| 1 | /* atof_ieee.c - turn a Flonum into an IEEE floating point number |
| 2 | Copyright 1987, 1992, 1994, 1996, 1997, 1998, 1999, 2000, 2001 |
| 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 | /* Some float formats are based on the IEEE standard, but use the |
| 23 | largest exponent for normal numbers instead of NaNs and infinites. |
| 24 | The macro TC_LARGEST_EXPONENT_IS_NORMAL should evaluate to true |
| 25 | if the target machine uses such a format. The macro can depend on |
| 26 | command line flags if necessary. There is no need to define the |
| 27 | macro if it would always be 0. */ |
| 28 | |
| 29 | #include "as.h" |
| 30 | |
| 31 | /* Flonums returned here. */ |
| 32 | extern FLONUM_TYPE generic_floating_point_number; |
| 33 | |
| 34 | static int next_bits PARAMS ((int)); |
| 35 | static void unget_bits PARAMS ((int)); |
| 36 | static void make_invalid_floating_point_number PARAMS ((LITTLENUM_TYPE *)); |
| 37 | |
| 38 | extern const char EXP_CHARS[]; |
| 39 | /* Precision in LittleNums. */ |
| 40 | /* Don't count the gap in the m68k extended precision format. */ |
| 41 | #define MAX_PRECISION (5) |
| 42 | #define F_PRECISION (2) |
| 43 | #define D_PRECISION (4) |
| 44 | #define X_PRECISION (5) |
| 45 | #define P_PRECISION (5) |
| 46 | |
| 47 | /* Length in LittleNums of guard bits. */ |
| 48 | #define GUARD (2) |
| 49 | |
| 50 | #ifndef TC_LARGEST_EXPONENT_IS_NORMAL |
| 51 | #define TC_LARGEST_EXPONENT_IS_NORMAL 0 |
| 52 | #endif |
| 53 | |
| 54 | static const unsigned long mask[] = |
| 55 | { |
| 56 | 0x00000000, |
| 57 | 0x00000001, |
| 58 | 0x00000003, |
| 59 | 0x00000007, |
| 60 | 0x0000000f, |
| 61 | 0x0000001f, |
| 62 | 0x0000003f, |
| 63 | 0x0000007f, |
| 64 | 0x000000ff, |
| 65 | 0x000001ff, |
| 66 | 0x000003ff, |
| 67 | 0x000007ff, |
| 68 | 0x00000fff, |
| 69 | 0x00001fff, |
| 70 | 0x00003fff, |
| 71 | 0x00007fff, |
| 72 | 0x0000ffff, |
| 73 | 0x0001ffff, |
| 74 | 0x0003ffff, |
| 75 | 0x0007ffff, |
| 76 | 0x000fffff, |
| 77 | 0x001fffff, |
| 78 | 0x003fffff, |
| 79 | 0x007fffff, |
| 80 | 0x00ffffff, |
| 81 | 0x01ffffff, |
| 82 | 0x03ffffff, |
| 83 | 0x07ffffff, |
| 84 | 0x0fffffff, |
| 85 | 0x1fffffff, |
| 86 | 0x3fffffff, |
| 87 | 0x7fffffff, |
| 88 | 0xffffffff, |
| 89 | }; |
| 90 | \f |
| 91 | static int bits_left_in_littlenum; |
| 92 | static int littlenums_left; |
| 93 | static LITTLENUM_TYPE *littlenum_pointer; |
| 94 | |
| 95 | static int |
| 96 | next_bits (number_of_bits) |
| 97 | int number_of_bits; |
| 98 | { |
| 99 | int return_value; |
| 100 | |
| 101 | if (!littlenums_left) |
| 102 | return (0); |
| 103 | if (number_of_bits >= bits_left_in_littlenum) |
| 104 | { |
| 105 | return_value = mask[bits_left_in_littlenum] & *littlenum_pointer; |
| 106 | number_of_bits -= bits_left_in_littlenum; |
| 107 | return_value <<= number_of_bits; |
| 108 | |
| 109 | if (--littlenums_left) |
| 110 | { |
| 111 | bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits; |
| 112 | --littlenum_pointer; |
| 113 | return_value |= |
| 114 | (*littlenum_pointer >> bits_left_in_littlenum) |
| 115 | & mask[number_of_bits]; |
| 116 | } |
| 117 | } |
| 118 | else |
| 119 | { |
| 120 | bits_left_in_littlenum -= number_of_bits; |
| 121 | return_value = |
| 122 | mask[number_of_bits] & (*littlenum_pointer >> bits_left_in_littlenum); |
| 123 | } |
| 124 | return return_value; |
| 125 | } |
| 126 | |
| 127 | /* Num had better be less than LITTLENUM_NUMBER_OF_BITS. */ |
| 128 | |
| 129 | static void |
| 130 | unget_bits (num) |
| 131 | int num; |
| 132 | { |
| 133 | if (!littlenums_left) |
| 134 | { |
| 135 | ++littlenum_pointer; |
| 136 | ++littlenums_left; |
| 137 | bits_left_in_littlenum = num; |
| 138 | } |
| 139 | else if (bits_left_in_littlenum + num > LITTLENUM_NUMBER_OF_BITS) |
| 140 | { |
| 141 | bits_left_in_littlenum = |
| 142 | num - (LITTLENUM_NUMBER_OF_BITS - bits_left_in_littlenum); |
| 143 | ++littlenum_pointer; |
| 144 | ++littlenums_left; |
| 145 | } |
| 146 | else |
| 147 | bits_left_in_littlenum += num; |
| 148 | } |
| 149 | |
| 150 | static void |
| 151 | make_invalid_floating_point_number (words) |
| 152 | LITTLENUM_TYPE *words; |
| 153 | { |
| 154 | as_bad (_("cannot create floating-point number")); |
| 155 | /* Zero the leftmost bit. */ |
| 156 | words[0] = (LITTLENUM_TYPE) ((unsigned) -1) >> 1; |
| 157 | words[1] = (LITTLENUM_TYPE) -1; |
| 158 | words[2] = (LITTLENUM_TYPE) -1; |
| 159 | words[3] = (LITTLENUM_TYPE) -1; |
| 160 | words[4] = (LITTLENUM_TYPE) -1; |
| 161 | words[5] = (LITTLENUM_TYPE) -1; |
| 162 | } |
| 163 | \f |
| 164 | /* Warning: This returns 16-bit LITTLENUMs. It is up to the caller to |
| 165 | figure out any alignment problems and to conspire for the |
| 166 | bytes/word to be emitted in the right order. Bigendians beware! */ |
| 167 | |
| 168 | /* Note that atof-ieee always has X and P precisions enabled. it is up |
| 169 | to md_atof to filter them out if the target machine does not support |
| 170 | them. */ |
| 171 | |
| 172 | /* Returns pointer past text consumed. */ |
| 173 | |
| 174 | char * |
| 175 | atof_ieee (str, what_kind, words) |
| 176 | char *str; /* Text to convert to binary. */ |
| 177 | int what_kind; /* 'd', 'f', 'g', 'h'. */ |
| 178 | LITTLENUM_TYPE *words; /* Build the binary here. */ |
| 179 | { |
| 180 | /* Extra bits for zeroed low-order bits. |
| 181 | The 1st MAX_PRECISION are zeroed, the last contain flonum bits. */ |
| 182 | static LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD]; |
| 183 | char *return_value; |
| 184 | /* Number of 16-bit words in the format. */ |
| 185 | int precision; |
| 186 | long exponent_bits; |
| 187 | FLONUM_TYPE save_gen_flonum; |
| 188 | |
| 189 | /* We have to save the generic_floating_point_number because it |
| 190 | contains storage allocation about the array of LITTLENUMs where |
| 191 | the value is actually stored. We will allocate our own array of |
| 192 | littlenums below, but have to restore the global one on exit. */ |
| 193 | save_gen_flonum = generic_floating_point_number; |
| 194 | |
| 195 | return_value = str; |
| 196 | generic_floating_point_number.low = bits + MAX_PRECISION; |
| 197 | generic_floating_point_number.high = NULL; |
| 198 | generic_floating_point_number.leader = NULL; |
| 199 | generic_floating_point_number.exponent = 0; |
| 200 | generic_floating_point_number.sign = '\0'; |
| 201 | |
| 202 | /* Use more LittleNums than seems necessary: the highest flonum may |
| 203 | have 15 leading 0 bits, so could be useless. */ |
| 204 | |
| 205 | memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION); |
| 206 | |
| 207 | switch (what_kind) |
| 208 | { |
| 209 | case 'f': |
| 210 | case 'F': |
| 211 | case 's': |
| 212 | case 'S': |
| 213 | precision = F_PRECISION; |
| 214 | exponent_bits = 8; |
| 215 | break; |
| 216 | |
| 217 | case 'd': |
| 218 | case 'D': |
| 219 | case 'r': |
| 220 | case 'R': |
| 221 | precision = D_PRECISION; |
| 222 | exponent_bits = 11; |
| 223 | break; |
| 224 | |
| 225 | case 'x': |
| 226 | case 'X': |
| 227 | case 'e': |
| 228 | case 'E': |
| 229 | precision = X_PRECISION; |
| 230 | exponent_bits = 15; |
| 231 | break; |
| 232 | |
| 233 | case 'p': |
| 234 | case 'P': |
| 235 | |
| 236 | precision = P_PRECISION; |
| 237 | exponent_bits = -1; |
| 238 | break; |
| 239 | |
| 240 | default: |
| 241 | make_invalid_floating_point_number (words); |
| 242 | return (NULL); |
| 243 | } |
| 244 | |
| 245 | generic_floating_point_number.high |
| 246 | = generic_floating_point_number.low + precision - 1 + GUARD; |
| 247 | |
| 248 | if (atof_generic (&return_value, ".", EXP_CHARS, |
| 249 | &generic_floating_point_number)) |
| 250 | { |
| 251 | make_invalid_floating_point_number (words); |
| 252 | return (NULL); |
| 253 | } |
| 254 | gen_to_words (words, precision, exponent_bits); |
| 255 | |
| 256 | /* Restore the generic_floating_point_number's storage alloc (and |
| 257 | everything else). */ |
| 258 | generic_floating_point_number = save_gen_flonum; |
| 259 | |
| 260 | return return_value; |
| 261 | } |
| 262 | |
| 263 | /* Turn generic_floating_point_number into a real float/double/extended. */ |
| 264 | |
| 265 | int |
| 266 | gen_to_words (words, precision, exponent_bits) |
| 267 | LITTLENUM_TYPE *words; |
| 268 | int precision; |
| 269 | long exponent_bits; |
| 270 | { |
| 271 | int return_value = 0; |
| 272 | |
| 273 | long exponent_1; |
| 274 | long exponent_2; |
| 275 | long exponent_3; |
| 276 | long exponent_4; |
| 277 | int exponent_skippage; |
| 278 | LITTLENUM_TYPE word1; |
| 279 | LITTLENUM_TYPE *lp; |
| 280 | LITTLENUM_TYPE *words_end; |
| 281 | |
| 282 | words_end = words + precision; |
| 283 | #ifdef TC_M68K |
| 284 | if (precision == X_PRECISION) |
| 285 | /* On the m68k the extended precision format has a gap of 16 bits |
| 286 | between the exponent and the mantissa. */ |
| 287 | words_end++; |
| 288 | #endif |
| 289 | |
| 290 | if (generic_floating_point_number.low > generic_floating_point_number.leader) |
| 291 | { |
| 292 | /* 0.0e0 seen. */ |
| 293 | if (generic_floating_point_number.sign == '+') |
| 294 | words[0] = 0x0000; |
| 295 | else |
| 296 | words[0] = 0x8000; |
| 297 | memset (&words[1], '\0', |
| 298 | (words_end - words - 1) * sizeof (LITTLENUM_TYPE)); |
| 299 | return return_value; |
| 300 | } |
| 301 | |
| 302 | /* NaN: Do the right thing. */ |
| 303 | if (generic_floating_point_number.sign == 0) |
| 304 | { |
| 305 | if (TC_LARGEST_EXPONENT_IS_NORMAL) |
| 306 | as_warn ("NaNs are not supported by this target\n"); |
| 307 | if (precision == F_PRECISION) |
| 308 | { |
| 309 | words[0] = 0x7fff; |
| 310 | words[1] = 0xffff; |
| 311 | } |
| 312 | else if (precision == X_PRECISION) |
| 313 | { |
| 314 | #ifdef TC_M68K |
| 315 | words[0] = 0x7fff; |
| 316 | words[1] = 0; |
| 317 | words[2] = 0xffff; |
| 318 | words[3] = 0xffff; |
| 319 | words[4] = 0xffff; |
| 320 | words[5] = 0xffff; |
| 321 | #else /* ! TC_M68K */ |
| 322 | #ifdef TC_I386 |
| 323 | words[0] = 0xffff; |
| 324 | words[1] = 0xc000; |
| 325 | words[2] = 0; |
| 326 | words[3] = 0; |
| 327 | words[4] = 0; |
| 328 | #else /* ! TC_I386 */ |
| 329 | abort (); |
| 330 | #endif /* ! TC_I386 */ |
| 331 | #endif /* ! TC_M68K */ |
| 332 | } |
| 333 | else |
| 334 | { |
| 335 | words[0] = 0x7fff; |
| 336 | words[1] = 0xffff; |
| 337 | words[2] = 0xffff; |
| 338 | words[3] = 0xffff; |
| 339 | } |
| 340 | return return_value; |
| 341 | } |
| 342 | else if (generic_floating_point_number.sign == 'P') |
| 343 | { |
| 344 | if (TC_LARGEST_EXPONENT_IS_NORMAL) |
| 345 | as_warn ("Infinities are not supported by this target\n"); |
| 346 | |
| 347 | /* +INF: Do the right thing. */ |
| 348 | if (precision == F_PRECISION) |
| 349 | { |
| 350 | words[0] = 0x7f80; |
| 351 | words[1] = 0; |
| 352 | } |
| 353 | else if (precision == X_PRECISION) |
| 354 | { |
| 355 | #ifdef TC_M68K |
| 356 | words[0] = 0x7fff; |
| 357 | words[1] = 0; |
| 358 | words[2] = 0; |
| 359 | words[3] = 0; |
| 360 | words[4] = 0; |
| 361 | words[5] = 0; |
| 362 | #else /* ! TC_M68K */ |
| 363 | #ifdef TC_I386 |
| 364 | words[0] = 0x7fff; |
| 365 | words[1] = 0x8000; |
| 366 | words[2] = 0; |
| 367 | words[3] = 0; |
| 368 | words[4] = 0; |
| 369 | #else /* ! TC_I386 */ |
| 370 | abort (); |
| 371 | #endif /* ! TC_I386 */ |
| 372 | #endif /* ! TC_M68K */ |
| 373 | } |
| 374 | else |
| 375 | { |
| 376 | words[0] = 0x7ff0; |
| 377 | words[1] = 0; |
| 378 | words[2] = 0; |
| 379 | words[3] = 0; |
| 380 | } |
| 381 | return return_value; |
| 382 | } |
| 383 | else if (generic_floating_point_number.sign == 'N') |
| 384 | { |
| 385 | if (TC_LARGEST_EXPONENT_IS_NORMAL) |
| 386 | as_warn ("Infinities are not supported by this target\n"); |
| 387 | |
| 388 | /* Negative INF. */ |
| 389 | if (precision == F_PRECISION) |
| 390 | { |
| 391 | words[0] = 0xff80; |
| 392 | words[1] = 0x0; |
| 393 | } |
| 394 | else if (precision == X_PRECISION) |
| 395 | { |
| 396 | #ifdef TC_M68K |
| 397 | words[0] = 0xffff; |
| 398 | words[1] = 0; |
| 399 | words[2] = 0; |
| 400 | words[3] = 0; |
| 401 | words[4] = 0; |
| 402 | words[5] = 0; |
| 403 | #else /* ! TC_M68K */ |
| 404 | #ifdef TC_I386 |
| 405 | words[0] = 0xffff; |
| 406 | words[1] = 0x8000; |
| 407 | words[2] = 0; |
| 408 | words[3] = 0; |
| 409 | words[4] = 0; |
| 410 | #else /* ! TC_I386 */ |
| 411 | abort (); |
| 412 | #endif /* ! TC_I386 */ |
| 413 | #endif /* ! TC_M68K */ |
| 414 | } |
| 415 | else |
| 416 | { |
| 417 | words[0] = 0xfff0; |
| 418 | words[1] = 0x0; |
| 419 | words[2] = 0x0; |
| 420 | words[3] = 0x0; |
| 421 | } |
| 422 | return return_value; |
| 423 | } |
| 424 | |
| 425 | /* The floating point formats we support have: |
| 426 | Bit 15 is sign bit. |
| 427 | Bits 14:n are excess-whatever exponent. |
| 428 | Bits n-1:0 (if any) are most significant bits of fraction. |
| 429 | Bits 15:0 of the next word(s) are the next most significant bits. |
| 430 | |
| 431 | So we need: number of bits of exponent, number of bits of |
| 432 | mantissa. */ |
| 433 | bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS; |
| 434 | littlenum_pointer = generic_floating_point_number.leader; |
| 435 | littlenums_left = (1 |
| 436 | + generic_floating_point_number.leader |
| 437 | - generic_floating_point_number.low); |
| 438 | |
| 439 | /* Seek (and forget) 1st significant bit. */ |
| 440 | for (exponent_skippage = 0; !next_bits (1); ++exponent_skippage);; |
| 441 | exponent_1 = (generic_floating_point_number.exponent |
| 442 | + generic_floating_point_number.leader |
| 443 | + 1 |
| 444 | - generic_floating_point_number.low); |
| 445 | |
| 446 | /* Radix LITTLENUM_RADIX, point just higher than |
| 447 | generic_floating_point_number.leader. */ |
| 448 | exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS; |
| 449 | |
| 450 | /* Radix 2. */ |
| 451 | exponent_3 = exponent_2 - exponent_skippage; |
| 452 | |
| 453 | /* Forget leading zeros, forget 1st bit. */ |
| 454 | exponent_4 = exponent_3 + ((1 << (exponent_bits - 1)) - 2); |
| 455 | |
| 456 | /* Offset exponent. */ |
| 457 | lp = words; |
| 458 | |
| 459 | /* Word 1. Sign, exponent and perhaps high bits. */ |
| 460 | word1 = ((generic_floating_point_number.sign == '+') |
| 461 | ? 0 |
| 462 | : (1 << (LITTLENUM_NUMBER_OF_BITS - 1))); |
| 463 | |
| 464 | /* Assume 2's complement integers. */ |
| 465 | if (exponent_4 <= 0) |
| 466 | { |
| 467 | int prec_bits; |
| 468 | int num_bits; |
| 469 | |
| 470 | unget_bits (1); |
| 471 | num_bits = -exponent_4; |
| 472 | prec_bits = |
| 473 | LITTLENUM_NUMBER_OF_BITS * precision - (exponent_bits + 1 + num_bits); |
| 474 | #ifdef TC_I386 |
| 475 | if (precision == X_PRECISION && exponent_bits == 15) |
| 476 | { |
| 477 | /* On the i386 a denormalized extended precision float is |
| 478 | shifted down by one, effectively decreasing the exponent |
| 479 | bias by one. */ |
| 480 | prec_bits -= 1; |
| 481 | num_bits += 1; |
| 482 | } |
| 483 | #endif |
| 484 | |
| 485 | if (num_bits >= LITTLENUM_NUMBER_OF_BITS - exponent_bits) |
| 486 | { |
| 487 | /* Bigger than one littlenum. */ |
| 488 | num_bits -= (LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits; |
| 489 | *lp++ = word1; |
| 490 | if (num_bits + exponent_bits + 1 |
| 491 | > precision * LITTLENUM_NUMBER_OF_BITS) |
| 492 | { |
| 493 | /* Exponent overflow. */ |
| 494 | make_invalid_floating_point_number (words); |
| 495 | return return_value; |
| 496 | } |
| 497 | #ifdef TC_M68K |
| 498 | if (precision == X_PRECISION && exponent_bits == 15) |
| 499 | *lp++ = 0; |
| 500 | #endif |
| 501 | while (num_bits >= LITTLENUM_NUMBER_OF_BITS) |
| 502 | { |
| 503 | num_bits -= LITTLENUM_NUMBER_OF_BITS; |
| 504 | *lp++ = 0; |
| 505 | } |
| 506 | if (num_bits) |
| 507 | *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS - (num_bits)); |
| 508 | } |
| 509 | else |
| 510 | { |
| 511 | if (precision == X_PRECISION && exponent_bits == 15) |
| 512 | { |
| 513 | *lp++ = word1; |
| 514 | #ifdef TC_M68K |
| 515 | *lp++ = 0; |
| 516 | #endif |
| 517 | *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS - num_bits); |
| 518 | } |
| 519 | else |
| 520 | { |
| 521 | word1 |= next_bits ((LITTLENUM_NUMBER_OF_BITS - 1) |
| 522 | - (exponent_bits + num_bits)); |
| 523 | *lp++ = word1; |
| 524 | } |
| 525 | } |
| 526 | while (lp < words_end) |
| 527 | *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS); |
| 528 | |
| 529 | /* Round the mantissa up, but don't change the number. */ |
| 530 | if (next_bits (1)) |
| 531 | { |
| 532 | --lp; |
| 533 | if (prec_bits >= LITTLENUM_NUMBER_OF_BITS) |
| 534 | { |
| 535 | int n = 0; |
| 536 | int tmp_bits; |
| 537 | |
| 538 | n = 0; |
| 539 | tmp_bits = prec_bits; |
| 540 | while (tmp_bits > LITTLENUM_NUMBER_OF_BITS) |
| 541 | { |
| 542 | if (lp[n] != (LITTLENUM_TYPE) - 1) |
| 543 | break; |
| 544 | --n; |
| 545 | tmp_bits -= LITTLENUM_NUMBER_OF_BITS; |
| 546 | } |
| 547 | if (tmp_bits > LITTLENUM_NUMBER_OF_BITS |
| 548 | || (lp[n] & mask[tmp_bits]) != mask[tmp_bits] |
| 549 | || (prec_bits != (precision * LITTLENUM_NUMBER_OF_BITS |
| 550 | - exponent_bits - 1) |
| 551 | #ifdef TC_I386 |
| 552 | /* An extended precision float with only the integer |
| 553 | bit set would be invalid. That must be converted |
| 554 | to the smallest normalized number. */ |
| 555 | && !(precision == X_PRECISION |
| 556 | && prec_bits == (precision * LITTLENUM_NUMBER_OF_BITS |
| 557 | - exponent_bits - 2)) |
| 558 | #endif |
| 559 | )) |
| 560 | { |
| 561 | unsigned long carry; |
| 562 | |
| 563 | for (carry = 1; carry && (lp >= words); lp--) |
| 564 | { |
| 565 | carry = *lp + carry; |
| 566 | *lp = carry; |
| 567 | carry >>= LITTLENUM_NUMBER_OF_BITS; |
| 568 | } |
| 569 | } |
| 570 | else |
| 571 | { |
| 572 | /* This is an overflow of the denormal numbers. We |
| 573 | need to forget what we have produced, and instead |
| 574 | generate the smallest normalized number. */ |
| 575 | lp = words; |
| 576 | word1 = ((generic_floating_point_number.sign == '+') |
| 577 | ? 0 |
| 578 | : (1 << (LITTLENUM_NUMBER_OF_BITS - 1))); |
| 579 | word1 |= (1 |
| 580 | << ((LITTLENUM_NUMBER_OF_BITS - 1) |
| 581 | - exponent_bits)); |
| 582 | *lp++ = word1; |
| 583 | #ifdef TC_I386 |
| 584 | /* Set the integer bit in the extended precision format. |
| 585 | This cannot happen on the m68k where the mantissa |
| 586 | just overflows into the integer bit above. */ |
| 587 | if (precision == X_PRECISION) |
| 588 | *lp++ = 1 << (LITTLENUM_NUMBER_OF_BITS - 1); |
| 589 | #endif |
| 590 | while (lp < words_end) |
| 591 | *lp++ = 0; |
| 592 | } |
| 593 | } |
| 594 | else |
| 595 | *lp += 1; |
| 596 | } |
| 597 | |
| 598 | return return_value; |
| 599 | } |
| 600 | else if ((unsigned long) exponent_4 > mask[exponent_bits] |
| 601 | || (! TC_LARGEST_EXPONENT_IS_NORMAL |
| 602 | && (unsigned long) exponent_4 == mask[exponent_bits])) |
| 603 | { |
| 604 | /* Exponent overflow. Lose immediately. */ |
| 605 | |
| 606 | /* We leave return_value alone: admit we read the |
| 607 | number, but return a floating exception |
| 608 | because we can't encode the number. */ |
| 609 | make_invalid_floating_point_number (words); |
| 610 | return return_value; |
| 611 | } |
| 612 | else |
| 613 | { |
| 614 | word1 |= (exponent_4 << ((LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits)) |
| 615 | | next_bits ((LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits); |
| 616 | } |
| 617 | |
| 618 | *lp++ = word1; |
| 619 | |
| 620 | /* X_PRECISION is special: on the 68k, it has 16 bits of zero in the |
| 621 | middle. Either way, it is then followed by a 1 bit. */ |
| 622 | if (exponent_bits == 15 && precision == X_PRECISION) |
| 623 | { |
| 624 | #ifdef TC_M68K |
| 625 | *lp++ = 0; |
| 626 | #endif |
| 627 | *lp++ = (1 << (LITTLENUM_NUMBER_OF_BITS - 1) |
| 628 | | next_bits (LITTLENUM_NUMBER_OF_BITS - 1)); |
| 629 | } |
| 630 | |
| 631 | /* The rest of the words are just mantissa bits. */ |
| 632 | while (lp < words_end) |
| 633 | *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS); |
| 634 | |
| 635 | if (next_bits (1)) |
| 636 | { |
| 637 | unsigned long carry; |
| 638 | /* Since the NEXT bit is a 1, round UP the mantissa. |
| 639 | The cunning design of these hidden-1 floats permits |
| 640 | us to let the mantissa overflow into the exponent, and |
| 641 | it 'does the right thing'. However, we lose if the |
| 642 | highest-order bit of the lowest-order word flips. |
| 643 | Is that clear? */ |
| 644 | |
| 645 | /* #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2) |
| 646 | Please allow at least 1 more bit in carry than is in a LITTLENUM. |
| 647 | We need that extra bit to hold a carry during a LITTLENUM carry |
| 648 | propagation. Another extra bit (kept 0) will assure us that we |
| 649 | don't get a sticky sign bit after shifting right, and that |
| 650 | permits us to propagate the carry without any masking of bits. |
| 651 | #endif */ |
| 652 | for (carry = 1, lp--; carry; lp--) |
| 653 | { |
| 654 | carry = *lp + carry; |
| 655 | *lp = carry; |
| 656 | carry >>= LITTLENUM_NUMBER_OF_BITS; |
| 657 | if (lp == words) |
| 658 | break; |
| 659 | } |
| 660 | if (precision == X_PRECISION && exponent_bits == 15) |
| 661 | { |
| 662 | /* Extended precision numbers have an explicit integer bit |
| 663 | that we may have to restore. */ |
| 664 | if (lp == words) |
| 665 | { |
| 666 | #ifdef TC_M68K |
| 667 | /* On the m68k there is a gap of 16 bits. We must |
| 668 | explicitly propagate the carry into the exponent. */ |
| 669 | words[0] += words[1]; |
| 670 | words[1] = 0; |
| 671 | lp++; |
| 672 | #endif |
| 673 | /* Put back the integer bit. */ |
| 674 | lp[1] |= 1 << (LITTLENUM_NUMBER_OF_BITS - 1); |
| 675 | } |
| 676 | } |
| 677 | if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1))) |
| 678 | { |
| 679 | /* We leave return_value alone: admit we read the number, |
| 680 | but return a floating exception because we can't encode |
| 681 | the number. */ |
| 682 | *words &= ~(1 << (LITTLENUM_NUMBER_OF_BITS - 1)); |
| 683 | #if 0 |
| 684 | make_invalid_floating_point_number (words); |
| 685 | return return_value; |
| 686 | #endif |
| 687 | } |
| 688 | } |
| 689 | return return_value; |
| 690 | } |
| 691 | |
| 692 | #if 0 |
| 693 | /* Unused. */ |
| 694 | /* This routine is a real kludge. Someone really should do it better, |
| 695 | but I'm too lazy, and I don't understand this stuff all too well |
| 696 | anyway. (JF) */ |
| 697 | |
| 698 | static void |
| 699 | int_to_gen (x) |
| 700 | long x; |
| 701 | { |
| 702 | char buf[20]; |
| 703 | char *bufp; |
| 704 | |
| 705 | sprintf (buf, "%ld", x); |
| 706 | bufp = &buf[0]; |
| 707 | if (atof_generic (&bufp, ".", EXP_CHARS, &generic_floating_point_number)) |
| 708 | as_bad (_("Error converting number to floating point (Exponent overflow?)")); |
| 709 | } |
| 710 | #endif |
| 711 | |
| 712 | #ifdef TEST |
| 713 | char * |
| 714 | print_gen (gen) |
| 715 | FLONUM_TYPE *gen; |
| 716 | { |
| 717 | FLONUM_TYPE f; |
| 718 | LITTLENUM_TYPE arr[10]; |
| 719 | double dv; |
| 720 | float fv; |
| 721 | static char sbuf[40]; |
| 722 | |
| 723 | if (gen) |
| 724 | { |
| 725 | f = generic_floating_point_number; |
| 726 | generic_floating_point_number = *gen; |
| 727 | } |
| 728 | gen_to_words (&arr[0], 4, 11); |
| 729 | memcpy (&dv, &arr[0], sizeof (double)); |
| 730 | sprintf (sbuf, "%x %x %x %x %.14G ", arr[0], arr[1], arr[2], arr[3], dv); |
| 731 | gen_to_words (&arr[0], 2, 8); |
| 732 | memcpy (&fv, &arr[0], sizeof (float)); |
| 733 | sprintf (sbuf + strlen (sbuf), "%x %x %.12g\n", arr[0], arr[1], fv); |
| 734 | |
| 735 | if (gen) |
| 736 | generic_floating_point_number = f; |
| 737 | |
| 738 | return (sbuf); |
| 739 | } |
| 740 | |
| 741 | #endif |