gas/config/atof-vax.c

   1 /* atof_vax.c - turn a Flonum into a VAX floating point number
   2    Copyright 1987, 1992, 1993, 1995, 1997, 1999, 2000
   3    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 2, or (at your option)
  10    any later version.
  11
  12    GAS is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public 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, 59 Temple Place - Suite 330, Boston, MA
  20    02111-1307, USA.  */
  21
  22 #include "as.h"
  23
  24 static int atof_vax_sizeof PARAMS ((int));
  25 static int next_bits PARAMS ((int));
  26 static void make_invalid_floating_point_number PARAMS ((LITTLENUM_TYPE *));
  27 static int what_kind_of_float PARAMS ((int, int *, long *));
  28 static char *atof_vax PARAMS ((char *, int, LITTLENUM_TYPE *));
  29
  30 /* Precision in LittleNums.  */
  31 #define MAX_PRECISION (8)
  32 #define H_PRECISION (8)
  33 #define G_PRECISION (4)
  34 #define D_PRECISION (4)
  35 #define F_PRECISION (2)
  36
  37 /* Length in LittleNums of guard bits.  */
  38 #define GUARD (2)
  39
  40 int flonum_gen2vax PARAMS ((int format_letter, FLONUM_TYPE * f,
  41                             LITTLENUM_TYPE * words));
  42
  43 /* Number of chars in flonum type 'letter'.  */
  44 static int
  45 atof_vax_sizeof (letter)
  46      int letter;
  47 {
  48   int return_value;
  49
  50   /*
  51    * Permitting uppercase letters is probably a bad idea.
  52    * Please use only lower-cased letters in case the upper-cased
  53    * ones become unsupported!
  54    */
  55   switch (letter)
  56     {
  57     case 'f':
  58     case 'F':
  59       return_value = 4;
  60       break;
  61
  62     case 'd':
  63     case 'D':
  64     case 'g':
  65     case 'G':
  66       return_value = 8;
  67       break;
  68
  69     case 'h':
  70     case 'H':
  71       return_value = 16;
  72       break;
  73
  74     default:
  75       return_value = 0;
  76       break;
  77     }
  78   return (return_value);
  79 }                               /* atof_vax_sizeof */
  80
  81 static const long mask[] =
  82 {
  83   0x00000000,
  84   0x00000001,
  85   0x00000003,
  86   0x00000007,
  87   0x0000000f,
  88   0x0000001f,
  89   0x0000003f,
  90   0x0000007f,
  91   0x000000ff,
  92   0x000001ff,
  93   0x000003ff,
  94   0x000007ff,
  95   0x00000fff,
  96   0x00001fff,
  97   0x00003fff,
  98   0x00007fff,
  99   0x0000ffff,
 100   0x0001ffff,
 101   0x0003ffff,
 102   0x0007ffff,
 103   0x000fffff,
 104   0x001fffff,
 105   0x003fffff,
 106   0x007fffff,
 107   0x00ffffff,
 108   0x01ffffff,
 109   0x03ffffff,
 110   0x07ffffff,
 111   0x0fffffff,
 112   0x1fffffff,
 113   0x3fffffff,
 114   0x7fffffff,
 115   0xffffffff
 116 };
 117 \f
 118
 119 /* Shared between flonum_gen2vax and next_bits */
 120 static int bits_left_in_littlenum;
 121 static LITTLENUM_TYPE *littlenum_pointer;
 122 static LITTLENUM_TYPE *littlenum_end;
 123
 124 static int
 125 next_bits (number_of_bits)
 126      int number_of_bits;
 127 {
 128   int return_value;
 129
 130   if (littlenum_pointer < littlenum_end)
 131     return 0;
 132   if (number_of_bits >= bits_left_in_littlenum)
 133     {
 134       return_value = mask[bits_left_in_littlenum] & *littlenum_pointer;
 135       number_of_bits -= bits_left_in_littlenum;
 136       return_value <<= number_of_bits;
 137       bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
 138       littlenum_pointer--;
 139       if (littlenum_pointer >= littlenum_end)
 140         return_value |= ((*littlenum_pointer) >> (bits_left_in_littlenum)) & mask[number_of_bits];
 141     }
 142   else
 143     {
 144       bits_left_in_littlenum -= number_of_bits;
 145       return_value = mask[number_of_bits] & ((*littlenum_pointer) >> bits_left_in_littlenum);
 146     }
 147   return (return_value);
 148 }
 149
 150 static void
 151 make_invalid_floating_point_number (words)
 152      LITTLENUM_TYPE *words;
 153 {
 154   *words = 0x8000;              /* Floating Reserved Operand Code */
 155 }
 156 \f
 157 static int                      /* 0 means letter is OK.  */
 158 what_kind_of_float (letter, precisionP, exponent_bitsP)
 159      int letter;                /* In: lowercase please. What kind of float? */
 160      int *precisionP;           /* Number of 16-bit words in the float.  */
 161      long *exponent_bitsP;      /* Number of exponent bits.  */
 162 {
 163   int retval;                   /* 0: OK.  */
 164
 165   retval = 0;
 166   switch (letter)
 167     {
 168     case 'f':
 169       *precisionP = F_PRECISION;
 170       *exponent_bitsP = 8;
 171       break;
 172
 173     case 'd':
 174       *precisionP = D_PRECISION;
 175       *exponent_bitsP = 8;
 176       break;
 177
 178     case 'g':
 179       *precisionP = G_PRECISION;
 180       *exponent_bitsP = 11;
 181       break;
 182
 183     case 'h':
 184       *precisionP = H_PRECISION;
 185       *exponent_bitsP = 15;
 186       break;
 187
 188     default:
 189       retval = 69;
 190       break;
 191     }
 192   return (retval);
 193 }
 194 \f
 195 /***********************************************************************\
 196  *                                                                      *
 197  *      Warning: this returns 16-bit LITTLENUMs, because that is        *
 198  *      what the VAX thinks in. It is up to the caller to figure        *
 199  *      out any alignment problems and to conspire for the bytes/word   *
 200  *      to be emitted in the right order. Bigendians beware!            *
 201  *                                                                      *
 202  \***********************************************************************/
 203
 204 static char *                           /* Return pointer past text consumed.  */
 205 atof_vax (str, what_kind, words)
 206      char *str;                 /* Text to convert to binary.  */
 207      int what_kind;             /* 'd', 'f', 'g', 'h' */
 208      LITTLENUM_TYPE *words;     /* Build the binary here.  */
 209 {
 210   FLONUM_TYPE f;
 211   LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
 212   /* Extra bits for zeroed low-order bits.  */
 213   /* The 1st MAX_PRECISION are zeroed, */
 214   /* the last contain flonum bits.  */
 215   char *return_value;
 216   int precision;                /* Number of 16-bit words in the format.  */
 217   long exponent_bits;
 218
 219   return_value = str;
 220   f.low = bits + MAX_PRECISION;
 221   f.high = NULL;
 222   f.leader = NULL;
 223   f.exponent = 0;
 224   f.sign = '\0';
 225
 226   if (what_kind_of_float (what_kind, &precision, &exponent_bits))
 227     {
 228       return_value = NULL;      /* We lost.  */
 229       make_invalid_floating_point_number (words);
 230     }
 231
 232   if (return_value)
 233     {
 234       memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION);
 235
 236       /* Use more LittleNums than seems */
 237       /* necessary: the highest flonum may have */
 238       /* 15 leading 0 bits, so could be useless.  */
 239       f.high = f.low + precision - 1 + GUARD;
 240
 241       if (atof_generic (&return_value, ".", "eE", &f))
 242         {
 243           make_invalid_floating_point_number (words);
 244           return_value = NULL;  /* we lost */
 245         }
 246       else
 247         {
 248           if (flonum_gen2vax (what_kind, &f, words))
 249             {
 250               return_value = NULL;
 251             }
 252         }
 253     }
 254   return (return_value);
 255 }                               /* atof_vax() */
 256 \f
 257 /*
 258  * In: a flonum, a vax floating point format.
 259  * Out: a vax floating-point bit pattern.
 260  */
 261
 262 int                             /* 0: OK.  */
 263 flonum_gen2vax (format_letter, f, words)
 264      int format_letter;         /* One of 'd' 'f' 'g' 'h'.  */
 265      FLONUM_TYPE *f;
 266      LITTLENUM_TYPE *words;     /* Deliver answer here.  */
 267 {
 268   LITTLENUM_TYPE *lp;
 269   int precision;
 270   long exponent_bits;
 271   int return_value;             /* 0 == OK.  */
 272
 273   return_value = what_kind_of_float (format_letter, &precision, &exponent_bits);
 274
 275   if (return_value != 0)
 276     {
 277       make_invalid_floating_point_number (words);
 278     }
 279   else
 280     {
 281       if (f->low > f->leader)
 282         {
 283           /* 0.0e0 seen.  */
 284           memset (words, '\0', sizeof (LITTLENUM_TYPE) * precision);
 285         }
 286       else
 287         {
 288           long exponent_1;
 289           long exponent_2;
 290           long exponent_3;
 291           long exponent_4;
 292           int exponent_skippage;
 293           LITTLENUM_TYPE word1;
 294
 295           /* JF: Deal with new Nan, +Inf and -Inf codes */
 296           if (f->sign != '-' && f->sign != '+')
 297             {
 298               make_invalid_floating_point_number (words);
 299               return return_value;
 300             }
 301           /*
 302                          * All vaxen floating_point formats (so far) have:
 303                          * Bit 15 is sign bit.
 304                          * Bits 14:n are excess-whatever exponent.
 305                          * Bits n-1:0 (if any) are most significant bits of fraction.
 306                          * Bits 15:0 of the next word are the next most significant bits.
 307                          * And so on for each other word.
 308                          *
 309                          * All this to be compatible with a KF11?? (Which is still faster
 310                          * than lots of vaxen I can think of, but it also has higher
 311                          * maintenance costs ... sigh).
 312                          *
 313                          * So we need: number of bits of exponent, number of bits of
 314                          * mantissa.
 315                          */
 316
 317 #ifdef NEVER                    /******* This zeroing seems redundant - Dean 3may86 **********/
 318           /*
 319                          * No matter how few bits we got back from the atof()
 320                          * routine, add enough zero littlenums so the rest of the
 321                          * code won't run out of "significant" bits in the mantissa.
 322                          */
 323           {
 324             LITTLENUM_TYPE *ltp;
 325             for (ltp = f->leader + 1;
 326                  ltp <= f->low + precision;
 327                  ltp++)
 328               {
 329                 *ltp = 0;
 330               }
 331           }
 332 #endif
 333
 334           bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
 335           littlenum_pointer = f->leader;
 336           littlenum_end = f->low;
 337           /* Seek (and forget) 1st significant bit */
 338           for (exponent_skippage = 0;
 339                !next_bits (1);
 340                exponent_skippage++);;
 341
 342           exponent_1 = f->exponent + f->leader + 1 - f->low;
 343           /* Radix LITTLENUM_RADIX, point just higher than f->leader.  */
 344           exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
 345           /* Radix 2.  */
 346           exponent_3 = exponent_2 - exponent_skippage;
 347           /* Forget leading zeros, forget 1st bit.  */
 348           exponent_4 = exponent_3 + (1 << (exponent_bits - 1));
 349           /* Offset exponent.  */
 350
 351           if (exponent_4 & ~mask[exponent_bits])
 352             {
 353               /*
 354                                  * Exponent overflow. Lose immediately.
 355                                  */
 356
 357               make_invalid_floating_point_number (words);
 358
 359               /*
 360                                  * We leave return_value alone: admit we read the
 361                                  * number, but return a floating exception
 362                                  * because we can't encode the number.
 363                                  */
 364             }
 365           else
 366             {
 367               lp = words;
 368
 369               /* Word 1. Sign, exponent and perhaps high bits.  */
 370               /* Assume 2's complement integers.  */
 371               word1 = (((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits))
 372                        | ((f->sign == '+') ? 0 : 0x8000)
 373                        | next_bits (15 - exponent_bits));
 374               *lp++ = word1;
 375
 376               /* The rest of the words are just mantissa bits.  */
 377               for (; lp < words + precision; lp++)
 378                 {
 379                   *lp = next_bits (LITTLENUM_NUMBER_OF_BITS);
 380                 }
 381
 382               if (next_bits (1))
 383                 {
 384                   /*
 385                                          * Since the NEXT bit is a 1, round UP the mantissa.
 386                                          * The cunning design of these hidden-1 floats permits
 387                                          * us to let the mantissa overflow into the exponent, and
 388                                          * it 'does the right thing'. However, we lose if the
 389                                          * highest-order bit of the lowest-order word flips.
 390                                          * Is that clear?
 391                                          */
 392
 393                   unsigned long carry;
 394
 395                   /*
 396                                           #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
 397                                           Please allow at least 1 more bit in carry than is in a LITTLENUM.
 398                                           We need that extra bit to hold a carry during a LITTLENUM carry
 399                                           propagation. Another extra bit (kept 0) will assure us that we
 400                                           don't get a sticky sign bit after shifting right, and that
 401                                           permits us to propagate the carry without any masking of bits.
 402                                           #endif
 403                                           */
 404                   for (carry = 1, lp--;
 405                        carry && (lp >= words);
 406                        lp--)
 407                     {
 408                       carry = *lp + carry;
 409                       *lp = carry;
 410                       carry >>= LITTLENUM_NUMBER_OF_BITS;
 411                     }
 412
 413                   if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)))
 414                     {
 415                       make_invalid_floating_point_number (words);
 416                       /*
 417                                                  * We leave return_value alone: admit we read the
 418                                                  * number, but return a floating exception
 419                                                  * because we can't encode the number.
 420                                                  */
 421                     }
 422                 }               /* if (we needed to round up) */
 423             }                   /* if (exponent overflow) */
 424         }                       /* if (0.0e0) */
 425     }                           /* if (float_type was OK) */
 426   return (return_value);
 427 }                               /* flonum_gen2vax() */
 428
 429 /* JF this used to be in vax.c but this looks like a better place for it */
 430
 431 /*
 432  *              md_atof()
 433  *
 434  * In:  input_line_pointer->the 1st character of a floating-point
 435  *              number.
 436  *      1 letter denoting the type of statement that wants a
 437  *              binary floating point number returned.
 438  *      Address of where to build floating point literal.
 439  *              Assumed to be 'big enough'.
 440  *      Address of where to return size of literal (in chars).
 441  *
 442  * Out: Input_line_pointer->of next char after floating number.
 443  *      Error message, or 0.
 444  *      Floating point literal.
 445  *      Number of chars we used for the literal.
 446  */
 447
 448 #define MAXIMUM_NUMBER_OF_LITTLENUMS (8)        /* For .hfloats.  */
 449
 450 char *
 451 md_atof (what_statement_type, literalP, sizeP)
 452      int what_statement_type;
 453      char *literalP;
 454      int *sizeP;
 455 {
 456   LITTLENUM_TYPE words[MAXIMUM_NUMBER_OF_LITTLENUMS];
 457   register char kind_of_float;
 458   register int number_of_chars;
 459   register LITTLENUM_TYPE *littlenumP;
 460
 461   switch (what_statement_type)
 462     {
 463     case 'F':                   /* .float */
 464     case 'f':                   /* .ffloat */
 465       kind_of_float = 'f';
 466       break;
 467
 468     case 'D':                   /* .double */
 469     case 'd':                   /* .dfloat */
 470       kind_of_float = 'd';
 471       break;
 472
 473     case 'g':                   /* .gfloat */
 474       kind_of_float = 'g';
 475       break;
 476
 477     case 'h':                   /* .hfloat */
 478       kind_of_float = 'h';
 479       break;
 480
 481     default:
 482       kind_of_float = 0;
 483       break;
 484     };
 485
 486   if (kind_of_float)
 487     {
 488       register LITTLENUM_TYPE *limit;
 489
 490       input_line_pointer = atof_vax (input_line_pointer,
 491                                      kind_of_float,
 492                                      words);
 493       /*
 494        * The atof_vax() builds up 16-bit numbers.
 495        * Since the assembler may not be running on
 496        * a little-endian machine, be very careful about
 497        * converting words to chars.
 498        */
 499       number_of_chars = atof_vax_sizeof (kind_of_float);
 500       know (number_of_chars <= MAXIMUM_NUMBER_OF_LITTLENUMS * sizeof (LITTLENUM_TYPE));
 501       limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE));
 502       for (littlenumP = words; littlenumP < limit; littlenumP++)
 503         {
 504           md_number_to_chars (literalP, *littlenumP, sizeof (LITTLENUM_TYPE));
 505           literalP += sizeof (LITTLENUM_TYPE);
 506         };
 507     }
 508   else
 509     {
 510       number_of_chars = 0;
 511     };
 512
 513   *sizeP = number_of_chars;
 514   return kind_of_float ? NULL : _("Bad call to md_atof()");
 515 }
 516
 517 /* end of atof-vax.c */