1/* atof_vax.c - turn a Flonum into a VAX floating point number 2 Copyright (C) 1987-2022 Free Software Foundation, Inc. 3 4 This file is part of GAS, the GNU Assembler. 5 6 GAS is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3, or (at your option) 9 any later version. 10 11 GAS is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GAS; see the file COPYING. If not, write to the Free 18 Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA 19 02110-1301, USA. */ 20 21#include "as.h" 22 23/* Precision in LittleNums. */ 24#define MAX_PRECISION 8 25#define H_PRECISION 8 26#define G_PRECISION 4 27#define D_PRECISION 4 28#define F_PRECISION 2 29 30/* Length in LittleNums of guard bits. */ 31#define GUARD 2 32 33int flonum_gen2vax (int, FLONUM_TYPE *, LITTLENUM_TYPE *); 34 35/* Number of chars in flonum type 'letter'. */ 36 37static unsigned int 38atof_vax_sizeof (int letter) 39{ 40 int return_value; 41 42 /* Permitting uppercase letters is probably a bad idea. 43 Please use only lower-cased letters in case the upper-cased 44 ones become unsupported! */ 45 switch (letter) 46 { 47 case 'f': 48 case 'F': 49 return_value = 4; 50 break; 51 52 case 'd': 53 case 'D': 54 case 'g': 55 case 'G': 56 return_value = 8; 57 break; 58 59 case 'h': 60 case 'H': 61 return_value = 16; 62 break; 63 64 default: 65 return_value = 0; 66 break; 67 } 68 69 return return_value; 70} 71 72static const long mask[] = 73{ 74 0x00000000, 75 0x00000001, 76 0x00000003, 77 0x00000007, 78 0x0000000f, 79 0x0000001f, 80 0x0000003f, 81 0x0000007f, 82 0x000000ff, 83 0x000001ff, 84 0x000003ff, 85 0x000007ff, 86 0x00000fff, 87 0x00001fff, 88 0x00003fff, 89 0x00007fff, 90 0x0000ffff, 91 0x0001ffff, 92 0x0003ffff, 93 0x0007ffff, 94 0x000fffff, 95 0x001fffff, 96 0x003fffff, 97 0x007fffff, 98 0x00ffffff, 99 0x01ffffff, 100 0x03ffffff, 101 0x07ffffff, 102 0x0fffffff, 103 0x1fffffff, 104 0x3fffffff, 105 0x7fffffff, 106 0xffffffff 107}; 108 109 110/* Shared between flonum_gen2vax and next_bits. */ 111static int bits_left_in_littlenum; 112static LITTLENUM_TYPE *littlenum_pointer; 113static LITTLENUM_TYPE *littlenum_end; 114 115static int 116next_bits (int number_of_bits) 117{ 118 int return_value; 119 120 if (littlenum_pointer < littlenum_end) 121 return 0; 122 if (number_of_bits >= bits_left_in_littlenum) 123 { 124 return_value = mask[bits_left_in_littlenum] & *littlenum_pointer; 125 number_of_bits -= bits_left_in_littlenum; 126 return_value <<= number_of_bits; 127 bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits; 128 littlenum_pointer--; 129 if (littlenum_pointer >= littlenum_end) 130 return_value |= ((*littlenum_pointer) >> (bits_left_in_littlenum)) & mask[number_of_bits]; 131 } 132 else 133 { 134 bits_left_in_littlenum -= number_of_bits; 135 return_value = mask[number_of_bits] & ((*littlenum_pointer) >> bits_left_in_littlenum); 136 } 137 return return_value; 138} 139 140static void 141make_invalid_floating_point_number (LITTLENUM_TYPE *words) 142{ 143 *words = 0x8000; /* Floating Reserved Operand Code. */ 144} 145 146 147static int /* 0 means letter is OK. */ 148what_kind_of_float (int letter, /* In: lowercase please. What kind of float? */ 149 int *precisionP, /* Number of 16-bit words in the float. */ 150 long *exponent_bitsP) /* Number of exponent bits. */ 151{ 152 int retval; 153 154 retval = 0; 155 switch (letter) 156 { 157 case 'f': 158 *precisionP = F_PRECISION; 159 *exponent_bitsP = 8; 160 break; 161 162 case 'd': 163 *precisionP = D_PRECISION; 164 *exponent_bitsP = 8; 165 break; 166 167 case 'g': 168 *precisionP = G_PRECISION; 169 *exponent_bitsP = 11; 170 break; 171 172 case 'h': 173 *precisionP = H_PRECISION; 174 *exponent_bitsP = 15; 175 break; 176 177 default: 178 retval = 69; 179 break; 180 } 181 return retval; 182} 183 184/* Warning: this returns 16-bit LITTLENUMs, because that is 185 what the VAX thinks in. It is up to the caller to figure 186 out any alignment problems and to conspire for the bytes/word 187 to be emitted in the right order. Bigendians beware! */ 188 189static char * 190atof_vax (char *str, /* Text to convert to binary. */ 191 int what_kind, /* 'd', 'f', 'g', 'h' */ 192 LITTLENUM_TYPE *words) /* Build the binary here. */ 193{ 194 FLONUM_TYPE f; 195 LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD]; 196 /* Extra bits for zeroed low-order bits. 197 The 1st MAX_PRECISION are zeroed, 198 the last contain flonum bits. */ 199 char *return_value; 200 int precision; /* Number of 16-bit words in the format. */ 201 long exponent_bits; 202 203 return_value = str; 204 f.low = bits + MAX_PRECISION; 205 f.high = NULL; 206 f.leader = NULL; 207 f.exponent = 0; 208 f.sign = '\0'; 209 210 if (what_kind_of_float (what_kind, &precision, &exponent_bits)) 211 { 212 return_value = NULL; 213 make_invalid_floating_point_number (words); 214 } 215 216 if (return_value) 217 { 218 memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION); 219 220 /* Use more LittleNums than seems 221 necessary: the highest flonum may have 222 15 leading 0 bits, so could be useless. */ 223 f.high = f.low + precision - 1 + GUARD; 224 225 if (atof_generic (&return_value, ".", "eE", &f)) 226 { 227 make_invalid_floating_point_number (words); 228 return_value = NULL; 229 } 230 else if (flonum_gen2vax (what_kind, &f, words)) 231 return_value = NULL; 232 } 233 234 return return_value; 235} 236 237/* In: a flonum, a vax floating point format. 238 Out: a vax floating-point bit pattern. */ 239 240int 241flonum_gen2vax (int format_letter, /* One of 'd' 'f' 'g' 'h'. */ 242 FLONUM_TYPE *f, 243 LITTLENUM_TYPE *words) /* Deliver answer here. */ 244{ 245 LITTLENUM_TYPE *lp; 246 int precision; 247 long exponent_bits; 248 int return_value; /* 0 == OK. */ 249 250 return_value = what_kind_of_float (format_letter, &precision, &exponent_bits); 251 252 if (return_value != 0) 253 make_invalid_floating_point_number (words); 254 255 else 256 { 257 if (f->low > f->leader) 258 /* 0.0e0 seen. */ 259 memset (words, '\0', sizeof (LITTLENUM_TYPE) * precision); 260 261 else 262 { 263 long exponent_1; 264 long exponent_2; 265 long exponent_3; 266 long exponent_4; 267 int exponent_skippage; 268 LITTLENUM_TYPE word1; 269 270 if (f->sign != '-' && f->sign != '+') 271 { 272 if (f->sign == 0) 273 { 274 /* All NaNs are 0. */ 275 memset (words, 0x00, sizeof (LITTLENUM_TYPE) * precision); 276 } 277 else if (f->sign == 'P') 278 { 279 /* Positive Infinity. */ 280 memset (words, 0xff, sizeof (LITTLENUM_TYPE) * precision); 281 words[0] &= 0x7fff; 282 } 283 else if (f->sign == 'N') 284 { 285 /* Negative Infinity. */ 286 memset (words, 0x00, sizeof (LITTLENUM_TYPE) * precision); 287 words[0] = 0x0080; 288 } 289 else 290 make_invalid_floating_point_number (words); 291 return return_value; 292 } 293 294 /* All vaxen floating_point formats (so far) have: 295 Bit 15 is sign bit. 296 Bits 14:n are excess-whatever exponent. 297 Bits n-1:0 (if any) are most significant bits of fraction. 298 Bits 15:0 of the next word are the next most significant bits. 299 And so on for each other word. 300 301 All this to be compatible with a KF11?? (Which is still faster 302 than lots of vaxen I can think of, but it also has higher 303 maintenance costs ... sigh). 304 305 So we need: number of bits of exponent, number of bits of 306 mantissa. */ 307 308 bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS; 309 littlenum_pointer = f->leader; 310 littlenum_end = f->low; 311 /* Seek (and forget) 1st significant bit. */ 312 for (exponent_skippage = 0; 313 !next_bits (1); 314 exponent_skippage++); 315 316 exponent_1 = f->exponent + f->leader + 1 - f->low; 317 /* Radix LITTLENUM_RADIX, point just higher than f->leader. */ 318 exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS; 319 /* Radix 2. */ 320 exponent_3 = exponent_2 - exponent_skippage; 321 /* Forget leading zeros, forget 1st bit. */ 322 exponent_4 = exponent_3 + (1 << (exponent_bits - 1)); 323 /* Offset exponent. */ 324 325 if (exponent_4 & ~mask[exponent_bits]) 326 { 327 /* Exponent overflow. Lose immediately. */ 328 make_invalid_floating_point_number (words); 329 330 /* We leave return_value alone: admit we read the 331 number, but return a floating exception 332 because we can't encode the number. */ 333 } 334 else 335 { 336 lp = words; 337 338 /* Word 1. Sign, exponent and perhaps high bits. 339 Assume 2's complement integers. */ 340 word1 = (((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits)) 341 | ((f->sign == '+') ? 0 : 0x8000) 342 | next_bits (15 - exponent_bits)); 343 *lp++ = word1; 344 345 /* The rest of the words are just mantissa bits. */ 346 for (; lp < words + precision; lp++) 347 *lp = next_bits (LITTLENUM_NUMBER_OF_BITS); 348 349 if (next_bits (1)) 350 { 351 /* Since the NEXT bit is a 1, round UP the mantissa. 352 The cunning design of these hidden-1 floats permits 353 us to let the mantissa overflow into the exponent, and 354 it 'does the right thing'. However, we lose if the 355 highest-order bit of the lowest-order word flips. 356 Is that clear? */ 357 unsigned long carry; 358 359 /* 360 #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2) 361 Please allow at least 1 more bit in carry than is in a LITTLENUM. 362 We need that extra bit to hold a carry during a LITTLENUM carry 363 propagation. Another extra bit (kept 0) will assure us that we 364 don't get a sticky sign bit after shifting right, and that 365 permits us to propagate the carry without any masking of bits. 366 #endif */ 367 for (carry = 1, lp--; 368 carry && (lp >= words); 369 lp--) 370 { 371 carry = *lp + carry; 372 *lp = carry; 373 carry >>= LITTLENUM_NUMBER_OF_BITS; 374 } 375 376 if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1))) 377 { 378 make_invalid_floating_point_number (words); 379 /* We leave return_value alone: admit we read the 380 number, but return a floating exception 381 because we can't encode the number. */ 382 } 383 } 384 } 385 } 386 } 387 return return_value; 388} 389 390/* JF this used to be in vax.c but this looks like a better place for it. */ 391 392/* In: input_line_pointer->the 1st character of a floating-point 393 number. 394 1 letter denoting the type of statement that wants a 395 binary floating point number returned. 396 Address of where to build floating point literal. 397 Assumed to be 'big enough'. 398 Address of where to return size of literal (in chars). 399 400 Out: Input_line_pointer->of next char after floating number. 401 Error message, or 0. 402 Floating point literal. 403 Number of chars we used for the literal. */ 404 405#define MAXIMUM_NUMBER_OF_LITTLENUMS 8 /* For .hfloats. */ 406 407const char * 408vax_md_atof (int what_statement_type, 409 char *literalP, 410 int *sizeP) 411{ 412 LITTLENUM_TYPE words[MAXIMUM_NUMBER_OF_LITTLENUMS]; 413 char kind_of_float; 414 unsigned int number_of_chars; 415 LITTLENUM_TYPE *littlenumP; 416 417 switch (what_statement_type) 418 { 419 case 'F': 420 case 'f': 421 kind_of_float = 'f'; 422 break; 423 424 case 'D': 425 case 'd': 426 kind_of_float = 'd'; 427 break; 428 429 case 'g': 430 kind_of_float = 'g'; 431 break; 432 433 case 'h': 434 kind_of_float = 'h'; 435 break; 436 437 default: 438 kind_of_float = 0; 439 break; 440 }; 441 442 if (kind_of_float) 443 { 444 LITTLENUM_TYPE *limit; 445 446 input_line_pointer = atof_vax (input_line_pointer, 447 kind_of_float, 448 words); 449 /* The atof_vax() builds up 16-bit numbers. 450 Since the assembler may not be running on 451 a little-endian machine, be very careful about 452 converting words to chars. */ 453 number_of_chars = atof_vax_sizeof (kind_of_float); 454 know (number_of_chars <= MAXIMUM_NUMBER_OF_LITTLENUMS * sizeof (LITTLENUM_TYPE)); 455 limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE)); 456 for (littlenumP = words; littlenumP < limit; littlenumP++) 457 { 458 md_number_to_chars (literalP, *littlenumP, sizeof (LITTLENUM_TYPE)); 459 literalP += sizeof (LITTLENUM_TYPE); 460 }; 461 } 462 else 463 number_of_chars = 0; 464 465 *sizeP = number_of_chars; 466 return kind_of_float ? NULL : _("Unrecognized or unsupported floating point constant"); 467} 468