lib/libc/stdtime/strftime.c

   1 /*
   2  * Copyright (c) 1989 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Copyright (c) 2011 The FreeBSD Foundation
   6  * All rights reserved.
   7  * Portions of this software were developed by David Chisnall
   8  * under sponsorship from the FreeBSD Foundation.
   9  *
  10  * Redistribution and use in source and binary forms are permitted
  11  * provided that the above copyright notice and this paragraph are
  12  * duplicated in all such forms and that any documentation,
  13  * advertising materials, and other materials related to such
  14  * distribution and use acknowledge that the software was developed
  15  * by the University of California, Berkeley. The name of the
  16  * University may not be used to endorse or promote products derived
  17  * from this software without specific prior written permission.
  18  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  19  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  20  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  21  *
  22  * @(#)strftime.c       5.4 (Berkeley) 3/14/89
  23  * $FreeBSD: head/lib/libc/stdtime/strftime.c 237211 2012-06-17 21:40:13Z jilles $
  24  */
  25
  26
  27 #include "namespace.h"
  28 #include "private.h"
  29
  30 #include "tzfile.h"
  31 #include <fcntl.h>
  32 #include <sys/stat.h>
  33 #include "un-namespace.h"
  34 #include "timelocal.h"
  35
  36 static char *   _add(const char *, char *, const char *);
  37 static char *   _conv(int, const char *, char *, const char *);
  38 static char *   _fmt(const char *, const struct tm *, char *, const char *,
  39                         int *, locale_t);
  40 static char *   _yconv(int, int, int, int, char *, const char *);
  41
  42 extern char *   tzname[];
  43
  44 #ifndef YEAR_2000_NAME
  45 #define YEAR_2000_NAME  "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
  46 #endif /* !defined YEAR_2000_NAME */
  47
  48 #define IN_NONE 0
  49 #define IN_SOME 1
  50 #define IN_THIS 2
  51 #define IN_ALL  3
  52
  53 #define PAD_DEFAULT     0
  54 #define PAD_LESS        1
  55 #define PAD_SPACE       2
  56 #define PAD_ZERO        3
  57
  58 static const char fmt_padding[][4][5] = {
  59         /* DEFAULT,     LESS,   SPACE,  ZERO */
  60 #define PAD_FMT_MONTHDAY        0
  61 #define PAD_FMT_HMS             0
  62 #define PAD_FMT_CENTURY         0
  63 #define PAD_FMT_SHORTYEAR       0
  64 #define PAD_FMT_MONTH           0
  65 #define PAD_FMT_WEEKOFYEAR      0
  66 #define PAD_FMT_DAYOFMONTH      0
  67         { "%02d",       "%d",   "%2d",  "%02d" },
  68 #define PAD_FMT_SDAYOFMONTH     1
  69 #define PAD_FMT_SHMS            1
  70         { "%2d",        "%d",   "%2d",  "%02d" },
  71 #define PAD_FMT_DAYOFYEAR       2
  72         { "%03d",       "%d",   "%3d",  "%03d" },
  73 #define PAD_FMT_YEAR            3
  74         { "%04d",       "%d",   "%4d",  "%04d" }
  75 };
  76
  77 size_t
  78 strftime_l(char * __restrict s, size_t maxsize, const char * __restrict format,
  79     const struct tm * __restrict t, locale_t loc)
  80 {
  81         char *  p;
  82         int     warn;
  83         FIX_LOCALE(loc);
  84
  85         tzset();
  86         warn = IN_NONE;
  87         p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn, loc);
  88 #ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
  89         if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
  90                 fprintf_l(stderr, loc, "\n");
  91                 if (format == NULL)
  92                         fprintf_l(stderr, loc, "NULL strftime format ");
  93                 else    fprintf_l(stderr, loc, "strftime format \"%s\" ",
  94                                 format);
  95                 fprintf_l(stderr, loc, "yields only two digits of years in ");
  96                 if (warn == IN_SOME)
  97                         fprintf_l(stderr, loc, "some locales");
  98                 else if (warn == IN_THIS)
  99                         fprintf_l(stderr, loc, "the current locale");
 100                 else    fprintf_l(stderr, loc, "all locales");
 101                 fprintf_l(stderr, loc, "\n");
 102         }
 103 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
 104         if (p == s + maxsize)
 105                 return 0;
 106         *p = '\0';
 107         return p - s;
 108 }
 109
 110 size_t
 111 strftime(char * __restrict s, size_t maxsize, const char * __restrict format,
 112     const struct tm * __restrict t)
 113 {
 114         return strftime_l(s, maxsize, format, t, __get_locale());
 115 }
 116
 117 static char *
 118 _fmt(const char *format, const struct tm * const t, char *pt,
 119     const char * const ptlim, int *warnp, locale_t loc)
 120 {
 121         int Ealternative, Oalternative, PadIndex;
 122         struct lc_time_T *tptr = __get_current_time_locale(loc);
 123
 124         for ( ; *format; ++format) {
 125                 if (*format == '%') {
 126                         Ealternative = 0;
 127                         Oalternative = 0;
 128                         PadIndex         = PAD_DEFAULT;
 129 label:
 130                         switch (*++format) {
 131                         case '\0':
 132                                 --format;
 133                                 break;
 134                         case 'A':
 135                                 pt = _add((t->tm_wday < 0 ||
 136                                         t->tm_wday >= DAYSPERWEEK) ?
 137                                         "?" : tptr->weekday[t->tm_wday],
 138                                         pt, ptlim);
 139                                 continue;
 140                         case 'a':
 141                                 pt = _add((t->tm_wday < 0 ||
 142                                         t->tm_wday >= DAYSPERWEEK) ?
 143                                         "?" : tptr->wday[t->tm_wday],
 144                                         pt, ptlim);
 145                                 continue;
 146                         case 'B':
 147                                 pt = _add((t->tm_mon < 0 ||
 148                                         t->tm_mon >= MONSPERYEAR) ?
 149                                         "?" : (Oalternative ? tptr->alt_month :
 150                                         tptr->month)[t->tm_mon],
 151                                         pt, ptlim);
 152                                 continue;
 153                         case 'b':
 154                         case 'h':
 155                                 pt = _add((t->tm_mon < 0 ||
 156                                         t->tm_mon >= MONSPERYEAR) ?
 157                                         "?" : tptr->mon[t->tm_mon],
 158                                         pt, ptlim);
 159                                 continue;
 160                         case 'C':
 161                                 /*
 162                                 ** %C used to do a...
 163                                 **      _fmt("%a %b %e %X %Y", t);
 164                                 ** ...whereas now POSIX 1003.2 calls for
 165                                 ** something completely different.
 166                                 ** (ado, 1993-05-24)
 167                                 */
 168                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
 169                                         pt, ptlim);
 170                                 continue;
 171                         case 'c':
 172                                 {
 173                                 int warn2 = IN_SOME;
 174
 175                                 pt = _fmt(tptr->c_fmt, t, pt, ptlim, &warn2, loc);
 176                                 if (warn2 == IN_ALL)
 177                                         warn2 = IN_THIS;
 178                                 if (warn2 > *warnp)
 179                                         *warnp = warn2;
 180                                 }
 181                                 continue;
 182                         case 'D':
 183                                 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp, loc);
 184                                 continue;
 185                         case 'd':
 186                                 pt = _conv(t->tm_mday, fmt_padding[PAD_FMT_DAYOFMONTH][PadIndex],
 187                                         pt, ptlim);
 188                                 continue;
 189                         case 'E':
 190                                 if (Ealternative || Oalternative)
 191                                         break;
 192                                 Ealternative++;
 193                                 goto label;
 194                         case 'O':
 195                                 /*
 196                                 ** C99 locale modifiers.
 197                                 ** The sequences
 198                                 **      %Ec %EC %Ex %EX %Ey %EY
 199                                 **      %Od %oe %OH %OI %Om %OM
 200                                 **      %OS %Ou %OU %OV %Ow %OW %Oy
 201                                 ** are supposed to provide alternate
 202                                 ** representations.
 203                                 **
 204                                 ** FreeBSD extension
 205                                 **      %OB
 206                                 */
 207                                 if (Ealternative || Oalternative)
 208                                         break;
 209                                 Oalternative++;
 210                                 goto label;
 211                         case 'e':
 212                                 pt = _conv(t->tm_mday,
 213                                         fmt_padding[PAD_FMT_SDAYOFMONTH][PadIndex], pt, ptlim);
 214                                 continue;
 215                         case 'F':
 216                                 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp, loc);
 217                                 continue;
 218                         case 'H':
 219                                 pt = _conv(t->tm_hour, fmt_padding[PAD_FMT_HMS][PadIndex],
 220                                         pt, ptlim);
 221                                 continue;
 222                         case 'I':
 223                                 pt = _conv((t->tm_hour % 12) ?
 224                                         (t->tm_hour % 12) : 12,
 225                                         fmt_padding[PAD_FMT_HMS][PadIndex], pt, ptlim);
 226                                 continue;
 227                         case 'j':
 228                                 pt = _conv(t->tm_yday + 1,
 229                                         fmt_padding[PAD_FMT_DAYOFYEAR][PadIndex], pt, ptlim);
 230                                 continue;
 231                         case 'k':
 232                                 /*
 233                                 ** This used to be...
 234                                 **      _conv(t->tm_hour % 12 ?
 235                                 **              t->tm_hour % 12 : 12, 2, ' ');
 236                                 ** ...and has been changed to the below to
 237                                 ** match SunOS 4.1.1 and Arnold Robbins'
 238                                 ** strftime version 3.0. That is, "%k" and
 239                                 ** "%l" have been swapped.
 240                                 ** (ado, 1993-05-24)
 241                                 */
 242                                 pt = _conv(t->tm_hour, fmt_padding[PAD_FMT_SHMS][PadIndex],
 243                                         pt, ptlim);
 244                                 continue;
 245 #ifdef KITCHEN_SINK
 246                         case 'K':
 247                                 /*
 248                                 ** After all this time, still unclaimed!
 249                                 */
 250                                 pt = _add("kitchen sink", pt, ptlim);
 251                                 continue;
 252 #endif /* defined KITCHEN_SINK */
 253                         case 'l':
 254                                 /*
 255                                 ** This used to be...
 256                                 **      _conv(t->tm_hour, 2, ' ');
 257                                 ** ...and has been changed to the below to
 258                                 ** match SunOS 4.1.1 and Arnold Robbin's
 259                                 ** strftime version 3.0. That is, "%k" and
 260                                 ** "%l" have been swapped.
 261                                 ** (ado, 1993-05-24)
 262                                 */
 263                                 pt = _conv((t->tm_hour % 12) ?
 264                                         (t->tm_hour % 12) : 12,
 265                                         fmt_padding[PAD_FMT_SHMS][PadIndex], pt, ptlim);
 266                                 continue;
 267                         case 'M':
 268                                 pt = _conv(t->tm_min, fmt_padding[PAD_FMT_HMS][PadIndex],
 269                                         pt, ptlim);
 270                                 continue;
 271                         case 'm':
 272                                 pt = _conv(t->tm_mon + 1,
 273                                         fmt_padding[PAD_FMT_MONTH][PadIndex], pt, ptlim);
 274                                 continue;
 275                         case 'n':
 276                                 pt = _add("\n", pt, ptlim);
 277                                 continue;
 278                         case 'p':
 279                                 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
 280                                         tptr->pm :
 281                                         tptr->am,
 282                                         pt, ptlim);
 283                                 continue;
 284                         case 'R':
 285                                 pt = _fmt("%H:%M", t, pt, ptlim, warnp, loc);
 286                                 continue;
 287                         case 'r':
 288                                 pt = _fmt(tptr->ampm_fmt, t, pt, ptlim,
 289                                         warnp, loc);
 290                                 continue;
 291                         case 'S':
 292                                 pt = _conv(t->tm_sec, fmt_padding[PAD_FMT_HMS][PadIndex],
 293                                         pt, ptlim);
 294                                 continue;
 295                         case 's':
 296                                 {
 297                                         struct tm       tm;
 298                                         char            buf[INT_STRLEN_MAXIMUM(
 299                                                                 time_t) + 1];
 300                                         time_t          mkt;
 301
 302                                         tm = *t;
 303                                         mkt = mktime(&tm);
 304                                         if (TYPE_SIGNED(time_t))
 305                                                 snprintf(buf, sizeof(buf),
 306                                                     "%"PRIdMAX,
 307                                                     (intmax_t) mkt);
 308                                         else    snprintf(buf, sizeof(buf),
 309                                                     "%"PRIuMAX,
 310                                                     (uintmax_t) mkt);
 311                                         pt = _add(buf, pt, ptlim);
 312                                 }
 313                                 continue;
 314                         case 'T':
 315                                 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp, loc);
 316                                 continue;
 317                         case 't':
 318                                 pt = _add("\t", pt, ptlim);
 319                                 continue;
 320                         case 'U':
 321                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 322                                         t->tm_wday) / DAYSPERWEEK,
 323                                         fmt_padding[PAD_FMT_WEEKOFYEAR][PadIndex], pt, ptlim);
 324                                 continue;
 325                         case 'u':
 326                                 /*
 327                                 ** From Arnold Robbins' strftime version 3.0:
 328                                 ** "ISO 8601: Weekday as a decimal number
 329                                 ** [1 (Monday) - 7]"
 330                                 ** (ado, 1993-05-24)
 331                                 */
 332                                 pt = _conv((t->tm_wday == 0) ?
 333                                         DAYSPERWEEK : t->tm_wday,
 334                                         "%d", pt, ptlim);
 335                                 continue;
 336                         case 'V':       /* ISO 8601 week number */
 337                         case 'G':       /* ISO 8601 year (four digits) */
 338                         case 'g':       /* ISO 8601 year (two digits) */
 339 /*
 340 ** From Arnold Robbins' strftime version 3.0: "the week number of the
 341 ** year (the first Monday as the first day of week 1) as a decimal number
 342 ** (01-53)."
 343 ** (ado, 1993-05-24)
 344 **
 345 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
 346 ** "Week 01 of a year is per definition the first week which has the
 347 ** Thursday in this year, which is equivalent to the week which contains
 348 ** the fourth day of January. In other words, the first week of a new year
 349 ** is the week which has the majority of its days in the new year. Week 01
 350 ** might also contain days from the previous year and the week before week
 351 ** 01 of a year is the last week (52 or 53) of the previous year even if
 352 ** it contains days from the new year. A week starts with Monday (day 1)
 353 ** and ends with Sunday (day 7). For example, the first week of the year
 354 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
 355 ** (ado, 1996-01-02)
 356 */
 357                                 {
 358                                         int     year;
 359                                         int     base;
 360                                         int     yday;
 361                                         int     wday;
 362                                         int     w;
 363
 364                                         year = t->tm_year;
 365                                         base = TM_YEAR_BASE;
 366                                         yday = t->tm_yday;
 367                                         wday = t->tm_wday;
 368                                         for ( ; ; ) {
 369                                                 int     len;
 370                                                 int     bot;
 371                                                 int     top;
 372
 373                                                 len = isleap_sum(year, base) ?
 374                                                         DAYSPERLYEAR :
 375                                                         DAYSPERNYEAR;
 376                                                 /*
 377                                                 ** What yday (-3 ... 3) does
 378                                                 ** the ISO year begin on?
 379                                                 */
 380                                                 bot = ((yday + 11 - wday) %
 381                                                         DAYSPERWEEK) - 3;
 382                                                 /*
 383                                                 ** What yday does the NEXT
 384                                                 ** ISO year begin on?
 385                                                 */
 386                                                 top = bot -
 387                                                         (len % DAYSPERWEEK);
 388                                                 if (top < -3)
 389                                                         top += DAYSPERWEEK;
 390                                                 top += len;
 391                                                 if (yday >= top) {
 392                                                         ++base;
 393                                                         w = 1;
 394                                                         break;
 395                                                 }
 396                                                 if (yday >= bot) {
 397                                                         w = 1 + ((yday - bot) /
 398                                                                 DAYSPERWEEK);
 399                                                         break;
 400                                                 }
 401                                                 --base;
 402                                                 yday += isleap_sum(year, base) ?
 403                                                         DAYSPERLYEAR :
 404                                                         DAYSPERNYEAR;
 405                                         }
 406 #ifdef XPG4_1994_04_09
 407                                         if ((w == 52 &&
 408                                                 t->tm_mon == TM_JANUARY) ||
 409                                                 (w == 1 &&
 410                                                 t->tm_mon == TM_DECEMBER))
 411                                                         w = 53;
 412 #endif /* defined XPG4_1994_04_09 */
 413                                         if (*format == 'V')
 414                                                 pt = _conv(w, fmt_padding[PAD_FMT_WEEKOFYEAR][PadIndex],
 415                                                         pt, ptlim);
 416                                         else if (*format == 'g') {
 417                                                 *warnp = IN_ALL;
 418                                                 pt = _yconv(year, base, 0, 1,
 419                                                         pt, ptlim);
 420                                         } else  pt = _yconv(year, base, 1, 1,
 421                                                         pt, ptlim);
 422                                 }
 423                                 continue;
 424                         case 'v':
 425                                 /*
 426                                 ** From Arnold Robbins' strftime version 3.0:
 427                                 ** "date as dd-bbb-YYYY"
 428                                 ** (ado, 1993-05-24)
 429                                 */
 430                                 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp, loc);
 431                                 continue;
 432                         case 'W':
 433                                 pt = _conv((t->tm_yday + DAYSPERWEEK -
 434                                         (t->tm_wday ?
 435                                         (t->tm_wday - 1) :
 436                                         (DAYSPERWEEK - 1))) / DAYSPERWEEK,
 437                                         fmt_padding[PAD_FMT_WEEKOFYEAR][PadIndex], pt, ptlim);
 438                                 continue;
 439                         case 'w':
 440                                 pt = _conv(t->tm_wday, "%d", pt, ptlim);
 441                                 continue;
 442                         case 'X':
 443                                 pt = _fmt(tptr->X_fmt, t, pt, ptlim, warnp, loc);
 444                                 continue;
 445                         case 'x':
 446                                 {
 447                                 int     warn2 = IN_SOME;
 448
 449                                 pt = _fmt(tptr->x_fmt, t, pt, ptlim, &warn2, loc);
 450                                 if (warn2 == IN_ALL)
 451                                         warn2 = IN_THIS;
 452                                 if (warn2 > *warnp)
 453                                         *warnp = warn2;
 454                                 }
 455                                 continue;
 456                         case 'y':
 457                                 *warnp = IN_ALL;
 458                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
 459                                         pt, ptlim);
 460                                 continue;
 461                         case 'Y':
 462                                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
 463                                         pt, ptlim);
 464                                 continue;
 465                         case 'Z':
 466 #ifdef TM_ZONE
 467                                 if (t->TM_ZONE != NULL)
 468                                         pt = _add(t->TM_ZONE, pt, ptlim);
 469                                 else
 470 #endif /* defined TM_ZONE */
 471                                 if (t->tm_isdst >= 0)
 472                                         pt = _add(tzname[t->tm_isdst != 0],
 473                                                 pt, ptlim);
 474                                 /*
 475                                 ** C99 says that %Z must be replaced by the
 476                                 ** empty string if the time zone is not
 477                                 ** determinable.
 478                                 */
 479                                 continue;
 480                         case 'z':
 481                                 {
 482                                 long            diff;
 483                                 char const *    sign;
 484
 485                                 if (t->tm_isdst < 0)
 486                                         continue;
 487 #ifdef TM_GMTOFF
 488                                 diff = t->TM_GMTOFF;
 489 #else /* !defined TM_GMTOFF */
 490                                 /*
 491                                 ** C99 says that the UT offset must
 492                                 ** be computed by looking only at
 493                                 ** tm_isdst. This requirement is
 494                                 ** incorrect, since it means the code
 495                                 ** must rely on magic (in this case
 496                                 ** altzone and timezone), and the
 497                                 ** magic might not have the correct
 498                                 ** offset. Doing things correctly is
 499                                 ** tricky and requires disobeying C99;
 500                                 ** see GNU C strftime for details.
 501                                 ** For now, punt and conform to the
 502                                 ** standard, even though it's incorrect.
 503                                 **
 504                                 ** C99 says that %z must be replaced by the
 505                                 ** empty string if the time zone is not
 506                                 ** determinable, so output nothing if the
 507                                 ** appropriate variables are not available.
 508                                 */
 509                                 if (t->tm_isdst == 0)
 510                                         diff = -timezone;
 511                                 else
 512                                         continue;
 513 #endif /* !defined TM_GMTOFF */
 514                                 if (diff < 0) {
 515                                         sign = "-";
 516                                         diff = -diff;
 517                                 } else  sign = "+";
 518                                 pt = _add(sign, pt, ptlim);
 519                                 diff /= SECSPERMIN;
 520                                 diff = (diff / MINSPERHOUR) * 100 +
 521                                         (diff % MINSPERHOUR);
 522                                 pt = _conv(diff,
 523                                         fmt_padding[PAD_FMT_YEAR][PadIndex], pt, ptlim);
 524                                 }
 525                                 continue;
 526                         case '+':
 527                                 pt = _fmt(tptr->date_fmt, t, pt, ptlim,
 528                                         warnp, loc);
 529                                 continue;
 530                         case '-':
 531                                 if (PadIndex != PAD_DEFAULT)
 532                                         break;
 533                                 PadIndex = PAD_LESS;
 534                                 goto label;
 535                         case '_':
 536                                 if (PadIndex != PAD_DEFAULT)
 537                                         break;
 538                                 PadIndex = PAD_SPACE;
 539                                 goto label;
 540                         case '0':
 541                                 if (PadIndex != PAD_DEFAULT)
 542                                         break;
 543                                 PadIndex = PAD_ZERO;
 544                                 goto label;
 545                         case '%':
 546                         /*
 547                         ** X311J/88-090 (4.12.3.5): if conversion char is
 548                         ** undefined, behavior is undefined. Print out the
 549                         ** character itself as printf(3) also does.
 550                         */
 551                         default:
 552                                 break;
 553                         }
 554                 }
 555                 if (pt == ptlim)
 556                         break;
 557                 *pt++ = *format;
 558         }
 559         return pt;
 560 }
 561
 562 static char *
 563 _conv(const int n, const char * const format, char * const pt,
 564     const char * const ptlim)
 565 {
 566         char    buf[INT_STRLEN_MAXIMUM(int) + 1];
 567
 568         snprintf(buf, sizeof(buf), format, n);
 569         return _add(buf, pt, ptlim);
 570 }
 571
 572 static char *
 573 _add(const char *str, char *pt, const char * const ptlim)
 574 {
 575         while (pt < ptlim && (*pt = *str++) != '\0')
 576                 ++pt;
 577         return pt;
 578 }
 579
 580 /*
 581 ** POSIX and the C Standard are unclear or inconsistent about
 582 ** what %C and %y do if the year is negative or exceeds 9999.
 583 ** Use the convention that %C concatenated with %y yields the
 584 ** same output as %Y, and that %Y contains at least 4 bytes,
 585 ** with more only if necessary.
 586 */
 587
 588 static char *
 589 _yconv(const int a, const int b, const int convert_top, const int convert_yy,
 590     char *pt, const char * const ptlim)
 591 {
 592         int     lead;
 593         int     trail;
 594
 595 #define DIVISOR 100
 596         trail = a % DIVISOR + b % DIVISOR;
 597         lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
 598         trail %= DIVISOR;
 599         if (trail < 0 && lead > 0) {
 600                 trail += DIVISOR;
 601                 --lead;
 602         } else if (lead < 0 && trail > 0) {
 603                 trail -= DIVISOR;
 604                 ++lead;
 605         }
 606         if (convert_top) {
 607                 if (lead == 0 && trail < 0)
 608                         pt = _add("-0", pt, ptlim);
 609                 else    pt = _conv(lead, "%02d", pt, ptlim);
 610         }
 611         if (convert_yy)
 612                 pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
 613         return pt;
 614 }