| 1 | /* fpu.c --- FPU emulator for stand-alone RX simulator. |
| 2 | |
| 3 | Copyright (C) 2008-2016 Free Software Foundation, Inc. |
| 4 | Contributed by Red Hat, Inc. |
| 5 | |
| 6 | This file is part of the GNU simulators. |
| 7 | |
| 8 | This program is free software; you can redistribute it and/or modify |
| 9 | it under the terms of the GNU General Public License as published by |
| 10 | the Free Software Foundation; either version 3 of the License, or |
| 11 | (at your option) any later version. |
| 12 | |
| 13 | This program is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
| 18 | You should have received a copy of the GNU General Public License |
| 19 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 20 | |
| 21 | #include "config.h" |
| 22 | #include <stdio.h> |
| 23 | #include <stdlib.h> |
| 24 | |
| 25 | #include "cpu.h" |
| 26 | #include "fpu.h" |
| 27 | |
| 28 | /* FPU encodings are as follows: |
| 29 | |
| 30 | S EXPONENT MANTISSA |
| 31 | 1 12345678 12345678901234567890123 |
| 32 | |
| 33 | 0 00000000 00000000000000000000000 +0 |
| 34 | 1 00000000 00000000000000000000000 -0 |
| 35 | |
| 36 | X 00000000 00000000000000000000001 Denormals |
| 37 | X 00000000 11111111111111111111111 |
| 38 | |
| 39 | X 00000001 XXXXXXXXXXXXXXXXXXXXXXX Normals |
| 40 | X 11111110 XXXXXXXXXXXXXXXXXXXXXXX |
| 41 | |
| 42 | 0 11111111 00000000000000000000000 +Inf |
| 43 | 1 11111111 00000000000000000000000 -Inf |
| 44 | |
| 45 | X 11111111 0XXXXXXXXXXXXXXXXXXXXXX SNaN (X != 0) |
| 46 | X 11111111 1XXXXXXXXXXXXXXXXXXXXXX QNaN (X != 0) |
| 47 | |
| 48 | */ |
| 49 | |
| 50 | #define trace 0 |
| 51 | #define tprintf if (trace) printf |
| 52 | |
| 53 | /* Some magic numbers. */ |
| 54 | #define PLUS_MAX 0x7f7fffffUL |
| 55 | #define MINUS_MAX 0xff7fffffUL |
| 56 | #define PLUS_INF 0x7f800000UL |
| 57 | #define MINUS_INF 0xff800000UL |
| 58 | #define PLUS_ZERO 0x00000000UL |
| 59 | #define MINUS_ZERO 0x80000000UL |
| 60 | |
| 61 | #define FP_RAISE(e) fp_raise(FPSWBITS_C##e) |
| 62 | static void |
| 63 | fp_raise (int mask) |
| 64 | { |
| 65 | regs.r_fpsw |= mask; |
| 66 | if (mask != FPSWBITS_CE) |
| 67 | { |
| 68 | if (regs.r_fpsw & (mask << FPSW_CESH)) |
| 69 | regs.r_fpsw |= (mask << FPSW_CFSH); |
| 70 | if (regs.r_fpsw & FPSWBITS_FMASK) |
| 71 | regs.r_fpsw |= FPSWBITS_FSUM; |
| 72 | else |
| 73 | regs.r_fpsw &= ~FPSWBITS_FSUM; |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | /* We classify all numbers as one of these. They correspond to the |
| 78 | rows/colums in the exception tables. */ |
| 79 | typedef enum { |
| 80 | FP_NORMAL, |
| 81 | FP_PZERO, |
| 82 | FP_NZERO, |
| 83 | FP_PINFINITY, |
| 84 | FP_NINFINITY, |
| 85 | FP_DENORMAL, |
| 86 | FP_QNAN, |
| 87 | FP_SNAN |
| 88 | } FP_Type; |
| 89 | |
| 90 | #if defined DEBUG0 |
| 91 | static const char *fpt_names[] = { |
| 92 | "Normal", "+0", "-0", "+Inf", "-Inf", "Denormal", "QNaN", "SNaN" |
| 93 | }; |
| 94 | #endif |
| 95 | |
| 96 | #define EXP_BIAS 127 |
| 97 | #define EXP_ZERO -127 |
| 98 | #define EXP_INF 128 |
| 99 | |
| 100 | #define MANT_BIAS 0x00080000UL |
| 101 | |
| 102 | typedef struct { |
| 103 | int exp; |
| 104 | unsigned int mant; /* 24 bits */ |
| 105 | char type; |
| 106 | char sign; |
| 107 | fp_t orig_value; |
| 108 | } FP_Parts; |
| 109 | |
| 110 | static void |
| 111 | fp_explode (fp_t f, FP_Parts *p) |
| 112 | { |
| 113 | int exp, mant, sign; |
| 114 | |
| 115 | exp = ((f & 0x7f800000UL) >> 23); |
| 116 | mant = f & 0x007fffffUL; |
| 117 | sign = f & 0x80000000UL; |
| 118 | /*printf("explode: %08x %x %2x %6x\n", f, sign, exp, mant);*/ |
| 119 | |
| 120 | p->sign = sign ? -1 : 1; |
| 121 | p->exp = exp - EXP_BIAS; |
| 122 | p->orig_value = f; |
| 123 | p->mant = mant | 0x00800000UL; |
| 124 | |
| 125 | if (p->exp == EXP_ZERO) |
| 126 | { |
| 127 | if (regs.r_fpsw & FPSWBITS_DN) |
| 128 | mant = 0; |
| 129 | if (mant) |
| 130 | p->type = FP_DENORMAL; |
| 131 | else |
| 132 | { |
| 133 | p->mant = 0; |
| 134 | p->type = sign ? FP_NZERO : FP_PZERO; |
| 135 | } |
| 136 | } |
| 137 | else if (p->exp == EXP_INF) |
| 138 | { |
| 139 | if (mant == 0) |
| 140 | p->type = sign ? FP_NINFINITY : FP_PINFINITY; |
| 141 | else if (mant & 0x00400000UL) |
| 142 | p->type = FP_QNAN; |
| 143 | else |
| 144 | p->type = FP_SNAN; |
| 145 | } |
| 146 | else |
| 147 | p->type = FP_NORMAL; |
| 148 | } |
| 149 | |
| 150 | static fp_t |
| 151 | fp_implode (FP_Parts *p) |
| 152 | { |
| 153 | int exp, mant; |
| 154 | |
| 155 | exp = p->exp + EXP_BIAS; |
| 156 | mant = p->mant; |
| 157 | /*printf("implode: exp %d mant 0x%x\n", exp, mant);*/ |
| 158 | if (p->type == FP_NORMAL) |
| 159 | { |
| 160 | while (mant |
| 161 | && exp > 0 |
| 162 | && mant < 0x00800000UL) |
| 163 | { |
| 164 | mant <<= 1; |
| 165 | exp --; |
| 166 | } |
| 167 | while (mant > 0x00ffffffUL) |
| 168 | { |
| 169 | mant >>= 1; |
| 170 | exp ++; |
| 171 | } |
| 172 | if (exp < 0) |
| 173 | { |
| 174 | /* underflow */ |
| 175 | exp = 0; |
| 176 | mant = 0; |
| 177 | FP_RAISE (E); |
| 178 | } |
| 179 | if (exp >= 255) |
| 180 | { |
| 181 | /* overflow */ |
| 182 | exp = 255; |
| 183 | mant = 0; |
| 184 | FP_RAISE (O); |
| 185 | } |
| 186 | } |
| 187 | mant &= 0x007fffffUL; |
| 188 | exp &= 0xff; |
| 189 | mant |= exp << 23; |
| 190 | if (p->sign < 0) |
| 191 | mant |= 0x80000000UL; |
| 192 | |
| 193 | return mant; |
| 194 | } |
| 195 | |
| 196 | typedef union { |
| 197 | unsigned long long ll; |
| 198 | double d; |
| 199 | } U_d_ll; |
| 200 | |
| 201 | static int checked_format = 0; |
| 202 | |
| 203 | /* We assume a double format like this: |
| 204 | S[1] E[11] M[52] |
| 205 | */ |
| 206 | |
| 207 | static double |
| 208 | fp_to_double (FP_Parts *p) |
| 209 | { |
| 210 | U_d_ll u; |
| 211 | |
| 212 | if (!checked_format) |
| 213 | { |
| 214 | u.d = 1.5; |
| 215 | if (u.ll != 0x3ff8000000000000ULL) |
| 216 | abort (); |
| 217 | u.d = -225; |
| 218 | if (u.ll != 0xc06c200000000000ULL) |
| 219 | abort (); |
| 220 | u.d = 10.1; |
| 221 | if (u.ll != 0x4024333333333333ULL) |
| 222 | abort (); |
| 223 | checked_format = 1; |
| 224 | } |
| 225 | |
| 226 | u.ll = 0; |
| 227 | if (p->sign < 0) |
| 228 | u.ll |= (1ULL << 63); |
| 229 | /* Make sure a zero encoding stays a zero. */ |
| 230 | if (p->exp != -EXP_BIAS) |
| 231 | u.ll |= ((unsigned long long)p->exp + 1023ULL) << 52; |
| 232 | u.ll |= (unsigned long long) (p->mant & 0x007fffffUL) << (52 - 23); |
| 233 | return u.d; |
| 234 | } |
| 235 | |
| 236 | static void |
| 237 | double_to_fp (double d, FP_Parts *p) |
| 238 | { |
| 239 | int exp; |
| 240 | U_d_ll u; |
| 241 | int sign; |
| 242 | |
| 243 | u.d = d; |
| 244 | |
| 245 | sign = (u.ll & 0x8000000000000000ULL) ? 1 : 0; |
| 246 | exp = u.ll >> 52; |
| 247 | exp = (exp & 0x7ff); |
| 248 | |
| 249 | if (exp == 0) |
| 250 | { |
| 251 | /* A generated denormal should show up as an underflow, not |
| 252 | here. */ |
| 253 | if (sign) |
| 254 | fp_explode (MINUS_ZERO, p); |
| 255 | else |
| 256 | fp_explode (PLUS_ZERO, p); |
| 257 | return; |
| 258 | } |
| 259 | |
| 260 | exp = exp - 1023; |
| 261 | if ((exp + EXP_BIAS) > 254) |
| 262 | { |
| 263 | FP_RAISE (O); |
| 264 | switch (regs.r_fpsw & FPSWBITS_RM) |
| 265 | { |
| 266 | case FPRM_NEAREST: |
| 267 | if (sign) |
| 268 | fp_explode (MINUS_INF, p); |
| 269 | else |
| 270 | fp_explode (PLUS_INF, p); |
| 271 | break; |
| 272 | case FPRM_ZERO: |
| 273 | if (sign) |
| 274 | fp_explode (MINUS_MAX, p); |
| 275 | else |
| 276 | fp_explode (PLUS_MAX, p); |
| 277 | break; |
| 278 | case FPRM_PINF: |
| 279 | if (sign) |
| 280 | fp_explode (MINUS_MAX, p); |
| 281 | else |
| 282 | fp_explode (PLUS_INF, p); |
| 283 | break; |
| 284 | case FPRM_NINF: |
| 285 | if (sign) |
| 286 | fp_explode (MINUS_INF, p); |
| 287 | else |
| 288 | fp_explode (PLUS_MAX, p); |
| 289 | break; |
| 290 | } |
| 291 | return; |
| 292 | } |
| 293 | if ((exp + EXP_BIAS) < 1) |
| 294 | { |
| 295 | if (sign) |
| 296 | fp_explode (MINUS_ZERO, p); |
| 297 | else |
| 298 | fp_explode (PLUS_ZERO, p); |
| 299 | FP_RAISE (U); |
| 300 | } |
| 301 | |
| 302 | p->sign = sign ? -1 : 1; |
| 303 | p->exp = exp; |
| 304 | p->mant = u.ll >> (52-23) & 0x007fffffUL; |
| 305 | p->mant |= 0x00800000UL; |
| 306 | p->type = FP_NORMAL; |
| 307 | |
| 308 | if (u.ll & 0x1fffffffULL) |
| 309 | { |
| 310 | switch (regs.r_fpsw & FPSWBITS_RM) |
| 311 | { |
| 312 | case FPRM_NEAREST: |
| 313 | if (u.ll & 0x10000000ULL) |
| 314 | p->mant ++; |
| 315 | break; |
| 316 | case FPRM_ZERO: |
| 317 | break; |
| 318 | case FPRM_PINF: |
| 319 | if (sign == 1) |
| 320 | p->mant ++; |
| 321 | break; |
| 322 | case FPRM_NINF: |
| 323 | if (sign == -1) |
| 324 | p->mant ++; |
| 325 | break; |
| 326 | } |
| 327 | FP_RAISE (X); |
| 328 | } |
| 329 | |
| 330 | } |
| 331 | |
| 332 | typedef enum { |
| 333 | eNR, /* Use the normal result. */ |
| 334 | ePZ, eNZ, /* +- zero */ |
| 335 | eSZ, /* signed zero - XOR signs of ops together. */ |
| 336 | eRZ, /* +- zero depending on rounding mode. */ |
| 337 | ePI, eNI, /* +- Infinity */ |
| 338 | eSI, /* signed infinity - XOR signs of ops together. */ |
| 339 | eQN, eSN, /* Quiet/Signalling NANs */ |
| 340 | eIn, /* Invalid. */ |
| 341 | eUn, /* Unimplemented. */ |
| 342 | eDZ, /* Divide-by-zero. */ |
| 343 | eLT, /* less than */ |
| 344 | eGT, /* greater than */ |
| 345 | eEQ, /* equal to */ |
| 346 | } FP_ExceptionCases; |
| 347 | |
| 348 | #if defined DEBUG0 |
| 349 | static const char *ex_names[] = { |
| 350 | "NR", "PZ", "NZ", "SZ", "RZ", "PI", "NI", "SI", "QN", "SN", "IN", "Un", "DZ", "LT", "GT", "EQ" |
| 351 | }; |
| 352 | #endif |
| 353 | |
| 354 | /* This checks for all exceptional cases (not all FP exceptions) and |
| 355 | returns TRUE if it is providing the result in *c. If it returns |
| 356 | FALSE, the caller should do the "normal" operation. */ |
| 357 | int |
| 358 | check_exceptions (FP_Parts *a, FP_Parts *b, fp_t *c, |
| 359 | FP_ExceptionCases ex_tab[5][5], |
| 360 | FP_ExceptionCases *case_ret) |
| 361 | { |
| 362 | FP_ExceptionCases fpec; |
| 363 | |
| 364 | if (a->type == FP_SNAN |
| 365 | || b->type == FP_SNAN) |
| 366 | fpec = eIn; |
| 367 | else if (a->type == FP_QNAN |
| 368 | || b->type == FP_QNAN) |
| 369 | fpec = eQN; |
| 370 | else if (a->type == FP_DENORMAL |
| 371 | || b->type == FP_DENORMAL) |
| 372 | fpec = eUn; |
| 373 | else |
| 374 | fpec = ex_tab[(int)(a->type)][(int)(b->type)]; |
| 375 | |
| 376 | /*printf("%s %s -> %s\n", fpt_names[(int)(a->type)], fpt_names[(int)(b->type)], ex_names[(int)(fpec)]);*/ |
| 377 | |
| 378 | if (case_ret) |
| 379 | *case_ret = fpec; |
| 380 | |
| 381 | switch (fpec) |
| 382 | { |
| 383 | case eNR: /* Use the normal result. */ |
| 384 | return 0; |
| 385 | |
| 386 | case ePZ: /* + zero */ |
| 387 | *c = 0x00000000; |
| 388 | return 1; |
| 389 | |
| 390 | case eNZ: /* - zero */ |
| 391 | *c = 0x80000000; |
| 392 | return 1; |
| 393 | |
| 394 | case eSZ: /* signed zero */ |
| 395 | *c = (a->sign == b->sign) ? PLUS_ZERO : MINUS_ZERO; |
| 396 | return 1; |
| 397 | |
| 398 | case eRZ: /* +- zero depending on rounding mode. */ |
| 399 | if ((regs.r_fpsw & FPSWBITS_RM) == FPRM_NINF) |
| 400 | *c = 0x80000000; |
| 401 | else |
| 402 | *c = 0x00000000; |
| 403 | return 1; |
| 404 | |
| 405 | case ePI: /* + Infinity */ |
| 406 | *c = 0x7F800000; |
| 407 | return 1; |
| 408 | |
| 409 | case eNI: /* - Infinity */ |
| 410 | *c = 0xFF800000; |
| 411 | return 1; |
| 412 | |
| 413 | case eSI: /* sign Infinity */ |
| 414 | *c = (a->sign == b->sign) ? PLUS_INF : MINUS_INF; |
| 415 | return 1; |
| 416 | |
| 417 | case eQN: /* Quiet NANs */ |
| 418 | if (a->type == FP_QNAN) |
| 419 | *c = a->orig_value; |
| 420 | else |
| 421 | *c = b->orig_value; |
| 422 | return 1; |
| 423 | |
| 424 | case eSN: /* Signalling NANs */ |
| 425 | if (a->type == FP_SNAN) |
| 426 | *c = a->orig_value; |
| 427 | else |
| 428 | *c = b->orig_value; |
| 429 | FP_RAISE (V); |
| 430 | return 1; |
| 431 | |
| 432 | case eIn: /* Invalid. */ |
| 433 | FP_RAISE (V); |
| 434 | if (a->type == FP_SNAN) |
| 435 | *c = a->orig_value | 0x00400000; |
| 436 | else if (b->type == FP_SNAN) |
| 437 | *c = b->orig_value | 0x00400000; |
| 438 | else |
| 439 | *c = 0x7fc00000; |
| 440 | return 1; |
| 441 | |
| 442 | case eUn: /* Unimplemented. */ |
| 443 | FP_RAISE (E); |
| 444 | return 1; |
| 445 | |
| 446 | case eDZ: /* Division-by-zero. */ |
| 447 | *c = (a->sign == b->sign) ? PLUS_INF : MINUS_INF; |
| 448 | FP_RAISE (Z); |
| 449 | return 1; |
| 450 | |
| 451 | default: |
| 452 | return 0; |
| 453 | } |
| 454 | } |
| 455 | |
| 456 | #define CHECK_EXCEPTIONS(FPPa, FPPb, fpc, ex_tab) \ |
| 457 | if (check_exceptions (&FPPa, &FPPb, &fpc, ex_tab, 0)) \ |
| 458 | return fpc; |
| 459 | |
| 460 | /* For each operation, we have two tables of how nonnormal cases are |
| 461 | handled. The DN=0 case is first, followed by the DN=1 case, with |
| 462 | each table using the following layout: */ |
| 463 | |
| 464 | static FP_ExceptionCases ex_add_tab[5][5] = { |
| 465 | /* N +0 -0 +In -In */ |
| 466 | { eNR, eNR, eNR, ePI, eNI }, /* Normal */ |
| 467 | { eNR, ePZ, eRZ, ePI, eNI }, /* +0 */ |
| 468 | { eNR, eRZ, eNZ, ePI, eNI }, /* -0 */ |
| 469 | { ePI, ePI, ePI, ePI, eIn }, /* +Inf */ |
| 470 | { eNI, eNI, eNI, eIn, eNI }, /* -Inf */ |
| 471 | }; |
| 472 | |
| 473 | fp_t |
| 474 | rxfp_add (fp_t fa, fp_t fb) |
| 475 | { |
| 476 | FP_Parts a, b, c; |
| 477 | fp_t rv; |
| 478 | double da, db; |
| 479 | |
| 480 | fp_explode (fa, &a); |
| 481 | fp_explode (fb, &b); |
| 482 | CHECK_EXCEPTIONS (a, b, rv, ex_add_tab); |
| 483 | |
| 484 | da = fp_to_double (&a); |
| 485 | db = fp_to_double (&b); |
| 486 | tprintf("%g + %g = %g\n", da, db, da+db); |
| 487 | |
| 488 | double_to_fp (da+db, &c); |
| 489 | rv = fp_implode (&c); |
| 490 | return rv; |
| 491 | } |
| 492 | |
| 493 | static FP_ExceptionCases ex_sub_tab[5][5] = { |
| 494 | /* N +0 -0 +In -In */ |
| 495 | { eNR, eNR, eNR, eNI, ePI }, /* Normal */ |
| 496 | { eNR, eRZ, ePZ, eNI, ePI }, /* +0 */ |
| 497 | { eNR, eNZ, eRZ, eNI, ePI }, /* -0 */ |
| 498 | { ePI, ePI, ePI, eIn, ePI }, /* +Inf */ |
| 499 | { eNI, eNI, eNI, eNI, eIn }, /* -Inf */ |
| 500 | }; |
| 501 | |
| 502 | fp_t |
| 503 | rxfp_sub (fp_t fa, fp_t fb) |
| 504 | { |
| 505 | FP_Parts a, b, c; |
| 506 | fp_t rv; |
| 507 | double da, db; |
| 508 | |
| 509 | fp_explode (fa, &a); |
| 510 | fp_explode (fb, &b); |
| 511 | CHECK_EXCEPTIONS (a, b, rv, ex_sub_tab); |
| 512 | |
| 513 | da = fp_to_double (&a); |
| 514 | db = fp_to_double (&b); |
| 515 | tprintf("%g - %g = %g\n", da, db, da-db); |
| 516 | |
| 517 | double_to_fp (da-db, &c); |
| 518 | rv = fp_implode (&c); |
| 519 | |
| 520 | return rv; |
| 521 | } |
| 522 | |
| 523 | static FP_ExceptionCases ex_mul_tab[5][5] = { |
| 524 | /* N +0 -0 +In -In */ |
| 525 | { eNR, eNR, eNR, eSI, eSI }, /* Normal */ |
| 526 | { eNR, ePZ, eNZ, eIn, eIn }, /* +0 */ |
| 527 | { eNR, eNZ, ePZ, eIn, eIn }, /* -0 */ |
| 528 | { eSI, eIn, eIn, ePI, eNI }, /* +Inf */ |
| 529 | { eSI, eIn, eIn, eNI, ePI }, /* -Inf */ |
| 530 | }; |
| 531 | |
| 532 | fp_t |
| 533 | rxfp_mul (fp_t fa, fp_t fb) |
| 534 | { |
| 535 | FP_Parts a, b, c; |
| 536 | fp_t rv; |
| 537 | double da, db; |
| 538 | |
| 539 | fp_explode (fa, &a); |
| 540 | fp_explode (fb, &b); |
| 541 | CHECK_EXCEPTIONS (a, b, rv, ex_mul_tab); |
| 542 | |
| 543 | da = fp_to_double (&a); |
| 544 | db = fp_to_double (&b); |
| 545 | tprintf("%g x %g = %g\n", da, db, da*db); |
| 546 | |
| 547 | double_to_fp (da*db, &c); |
| 548 | rv = fp_implode (&c); |
| 549 | |
| 550 | return rv; |
| 551 | } |
| 552 | |
| 553 | static FP_ExceptionCases ex_div_tab[5][5] = { |
| 554 | /* N +0 -0 +In -In */ |
| 555 | { eNR, eDZ, eDZ, eSZ, eSZ }, /* Normal */ |
| 556 | { eSZ, eIn, eIn, ePZ, eNZ }, /* +0 */ |
| 557 | { eSZ, eIn, eIn, eNZ, ePZ }, /* -0 */ |
| 558 | { eSI, ePI, eNI, eIn, eIn }, /* +Inf */ |
| 559 | { eSI, eNI, ePI, eIn, eIn }, /* -Inf */ |
| 560 | }; |
| 561 | |
| 562 | fp_t |
| 563 | rxfp_div (fp_t fa, fp_t fb) |
| 564 | { |
| 565 | FP_Parts a, b, c; |
| 566 | fp_t rv; |
| 567 | double da, db; |
| 568 | |
| 569 | fp_explode (fa, &a); |
| 570 | fp_explode (fb, &b); |
| 571 | CHECK_EXCEPTIONS (a, b, rv, ex_div_tab); |
| 572 | |
| 573 | da = fp_to_double (&a); |
| 574 | db = fp_to_double (&b); |
| 575 | tprintf("%g / %g = %g\n", da, db, da/db); |
| 576 | |
| 577 | double_to_fp (da/db, &c); |
| 578 | rv = fp_implode (&c); |
| 579 | |
| 580 | return rv; |
| 581 | } |
| 582 | |
| 583 | static FP_ExceptionCases ex_cmp_tab[5][5] = { |
| 584 | /* N +0 -0 +In -In */ |
| 585 | { eNR, eNR, eNR, eLT, eGT }, /* Normal */ |
| 586 | { eNR, eEQ, eEQ, eLT, eGT }, /* +0 */ |
| 587 | { eNR, eEQ, eEQ, eLT, eGT }, /* -0 */ |
| 588 | { eGT, eGT, eGT, eEQ, eGT }, /* +Inf */ |
| 589 | { eLT, eLT, eLT, eLT, eEQ }, /* -Inf */ |
| 590 | }; |
| 591 | |
| 592 | void |
| 593 | rxfp_cmp (fp_t fa, fp_t fb) |
| 594 | { |
| 595 | FP_Parts a, b; |
| 596 | fp_t c; |
| 597 | FP_ExceptionCases reason; |
| 598 | int flags = 0; |
| 599 | double da, db; |
| 600 | |
| 601 | fp_explode (fa, &a); |
| 602 | fp_explode (fb, &b); |
| 603 | |
| 604 | if (check_exceptions (&a, &b, &c, ex_cmp_tab, &reason)) |
| 605 | { |
| 606 | if (reason == eQN) |
| 607 | { |
| 608 | /* Special case - incomparable. */ |
| 609 | set_flags (FLAGBIT_Z | FLAGBIT_S | FLAGBIT_O, FLAGBIT_O); |
| 610 | return; |
| 611 | } |
| 612 | return; |
| 613 | } |
| 614 | |
| 615 | switch (reason) |
| 616 | { |
| 617 | case eEQ: |
| 618 | flags = FLAGBIT_Z; |
| 619 | break; |
| 620 | case eLT: |
| 621 | flags = FLAGBIT_S; |
| 622 | break; |
| 623 | case eGT: |
| 624 | flags = 0; |
| 625 | break; |
| 626 | case eNR: |
| 627 | da = fp_to_double (&a); |
| 628 | db = fp_to_double (&b); |
| 629 | tprintf("fcmp: %g cmp %g\n", da, db); |
| 630 | if (da < db) |
| 631 | flags = FLAGBIT_S; |
| 632 | else if (da == db) |
| 633 | flags = FLAGBIT_Z; |
| 634 | else |
| 635 | flags = 0; |
| 636 | break; |
| 637 | default: |
| 638 | abort(); |
| 639 | } |
| 640 | |
| 641 | set_flags (FLAGBIT_Z | FLAGBIT_S | FLAGBIT_O, flags); |
| 642 | } |
| 643 | |
| 644 | long |
| 645 | rxfp_ftoi (fp_t fa, int round_mode) |
| 646 | { |
| 647 | FP_Parts a; |
| 648 | fp_t rv; |
| 649 | int sign; |
| 650 | int whole_bits, frac_bits; |
| 651 | |
| 652 | fp_explode (fa, &a); |
| 653 | sign = fa & 0x80000000UL; |
| 654 | |
| 655 | switch (a.type) |
| 656 | { |
| 657 | case FP_NORMAL: |
| 658 | break; |
| 659 | case FP_PZERO: |
| 660 | case FP_NZERO: |
| 661 | return 0; |
| 662 | case FP_PINFINITY: |
| 663 | FP_RAISE (V); |
| 664 | return 0x7fffffffL; |
| 665 | case FP_NINFINITY: |
| 666 | FP_RAISE (V); |
| 667 | return 0x80000000L; |
| 668 | case FP_DENORMAL: |
| 669 | FP_RAISE (E); |
| 670 | return 0; |
| 671 | case FP_QNAN: |
| 672 | case FP_SNAN: |
| 673 | FP_RAISE (V); |
| 674 | return sign ? 0x80000000U : 0x7fffffff; |
| 675 | } |
| 676 | |
| 677 | if (a.exp >= 31) |
| 678 | { |
| 679 | FP_RAISE (V); |
| 680 | return sign ? 0x80000000U : 0x7fffffff; |
| 681 | } |
| 682 | |
| 683 | a.exp -= 23; |
| 684 | |
| 685 | if (a.exp <= -25) |
| 686 | { |
| 687 | /* Less than 0.49999 */ |
| 688 | frac_bits = a.mant; |
| 689 | whole_bits = 0; |
| 690 | } |
| 691 | else if (a.exp < 0) |
| 692 | { |
| 693 | frac_bits = a.mant << (32 + a.exp); |
| 694 | whole_bits = a.mant >> (-a.exp); |
| 695 | } |
| 696 | else |
| 697 | { |
| 698 | frac_bits = 0; |
| 699 | whole_bits = a.mant << a.exp; |
| 700 | } |
| 701 | |
| 702 | if (frac_bits) |
| 703 | { |
| 704 | switch (round_mode & 3) |
| 705 | { |
| 706 | case FPRM_NEAREST: |
| 707 | if (frac_bits & 0x80000000UL) |
| 708 | whole_bits ++; |
| 709 | break; |
| 710 | case FPRM_ZERO: |
| 711 | break; |
| 712 | case FPRM_PINF: |
| 713 | if (!sign) |
| 714 | whole_bits ++; |
| 715 | break; |
| 716 | case FPRM_NINF: |
| 717 | if (sign) |
| 718 | whole_bits ++; |
| 719 | break; |
| 720 | } |
| 721 | } |
| 722 | |
| 723 | rv = sign ? -whole_bits : whole_bits; |
| 724 | |
| 725 | return rv; |
| 726 | } |
| 727 | |
| 728 | fp_t |
| 729 | rxfp_itof (long fa, int round_mode) |
| 730 | { |
| 731 | fp_t rv; |
| 732 | int sign = 0; |
| 733 | unsigned int frac_bits; |
| 734 | volatile unsigned int whole_bits; |
| 735 | FP_Parts a; |
| 736 | |
| 737 | if (fa == 0) |
| 738 | return PLUS_ZERO; |
| 739 | |
| 740 | if (fa < 0) |
| 741 | { |
| 742 | fa = -fa; |
| 743 | sign = 1; |
| 744 | a.sign = -1; |
| 745 | } |
| 746 | else |
| 747 | a.sign = 1; |
| 748 | |
| 749 | whole_bits = fa; |
| 750 | a.exp = 31; |
| 751 | |
| 752 | while (! (whole_bits & 0x80000000UL)) |
| 753 | { |
| 754 | a.exp --; |
| 755 | whole_bits <<= 1; |
| 756 | } |
| 757 | frac_bits = whole_bits & 0xff; |
| 758 | whole_bits = whole_bits >> 8; |
| 759 | |
| 760 | if (frac_bits) |
| 761 | { |
| 762 | /* We must round */ |
| 763 | switch (round_mode & 3) |
| 764 | { |
| 765 | case FPRM_NEAREST: |
| 766 | if (frac_bits & 0x80) |
| 767 | whole_bits ++; |
| 768 | break; |
| 769 | case FPRM_ZERO: |
| 770 | break; |
| 771 | case FPRM_PINF: |
| 772 | if (!sign) |
| 773 | whole_bits ++; |
| 774 | break; |
| 775 | case FPRM_NINF: |
| 776 | if (sign) |
| 777 | whole_bits ++; |
| 778 | break; |
| 779 | } |
| 780 | } |
| 781 | |
| 782 | a.mant = whole_bits; |
| 783 | if (whole_bits & 0xff000000UL) |
| 784 | { |
| 785 | a.mant >>= 1; |
| 786 | a.exp ++; |
| 787 | } |
| 788 | |
| 789 | rv = fp_implode (&a); |
| 790 | return rv; |
| 791 | } |
| 792 | |