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   1 /*
   2  *  linux/arch/arm/vfp/vfpdouble.c
   3  *
   4  * This code is derived in part from John R. Housers softfloat library, which
   5  * carries the following notice:
   6  *
   7  * ===========================================================================
   8  * This C source file is part of the SoftFloat IEC/IEEE Floating-point
   9  * Arithmetic Package, Release 2.
  10  *
  11  * Written by John R. Hauser.  This work was made possible in part by the
  12  * International Computer Science Institute, located at Suite 600, 1947 Center
  13  * Street, Berkeley, California 94704.  Funding was partially provided by the
  14  * National Science Foundation under grant MIP-9311980.  The original version
  15  * of this code was written as part of a project to build a fixed-point vector
  16  * processor in collaboration with the University of California at Berkeley,
  17  * overseen by Profs. Nelson Morgan and John Wawrzynek.  More information
  18  * is available through the web page `http://HTTP.CS.Berkeley.EDU/~jhauser/
  19  * arithmetic/softfloat.html'.
  20  *
  21  * THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE.  Although reasonable effort
  22  * has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT
  23  * TIMES RESULT IN INCORRECT BEHAVIOR.  USE OF THIS SOFTWARE IS RESTRICTED TO
  24  * PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY
  25  * AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE.
  26  *
  27  * Derivative works are acceptable, even for commercial purposes, so long as
  28  * (1) they include prominent notice that the work is derivative, and (2) they
  29  * include prominent notice akin to these three paragraphs for those parts of
  30  * this code that are retained.
  31  * ===========================================================================
  32  */
  33 #include <linux/kernel.h>
  34 #include <linux/bitops.h>
  35 #include <asm/ptrace.h>
  36 #include <asm/vfp.h>
  37
  38 #include "vfpinstr.h"
  39 #include "vfp.h"
  40
  41 static struct vfp_double vfp_double_default_qnan = {
  42         .exponent       = 2047,
  43         .sign           = 0,
  44         .significand    = VFP_DOUBLE_SIGNIFICAND_QNAN,
  45 };
  46
  47 static void vfp_double_dump(const char *str, struct vfp_double *d)
  48 {
  49         pr_debug("VFP: %s: sign=%d exponent=%d significand=%016llx\n",
  50                  str, d->sign != 0, d->exponent, d->significand);
  51 }
  52
  53 static void vfp_double_normalise_denormal(struct vfp_double *vd)
  54 {
  55         int bits = 31 - fls(vd->significand >> 32);
  56         if (bits == 31)
  57                 bits = 62 - fls(vd->significand);
  58
  59         vfp_double_dump("normalise_denormal: in", vd);
  60
  61         if (bits) {
  62                 vd->exponent -= bits - 1;
  63                 vd->significand <<= bits;
  64         }
  65
  66         vfp_double_dump("normalise_denormal: out", vd);
  67 }
  68
  69 u32 vfp_double_normaliseround(int dd, struct vfp_double *vd, u32 fpscr, u32 exceptions, const char *func)
  70 {
  71         u64 significand, incr;
  72         int exponent, shift, underflow;
  73         u32 rmode;
  74
  75         vfp_double_dump("pack: in", vd);
  76
  77         /*
  78          * Infinities and NaNs are a special case.
  79          */
  80         if (vd->exponent == 2047 && (vd->significand == 0 || exceptions))
  81                 goto pack;
  82
  83         /*
  84          * Special-case zero.
  85          */
  86         if (vd->significand == 0) {
  87                 vd->exponent = 0;
  88                 goto pack;
  89         }
  90
  91         exponent = vd->exponent;
  92         significand = vd->significand;
  93
  94         shift = 32 - fls(significand >> 32);
  95         if (shift == 32)
  96                 shift = 64 - fls(significand);
  97         if (shift) {
  98                 exponent -= shift;
  99                 significand <<= shift;
 100         }
 101
 102 #ifdef DEBUG
 103         vd->exponent = exponent;
 104         vd->significand = significand;
 105         vfp_double_dump("pack: normalised", vd);
 106 #endif
 107
 108         /*
 109          * Tiny number?
 110          */
 111         underflow = exponent < 0;
 112         if (underflow) {
 113                 significand = vfp_shiftright64jamming(significand, -exponent);
 114                 exponent = 0;
 115 #ifdef DEBUG
 116                 vd->exponent = exponent;
 117                 vd->significand = significand;
 118                 vfp_double_dump("pack: tiny number", vd);
 119 #endif
 120                 if (!(significand & ((1ULL << (VFP_DOUBLE_LOW_BITS + 1)) - 1)))
 121                         underflow = 0;
 122         }
 123
 124         /*
 125          * Select rounding increment.
 126          */
 127         incr = 0;
 128         rmode = fpscr & FPSCR_RMODE_MASK;
 129
 130         if (rmode == FPSCR_ROUND_NEAREST) {
 131                 incr = 1ULL << VFP_DOUBLE_LOW_BITS;
 132                 if ((significand & (1ULL << (VFP_DOUBLE_LOW_BITS + 1))) == 0)
 133                         incr -= 1;
 134         } else if (rmode == FPSCR_ROUND_TOZERO) {
 135                 incr = 0;
 136         } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vd->sign != 0))
 137                 incr = (1ULL << (VFP_DOUBLE_LOW_BITS + 1)) - 1;
 138
 139         pr_debug("VFP: rounding increment = 0x%08llx\n", incr);
 140
 141         /*
 142          * Is our rounding going to overflow?
 143          */
 144         if ((significand + incr) < significand) {
 145                 exponent += 1;
 146                 significand = (significand >> 1) | (significand & 1);
 147                 incr >>= 1;
 148 #ifdef DEBUG
 149                 vd->exponent = exponent;
 150                 vd->significand = significand;
 151                 vfp_double_dump("pack: overflow", vd);
 152 #endif
 153         }
 154
 155         /*
 156          * If any of the low bits (which will be shifted out of the
 157          * number) are non-zero, the result is inexact.
 158          */
 159         if (significand & ((1 << (VFP_DOUBLE_LOW_BITS + 1)) - 1))
 160                 exceptions |= FPSCR_IXC;
 161
 162         /*
 163          * Do our rounding.
 164          */
 165         significand += incr;
 166
 167         /*
 168          * Infinity?
 169          */
 170         if (exponent >= 2046) {
 171                 exceptions |= FPSCR_OFC | FPSCR_IXC;
 172                 if (incr == 0) {
 173                         vd->exponent = 2045;
 174                         vd->significand = 0x7fffffffffffffffULL;
 175                 } else {
 176                         vd->exponent = 2047;            /* infinity */
 177                         vd->significand = 0;
 178                 }
 179         } else {
 180                 if (significand >> (VFP_DOUBLE_LOW_BITS + 1) == 0)
 181                         exponent = 0;
 182                 if (exponent || significand > 0x8000000000000000ULL)
 183                         underflow = 0;
 184                 if (underflow)
 185                         exceptions |= FPSCR_UFC;
 186                 vd->exponent = exponent;
 187                 vd->significand = significand >> 1;
 188         }
 189
 190  pack:
 191         vfp_double_dump("pack: final", vd);
 192         {
 193                 s64 d = vfp_double_pack(vd);
 194                 pr_debug("VFP: %s: d(d%d)=%016llx exceptions=%08x\n", func,
 195                          dd, d, exceptions);
 196                 vfp_put_double(dd, d);
 197         }
 198         return exceptions & ~VFP_NAN_FLAG;
 199 }
 200
 201 /*
 202  * Propagate the NaN, setting exceptions if it is signalling.
 203  * 'n' is always a NaN.  'm' may be a number, NaN or infinity.
 204  */
 205 static u32
 206 vfp_propagate_nan(struct vfp_double *vdd, struct vfp_double *vdn,
 207                   struct vfp_double *vdm, u32 fpscr)
 208 {
 209         struct vfp_double *nan;
 210         int tn, tm = 0;
 211
 212         tn = vfp_double_type(vdn);
 213
 214         if (vdm)
 215                 tm = vfp_double_type(vdm);
 216
 217         if (fpscr & FPSCR_DEFAULT_NAN)
 218                 /*
 219                  * Default NaN mode - always returns a quiet NaN
 220                  */
 221                 nan = &vfp_double_default_qnan;
 222         else {
 223                 /*
 224                  * Contemporary mode - select the first signalling
 225                  * NAN, or if neither are signalling, the first
 226                  * quiet NAN.
 227                  */
 228                 if (tn == VFP_SNAN || (tm != VFP_SNAN && tn == VFP_QNAN))
 229                         nan = vdn;
 230                 else
 231                         nan = vdm;
 232                 /*
 233                  * Make the NaN quiet.
 234                  */
 235                 nan->significand |= VFP_DOUBLE_SIGNIFICAND_QNAN;
 236         }
 237
 238         *vdd = *nan;
 239
 240         /*
 241          * If one was a signalling NAN, raise invalid operation.
 242          */
 243         return tn == VFP_SNAN || tm == VFP_SNAN ? FPSCR_IOC : VFP_NAN_FLAG;
 244 }
 245
 246 /*
 247  * Extended operations
 248  */
 249 static u32 vfp_double_fabs(int dd, int unused, int dm, u32 fpscr)
 250 {
 251         vfp_put_double(dd, vfp_double_packed_abs(vfp_get_double(dm)));
 252         return 0;
 253 }
 254
 255 static u32 vfp_double_fcpy(int dd, int unused, int dm, u32 fpscr)
 256 {
 257         vfp_put_double(dd, vfp_get_double(dm));
 258         return 0;
 259 }
 260
 261 static u32 vfp_double_fneg(int dd, int unused, int dm, u32 fpscr)
 262 {
 263         vfp_put_double(dd, vfp_double_packed_negate(vfp_get_double(dm)));
 264         return 0;
 265 }
 266
 267 static u32 vfp_double_fsqrt(int dd, int unused, int dm, u32 fpscr)
 268 {
 269         struct vfp_double vdm, vdd;
 270         int ret, tm;
 271
 272         vfp_double_unpack(&vdm, vfp_get_double(dm));
 273         tm = vfp_double_type(&vdm);
 274         if (tm & (VFP_NAN|VFP_INFINITY)) {
 275                 struct vfp_double *vdp = &vdd;
 276
 277                 if (tm & VFP_NAN)
 278                         ret = vfp_propagate_nan(vdp, &vdm, NULL, fpscr);
 279                 else if (vdm.sign == 0) {
 280  sqrt_copy:
 281                         vdp = &vdm;
 282                         ret = 0;
 283                 } else {
 284  sqrt_invalid:
 285                         vdp = &vfp_double_default_qnan;
 286                         ret = FPSCR_IOC;
 287                 }
 288                 vfp_put_double(dd, vfp_double_pack(vdp));
 289                 return ret;
 290         }
 291
 292         /*
 293          * sqrt(+/- 0) == +/- 0
 294          */
 295         if (tm & VFP_ZERO)
 296                 goto sqrt_copy;
 297
 298         /*
 299          * Normalise a denormalised number
 300          */
 301         if (tm & VFP_DENORMAL)
 302                 vfp_double_normalise_denormal(&vdm);
 303
 304         /*
 305          * sqrt(<0) = invalid
 306          */
 307         if (vdm.sign)
 308                 goto sqrt_invalid;
 309
 310         vfp_double_dump("sqrt", &vdm);
 311
 312         /*
 313          * Estimate the square root.
 314          */
 315         vdd.sign = 0;
 316         vdd.exponent = ((vdm.exponent - 1023) >> 1) + 1023;
 317         vdd.significand = (u64)vfp_estimate_sqrt_significand(vdm.exponent, vdm.significand >> 32) << 31;
 318
 319         vfp_double_dump("sqrt estimate1", &vdd);
 320
 321         vdm.significand >>= 1 + (vdm.exponent & 1);
 322         vdd.significand += 2 + vfp_estimate_div128to64(vdm.significand, 0, vdd.significand);
 323
 324         vfp_double_dump("sqrt estimate2", &vdd);
 325
 326         /*
 327          * And now adjust.
 328          */
 329         if ((vdd.significand & VFP_DOUBLE_LOW_BITS_MASK) <= 5) {
 330                 if (vdd.significand < 2) {
 331                         vdd.significand = ~0ULL;
 332                 } else {
 333                         u64 termh, terml, remh, reml;
 334                         vdm.significand <<= 2;
 335                         mul64to128(&termh, &terml, vdd.significand, vdd.significand);
 336                         sub128(&remh, &reml, vdm.significand, 0, termh, terml);
 337                         while ((s64)remh < 0) {
 338                                 vdd.significand -= 1;
 339                                 shift64left(&termh, &terml, vdd.significand);
 340                                 terml |= 1;
 341                                 add128(&remh, &reml, remh, reml, termh, terml);
 342                         }
 343                         vdd.significand |= (remh | reml) != 0;
 344                 }
 345         }
 346         vdd.significand = vfp_shiftright64jamming(vdd.significand, 1);
 347
 348         return vfp_double_normaliseround(dd, &vdd, fpscr, 0, "fsqrt");
 349 }
 350
 351 /*
 352  * Equal        := ZC
 353  * Less than    := N
 354  * Greater than := C
 355  * Unordered    := CV
 356  */
 357 static u32 vfp_compare(int dd, int signal_on_qnan, int dm, u32 fpscr)
 358 {
 359         s64 d, m;
 360         u32 ret = 0;
 361
 362         m = vfp_get_double(dm);
 363         if (vfp_double_packed_exponent(m) == 2047 && vfp_double_packed_mantissa(m)) {
 364                 ret |= FPSCR_C | FPSCR_V;
 365                 if (signal_on_qnan || !(vfp_double_packed_mantissa(m) & (1ULL << (VFP_DOUBLE_MANTISSA_BITS - 1))))
 366                         /*
 367                          * Signalling NaN, or signalling on quiet NaN
 368                          */
 369                         ret |= FPSCR_IOC;
 370         }
 371
 372         d = vfp_get_double(dd);
 373         if (vfp_double_packed_exponent(d) == 2047 && vfp_double_packed_mantissa(d)) {
 374                 ret |= FPSCR_C | FPSCR_V;
 375                 if (signal_on_qnan || !(vfp_double_packed_mantissa(d) & (1ULL << (VFP_DOUBLE_MANTISSA_BITS - 1))))
 376                         /*
 377                          * Signalling NaN, or signalling on quiet NaN
 378                          */
 379                         ret |= FPSCR_IOC;
 380         }
 381
 382         if (ret == 0) {
 383                 if (d == m || vfp_double_packed_abs(d | m) == 0) {
 384                         /*
 385                          * equal
 386                          */
 387                         ret |= FPSCR_Z | FPSCR_C;
 388                 } else if (vfp_double_packed_sign(d ^ m)) {
 389                         /*
 390                          * different signs
 391                          */
 392                         if (vfp_double_packed_sign(d))
 393                                 /*
 394                                  * d is negative, so d < m
 395                                  */
 396                                 ret |= FPSCR_N;
 397                         else
 398                                 /*
 399                                  * d is positive, so d > m
 400                                  */
 401                                 ret |= FPSCR_C;
 402                 } else if ((vfp_double_packed_sign(d) != 0) ^ (d < m)) {
 403                         /*
 404                          * d < m
 405                          */
 406                         ret |= FPSCR_N;
 407                 } else if ((vfp_double_packed_sign(d) != 0) ^ (d > m)) {
 408                         /*
 409                          * d > m
 410                          */
 411                         ret |= FPSCR_C;
 412                 }
 413         }
 414
 415         return ret;
 416 }
 417
 418 static u32 vfp_double_fcmp(int dd, int unused, int dm, u32 fpscr)
 419 {
 420         return vfp_compare(dd, 0, dm, fpscr);
 421 }
 422
 423 static u32 vfp_double_fcmpe(int dd, int unused, int dm, u32 fpscr)
 424 {
 425         return vfp_compare(dd, 1, dm, fpscr);
 426 }
 427
 428 static u32 vfp_double_fcmpz(int dd, int unused, int dm, u32 fpscr)
 429 {
 430         return vfp_compare(dd, 0, VFP_REG_ZERO, fpscr);
 431 }
 432
 433 static u32 vfp_double_fcmpez(int dd, int unused, int dm, u32 fpscr)
 434 {
 435         return vfp_compare(dd, 1, VFP_REG_ZERO, fpscr);
 436 }
 437
 438 static u32 vfp_double_fcvts(int sd, int unused, int dm, u32 fpscr)
 439 {
 440         struct vfp_double vdm;
 441         struct vfp_single vsd;
 442         int tm;
 443         u32 exceptions = 0;
 444
 445         vfp_double_unpack(&vdm, vfp_get_double(dm));
 446
 447         tm = vfp_double_type(&vdm);
 448
 449         /*
 450          * If we have a signalling NaN, signal invalid operation.
 451          */
 452         if (tm == VFP_SNAN)
 453                 exceptions = FPSCR_IOC;
 454
 455         if (tm & VFP_DENORMAL)
 456                 vfp_double_normalise_denormal(&vdm);
 457
 458         vsd.sign = vdm.sign;
 459         vsd.significand = vfp_hi64to32jamming(vdm.significand);
 460
 461         /*
 462          * If we have an infinity or a NaN, the exponent must be 255
 463          */
 464         if (tm & (VFP_INFINITY|VFP_NAN)) {
 465                 vsd.exponent = 255;
 466                 if (tm & VFP_NAN)
 467                         vsd.significand |= VFP_SINGLE_SIGNIFICAND_QNAN;
 468                 goto pack_nan;
 469         } else if (tm & VFP_ZERO)
 470                 vsd.exponent = 0;
 471         else
 472                 vsd.exponent = vdm.exponent - (1023 - 127);
 473
 474         return vfp_single_normaliseround(sd, &vsd, fpscr, exceptions, "fcvts");
 475
 476  pack_nan:
 477         vfp_put_float(sd, vfp_single_pack(&vsd));
 478         return exceptions;
 479 }
 480
 481 static u32 vfp_double_fuito(int dd, int unused, int dm, u32 fpscr)
 482 {
 483         struct vfp_double vdm;
 484         u32 m = vfp_get_float(dm);
 485
 486         vdm.sign = 0;
 487         vdm.exponent = 1023 + 63 - 1;
 488         vdm.significand = (u64)m;
 489
 490         return vfp_double_normaliseround(dd, &vdm, fpscr, 0, "fuito");
 491 }
 492
 493 static u32 vfp_double_fsito(int dd, int unused, int dm, u32 fpscr)
 494 {
 495         struct vfp_double vdm;
 496         u32 m = vfp_get_float(dm);
 497
 498         vdm.sign = (m & 0x80000000) >> 16;
 499         vdm.exponent = 1023 + 63 - 1;
 500         vdm.significand = vdm.sign ? -m : m;
 501
 502         return vfp_double_normaliseround(dd, &vdm, fpscr, 0, "fsito");
 503 }
 504
 505 static u32 vfp_double_ftoui(int sd, int unused, int dm, u32 fpscr)
 506 {
 507         struct vfp_double vdm;
 508         u32 d, exceptions = 0;
 509         int rmode = fpscr & FPSCR_RMODE_MASK;
 510         int tm;
 511
 512         vfp_double_unpack(&vdm, vfp_get_double(dm));
 513
 514         /*
 515          * Do we have a denormalised number?
 516          */
 517         tm = vfp_double_type(&vdm);
 518         if (tm & VFP_DENORMAL)
 519                 exceptions |= FPSCR_IDC;
 520
 521         if (tm & VFP_NAN)
 522                 vdm.sign = 0;
 523
 524         if (vdm.exponent >= 1023 + 32) {
 525                 d = vdm.sign ? 0 : 0xffffffff;
 526                 exceptions = FPSCR_IOC;
 527         } else if (vdm.exponent >= 1023 - 1) {
 528                 int shift = 1023 + 63 - vdm.exponent;
 529                 u64 rem, incr = 0;
 530
 531                 /*
 532                  * 2^0 <= m < 2^32-2^8
 533                  */
 534                 d = (vdm.significand << 1) >> shift;
 535                 rem = vdm.significand << (65 - shift);
 536
 537                 if (rmode == FPSCR_ROUND_NEAREST) {
 538                         incr = 0x8000000000000000ULL;
 539                         if ((d & 1) == 0)
 540                                 incr -= 1;
 541                 } else if (rmode == FPSCR_ROUND_TOZERO) {
 542                         incr = 0;
 543                 } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vdm.sign != 0)) {
 544                         incr = ~0ULL;
 545                 }
 546
 547                 if ((rem + incr) < rem) {
 548                         if (d < 0xffffffff)
 549                                 d += 1;
 550                         else
 551                                 exceptions |= FPSCR_IOC;
 552                 }
 553
 554                 if (d && vdm.sign) {
 555                         d = 0;
 556                         exceptions |= FPSCR_IOC;
 557                 } else if (rem)
 558                         exceptions |= FPSCR_IXC;
 559         } else {
 560                 d = 0;
 561                 if (vdm.exponent | vdm.significand) {
 562                         exceptions |= FPSCR_IXC;
 563                         if (rmode == FPSCR_ROUND_PLUSINF && vdm.sign == 0)
 564                                 d = 1;
 565                         else if (rmode == FPSCR_ROUND_MINUSINF && vdm.sign) {
 566                                 d = 0;
 567                                 exceptions |= FPSCR_IOC;
 568                         }
 569                 }
 570         }
 571
 572         pr_debug("VFP: ftoui: d(s%d)=%08x exceptions=%08x\n", sd, d, exceptions);
 573
 574         vfp_put_float(sd, d);
 575
 576         return exceptions;
 577 }
 578
 579 static u32 vfp_double_ftouiz(int sd, int unused, int dm, u32 fpscr)
 580 {
 581         return vfp_double_ftoui(sd, unused, dm, FPSCR_ROUND_TOZERO);
 582 }
 583
 584 static u32 vfp_double_ftosi(int sd, int unused, int dm, u32 fpscr)
 585 {
 586         struct vfp_double vdm;
 587         u32 d, exceptions = 0;
 588         int rmode = fpscr & FPSCR_RMODE_MASK;
 589
 590         vfp_double_unpack(&vdm, vfp_get_double(dm));
 591         vfp_double_dump("VDM", &vdm);
 592
 593         /*
 594          * Do we have denormalised number?
 595          */
 596         if (vfp_double_type(&vdm) & VFP_DENORMAL)
 597                 exceptions |= FPSCR_IDC;
 598
 599         if (vdm.exponent >= 1023 + 32) {
 600                 d = 0x7fffffff;
 601                 if (vdm.sign)
 602                         d = ~d;
 603                 exceptions |= FPSCR_IOC;
 604         } else if (vdm.exponent >= 1023 - 1) {
 605                 int shift = 1023 + 63 - vdm.exponent;   /* 58 */
 606                 u64 rem, incr = 0;
 607
 608                 d = (vdm.significand << 1) >> shift;
 609                 rem = vdm.significand << (65 - shift);
 610
 611                 if (rmode == FPSCR_ROUND_NEAREST) {
 612                         incr = 0x8000000000000000ULL;
 613                         if ((d & 1) == 0)
 614                                 incr -= 1;
 615                 } else if (rmode == FPSCR_ROUND_TOZERO) {
 616                         incr = 0;
 617                 } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vdm.sign != 0)) {
 618                         incr = ~0ULL;
 619                 }
 620
 621                 if ((rem + incr) < rem && d < 0xffffffff)
 622                         d += 1;
 623                 if (d > 0x7fffffff + (vdm.sign != 0)) {
 624                         d = 0x7fffffff + (vdm.sign != 0);
 625                         exceptions |= FPSCR_IOC;
 626                 } else if (rem)
 627                         exceptions |= FPSCR_IXC;
 628
 629                 if (vdm.sign)
 630                         d = -d;
 631         } else {
 632                 d = 0;
 633                 if (vdm.exponent | vdm.significand) {
 634                         exceptions |= FPSCR_IXC;
 635                         if (rmode == FPSCR_ROUND_PLUSINF && vdm.sign == 0)
 636                                 d = 1;
 637                         else if (rmode == FPSCR_ROUND_MINUSINF && vdm.sign)
 638                                 d = -1;
 639                 }
 640         }
 641
 642         pr_debug("VFP: ftosi: d(s%d)=%08x exceptions=%08x\n", sd, d, exceptions);
 643
 644         vfp_put_float(sd, (s32)d);
 645
 646         return exceptions;
 647 }
 648
 649 static u32 vfp_double_ftosiz(int dd, int unused, int dm, u32 fpscr)
 650 {
 651         return vfp_double_ftosi(dd, unused, dm, FPSCR_ROUND_TOZERO);
 652 }
 653
 654
 655 static u32 (* const fop_extfns[32])(int dd, int unused, int dm, u32 fpscr) = {
 656         [FEXT_TO_IDX(FEXT_FCPY)]        = vfp_double_fcpy,
 657         [FEXT_TO_IDX(FEXT_FABS)]        = vfp_double_fabs,
 658         [FEXT_TO_IDX(FEXT_FNEG)]        = vfp_double_fneg,
 659         [FEXT_TO_IDX(FEXT_FSQRT)]       = vfp_double_fsqrt,
 660         [FEXT_TO_IDX(FEXT_FCMP)]        = vfp_double_fcmp,
 661         [FEXT_TO_IDX(FEXT_FCMPE)]       = vfp_double_fcmpe,
 662         [FEXT_TO_IDX(FEXT_FCMPZ)]       = vfp_double_fcmpz,
 663         [FEXT_TO_IDX(FEXT_FCMPEZ)]      = vfp_double_fcmpez,
 664         [FEXT_TO_IDX(FEXT_FCVT)]        = vfp_double_fcvts,
 665         [FEXT_TO_IDX(FEXT_FUITO)]       = vfp_double_fuito,
 666         [FEXT_TO_IDX(FEXT_FSITO)]       = vfp_double_fsito,
 667         [FEXT_TO_IDX(FEXT_FTOUI)]       = vfp_double_ftoui,
 668         [FEXT_TO_IDX(FEXT_FTOUIZ)]      = vfp_double_ftouiz,
 669         [FEXT_TO_IDX(FEXT_FTOSI)]       = vfp_double_ftosi,
 670         [FEXT_TO_IDX(FEXT_FTOSIZ)]      = vfp_double_ftosiz,
 671 };
 672
 673
 674
 675
 676 static u32
 677 vfp_double_fadd_nonnumber(struct vfp_double *vdd, struct vfp_double *vdn,
 678                           struct vfp_double *vdm, u32 fpscr)
 679 {
 680         struct vfp_double *vdp;
 681         u32 exceptions = 0;
 682         int tn, tm;
 683
 684         tn = vfp_double_type(vdn);
 685         tm = vfp_double_type(vdm);
 686
 687         if (tn & tm & VFP_INFINITY) {
 688                 /*
 689                  * Two infinities.  Are they different signs?
 690                  */
 691                 if (vdn->sign ^ vdm->sign) {
 692                         /*
 693                          * different signs -> invalid
 694                          */
 695                         exceptions = FPSCR_IOC;
 696                         vdp = &vfp_double_default_qnan;
 697                 } else {
 698                         /*
 699                          * same signs -> valid
 700                          */
 701                         vdp = vdn;
 702                 }
 703         } else if (tn & VFP_INFINITY && tm & VFP_NUMBER) {
 704                 /*
 705                  * One infinity and one number -> infinity
 706                  */
 707                 vdp = vdn;
 708         } else {
 709                 /*
 710                  * 'n' is a NaN of some type
 711                  */
 712                 return vfp_propagate_nan(vdd, vdn, vdm, fpscr);
 713         }
 714         *vdd = *vdp;
 715         return exceptions;
 716 }
 717
 718 static u32
 719 vfp_double_add(struct vfp_double *vdd, struct vfp_double *vdn,
 720                struct vfp_double *vdm, u32 fpscr)
 721 {
 722         u32 exp_diff;
 723         u64 m_sig;
 724
 725         if (vdn->significand & (1ULL << 63) ||
 726             vdm->significand & (1ULL << 63)) {
 727                 pr_info("VFP: bad FP values in %s\n", __func__);
 728                 vfp_double_dump("VDN", vdn);
 729                 vfp_double_dump("VDM", vdm);
 730         }
 731
 732         /*
 733          * Ensure that 'n' is the largest magnitude number.  Note that
 734          * if 'n' and 'm' have equal exponents, we do not swap them.
 735          * This ensures that NaN propagation works correctly.
 736          */
 737         if (vdn->exponent < vdm->exponent) {
 738                 struct vfp_double *t = vdn;
 739                 vdn = vdm;
 740                 vdm = t;
 741         }
 742
 743         /*
 744          * Is 'n' an infinity or a NaN?  Note that 'm' may be a number,
 745          * infinity or a NaN here.
 746          */
 747         if (vdn->exponent == 2047)
 748                 return vfp_double_fadd_nonnumber(vdd, vdn, vdm, fpscr);
 749
 750         /*
 751          * We have two proper numbers, where 'vdn' is the larger magnitude.
 752          *
 753          * Copy 'n' to 'd' before doing the arithmetic.
 754          */
 755         *vdd = *vdn;
 756
 757         /*
 758          * Align 'm' with the result.
 759          */
 760         exp_diff = vdn->exponent - vdm->exponent;
 761         m_sig = vfp_shiftright64jamming(vdm->significand, exp_diff);
 762
 763         /*
 764          * If the signs are different, we are really subtracting.
 765          */
 766         if (vdn->sign ^ vdm->sign) {
 767                 m_sig = vdn->significand - m_sig;
 768                 if ((s64)m_sig < 0) {
 769                         vdd->sign = vfp_sign_negate(vdd->sign);
 770                         m_sig = -m_sig;
 771                 }
 772         } else {
 773                 m_sig += vdn->significand;
 774         }
 775         vdd->significand = m_sig;
 776
 777         return 0;
 778 }
 779
 780 static u32
 781 vfp_double_multiply(struct vfp_double *vdd, struct vfp_double *vdn,
 782                     struct vfp_double *vdm, u32 fpscr)
 783 {
 784         vfp_double_dump("VDN", vdn);
 785         vfp_double_dump("VDM", vdm);
 786
 787         /*
 788          * Ensure that 'n' is the largest magnitude number.  Note that
 789          * if 'n' and 'm' have equal exponents, we do not swap them.
 790          * This ensures that NaN propagation works correctly.
 791          */
 792         if (vdn->exponent < vdm->exponent) {
 793                 struct vfp_double *t = vdn;
 794                 vdn = vdm;
 795                 vdm = t;
 796                 pr_debug("VFP: swapping M <-> N\n");
 797         }
 798
 799         vdd->sign = vdn->sign ^ vdm->sign;
 800
 801         /*
 802          * If 'n' is an infinity or NaN, handle it.  'm' may be anything.
 803          */
 804         if (vdn->exponent == 2047) {
 805                 if (vdn->significand || (vdm->exponent == 2047 && vdm->significand))
 806                         return vfp_propagate_nan(vdd, vdn, vdm, fpscr);
 807                 if ((vdm->exponent | vdm->significand) == 0) {
 808                         *vdd = vfp_double_default_qnan;
 809                         return FPSCR_IOC;
 810                 }
 811                 vdd->exponent = vdn->exponent;
 812                 vdd->significand = 0;
 813                 return 0;
 814         }
 815
 816         /*
 817          * If 'm' is zero, the result is always zero.  In this case,
 818          * 'n' may be zero or a number, but it doesn't matter which.
 819          */
 820         if ((vdm->exponent | vdm->significand) == 0) {
 821                 vdd->exponent = 0;
 822                 vdd->significand = 0;
 823                 return 0;
 824         }
 825
 826         /*
 827          * We add 2 to the destination exponent for the same reason
 828          * as the addition case - though this time we have +1 from
 829          * each input operand.
 830          */
 831         vdd->exponent = vdn->exponent + vdm->exponent - 1023 + 2;
 832         vdd->significand = vfp_hi64multiply64(vdn->significand, vdm->significand);
 833
 834         vfp_double_dump("VDD", vdd);
 835         return 0;
 836 }
 837
 838 #define NEG_MULTIPLY    (1 << 0)
 839 #define NEG_SUBTRACT    (1 << 1)
 840
 841 static u32
 842 vfp_double_multiply_accumulate(int dd, int dn, int dm, u32 fpscr, u32 negate, char *func)
 843 {
 844         struct vfp_double vdd, vdp, vdn, vdm;
 845         u32 exceptions;
 846
 847         vfp_double_unpack(&vdn, vfp_get_double(dn));
 848         if (vdn.exponent == 0 && vdn.significand)
 849                 vfp_double_normalise_denormal(&vdn);
 850
 851         vfp_double_unpack(&vdm, vfp_get_double(dm));
 852         if (vdm.exponent == 0 && vdm.significand)
 853                 vfp_double_normalise_denormal(&vdm);
 854
 855         exceptions = vfp_double_multiply(&vdp, &vdn, &vdm, fpscr);
 856         if (negate & NEG_MULTIPLY)
 857                 vdp.sign = vfp_sign_negate(vdp.sign);
 858
 859         vfp_double_unpack(&vdn, vfp_get_double(dd));
 860         if (negate & NEG_SUBTRACT)
 861                 vdn.sign = vfp_sign_negate(vdn.sign);
 862
 863         exceptions |= vfp_double_add(&vdd, &vdn, &vdp, fpscr);
 864
 865         return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, func);
 866 }
 867
 868 /*
 869  * Standard operations
 870  */
 871
 872 /*
 873  * sd = sd + (sn * sm)
 874  */
 875 static u32 vfp_double_fmac(int dd, int dn, int dm, u32 fpscr)
 876 {
 877         return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, 0, "fmac");
 878 }
 879
 880 /*
 881  * sd = sd - (sn * sm)
 882  */
 883 static u32 vfp_double_fnmac(int dd, int dn, int dm, u32 fpscr)
 884 {
 885         return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_MULTIPLY, "fnmac");
 886 }
 887
 888 /*
 889  * sd = -sd + (sn * sm)
 890  */
 891 static u32 vfp_double_fmsc(int dd, int dn, int dm, u32 fpscr)
 892 {
 893         return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_SUBTRACT, "fmsc");
 894 }
 895
 896 /*
 897  * sd = -sd - (sn * sm)
 898  */
 899 static u32 vfp_double_fnmsc(int dd, int dn, int dm, u32 fpscr)
 900 {
 901         return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_SUBTRACT | NEG_MULTIPLY, "fnmsc");
 902 }
 903
 904 /*
 905  * sd = sn * sm
 906  */
 907 static u32 vfp_double_fmul(int dd, int dn, int dm, u32 fpscr)
 908 {
 909         struct vfp_double vdd, vdn, vdm;
 910         u32 exceptions;
 911
 912         vfp_double_unpack(&vdn, vfp_get_double(dn));
 913         if (vdn.exponent == 0 && vdn.significand)
 914                 vfp_double_normalise_denormal(&vdn);
 915
 916         vfp_double_unpack(&vdm, vfp_get_double(dm));
 917         if (vdm.exponent == 0 && vdm.significand)
 918                 vfp_double_normalise_denormal(&vdm);
 919
 920         exceptions = vfp_double_multiply(&vdd, &vdn, &vdm, fpscr);
 921         return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fmul");
 922 }
 923
 924 /*
 925  * sd = -(sn * sm)
 926  */
 927 static u32 vfp_double_fnmul(int dd, int dn, int dm, u32 fpscr)
 928 {
 929         struct vfp_double vdd, vdn, vdm;
 930         u32 exceptions;
 931
 932         vfp_double_unpack(&vdn, vfp_get_double(dn));
 933         if (vdn.exponent == 0 && vdn.significand)
 934                 vfp_double_normalise_denormal(&vdn);
 935
 936         vfp_double_unpack(&vdm, vfp_get_double(dm));
 937         if (vdm.exponent == 0 && vdm.significand)
 938                 vfp_double_normalise_denormal(&vdm);
 939
 940         exceptions = vfp_double_multiply(&vdd, &vdn, &vdm, fpscr);
 941         vdd.sign = vfp_sign_negate(vdd.sign);
 942
 943         return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fnmul");
 944 }
 945
 946 /*
 947  * sd = sn + sm
 948  */
 949 static u32 vfp_double_fadd(int dd, int dn, int dm, u32 fpscr)
 950 {
 951         struct vfp_double vdd, vdn, vdm;
 952         u32 exceptions;
 953
 954         vfp_double_unpack(&vdn, vfp_get_double(dn));
 955         if (vdn.exponent == 0 && vdn.significand)
 956                 vfp_double_normalise_denormal(&vdn);
 957
 958         vfp_double_unpack(&vdm, vfp_get_double(dm));
 959         if (vdm.exponent == 0 && vdm.significand)
 960                 vfp_double_normalise_denormal(&vdm);
 961
 962         exceptions = vfp_double_add(&vdd, &vdn, &vdm, fpscr);
 963
 964         return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fadd");
 965 }
 966
 967 /*
 968  * sd = sn - sm
 969  */
 970 static u32 vfp_double_fsub(int dd, int dn, int dm, u32 fpscr)
 971 {
 972         struct vfp_double vdd, vdn, vdm;
 973         u32 exceptions;
 974
 975         vfp_double_unpack(&vdn, vfp_get_double(dn));
 976         if (vdn.exponent == 0 && vdn.significand)
 977                 vfp_double_normalise_denormal(&vdn);
 978
 979         vfp_double_unpack(&vdm, vfp_get_double(dm));
 980         if (vdm.exponent == 0 && vdm.significand)
 981                 vfp_double_normalise_denormal(&vdm);
 982
 983         /*
 984          * Subtraction is like addition, but with a negated operand.
 985          */
 986         vdm.sign = vfp_sign_negate(vdm.sign);
 987
 988         exceptions = vfp_double_add(&vdd, &vdn, &vdm, fpscr);
 989
 990         return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fsub");
 991 }
 992
 993 /*
 994  * sd = sn / sm
 995  */
 996 static u32 vfp_double_fdiv(int dd, int dn, int dm, u32 fpscr)
 997 {
 998         struct vfp_double vdd, vdn, vdm;
 999         u32 exceptions = 0;
1000         int tm, tn;
1001
1002         vfp_double_unpack(&vdn, vfp_get_double(dn));
1003         vfp_double_unpack(&vdm, vfp_get_double(dm));
1004
1005         vdd.sign = vdn.sign ^ vdm.sign;
1006
1007         tn = vfp_double_type(&vdn);
1008         tm = vfp_double_type(&vdm);
1009
1010         /*
1011          * Is n a NAN?
1012          */
1013         if (tn & VFP_NAN)
1014                 goto vdn_nan;
1015
1016         /*
1017          * Is m a NAN?
1018          */
1019         if (tm & VFP_NAN)
1020                 goto vdm_nan;
1021
1022         /*
1023          * If n and m are infinity, the result is invalid
1024          * If n and m are zero, the result is invalid
1025          */
1026         if (tm & tn & (VFP_INFINITY|VFP_ZERO))
1027                 goto invalid;
1028
1029         /*
1030          * If n is infinity, the result is infinity
1031          */
1032         if (tn & VFP_INFINITY)
1033                 goto infinity;
1034
1035         /*
1036          * If m is zero, raise div0 exceptions
1037          */
1038         if (tm & VFP_ZERO)
1039                 goto divzero;
1040
1041         /*
1042          * If m is infinity, or n is zero, the result is zero
1043          */
1044         if (tm & VFP_INFINITY || tn & VFP_ZERO)
1045                 goto zero;
1046
1047         if (tn & VFP_DENORMAL)
1048                 vfp_double_normalise_denormal(&vdn);
1049         if (tm & VFP_DENORMAL)
1050                 vfp_double_normalise_denormal(&vdm);
1051
1052         /*
1053          * Ok, we have two numbers, we can perform division.
1054          */
1055         vdd.exponent = vdn.exponent - vdm.exponent + 1023 - 1;
1056         vdm.significand <<= 1;
1057         if (vdm.significand <= (2 * vdn.significand)) {
1058                 vdn.significand >>= 1;
1059                 vdd.exponent++;
1060         }
1061         vdd.significand = vfp_estimate_div128to64(vdn.significand, 0, vdm.significand);
1062         if ((vdd.significand & 0x1ff) <= 2) {
1063                 u64 termh, terml, remh, reml;
1064                 mul64to128(&termh, &terml, vdm.significand, vdd.significand);
1065                 sub128(&remh, &reml, vdn.significand, 0, termh, terml);
1066                 while ((s64)remh < 0) {
1067                         vdd.significand -= 1;
1068                         add128(&remh, &reml, remh, reml, 0, vdm.significand);
1069                 }
1070                 vdd.significand |= (reml != 0);
1071         }
1072         return vfp_double_normaliseround(dd, &vdd, fpscr, 0, "fdiv");
1073
1074  vdn_nan:
1075         exceptions = vfp_propagate_nan(&vdd, &vdn, &vdm, fpscr);
1076  pack:
1077         vfp_put_double(dd, vfp_double_pack(&vdd));
1078         return exceptions;
1079
1080  vdm_nan:
1081         exceptions = vfp_propagate_nan(&vdd, &vdm, &vdn, fpscr);
1082         goto pack;
1083
1084  zero:
1085         vdd.exponent = 0;
1086         vdd.significand = 0;
1087         goto pack;
1088
1089  divzero:
1090         exceptions = FPSCR_DZC;
1091  infinity:
1092         vdd.exponent = 2047;
1093         vdd.significand = 0;
1094         goto pack;
1095
1096  invalid:
1097         vfp_put_double(dd, vfp_double_pack(&vfp_double_default_qnan));
1098         return FPSCR_IOC;
1099 }
1100
1101 static u32 (* const fop_fns[16])(int dd, int dn, int dm, u32 fpscr) = {
1102         [FOP_TO_IDX(FOP_FMAC)]  = vfp_double_fmac,
1103         [FOP_TO_IDX(FOP_FNMAC)] = vfp_double_fnmac,
1104         [FOP_TO_IDX(FOP_FMSC)]  = vfp_double_fmsc,
1105         [FOP_TO_IDX(FOP_FNMSC)] = vfp_double_fnmsc,
1106         [FOP_TO_IDX(FOP_FMUL)]  = vfp_double_fmul,
1107         [FOP_TO_IDX(FOP_FNMUL)] = vfp_double_fnmul,
1108         [FOP_TO_IDX(FOP_FADD)]  = vfp_double_fadd,
1109         [FOP_TO_IDX(FOP_FSUB)]  = vfp_double_fsub,
1110         [FOP_TO_IDX(FOP_FDIV)]  = vfp_double_fdiv,
1111 };
1112
1113 #define FREG_BANK(x)    ((x) & 0x0c)
1114 #define FREG_IDX(x)     ((x) & 3)
1115
1116 u32 vfp_double_cpdo(u32 inst, u32 fpscr)
1117 {
1118         u32 op = inst & FOP_MASK;
1119         u32 exceptions = 0;
1120         unsigned int dd = vfp_get_sd(inst);
1121         unsigned int dn = vfp_get_sn(inst);
1122         unsigned int dm = vfp_get_sm(inst);
1123         unsigned int vecitr, veclen, vecstride;
1124         u32 (*fop)(int, int, s32, u32);
1125
1126         veclen = fpscr & FPSCR_LENGTH_MASK;
1127         vecstride = (1 + ((fpscr & FPSCR_STRIDE_MASK) == FPSCR_STRIDE_MASK)) * 2;
1128
1129         /*
1130          * If destination bank is zero, vector length is always '1'.
1131          * ARM DDI0100F C5.1.3, C5.3.2.
1132          */
1133         if (FREG_BANK(dd) == 0)
1134                 veclen = 0;
1135
1136         pr_debug("VFP: vecstride=%u veclen=%u\n", vecstride,
1137                  (veclen >> FPSCR_LENGTH_BIT) + 1);
1138
1139         fop = (op == FOP_EXT) ? fop_extfns[dn] : fop_fns[FOP_TO_IDX(op)];
1140         if (!fop)
1141                 goto invalid;
1142
1143         for (vecitr = 0; vecitr <= veclen; vecitr += 1 << FPSCR_LENGTH_BIT) {
1144                 u32 except;
1145
1146                 if (op == FOP_EXT)
1147                         pr_debug("VFP: itr%d (d%u.%u) = op[%u] (d%u.%u)\n",
1148                                  vecitr >> FPSCR_LENGTH_BIT,
1149                                  dd >> 1, dd & 1, dn,
1150                                  dm >> 1, dm & 1);
1151                 else
1152                         pr_debug("VFP: itr%d (d%u.%u) = (d%u.%u) op[%u] (d%u.%u)\n",
1153                                  vecitr >> FPSCR_LENGTH_BIT,
1154                                  dd >> 1, dd & 1,
1155                                  dn >> 1, dn & 1,
1156                                  FOP_TO_IDX(op),
1157                                  dm >> 1, dm & 1);
1158
1159                 except = fop(dd, dn, dm, fpscr);
1160                 pr_debug("VFP: itr%d: exceptions=%08x\n",
1161                          vecitr >> FPSCR_LENGTH_BIT, except);
1162
1163                 exceptions |= except;
1164
1165                 /*
1166                  * This ensures that comparisons only operate on scalars;
1167                  * comparisons always return with one FPSCR status bit set.
1168                  */
1169                 if (except & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
1170                         break;
1171
1172                 /*
1173                  * CHECK: It appears to be undefined whether we stop when
1174                  * we encounter an exception.  We continue.
1175                  */
1176
1177                 dd = FREG_BANK(dd) + ((FREG_IDX(dd) + vecstride) & 6);
1178                 dn = FREG_BANK(dn) + ((FREG_IDX(dn) + vecstride) & 6);
1179                 if (FREG_BANK(dm) != 0)
1180                         dm = FREG_BANK(dm) + ((FREG_IDX(dm) + vecstride) & 6);
1181         }
1182         return exceptions;
1183
1184  invalid:
1185         return ~0;
1186 }