libc/stdlib/_strtod.c

   1 /*
   2  * Copyright (C) 2000-2005     Manuel Novoa III
   3  *
   4  * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
   5  */
   6
   7 /* Notes:
   8  *
   9  * The primary objective of this implementation was minimal size and
  10  * portablility, while providing robustness and resonable accuracy.
  11  *
  12  * This implementation depends on IEEE floating point behavior and expects
  13  * to be able to generate +/- infinity as a result.
  14  *
  15  * There are a number of compile-time options below.
  16  */
  17
  18 /* July 27, 2003
  19  *
  20  * General cleanup and some minor size optimizations.
  21  * Change implementation to support __strtofpmax() rather than strtod().
  22  *   Now all the strto{floating pt}() funcs are implemented in terms of
  23  *   of the internal __strtofpmax() function.
  24  * Support "nan", "inf", and "infinity" strings (case-insensitive).
  25  * Support hexadecimal floating point notation.
  26  * Support wchar variants.
  27  * Support xlocale variants.
  28  *
  29  * TODO:
  30  *
  31  * Consider accumulating blocks of digits in longs to save floating pt mults.
  32  *   This would likely be much better on anything that only supported floats
  33  *   where DECIMAL_DIG == 9.  Actually, if floats have FLT_MAX_10_EXP == 38,
  34  *   we could calculate almost all the exponent multipliers (p_base) in
  35  *   long arithmetic as well.
  36  */
  37
  38 /**********************************************************************/
  39 /*                      OPTIONS                                       */
  40 /**********************************************************************/
  41
  42 /* Defined if we want to recognize "nan", "inf", and "infinity". (C99) */
  43 #define _STRTOD_NAN_INF_STRINGS  1
  44
  45 /* Defined if we want support hexadecimal floating point notation. (C99) */
  46 /* Note!  Now controlled by uClibc configuration.  See below. */
  47 #define _STRTOD_HEXADECIMAL_FLOATS 1
  48
  49 /* Defined if we want to scale with a O(log2(exp)) multiplications.
  50  * This is generally a good thing to do unless you are really tight
  51  * on space and do not expect to convert values of large magnitude. */
  52
  53 #define _STRTOD_LOG_SCALING       1
  54
  55 /* WARNING!!!   WARNING!!!   WARNING!!!   WARNING!!!   WARNING!!!
  56  *
  57  * Clearing any of the options below this point is not advised (or tested).
  58  *
  59  * WARNING!!!   WARNING!!!   WARNING!!!   WARNING!!!   WARNING!!! */
  60
  61 /* Defined if we want strtod to set errno appropriately. */
  62 /* NOTE: Implies all options below. */
  63 #define _STRTOD_ERRNO                   1
  64
  65 /* Defined if we want support for the endptr arg. */
  66 /* Implied by _STRTOD_ERRNO. */
  67 #define _STRTOD_ENDPTR             1
  68
  69 /* Defined if we want to prevent overflow in accumulating the exponent. */
  70 /* Implied by _STRTOD_ERRNO. */
  71 #define _STRTOD_RESTRICT_EXP     1
  72
  73 /* Defined if we want to process mantissa digits more intelligently. */
  74 /* Implied by _STRTOD_ERRNO. */
  75 #define _STRTOD_RESTRICT_DIGITS  1
  76
  77 /* Defined if we want to skip scaling 0 for the exponent. */
  78 /* Implied by _STRTOD_ERRNO. */
  79 #define _STRTOD_ZERO_CHECK         1
  80
  81 /**********************************************************************/
  82 /* Don't change anything that follows.                                */
  83 /**********************************************************************/
  84
  85 #ifdef _STRTOD_ERRNO
  86 #undef _STRTOD_ENDPTR
  87 #undef _STRTOD_RESTRICT_EXP
  88 #undef _STRTOD_RESTRICT_DIGITS
  89 #undef _STRTOD_ZERO_CHECK
  90 #define _STRTOD_ENDPTR             1
  91 #define _STRTOD_RESTRICT_EXP     1
  92 #define _STRTOD_RESTRICT_DIGITS  1
  93 #define _STRTOD_ZERO_CHECK         1
  94 #endif
  95
  96 /**********************************************************************/
  97
  98 #include <stdlib.h>
  99 #include <string.h>
 100 #include <ctype.h>
 101 #include <errno.h>
 102 #include <limits.h>
 103 #include <float.h>
 104 #include <bits/uClibc_fpmax.h>
 105
 106 #include <locale.h>
 107
 108 #ifdef __UCLIBC_HAS_WCHAR__
 109 # include <wchar.h>
 110 # include <wctype.h>
 111 # include <bits/uClibc_uwchar.h>
 112 #endif
 113
 114 /* Handle _STRTOD_HEXADECIMAL_FLOATS via uClibc config now. */
 115 #undef _STRTOD_HEXADECIMAL_FLOATS
 116 #ifdef __UCLIBC_HAS_HEXADECIMAL_FLOATS__
 117 # define _STRTOD_HEXADECIMAL_FLOATS 1
 118 #endif
 119
 120 /**********************************************************************/
 121
 122 #undef _STRTOD_FPMAX
 123
 124 #if FPMAX_TYPE == 3
 125
 126 #define NEED_STRTOLD_WRAPPER
 127 #define NEED_STRTOD_WRAPPER
 128 #define NEED_STRTOF_WRAPPER
 129
 130 #elif FPMAX_TYPE == 2
 131
 132 #define NEED_STRTOD_WRAPPER
 133 #define NEED_STRTOF_WRAPPER
 134
 135 #elif FPMAX_TYPE == 1
 136
 137 #define NEED_STRTOF_WRAPPER
 138
 139 #else
 140
 141 #error unknown FPMAX_TYPE!
 142
 143 #endif
 144
 145 extern void __fp_range_check(__fpmax_t y, __fpmax_t x) attribute_hidden;
 146
 147 /**********************************************************************/
 148
 149 #ifdef _STRTOD_RESTRICT_DIGITS
 150 #define EXP_DENORM_ADJUST DECIMAL_DIG
 151 #define MAX_ALLOWED_EXP (DECIMAL_DIG  + EXP_DENORM_ADJUST - FPMAX_MIN_10_EXP)
 152
 153 #if MAX_ALLOWED_EXP > INT_MAX
 154 #error size assumption violated for MAX_ALLOWED_EXP
 155 #endif
 156 #else
 157 /* We want some excess if we're not restricting mantissa digits. */
 158 #define MAX_ALLOWED_EXP ((20 - FPMAX_MIN_10_EXP) * 2)
 159 #endif
 160
 161
 162 #if defined(_STRTOD_RESTRICT_DIGITS) || defined(_STRTOD_ENDPTR) || defined(_STRTOD_HEXADECIMAL_FLOATS)
 163 #undef _STRTOD_NEED_NUM_DIGITS
 164 #define _STRTOD_NEED_NUM_DIGITS 1
 165 #endif
 166
 167 /**********************************************************************/
 168 #if defined(L___strtofpmax) || defined(L___strtofpmax_l) || defined(L___wcstofpmax) || defined(L___wcstofpmax_l)
 169
 170 #if defined(L___wcstofpmax) || defined(L___wcstofpmax_l)
 171
 172 #define __strtofpmax    __wcstofpmax
 173 #define __strtofpmax_l  __wcstofpmax_l
 174
 175 #define Wchar wchar_t
 176 #ifdef __UCLIBC_DO_XLOCALE
 177 #define ISSPACE(C) iswspace_l((C), locale_arg)
 178 #else
 179 #define ISSPACE(C) iswspace((C))
 180 #endif
 181
 182 #else  /* defined(L___wcstofpmax) || defined(L___wcstofpmax_l) */
 183
 184 #define Wchar char
 185 #ifdef __UCLIBC_DO_XLOCALE
 186 #define ISSPACE(C) isspace_l((C), locale_arg)
 187 #else
 188 #define ISSPACE(C) isspace((C))
 189 #endif
 190
 191 #endif /* defined(L___wcstofpmax) || defined(L___wcstofpmax_l) */
 192
 193
 194 #if defined(__UCLIBC_HAS_XLOCALE__) && !defined(__UCLIBC_DO_XLOCALE)
 195
 196 __fpmax_t attribute_hidden __strtofpmax(const Wchar *str, Wchar **endptr, int exponent_power)
 197 {
 198         return __strtofpmax_l(str, endptr, exponent_power, __UCLIBC_CURLOCALE);
 199 }
 200
 201 #else  /* defined(__UCLIBC_HAS_XLOCALE__) && !defined(__UCLIBC_DO_XLOCALE) */
 202
 203
 204 __fpmax_t attribute_hidden __XL_NPP(__strtofpmax)(const Wchar *str, Wchar **endptr, int exponent_power
 205                                                                  __LOCALE_PARAM )
 206 {
 207         __fpmax_t number;
 208         __fpmax_t p_base = 10;                  /* Adjusted to 16 in the hex case. */
 209         Wchar *pos0;
 210 #ifdef _STRTOD_ENDPTR
 211         Wchar *pos1;
 212 #endif
 213         Wchar *pos = (Wchar *) str;
 214         int exponent_temp;
 215         int negative; /* A flag for the number, a multiplier for the exponent. */
 216 #ifdef _STRTOD_NEED_NUM_DIGITS
 217         int num_digits;
 218 #endif
 219 #ifdef __UCLIBC_HAS_LOCALE__
 220 #if defined(L___wcstofpmax) || defined(L___wcstofpmax_l)
 221         wchar_t decpt_wc = __LOCALE_PTR->decimal_point_wc;
 222 #else
 223         const char *decpt = __LOCALE_PTR->decimal_point;
 224         int decpt_len = __LOCALE_PTR->decimal_point_len;
 225 #endif
 226 #endif
 227
 228 #ifdef _STRTOD_HEXADECIMAL_FLOATS
 229         Wchar expchar = 'e';
 230         Wchar *poshex = NULL;
 231         __uint16_t is_mask = _ISdigit;
 232 #define EXPCHAR         expchar
 233 #define IS_X_DIGIT(C) __isctype((C), is_mask)
 234 #else  /* _STRTOD_HEXADECIMAL_FLOATS */
 235 #define EXPCHAR         'e'
 236 #define IS_X_DIGIT(C) isdigit((C))
 237 #endif /* _STRTOD_HEXADECIMAL_FLOATS */
 238
 239         while (ISSPACE(*pos)) {         /* Skip leading whitespace. */
 240                 ++pos;
 241         }
 242
 243         negative = 0;
 244         switch(*pos) {                          /* Handle optional sign. */
 245                 case '-': negative = 1; /* Fall through to increment position. */
 246                 case '+': ++pos;
 247         }
 248
 249 #ifdef _STRTOD_HEXADECIMAL_FLOATS
 250         if ((*pos == '0') && (((pos[1])|0x20) == 'x')) {
 251                 poshex = ++pos;                 /* Save position of 'x' in case no digits */
 252                 ++pos;                                  /*   and advance past it.  */
 253                 is_mask = _ISxdigit;    /* Used by IS_X_DIGIT. */
 254                 expchar = 'p';                  /* Adjust exponent char. */
 255                 p_base = 16;                    /* Adjust base multiplier. */
 256         }
 257 #endif
 258
 259         number = 0.;
 260 #ifdef _STRTOD_NEED_NUM_DIGITS
 261         num_digits = -1;
 262 #endif
 263 /*      exponent_power = 0; */
 264         pos0 = NULL;
 265
 266  LOOP:
 267         while (IS_X_DIGIT(*pos)) {      /* Process string of (hex) digits. */
 268 #ifdef _STRTOD_RESTRICT_DIGITS
 269                 if (num_digits < 0) {   /* First time through? */
 270                         ++num_digits;           /* We've now seen a digit. */
 271                 }
 272                 if (num_digits || (*pos != '0')) { /* Had/have nonzero. */
 273                         ++num_digits;
 274                         if (num_digits <= DECIMAL_DIG) { /* Is digit significant? */
 275 #ifdef _STRTOD_HEXADECIMAL_FLOATS
 276                                 number = number * p_base
 277                                         + (isdigit(*pos)
 278                                            ? (*pos - '0')
 279                                            : (((*pos)|0x20) - ('a' - 10)));
 280 #else  /* _STRTOD_HEXADECIMAL_FLOATS */
 281                                 number = number * p_base + (*pos - '0');
 282 #endif /* _STRTOD_HEXADECIMAL_FLOATS */
 283                         }
 284                 }
 285 #else  /* _STRTOD_RESTRICT_DIGITS */
 286 #ifdef _STRTOD_NEED_NUM_DIGITS
 287                 ++num_digits;
 288 #endif
 289 #ifdef _STRTOD_HEXADECIMAL_FLOATS
 290                 number = number * p_base
 291                         + (isdigit(*pos)
 292                            ? (*pos - '0')
 293                            : (((*pos)|0x20) - ('a' - 10)));
 294 #else  /* _STRTOD_HEXADECIMAL_FLOATS */
 295                 number = number * p_base + (*pos - '0');
 296 #endif /* _STRTOD_HEXADECIMAL_FLOATS */
 297 #endif /* _STRTOD_RESTRICT_DIGITS */
 298                 ++pos;
 299         }
 300
 301 #ifdef __UCLIBC_HAS_LOCALE__
 302 #if defined(L___wcstofpmax) || defined(L___wcstofpmax_l)
 303         if (!pos0 && (*pos == decpt_wc)) { /* First decimal point? */
 304                 pos0 = ++pos;
 305                 goto LOOP;
 306         }
 307 #else
 308         if (!pos0 && !memcmp(pos, decpt, decpt_len)) { /* First decimal point? */
 309                 pos0 = (pos += decpt_len);
 310                 goto LOOP;
 311         }
 312 #endif
 313 #else  /* __UCLIBC_HAS_LOCALE__ */
 314         if ((*pos == '.') && !pos0) { /* First decimal point? */
 315                 pos0 = ++pos;                   /* Save position of decimal point */
 316                 goto LOOP;                              /*   and process rest of digits. */
 317         }
 318 #endif /* __UCLIBC_HAS_LOCALE__ */
 319
 320 #ifdef _STRTOD_NEED_NUM_DIGITS
 321         if (num_digits<0) {                     /* Must have at least one digit. */
 322 #ifdef _STRTOD_HEXADECIMAL_FLOATS
 323                 if (poshex) {                   /* Back up to '0' in '0x' prefix. */
 324                         pos = poshex;
 325                         goto DONE;
 326                 }
 327 #endif /* _STRTOD_HEXADECIMAL_FLOATS */
 328
 329 #ifdef _STRTOD_NAN_INF_STRINGS
 330                 if (!pos0) {                    /* No decimal point, so check for inf/nan. */
 331                         /* Note: nan is the first string so 'number = i/0.;' works. */
 332                         static const char nan_inf_str[] = "\05nan\0\012infinity\0\05inf\0";
 333                         int i = 0;
 334
 335                         do {
 336                                 /* Unfortunately, we have no memcasecmp(). */
 337                                 int j = 0;
 338                                 /* | 0x20 is a cheap lowercasing (valid for ASCII letters and numbers only) */
 339                                 while ((pos[j] | 0x20) == nan_inf_str[i+1+j]) {
 340                                         ++j;
 341                                         if (!nan_inf_str[i+1+j]) {
 342                                                 number = i / 0.;
 343                                                 if (negative) { /* Correct for sign. */
 344                                                         number = -number;
 345                                                 }
 346                                                 pos += nan_inf_str[i] - 2;
 347                                                 goto DONE;
 348                                         }
 349                                 }
 350                                 i += nan_inf_str[i];
 351                         } while (nan_inf_str[i]);
 352                 }
 353
 354 #endif /* STRTOD_NAN_INF_STRINGS */
 355 #ifdef _STRTOD_ENDPTR
 356                 pos = (Wchar *) str;
 357 #endif
 358                 goto DONE;
 359         }
 360 #endif /* _STRTOD_NEED_NUM_DIGITS */
 361
 362 #ifdef _STRTOD_RESTRICT_DIGITS
 363         if (num_digits > DECIMAL_DIG) { /* Adjust exponent for skipped digits. */
 364                 exponent_power += num_digits - DECIMAL_DIG;
 365         }
 366 #endif
 367
 368         if (pos0) {
 369                 exponent_power += pos0 - pos; /* Adjust exponent for decimal point. */
 370         }
 371
 372 #ifdef _STRTOD_HEXADECIMAL_FLOATS
 373         if (poshex) {
 374                 exponent_power *= 4;    /* Above is 2**4, but below is 2. */
 375                 p_base = 2;
 376         }
 377 #endif /* _STRTOD_HEXADECIMAL_FLOATS */
 378
 379         if (negative) {                         /* Correct for sign. */
 380                 number = -number;
 381         }
 382
 383         /* process an exponent string */
 384         if (((*pos)|0x20) == EXPCHAR) {
 385 #ifdef _STRTOD_ENDPTR
 386                 pos1 = pos;
 387 #endif
 388                 negative = 1;
 389                 switch(*++pos) {                /* Handle optional sign. */
 390                         case '-': negative = -1; /* Fall through to increment pos. */
 391                         case '+': ++pos;
 392                 }
 393
 394                 pos0 = pos;
 395                 exponent_temp = 0;
 396                 while (isdigit(*pos)) { /* Process string of digits. */
 397 #ifdef _STRTOD_RESTRICT_EXP
 398                         if (exponent_temp < MAX_ALLOWED_EXP) { /* Avoid overflow. */
 399                                 exponent_temp = exponent_temp * 10 + (*pos - '0');
 400                         }
 401 #else
 402                         exponent_temp = exponent_temp * 10 + (*pos - '0');
 403 #endif
 404                         ++pos;
 405                 }
 406
 407 #ifdef _STRTOD_ENDPTR
 408                 if (pos == pos0) {      /* No digits? */
 409                         pos = pos1;             /* Back up to {e|E}/{p|P}. */
 410                 } /* else */
 411 #endif
 412
 413                 exponent_power += negative * exponent_temp;
 414         }
 415
 416 #ifdef _STRTOD_ZERO_CHECK
 417         if (number == 0.) {
 418                 goto DONE;
 419         }
 420 #endif
 421
 422         /* scale the result */
 423 #ifdef _STRTOD_LOG_SCALING
 424         exponent_temp = exponent_power;
 425
 426         if (exponent_temp < 0) {
 427                 exponent_temp = -exponent_temp;
 428         }
 429
 430         while (exponent_temp) {
 431                 if (exponent_temp & 1) {
 432                         if (exponent_power < 0) {
 433                                 /* Warning... caluclating a factor for the exponent and
 434                                  * then dividing could easily be faster.  But doing so
 435                                  * might cause problems when dealing with denormals. */
 436                                 number /= p_base;
 437                         } else {
 438                                 number *= p_base;
 439                         }
 440                 }
 441                 exponent_temp >>= 1;
 442                 p_base *= p_base;
 443         }
 444
 445 #else  /* _STRTOD_LOG_SCALING */
 446         while (exponent_power) {
 447                 if (exponent_power < 0) {
 448                         number /= p_base;
 449                         exponent_power++;
 450                 } else {
 451                         number *= p_base;
 452                         exponent_power--;
 453                 }
 454         }
 455 #endif /* _STRTOD_LOG_SCALING */
 456
 457 #ifdef _STRTOD_ERRNO
 458         if (__FPMAX_ZERO_OR_INF_CHECK(number)) {
 459                 __set_errno(ERANGE);
 460         }
 461 #endif
 462
 463  DONE:
 464 #ifdef _STRTOD_ENDPTR
 465         if (endptr) {
 466                 *endptr = pos;
 467         }
 468 #endif
 469
 470         return number;
 471 }
 472
 473 #endif /* defined(__UCLIBC_HAS_XLOCALE__) && !defined(__UCLIBC_DO_XLOCALE) */
 474
 475 #endif
 476 /**********************************************************************/
 477 #ifdef L___fp_range_check
 478 #if defined(NEED_STRTOF_WRAPPER) || defined(NEED_STRTOD_WRAPPER)
 479
 480 void attribute_hidden __fp_range_check(__fpmax_t y, __fpmax_t x)
 481 {
 482         if (__FPMAX_ZERO_OR_INF_CHECK(y) /* y is 0 or +/- infinity */
 483                 && (y != 0)     /* y is not 0 (could have x>0, y==0 if underflow) */
 484                 && !__FPMAX_ZERO_OR_INF_CHECK(x) /* x is not 0 or +/- infinity */
 485                 ) {
 486                 __set_errno(ERANGE);    /* Then x is not in y's range. */
 487         }
 488 }
 489
 490 #endif
 491 #endif
 492 /**********************************************************************/
 493 #if defined(L_strtof) || defined(L_strtof_l) || defined(L_wcstof) || defined(L_wcstof_l)
 494 #if defined(NEED_STRTOF_WRAPPER)
 495
 496 #if defined(L_wcstof) || defined(L_wcstof_l)
 497 #define strtof           wcstof
 498 #define strtof_l         wcstof_l
 499 #define __strtofpmax     __wcstofpmax
 500 #define __strtofpmax_l   __wcstofpmax_l
 501 #define Wchar wchar_t
 502 #else
 503 #define Wchar char
 504 #endif
 505
 506
 507 float __XL_NPP(strtof)(const Wchar *str, Wchar **endptr   __LOCALE_PARAM )
 508 {
 509 #if FPMAX_TYPE == 1
 510         return __XL_NPP(__strtofpmax)(str, endptr, 0   __LOCALE_ARG );
 511 #else
 512         __fpmax_t x;
 513         float y;
 514
 515         x = __XL_NPP(__strtofpmax)(str, endptr, 0   __LOCALE_ARG );
 516         y = (float) x;
 517
 518         __fp_range_check(y, x);
 519
 520         return y;
 521 #endif
 522 }
 523
 524 #endif
 525 #endif
 526 /**********************************************************************/
 527 #if defined(L_strtod) || defined(L_strtod_l) || defined(L_wcstod) || defined(L_wcstod_l)
 528 #if defined(NEED_STRTOD_WRAPPER)
 529
 530 #if defined(L_wcstod) || defined(L_wcstod_l)
 531 #define strtod           wcstod
 532 #define strtod_l         wcstod_l
 533 #define __strtofpmax     __wcstofpmax
 534 #define __strtofpmax_l   __wcstofpmax_l
 535 #define Wchar wchar_t
 536 #else
 537 #define Wchar char
 538 #endif
 539
 540 double __XL_NPP(strtod)(const Wchar *__restrict str,
 541                                         Wchar **__restrict endptr   __LOCALE_PARAM )
 542 {
 543 #if FPMAX_TYPE == 2
 544         return __XL_NPP(__strtofpmax)(str, endptr, 0   __LOCALE_ARG );
 545 #else
 546         __fpmax_t x;
 547         double y;
 548
 549         x = __XL_NPP(__strtofpmax)(str, endptr, 0   __LOCALE_ARG );
 550         y = (double) x;
 551
 552         __fp_range_check(y, x);
 553
 554         return y;
 555 #endif
 556 }
 557 #ifdef L_strtod
 558 libc_hidden_def(strtod)
 559 #endif
 560
 561 #endif
 562 #endif
 563 /**********************************************************************/
 564 #if defined(L_strtold) || defined(L_strtold_l) || defined(L_wcstold) || defined(L_wcstold_l)
 565 #if defined(NEED_STRTOLD_WRAPPER)
 566
 567 #if defined(L_wcstold) || defined(L_wcstold_l)
 568 #define strtold           wcstold
 569 #define strtold_l         wcstold_l
 570 #define __strtofpmax     __wcstofpmax
 571 #define __strtofpmax_l   __wcstofpmax_l
 572 #define Wchar wchar_t
 573 #else
 574 #define Wchar char
 575 #endif
 576
 577 long double __XL_NPP(strtold) (const Wchar *str, Wchar **endptr   __LOCALE_PARAM )
 578 {
 579 #if FPMAX_TYPE == 3
 580         return __XL_NPP(__strtofpmax)(str, endptr, 0   __LOCALE_ARG );
 581 #else
 582         __fpmax_t x;
 583         long double y;
 584
 585         x = __XL_NPP(__strtofpmax)(str, endptr, 0   __LOCALE_ARG );
 586         y = (long double) x;
 587
 588         __fp_range_check(y, x);
 589
 590         return y;
 591 #endif
 592 }
 593
 594 #endif
 595 #endif
 596 /**********************************************************************/