gas/atof-generic.c

   1 /* atof_generic.c - turn a string of digits into a Flonum
   2    Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2000,
   3    2001, 2003, 2005, 2006, 2007 Free Software Foundation, Inc.
   4
   5    This file is part of GAS, the GNU Assembler.
   6
   7    GAS is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    GAS is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GAS; see the file COPYING.  If not, write to the Free
  19    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  20    02110-1301, USA.  */
  21
  22 #include "as.h"
  23 #include "safe-ctype.h"
  24
  25 #ifndef FALSE
  26 #define FALSE (0)
  27 #endif
  28 #ifndef TRUE
  29 #define TRUE  (1)
  30 #endif
  31
  32 #ifdef TRACE
  33 static void flonum_print (const FLONUM_TYPE *);
  34 #endif
  35
  36 #define ASSUME_DECIMAL_MARK_IS_DOT
  37
  38 /***********************************************************************\
  39  *                                                                      *
  40  *      Given a string of decimal digits , with optional decimal        *
  41  *      mark and optional decimal exponent (place value) of the         *
  42  *      lowest_order decimal digit: produce a floating point            *
  43  *      number. The number is 'generic' floating point: our             *
  44  *      caller will encode it for a specific machine architecture.      *
  45  *                                                                      *
  46  *      Assumptions                                                     *
  47  *              uses base (radix) 2                                     *
  48  *              this machine uses 2's complement binary integers        *
  49  *              target flonums use "      "         "       "           *
  50  *              target flonums exponents fit in a long                  *
  51  *                                                                      *
  52  \***********************************************************************/
  53
  54 /*
  55
  56   Syntax:
  57
  58   <flonum> ::= <optional-sign> <decimal-number> <optional-exponent>
  59   <optional-sign> ::= '+' | '-' | {empty}
  60   <decimal-number> ::= <integer>
  61   | <integer> <radix-character>
  62   | <integer> <radix-character> <integer>
  63   | <radix-character> <integer>
  64
  65   <optional-exponent> ::= {empty}
  66   | <exponent-character> <optional-sign> <integer>
  67
  68   <integer> ::= <digit> | <digit> <integer>
  69   <digit> ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
  70   <exponent-character> ::= {one character from "string_of_decimal_exponent_marks"}
  71   <radix-character> ::= {one character from "string_of_decimal_marks"}
  72
  73   */
  74
  75 int
  76 atof_generic (/* return pointer to just AFTER number we read.  */
  77               char **address_of_string_pointer,
  78               /* At most one per number.  */
  79               const char *string_of_decimal_marks,
  80               const char *string_of_decimal_exponent_marks,
  81               FLONUM_TYPE *address_of_generic_floating_point_number)
  82 {
  83   int return_value;             /* 0 means OK.  */
  84   char *first_digit;
  85   unsigned int number_of_digits_before_decimal;
  86   unsigned int number_of_digits_after_decimal;
  87   long decimal_exponent;
  88   unsigned int number_of_digits_available;
  89   char digits_sign_char;
  90
  91   /*
  92    * Scan the input string, abstracting (1)digits (2)decimal mark (3) exponent.
  93    * It would be simpler to modify the string, but we don't; just to be nice
  94    * to caller.
  95    * We need to know how many digits we have, so we can allocate space for
  96    * the digits' value.
  97    */
  98
  99   char *p;
 100   char c;
 101   int seen_significant_digit;
 102
 103 #ifdef ASSUME_DECIMAL_MARK_IS_DOT
 104   assert (string_of_decimal_marks[0] == '.'
 105           && string_of_decimal_marks[1] == 0);
 106 #define IS_DECIMAL_MARK(c)      ((c) == '.')
 107 #else
 108 #define IS_DECIMAL_MARK(c)      (0 != strchr (string_of_decimal_marks, (c)))
 109 #endif
 110
 111   first_digit = *address_of_string_pointer;
 112   c = *first_digit;
 113
 114   if (c == '-' || c == '+')
 115     {
 116       digits_sign_char = c;
 117       first_digit++;
 118     }
 119   else
 120     digits_sign_char = '+';
 121
 122   switch (first_digit[0])
 123     {
 124     case 'n':
 125     case 'N':
 126       if (!strncasecmp ("nan", first_digit, 3))
 127         {
 128           address_of_generic_floating_point_number->sign = 0;
 129           address_of_generic_floating_point_number->exponent = 0;
 130           address_of_generic_floating_point_number->leader =
 131             address_of_generic_floating_point_number->low;
 132           *address_of_string_pointer = first_digit + 3;
 133           return 0;
 134         }
 135       break;
 136
 137     case 'i':
 138     case 'I':
 139       if (!strncasecmp ("inf", first_digit, 3))
 140         {
 141           address_of_generic_floating_point_number->sign =
 142             digits_sign_char == '+' ? 'P' : 'N';
 143           address_of_generic_floating_point_number->exponent = 0;
 144           address_of_generic_floating_point_number->leader =
 145             address_of_generic_floating_point_number->low;
 146
 147           first_digit += 3;
 148           if (!strncasecmp ("inity", first_digit, 5))
 149             first_digit += 5;
 150
 151           *address_of_string_pointer = first_digit;
 152
 153           return 0;
 154         }
 155       break;
 156     }
 157
 158   number_of_digits_before_decimal = 0;
 159   number_of_digits_after_decimal = 0;
 160   decimal_exponent = 0;
 161   seen_significant_digit = 0;
 162   for (p = first_digit;
 163        (((c = *p) != '\0')
 164         && (!c || !IS_DECIMAL_MARK (c))
 165         && (!c || !strchr (string_of_decimal_exponent_marks, c)));
 166        p++)
 167     {
 168       if (ISDIGIT (c))
 169         {
 170           if (seen_significant_digit || c > '0')
 171             {
 172               ++number_of_digits_before_decimal;
 173               seen_significant_digit = 1;
 174             }
 175           else
 176             {
 177               first_digit++;
 178             }
 179         }
 180       else
 181         {
 182           break;                /* p -> char after pre-decimal digits.  */
 183         }
 184     }                           /* For each digit before decimal mark.  */
 185
 186 #ifndef OLD_FLOAT_READS
 187   /* Ignore trailing 0's after the decimal point.  The original code here
 188    * (ifdef'd out) does not do this, and numbers like
 189    *    4.29496729600000000000e+09      (2**31)
 190    * come out inexact for some reason related to length of the digit
 191    * string.
 192    */
 193   if (c && IS_DECIMAL_MARK (c))
 194     {
 195       unsigned int zeros = 0;   /* Length of current string of zeros */
 196
 197       for (p++; (c = *p) && ISDIGIT (c); p++)
 198         {
 199           if (c == '0')
 200             {
 201               zeros++;
 202             }
 203           else
 204             {
 205               number_of_digits_after_decimal += 1 + zeros;
 206               zeros = 0;
 207             }
 208         }
 209     }
 210 #else
 211   if (c && IS_DECIMAL_MARK (c))
 212     {
 213       for (p++;
 214            (((c = *p) != '\0')
 215             && (!c || !strchr (string_of_decimal_exponent_marks, c)));
 216            p++)
 217         {
 218           if (ISDIGIT (c))
 219             {
 220               /* This may be retracted below.  */
 221               number_of_digits_after_decimal++;
 222
 223               if ( /* seen_significant_digit || */ c > '0')
 224                 {
 225                   seen_significant_digit = TRUE;
 226                 }
 227             }
 228           else
 229             {
 230               if (!seen_significant_digit)
 231                 {
 232                   number_of_digits_after_decimal = 0;
 233                 }
 234               break;
 235             }
 236         }                       /* For each digit after decimal mark.  */
 237     }
 238
 239   while (number_of_digits_after_decimal
 240          && first_digit[number_of_digits_before_decimal
 241                         + number_of_digits_after_decimal] == '0')
 242     --number_of_digits_after_decimal;
 243 #endif
 244
 245   if (flag_m68k_mri)
 246     {
 247       while (c == '_')
 248         c = *++p;
 249     }
 250   if (c && strchr (string_of_decimal_exponent_marks, c))
 251     {
 252       char digits_exponent_sign_char;
 253
 254       c = *++p;
 255       if (flag_m68k_mri)
 256         {
 257           while (c == '_')
 258             c = *++p;
 259         }
 260       if (c && strchr ("+-", c))
 261         {
 262           digits_exponent_sign_char = c;
 263           c = *++p;
 264         }
 265       else
 266         {
 267           digits_exponent_sign_char = '+';
 268         }
 269
 270       for (; (c); c = *++p)
 271         {
 272           if (ISDIGIT (c))
 273             {
 274               decimal_exponent = decimal_exponent * 10 + c - '0';
 275               /*
 276                * BUG! If we overflow here, we lose!
 277                */
 278             }
 279           else
 280             {
 281               break;
 282             }
 283         }
 284
 285       if (digits_exponent_sign_char == '-')
 286         {
 287           decimal_exponent = -decimal_exponent;
 288         }
 289     }
 290
 291   *address_of_string_pointer = p;
 292
 293   number_of_digits_available =
 294     number_of_digits_before_decimal + number_of_digits_after_decimal;
 295   return_value = 0;
 296   if (number_of_digits_available == 0)
 297     {
 298       address_of_generic_floating_point_number->exponent = 0;   /* Not strictly necessary */
 299       address_of_generic_floating_point_number->leader
 300         = -1 + address_of_generic_floating_point_number->low;
 301       address_of_generic_floating_point_number->sign = digits_sign_char;
 302       /* We have just concocted (+/-)0.0E0 */
 303
 304     }
 305   else
 306     {
 307       int count;                /* Number of useful digits left to scan.  */
 308
 309       LITTLENUM_TYPE *digits_binary_low;
 310       unsigned int precision;
 311       unsigned int maximum_useful_digits;
 312       unsigned int number_of_digits_to_use;
 313       unsigned int more_than_enough_bits_for_digits;
 314       unsigned int more_than_enough_littlenums_for_digits;
 315       unsigned int size_of_digits_in_littlenums;
 316       unsigned int size_of_digits_in_chars;
 317       FLONUM_TYPE power_of_10_flonum;
 318       FLONUM_TYPE digits_flonum;
 319
 320       precision = (address_of_generic_floating_point_number->high
 321                    - address_of_generic_floating_point_number->low
 322                    + 1);        /* Number of destination littlenums.  */
 323
 324       /* Includes guard bits (two littlenums worth) */
 325       maximum_useful_digits = (((precision - 2))
 326                                * ( (LITTLENUM_NUMBER_OF_BITS))
 327                                * 1000000 / 3321928)
 328         + 2;                    /* 2 :: guard digits.  */
 329
 330       if (number_of_digits_available > maximum_useful_digits)
 331         {
 332           number_of_digits_to_use = maximum_useful_digits;
 333         }
 334       else
 335         {
 336           number_of_digits_to_use = number_of_digits_available;
 337         }
 338
 339       /* Cast these to SIGNED LONG first, otherwise, on systems with
 340          LONG wider than INT (such as Alpha OSF/1), unsignedness may
 341          cause unexpected results.  */
 342       decimal_exponent += ((long) number_of_digits_before_decimal
 343                            - (long) number_of_digits_to_use);
 344
 345       more_than_enough_bits_for_digits
 346         = (number_of_digits_to_use * 3321928 / 1000000 + 1);
 347
 348       more_than_enough_littlenums_for_digits
 349         = (more_than_enough_bits_for_digits
 350            / LITTLENUM_NUMBER_OF_BITS)
 351         + 2;
 352
 353       /* Compute (digits) part. In "12.34E56" this is the "1234" part.
 354          Arithmetic is exact here. If no digits are supplied then this
 355          part is a 0 valued binary integer.  Allocate room to build up
 356          the binary number as littlenums.  We want this memory to
 357          disappear when we leave this function.  Assume no alignment
 358          problems => (room for n objects) == n * (room for 1
 359          object).  */
 360
 361       size_of_digits_in_littlenums = more_than_enough_littlenums_for_digits;
 362       size_of_digits_in_chars = size_of_digits_in_littlenums
 363         * sizeof (LITTLENUM_TYPE);
 364
 365       digits_binary_low = (LITTLENUM_TYPE *)
 366         alloca (size_of_digits_in_chars);
 367
 368       memset ((char *) digits_binary_low, '\0', size_of_digits_in_chars);
 369
 370       /* Digits_binary_low[] is allocated and zeroed.  */
 371
 372       /*
 373        * Parse the decimal digits as if * digits_low was in the units position.
 374        * Emit a binary number into digits_binary_low[].
 375        *
 376        * Use a large-precision version of:
 377        * (((1st-digit) * 10 + 2nd-digit) * 10 + 3rd-digit ...) * 10 + last-digit
 378        */
 379
 380       for (p = first_digit, count = number_of_digits_to_use; count; p++, --count)
 381         {
 382           c = *p;
 383           if (ISDIGIT (c))
 384             {
 385               /*
 386                * Multiply by 10. Assume can never overflow.
 387                * Add this digit to digits_binary_low[].
 388                */
 389
 390               long carry;
 391               LITTLENUM_TYPE *littlenum_pointer;
 392               LITTLENUM_TYPE *littlenum_limit;
 393
 394               littlenum_limit = digits_binary_low
 395                 + more_than_enough_littlenums_for_digits
 396                 - 1;
 397
 398               carry = c - '0';  /* char -> binary */
 399
 400               for (littlenum_pointer = digits_binary_low;
 401                    littlenum_pointer <= littlenum_limit;
 402                    littlenum_pointer++)
 403                 {
 404                   long work;
 405
 406                   work = carry + 10 * (long) (*littlenum_pointer);
 407                   *littlenum_pointer = work & LITTLENUM_MASK;
 408                   carry = work >> LITTLENUM_NUMBER_OF_BITS;
 409                 }
 410
 411               if (carry != 0)
 412                 {
 413                   /*
 414                    * We have a GROSS internal error.
 415                    * This should never happen.
 416                    */
 417                   as_fatal (_("failed sanity check"));
 418                 }
 419             }
 420           else
 421             {
 422               ++count;          /* '.' doesn't alter digits used count.  */
 423             }
 424         }
 425
 426       /*
 427        * Digits_binary_low[] properly encodes the value of the digits.
 428        * Forget about any high-order littlenums that are 0.
 429        */
 430       while (digits_binary_low[size_of_digits_in_littlenums - 1] == 0
 431              && size_of_digits_in_littlenums >= 2)
 432         size_of_digits_in_littlenums--;
 433
 434       digits_flonum.low = digits_binary_low;
 435       digits_flonum.high = digits_binary_low + size_of_digits_in_littlenums - 1;
 436       digits_flonum.leader = digits_flonum.high;
 437       digits_flonum.exponent = 0;
 438       /*
 439        * The value of digits_flonum . sign should not be important.
 440        * We have already decided the output's sign.
 441        * We trust that the sign won't influence the other parts of the number!
 442        * So we give it a value for these reasons:
 443        * (1) courtesy to humans reading/debugging
 444        *     these numbers so they don't get excited about strange values
 445        * (2) in future there may be more meaning attached to sign,
 446        *     and what was
 447        *     harmless noise may become disruptive, ill-conditioned (or worse)
 448        *     input.
 449        */
 450       digits_flonum.sign = '+';
 451
 452       {
 453         /*
 454          * Compute the mantssa (& exponent) of the power of 10.
 455          * If successful, then multiply the power of 10 by the digits
 456          * giving return_binary_mantissa and return_binary_exponent.
 457          */
 458
 459         LITTLENUM_TYPE *power_binary_low;
 460         int decimal_exponent_is_negative;
 461         /* This refers to the "-56" in "12.34E-56".  */
 462         /* FALSE: decimal_exponent is positive (or 0) */
 463         /* TRUE:  decimal_exponent is negative */
 464         FLONUM_TYPE temporary_flonum;
 465         LITTLENUM_TYPE *temporary_binary_low;
 466         unsigned int size_of_power_in_littlenums;
 467         unsigned int size_of_power_in_chars;
 468
 469         size_of_power_in_littlenums = precision;
 470         /* Precision has a built-in fudge factor so we get a few guard bits.  */
 471
 472         decimal_exponent_is_negative = decimal_exponent < 0;
 473         if (decimal_exponent_is_negative)
 474           {
 475             decimal_exponent = -decimal_exponent;
 476           }
 477
 478         /* From now on: the decimal exponent is > 0. Its sign is separate.  */
 479
 480         size_of_power_in_chars = size_of_power_in_littlenums
 481           * sizeof (LITTLENUM_TYPE) + 2;
 482
 483         power_binary_low = (LITTLENUM_TYPE *) alloca (size_of_power_in_chars);
 484         temporary_binary_low = (LITTLENUM_TYPE *) alloca (size_of_power_in_chars);
 485         memset ((char *) power_binary_low, '\0', size_of_power_in_chars);
 486         *power_binary_low = 1;
 487         power_of_10_flonum.exponent = 0;
 488         power_of_10_flonum.low = power_binary_low;
 489         power_of_10_flonum.leader = power_binary_low;
 490         power_of_10_flonum.high = power_binary_low + size_of_power_in_littlenums - 1;
 491         power_of_10_flonum.sign = '+';
 492         temporary_flonum.low = temporary_binary_low;
 493         temporary_flonum.high = temporary_binary_low + size_of_power_in_littlenums - 1;
 494         /*
 495          * (power) == 1.
 496          * Space for temporary_flonum allocated.
 497          */
 498
 499         /*
 500          * ...
 501          *
 502          * WHILE        more bits
 503          * DO   find next bit (with place value)
 504          *      multiply into power mantissa
 505          * OD
 506          */
 507         {
 508           int place_number_limit;
 509           /* Any 10^(2^n) whose "n" exceeds this */
 510           /* value will fall off the end of */
 511           /* flonum_XXXX_powers_of_ten[].  */
 512           int place_number;
 513           const FLONUM_TYPE *multiplicand;      /* -> 10^(2^n) */
 514
 515           place_number_limit = table_size_of_flonum_powers_of_ten;
 516
 517           multiplicand = (decimal_exponent_is_negative
 518                           ? flonum_negative_powers_of_ten
 519                           : flonum_positive_powers_of_ten);
 520
 521           for (place_number = 1;/* Place value of this bit of exponent.  */
 522                decimal_exponent;/* Quit when no more 1 bits in exponent.  */
 523                decimal_exponent >>= 1, place_number++)
 524             {
 525               if (decimal_exponent & 1)
 526                 {
 527                   if (place_number > place_number_limit)
 528                     {
 529                       /* The decimal exponent has a magnitude so great
 530                          that our tables can't help us fragment it.
 531                          Although this routine is in error because it
 532                          can't imagine a number that big, signal an
 533                          error as if it is the user's fault for
 534                          presenting such a big number.  */
 535                       return_value = ERROR_EXPONENT_OVERFLOW;
 536                       /* quit out of loop gracefully */
 537                       decimal_exponent = 0;
 538                     }
 539                   else
 540                     {
 541 #ifdef TRACE
 542                       printf ("before multiply, place_number = %d., power_of_10_flonum:\n",
 543                               place_number);
 544
 545                       flonum_print (&power_of_10_flonum);
 546                       (void) putchar ('\n');
 547 #endif
 548 #ifdef TRACE
 549                       printf ("multiplier:\n");
 550                       flonum_print (multiplicand + place_number);
 551                       (void) putchar ('\n');
 552 #endif
 553                       flonum_multip (multiplicand + place_number,
 554                                      &power_of_10_flonum, &temporary_flonum);
 555 #ifdef TRACE
 556                       printf ("after multiply:\n");
 557                       flonum_print (&temporary_flonum);
 558                       (void) putchar ('\n');
 559 #endif
 560                       flonum_copy (&temporary_flonum, &power_of_10_flonum);
 561 #ifdef TRACE
 562                       printf ("after copy:\n");
 563                       flonum_print (&power_of_10_flonum);
 564                       (void) putchar ('\n');
 565 #endif
 566                     } /* If this bit of decimal_exponent was computable.*/
 567                 } /* If this bit of decimal_exponent was set.  */
 568             } /* For each bit of binary representation of exponent */
 569 #ifdef TRACE
 570           printf ("after computing power_of_10_flonum:\n");
 571           flonum_print (&power_of_10_flonum);
 572           (void) putchar ('\n');
 573 #endif
 574         }
 575
 576       }
 577
 578       /*
 579        * power_of_10_flonum is power of ten in binary (mantissa) , (exponent).
 580        * It may be the number 1, in which case we don't NEED to multiply.
 581        *
 582        * Multiply (decimal digits) by power_of_10_flonum.
 583        */
 584
 585       flonum_multip (&power_of_10_flonum, &digits_flonum, address_of_generic_floating_point_number);
 586       /* Assert sign of the number we made is '+'.  */
 587       address_of_generic_floating_point_number->sign = digits_sign_char;
 588
 589     }
 590   return return_value;
 591 }
 592
 593 #ifdef TRACE
 594 static void
 595 flonum_print (f)
 596      const FLONUM_TYPE *f;
 597 {
 598   LITTLENUM_TYPE *lp;
 599   char littlenum_format[10];
 600   sprintf (littlenum_format, " %%0%dx", sizeof (LITTLENUM_TYPE) * 2);
 601 #define print_littlenum(LP)     (printf (littlenum_format, LP))
 602   printf ("flonum @%p %c e%ld", f, f->sign, f->exponent);
 603   if (f->low < f->high)
 604     for (lp = f->high; lp >= f->low; lp--)
 605       print_littlenum (*lp);
 606   else
 607     for (lp = f->low; lp <= f->high; lp++)
 608       print_littlenum (*lp);
 609   printf ("\n");
 610   fflush (stdout);
 611 }
 612 #endif
 613
 614 /* end of atof_generic.c */