| 1 | /* atof_vax.c - turn a Flonum into a VAX floating point number |
| 2 | Copyright (C) 1987-2020 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 | |
| 33 | int flonum_gen2vax (int, FLONUM_TYPE *, LITTLENUM_TYPE *); |
| 34 | |
| 35 | /* Number of chars in flonum type 'letter'. */ |
| 36 | |
| 37 | static unsigned int |
| 38 | atof_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 | |
| 72 | static 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 | \f |
| 109 | |
| 110 | /* Shared between flonum_gen2vax and next_bits. */ |
| 111 | static int bits_left_in_littlenum; |
| 112 | static LITTLENUM_TYPE *littlenum_pointer; |
| 113 | static LITTLENUM_TYPE *littlenum_end; |
| 114 | |
| 115 | static int |
| 116 | next_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 | |
| 140 | static void |
| 141 | make_invalid_floating_point_number (LITTLENUM_TYPE *words) |
| 142 | { |
| 143 | *words = 0x8000; /* Floating Reserved Operand Code. */ |
| 144 | } |
| 145 | |
| 146 | \f |
| 147 | static int /* 0 means letter is OK. */ |
| 148 | what_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 | \f |
| 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 | |
| 189 | static char * |
| 190 | atof_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 | \f |
| 237 | /* In: a flonum, a vax floating point format. |
| 238 | Out: a vax floating-point bit pattern. */ |
| 239 | |
| 240 | int |
| 241 | flonum_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 | /* JF: Deal with new Nan, +Inf and -Inf codes. */ |
| 271 | if (f->sign != '-' && f->sign != '+') |
| 272 | { |
| 273 | make_invalid_floating_point_number (words); |
| 274 | return return_value; |
| 275 | } |
| 276 | |
| 277 | /* All vaxen floating_point formats (so far) have: |
| 278 | Bit 15 is sign bit. |
| 279 | Bits 14:n are excess-whatever exponent. |
| 280 | Bits n-1:0 (if any) are most significant bits of fraction. |
| 281 | Bits 15:0 of the next word are the next most significant bits. |
| 282 | And so on for each other word. |
| 283 | |
| 284 | All this to be compatible with a KF11?? (Which is still faster |
| 285 | than lots of vaxen I can think of, but it also has higher |
| 286 | maintenance costs ... sigh). |
| 287 | |
| 288 | So we need: number of bits of exponent, number of bits of |
| 289 | mantissa. */ |
| 290 | |
| 291 | bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS; |
| 292 | littlenum_pointer = f->leader; |
| 293 | littlenum_end = f->low; |
| 294 | /* Seek (and forget) 1st significant bit. */ |
| 295 | for (exponent_skippage = 0; |
| 296 | !next_bits (1); |
| 297 | exponent_skippage++); |
| 298 | |
| 299 | exponent_1 = f->exponent + f->leader + 1 - f->low; |
| 300 | /* Radix LITTLENUM_RADIX, point just higher than f->leader. */ |
| 301 | exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS; |
| 302 | /* Radix 2. */ |
| 303 | exponent_3 = exponent_2 - exponent_skippage; |
| 304 | /* Forget leading zeros, forget 1st bit. */ |
| 305 | exponent_4 = exponent_3 + (1 << (exponent_bits - 1)); |
| 306 | /* Offset exponent. */ |
| 307 | |
| 308 | if (exponent_4 & ~mask[exponent_bits]) |
| 309 | { |
| 310 | /* Exponent overflow. Lose immediately. */ |
| 311 | make_invalid_floating_point_number (words); |
| 312 | |
| 313 | /* We leave return_value alone: admit we read the |
| 314 | number, but return a floating exception |
| 315 | because we can't encode the number. */ |
| 316 | } |
| 317 | else |
| 318 | { |
| 319 | lp = words; |
| 320 | |
| 321 | /* Word 1. Sign, exponent and perhaps high bits. |
| 322 | Assume 2's complement integers. */ |
| 323 | word1 = (((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits)) |
| 324 | | ((f->sign == '+') ? 0 : 0x8000) |
| 325 | | next_bits (15 - exponent_bits)); |
| 326 | *lp++ = word1; |
| 327 | |
| 328 | /* The rest of the words are just mantissa bits. */ |
| 329 | for (; lp < words + precision; lp++) |
| 330 | *lp = next_bits (LITTLENUM_NUMBER_OF_BITS); |
| 331 | |
| 332 | if (next_bits (1)) |
| 333 | { |
| 334 | /* Since the NEXT bit is a 1, round UP the mantissa. |
| 335 | The cunning design of these hidden-1 floats permits |
| 336 | us to let the mantissa overflow into the exponent, and |
| 337 | it 'does the right thing'. However, we lose if the |
| 338 | highest-order bit of the lowest-order word flips. |
| 339 | Is that clear? */ |
| 340 | unsigned long carry; |
| 341 | |
| 342 | /* |
| 343 | #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2) |
| 344 | Please allow at least 1 more bit in carry than is in a LITTLENUM. |
| 345 | We need that extra bit to hold a carry during a LITTLENUM carry |
| 346 | propagation. Another extra bit (kept 0) will assure us that we |
| 347 | don't get a sticky sign bit after shifting right, and that |
| 348 | permits us to propagate the carry without any masking of bits. |
| 349 | #endif */ |
| 350 | for (carry = 1, lp--; |
| 351 | carry && (lp >= words); |
| 352 | lp--) |
| 353 | { |
| 354 | carry = *lp + carry; |
| 355 | *lp = carry; |
| 356 | carry >>= LITTLENUM_NUMBER_OF_BITS; |
| 357 | } |
| 358 | |
| 359 | if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1))) |
| 360 | { |
| 361 | make_invalid_floating_point_number (words); |
| 362 | /* We leave return_value alone: admit we read the |
| 363 | number, but return a floating exception |
| 364 | because we can't encode the number. */ |
| 365 | } |
| 366 | } |
| 367 | } |
| 368 | } |
| 369 | } |
| 370 | return return_value; |
| 371 | } |
| 372 | |
| 373 | /* JF this used to be in vax.c but this looks like a better place for it. */ |
| 374 | |
| 375 | /* In: input_line_pointer->the 1st character of a floating-point |
| 376 | number. |
| 377 | 1 letter denoting the type of statement that wants a |
| 378 | binary floating point number returned. |
| 379 | Address of where to build floating point literal. |
| 380 | Assumed to be 'big enough'. |
| 381 | Address of where to return size of literal (in chars). |
| 382 | |
| 383 | Out: Input_line_pointer->of next char after floating number. |
| 384 | Error message, or 0. |
| 385 | Floating point literal. |
| 386 | Number of chars we used for the literal. */ |
| 387 | |
| 388 | #define MAXIMUM_NUMBER_OF_LITTLENUMS 8 /* For .hfloats. */ |
| 389 | |
| 390 | const char * |
| 391 | vax_md_atof (int what_statement_type, |
| 392 | char *literalP, |
| 393 | int *sizeP) |
| 394 | { |
| 395 | LITTLENUM_TYPE words[MAXIMUM_NUMBER_OF_LITTLENUMS]; |
| 396 | char kind_of_float; |
| 397 | unsigned int number_of_chars; |
| 398 | LITTLENUM_TYPE *littlenumP; |
| 399 | |
| 400 | switch (what_statement_type) |
| 401 | { |
| 402 | case 'F': |
| 403 | case 'f': |
| 404 | kind_of_float = 'f'; |
| 405 | break; |
| 406 | |
| 407 | case 'D': |
| 408 | case 'd': |
| 409 | kind_of_float = 'd'; |
| 410 | break; |
| 411 | |
| 412 | case 'g': |
| 413 | kind_of_float = 'g'; |
| 414 | break; |
| 415 | |
| 416 | case 'h': |
| 417 | kind_of_float = 'h'; |
| 418 | break; |
| 419 | |
| 420 | default: |
| 421 | kind_of_float = 0; |
| 422 | break; |
| 423 | }; |
| 424 | |
| 425 | if (kind_of_float) |
| 426 | { |
| 427 | LITTLENUM_TYPE *limit; |
| 428 | |
| 429 | input_line_pointer = atof_vax (input_line_pointer, |
| 430 | kind_of_float, |
| 431 | words); |
| 432 | /* The atof_vax() builds up 16-bit numbers. |
| 433 | Since the assembler may not be running on |
| 434 | a little-endian machine, be very careful about |
| 435 | converting words to chars. */ |
| 436 | number_of_chars = atof_vax_sizeof (kind_of_float); |
| 437 | know (number_of_chars <= MAXIMUM_NUMBER_OF_LITTLENUMS * sizeof (LITTLENUM_TYPE)); |
| 438 | limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE)); |
| 439 | for (littlenumP = words; littlenumP < limit; littlenumP++) |
| 440 | { |
| 441 | md_number_to_chars (literalP, *littlenumP, sizeof (LITTLENUM_TYPE)); |
| 442 | literalP += sizeof (LITTLENUM_TYPE); |
| 443 | }; |
| 444 | } |
| 445 | else |
| 446 | number_of_chars = 0; |
| 447 | |
| 448 | *sizeP = number_of_chars; |
| 449 | return kind_of_float ? NULL : _("Unrecognized or unsupported floating point constant"); |
| 450 | } |