt = fmt0; 300 uio.uio_iov = iovp = iov; 301 uio.uio_resid = 0; 302 uio.uio_iovcnt = 0; 303 ret = 0; 304 305 /* 306 * Scan the format for conversions (`%' character). 307 */ 308 for (;;) { 309 cp = fmt; 310 while ((n = mbtowc(&wc, fmt, MB_CUR_MAX)) > 0) { 311 fmt += n; 312 if (wc == '%') { 313 fmt--; 314 break; 315 } 316 } 317 if ((m = fmt - cp) != 0) { 318 PRINT(cp, m); 319 ret += m; 320 } 321 if (n <= 0) 322 goto done; 323 fmt++; /* skip over '%' */ 324 325 flags = 0; 326 dprec = 0; 327 width = 0; 328 prec = -1; 329 sign = '\0'; 330 331 rflag: ch = *fmt++; 332 reswitch: switch (ch) { 333 case ' ': 334 /* 335 * ``If the space and + flags both appear, the space 336 * flag will be ignored.'' 337 * -- ANSI X3J11 338 */ 339 if (!sign) 340 sign = ' '; 341 goto rflag; 342 case '#': 343 flags |= ALT; 344 goto rflag; 345 case '*': 346 /* 347 * ``A negative field width argument is taken as a 348 * - flag followed by a positive field width.'' 349 * -- ANSI X3J11 350 * They don't exclude field widths read from args. 351 */ 352 if ((width = va_arg(ap, int)) >= 0) 353 goto rflag; 354 width = -width; 355 /* FALLTHROUGH */ 356 case '-': 357 flags |= LADJUST; 358 goto rflag; 359 case '+': 360 sign = '+'; 361 goto rflag; 362 case '.': 363 if ((ch = *fmt++) == '*') { 364 n = va_arg(ap, int); 365 prec = n < 0 ? -1 : n; 366 goto rflag; 367 } 368 n = 0; 369 while (is_digit(ch)) { 370 n = 10 * n + to_digit(ch); 371 ch = *fmt++; 372 } 373 prec = n < 0 ? -1 : n; 374 goto reswitch; 375 case '0': 376 /* 377 * ``Note that 0 is taken as a flag, not as the 378 * beginning of a field width.'' 379 * -- ANSI X3J11 380 */ 381 flags |= ZEROPAD; 382 goto rflag; 383 case '1': case '2': case '3': case '4': 384 case '5': case '6': case '7': case '8': case '9': 385 n = 0; 386 do { 387 n = 10 * n + to_digit(ch); 388 ch = *fmt++; 389 } while (is_digit(ch)); 390 width = n; 391 goto reswitch; 392 #ifdef FLOATING_POINT 393 case 'L': 394 flags |= LONGDBL; 395 goto rflag; 396 #endif 397 case 'h': 398 flags |= SHORTINT; 399 goto rflag; 400 case 'l': 401 if (*fmt == 'l') { 402 fmt++; 403 flags |= QUADINT; 404 } else { 405 flags |= LONGINT; 406 } 407 goto rflag; 408 case 'q': 409 flags |= QUADINT; 410 goto rflag; 411 case 'c': 412 *buf = va_arg(ap, int); 413 cp = buf; 414 size = 1; 415 sign = '\0'; 416 break; 417 case 'D': 418 flags |= LONGINT; 419 /*FALLTHROUGH*/ 420 case 'd': 421 case 'i': 422 _uquad = SARG(); 423 if ((quad_t)_uquad < 0) { 424 _uquad = -_uquad; 425 sign = '-'; 426 } 427 base = DEC; 428 goto number; 429 #ifdef FLOATING_POINT 430 case 'e': 431 case 'E': 432 case 'f': 433 case 'g': 434 case 'G': 435 if (prec == -1) { 436 prec = DEFPREC; 437 } else if ((ch == 'g' || ch == 'G') && prec == 0) { 438 prec = 1; 439 } 440 441 if (flags & LONGDBL) { 442 _double = (double) va_arg(ap, long double); 443 } else { 444 _double = va_arg(ap, double); 445 } 446 447 /* do this before tricky precision changes */ 448 if (isinf(_double)) { 449 if (_double < 0) 450 sign = '-'; 451 cp = "Inf"; 452 size = 3; 453 break; 454 } 455 if (isnan(_double)) { 456 cp = "NaN"; 457 size = 3; 458 break; 459 } 460 461 flags |= FPT; 462 cp = cvt(_double, prec, flags, &softsign, 463 &expt, ch, &ndig); 464 if (ch == 'g' || ch == 'G') { 465 if (expt <= -4 || expt > prec) 466 ch = (ch == 'g') ? 'e' : 'E'; 467 else 468 ch = 'g'; 469 } 470 if (ch <= 'e') { /* 'e' or 'E' fmt */ 471 --expt; 472 expsize = exponent(expstr, expt, ch); 473 size = expsize + ndig; 474 if (ndig > 1 || flags & ALT) 475 ++size; 476 } else if (ch == 'f') { /* f fmt */ 477 if (expt > 0) { 478 size = expt; 479 if (prec || flags & ALT) 480 size += prec + 1; 481 } else /* "0.X" */ 482 size = prec + 2; 483 } else if (expt >= ndig) { /* fixed g fmt */ 484 size = expt; 485 if (flags & ALT) 486 ++size; 487 } else 488 size = ndig + (expt > 0 ? 489 1 : 2 - expt); 490 491 if (softsign) 492 sign = '-'; 493 break; 494 #endif /* FLOATING_POINT */ 495 case 'n': 496 if (flags & QUADINT) 497 *va_arg(ap, quad_t *) = ret; 498 else if (flags & LONGINT) 499 *va_arg(ap, long *) = ret; 500 else if (flags & SHORTINT) 501 *va_arg(ap, short *) = ret; 502 else 503 *va_arg(ap, int *) = ret; 504 continue; /* no output */ 505 case 'O': 506 flags |= LONGINT; 507 /*FALLTHROUGH*/ 508 case 'o': 509 _uquad = UARG(); 510 base = OCT; 511 goto nosign; 512 case 'p': 513 /* 514 * ``The argument shall be a pointer to void. The 515 * value of the pointer is converted to a sequence 516 * of printable characters, in an implementation- 517 * defined manner.'' 518 * -- ANSI X3J11 519 */ 520 /* NOSTRICT */ 521 _uquad = (u_long)va_arg(ap, void *); 522 base = HEX; 523 xdigs = "0123456789abcdef"; 524 flags |= HEXPREFIX; 525 ch = 'x'; 526 goto nosign; 527 case 's': 528 if ((cp = va_arg(ap, char *)) == NULL) 529 cp = "(null)"; 530 if (prec >= 0) { 531 /* 532 * can't use strlen; can only look for the 533 * NUL in the first `prec' characters, and 534 * strlen() will go further. 535 */ 536 char *p = memchr(cp, 0, (size_t)prec); 537 538 if (p != NULL) { 539 size = p - cp; 540 if (size > prec) 541 size = prec; 542 } else 543 size = prec; 544 } else 545 size = strlen(cp); 546 sign = '\0'; 547 break; 548 case 'U': 549 flags |= LONGINT; 550 /*FALLTHROUGH*/ 551 case 'u': 552 _uquad = UARG(); 553 base = DEC; 554 goto nosign; 555 case 'X': 556 xdigs = "0123456789ABCDEF"; 557 goto hex; 558 case 'x': 559 xdigs = "0123456789abcdef"; 560 hex: _uquad = UARG(); 561 base = HEX; 562 /* leading 0x/X only if non-zero */ 563 if (flags & ALT && _uquad != 0) 564 flags |= HEXPREFIX; 565 566 /* unsigned conversions */ 567 nosign: sign = '\0'; 568 /* 569 * ``... diouXx conversions ... if a precision is 570 * specified, the 0 flag will be ignored.'' 571 * -- ANSI X3J11 572 */ 573 number: if ((dprec = prec) >= 0) 574 flags &= ~ZEROPAD; 575 576 /* 577 * ``The result of converting a zero value with an 578 * explicit precision of zero is no characters.'' 579 * -- ANSI X3J11 580 */ 581 bp = buf + BUF; 582 if (_uquad != 0 || prec != 0) { 583 /* 584 * Unsigned mod is hard, and unsigned mod 585 * by a constant is easier than that by 586 * a variable; hence this switch. 587 */ 588 switch (base) { 589 case OCT: 590 do { 591 *--bp = to_char(_uquad & 7); 592 _uquad >>= 3; 593 } while (_uquad); 594 /* handle octal leading 0 */ 595 if (flags & ALT && *bp != '0') 596 *--bp = '0'; 597 break; 598 599 case DEC: 600 /* many numbers are 1 digit */ 601 while (_uquad >= 10) { 602 *--bp = to_char(_uquad % 10); 603 _uquad /= 10; 604 } 605 *--bp = to_char(_uquad); 606 break; 607 608 case HEX: 609 do { 610 *--bp = xdigs[(size_t) 611 (_uquad & 15)]; 612 _uquad >>= 4; 613 } while (_uquad); 614 break; 615 616 default: 617 cp = "bug in vfprintf: bad base"; 618 size = strlen(cp); 619 goto skipsize; 620 } 621 } 622 cp = bp; 623 size = buf + BUF - bp; 624 skipsize: 625 break; 626 default: /* "%?" prints ?, unless ? is NUL */ 627 if (ch == '\0') 628 goto done; 629 /* pretend it was %c with argument ch */ 630 *buf = ch; 631 cp = buf; 632 size = 1; 633 sign = '\0'; 634 break; 635 } 636 637 /* 638 * All reasonable formats wind up here. At this point, `cp' 639 * points to a string which (if not flags&LADJUST) should be 640 * padded out to `width' places. If flags&ZEROPAD, it should 641 * first be prefixed by any sign or other prefix; otherwise, 642 * it should be blank padded before the prefix is emitted. 643 * After any left-hand padding and prefixing, emit zeroes 644 * required by a decimal [diouxX] precision, then print the 645 * string proper, then emit zeroes required by any leftover 646 * floating precision; finally, if LADJUST, pad with blanks. 647 * 648 * Compute actual size, so we know how much to pad. 649 * size excludes decimal prec; realsz includes it. 650 */ 651 realsz = dprec > size ? dprec : size; 652 if (sign) 653 realsz++; 654 else if (flags & HEXPREFIX) 655 realsz+= 2; 656 657 /* right-adjusting blank padding */ 658 if ((flags & (LADJUST|ZEROPAD)) == 0) 659 PAD(width - realsz, blanks); 660 661 /* prefix */ 662 if (sign) { 663 PRINT(&sign, 1); 664 } else if (flags & HEXPREFIX) { 665 ox[0] = '0'; 666 ox[1] = ch; 667 PRINT(ox, 2); 668 } 669 670 /* right-adjusting zero padding */ 671 if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD) 672 PAD(width - realsz, zeroes); 673 674 /* leading zeroes from decimal precision */ 675 PAD(dprec - size, zeroes); 676 677 /* the string or number proper */ 678 #ifdef FLOATING_POINT 679 if ((flags & FPT) == 0) { 680 PRINT(cp, size); 681 } else { /* glue together f_p fragments */ 682 if (ch >= 'f') { /* 'f' or 'g' */ 683 if (_double == 0) { 684 /* kludge for __dtoa irregularity */ 685 PRINT("0", 1); 686 if (expt < ndig || (flags & ALT) != 0) { 687 PRINT(decimal_point, 1); 688 PAD(ndig - 1, zeroes); 689 } 690 } else if (expt <= 0) { 691 PRINT("0", 1); 692 PRINT(decimal_point, 1); 693 PAD(-expt, zeroes); 694 PRINT(cp, ndig); 695 } else if (expt >= ndig) { 696 PRINT(cp, ndig); 697 PAD(expt - ndig, zeroes); 698 if (flags & ALT) 699 PRINT(".", 1); 700 } else { 701 PRINT(cp, expt); 702 cp += expt; 703 PRINT(".", 1); 704 PRINT(cp, ndig-expt); 705 } 706 } else { /* 'e' or 'E' */ 707 if (ndig > 1 || flags & ALT) { 708 ox[0] = *cp++; 709 ox[1] = '.'; 710 PRINT(ox, 2); 711 if (_double) { 712 PRINT(cp, ndig-1); 713 } else /* 0.[0..] */ 714 /* __dtoa irregularity */ 715 PAD(ndig - 1, zeroes); 716 } else /* XeYYY */ 717 PRINT(cp, 1); 718 PRINT(expstr, expsize); 719 } 720 } 721 #else 722 PRINT(cp, size); 723 #endif 724 /* left-adjusting padding (always blank) */ 725 if (flags & LADJUST) 726 PAD(width - realsz, blanks); 727 728 /* finally, adjust ret */ 729 ret += width > realsz ? width : realsz; 730 731 FLUSH(); /* copy out the I/O vectors */ 732 } 733 done: 734 FLUSH(); 735 error: 736 if (__sferror(fp)) 737 ret = -1; 738 FUNLOCKFILE(fp); 739 return (ret); 740 } 741 742 #ifdef FLOATING_POINT 743 744 static char * 745 cvt(value, ndigits, flags, sign, decpt, ch, length) 746 double value; 747 int ndigits, flags, *decpt, ch, *length; 748 char *sign; 749 { 750 int mode, dsgn; 751 char *digits, *bp, *rve; 752 753 if (ch == 'f') { 754 mode = 3; /* ndigits after the decimal point */ 755 } else { 756 /* To obtain ndigits after the decimal point for the 'e' 757 * and 'E' formats, round to ndigits + 1 significant 758 * figures. 759 */ 760 if (ch == 'e' || ch == 'E') { 761 ndigits++; 762 } 763 mode = 2; /* ndigits significant digits */ 764 } 765 766 if (value < 0) { 767 value = -value; 768 *sign = '-'; 769 } else 770 *sign = '\000'; 771 digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve); 772 if ((ch != 'g' && ch != 'G') || flags & ALT) { /* Print trailing zeros */ 773 bp = digits + ndigits; 774 if (ch == 'f') { 775 if (*digits == '0' && value) 776 *decpt = -ndigits + 1; 777 bp += *decpt; 778 } 779 if (value == 0) /* kludge for __dtoa irregularity */ 780 rve = bp; 781 while (rve < bp) 782 *rve++ = '0'; 783 } 784 *length = rve - digits; 785 return (digits); 786 } 787 788 static int 789 exponent(p0, exp, fmtch) 790 char *p0; 791 int exp, fmtch; 792 { 793 char *p, *t; 794 char expbuf[MAXEXP]; 795 796 p = p0; 797 *p++ = fmtch; 798 if (exp < 0) { 799 exp = -exp; 800 *p++ = '-'; 801 } 802 else 803 *p++ = '+'; 804 t = expbuf + MAXEXP; 805 if (exp > 9) { 806 do { 807 *--t = to_char(exp % 10); 808 } while ((exp /= 10) > 9); 809 *--t = to_char(exp); 810 for (; t < expbuf + MAXEXP; *p++ = *t++); 811 } 812 else { 813 *p++ = '0'; 814 *p++ = to_char(exp); 815 } 816 return (p - p0); 817 } 818 #endif /* FLOATING_POINT */ 819