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vfpdouble.c
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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 
36 #include <asm/div64.h>
37 #include <asm/vfp.h>
38 
39 #include "vfpinstr.h"
40 #include "vfp.h"
41 
42 static struct vfp_double vfp_double_default_qnan = {
43  .exponent = 2047,
44  .sign = 0,
45  .significand = VFP_DOUBLE_SIGNIFICAND_QNAN,
46 };
47 
48 static void vfp_double_dump(const char *str, struct vfp_double *d)
49 {
50  pr_debug("VFP: %s: sign=%d exponent=%d significand=%016llx\n",
51  str, d->sign != 0, d->exponent, d->significand);
52 }
53 
54 static void vfp_double_normalise_denormal(struct vfp_double *vd)
55 {
56  int bits = 31 - fls(vd->significand >> 32);
57  if (bits == 31)
58  bits = 63 - fls(vd->significand);
59 
60  vfp_double_dump("normalise_denormal: in", vd);
61 
62  if (bits) {
63  vd->exponent -= bits - 1;
64  vd->significand <<= bits;
65  }
66 
67  vfp_double_dump("normalise_denormal: out", vd);
68 }
69 
70 u32 vfp_double_normaliseround(int dd, struct vfp_double *vd, u32 fpscr, u32 exceptions, const char *func)
71 {
72  u64 significand, incr;
73  int exponent, shift, underflow;
74  u32 rmode;
75 
76  vfp_double_dump("pack: in", vd);
77 
78  /*
79  * Infinities and NaNs are a special case.
80  */
81  if (vd->exponent == 2047 && (vd->significand == 0 || exceptions))
82  goto pack;
83 
84  /*
85  * Special-case zero.
86  */
87  if (vd->significand == 0) {
88  vd->exponent = 0;
89  goto pack;
90  }
91 
92  exponent = vd->exponent;
93  significand = vd->significand;
94 
95  shift = 32 - fls(significand >> 32);
96  if (shift == 32)
97  shift = 64 - fls(significand);
98  if (shift) {
99  exponent -= shift;
100  significand <<= shift;
101  }
102 
103 #ifdef DEBUG
104  vd->exponent = exponent;
105  vd->significand = significand;
106  vfp_double_dump("pack: normalised", vd);
107 #endif
108 
109  /*
110  * Tiny number?
111  */
112  underflow = exponent < 0;
113  if (underflow) {
114  significand = vfp_shiftright64jamming(significand, -exponent);
115  exponent = 0;
116 #ifdef DEBUG
117  vd->exponent = exponent;
118  vd->significand = significand;
119  vfp_double_dump("pack: tiny number", vd);
120 #endif
121  if (!(significand & ((1ULL << (VFP_DOUBLE_LOW_BITS + 1)) - 1)))
122  underflow = 0;
123  }
124 
125  /*
126  * Select rounding increment.
127  */
128  incr = 0;
129  rmode = fpscr & FPSCR_RMODE_MASK;
130 
131  if (rmode == FPSCR_ROUND_NEAREST) {
132  incr = 1ULL << VFP_DOUBLE_LOW_BITS;
133  if ((significand & (1ULL << (VFP_DOUBLE_LOW_BITS + 1))) == 0)
134  incr -= 1;
135  } else if (rmode == FPSCR_ROUND_TOZERO) {
136  incr = 0;
137  } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vd->sign != 0))
138  incr = (1ULL << (VFP_DOUBLE_LOW_BITS + 1)) - 1;
139 
140  pr_debug("VFP: rounding increment = 0x%08llx\n", incr);
141 
142  /*
143  * Is our rounding going to overflow?
144  */
145  if ((significand + incr) < significand) {
146  exponent += 1;
147  significand = (significand >> 1) | (significand & 1);
148  incr >>= 1;
149 #ifdef DEBUG
150  vd->exponent = exponent;
151  vd->significand = significand;
152  vfp_double_dump("pack: overflow", vd);
153 #endif
154  }
155 
156  /*
157  * If any of the low bits (which will be shifted out of the
158  * number) are non-zero, the result is inexact.
159  */
160  if (significand & ((1 << (VFP_DOUBLE_LOW_BITS + 1)) - 1))
161  exceptions |= FPSCR_IXC;
162 
163  /*
164  * Do our rounding.
165  */
166  significand += incr;
167 
168  /*
169  * Infinity?
170  */
171  if (exponent >= 2046) {
172  exceptions |= FPSCR_OFC | FPSCR_IXC;
173  if (incr == 0) {
174  vd->exponent = 2045;
175  vd->significand = 0x7fffffffffffffffULL;
176  } else {
177  vd->exponent = 2047; /* infinity */
178  vd->significand = 0;
179  }
180  } else {
181  if (significand >> (VFP_DOUBLE_LOW_BITS + 1) == 0)
182  exponent = 0;
183  if (exponent || significand > 0x8000000000000000ULL)
184  underflow = 0;
185  if (underflow)
186  exceptions |= FPSCR_UFC;
187  vd->exponent = exponent;
188  vd->significand = significand >> 1;
189  }
190 
191  pack:
192  vfp_double_dump("pack: final", vd);
193  {
194  s64 d = vfp_double_pack(vd);
195  pr_debug("VFP: %s: d(d%d)=%016llx exceptions=%08x\n", func,
196  dd, d, exceptions);
197  vfp_put_double(d, dd);
198  }
199  return exceptions;
200 }
201 
202 /*
203  * Propagate the NaN, setting exceptions if it is signalling.
204  * 'n' is always a NaN. 'm' may be a number, NaN or infinity.
205  */
206 static u32
207 vfp_propagate_nan(struct vfp_double *vdd, struct vfp_double *vdn,
208  struct vfp_double *vdm, u32 fpscr)
209 {
210  struct vfp_double *nan;
211  int tn, tm = 0;
212 
213  tn = vfp_double_type(vdn);
214 
215  if (vdm)
216  tm = vfp_double_type(vdm);
217 
218  if (fpscr & FPSCR_DEFAULT_NAN)
219  /*
220  * Default NaN mode - always returns a quiet NaN
221  */
222  nan = &vfp_double_default_qnan;
223  else {
224  /*
225  * Contemporary mode - select the first signalling
226  * NAN, or if neither are signalling, the first
227  * quiet NAN.
228  */
229  if (tn == VFP_SNAN || (tm != VFP_SNAN && tn == VFP_QNAN))
230  nan = vdn;
231  else
232  nan = vdm;
233  /*
234  * Make the NaN quiet.
235  */
237  }
238 
239  *vdd = *nan;
240 
241  /*
242  * If one was a signalling NAN, raise invalid operation.
243  */
244  return tn == VFP_SNAN || tm == VFP_SNAN ? FPSCR_IOC : VFP_NAN_FLAG;
245 }
246 
247 /*
248  * Extended operations
249  */
250 static u32 vfp_double_fabs(int dd, int unused, int dm, u32 fpscr)
251 {
253  return 0;
254 }
255 
256 static u32 vfp_double_fcpy(int dd, int unused, int dm, u32 fpscr)
257 {
259  return 0;
260 }
261 
262 static u32 vfp_double_fneg(int dd, int unused, int dm, u32 fpscr)
263 {
265  return 0;
266 }
267 
268 static u32 vfp_double_fsqrt(int dd, int unused, int dm, u32 fpscr)
269 {
270  struct vfp_double vdm, vdd;
271  int ret, tm;
272 
273  vfp_double_unpack(&vdm, vfp_get_double(dm));
274  tm = vfp_double_type(&vdm);
275  if (tm & (VFP_NAN|VFP_INFINITY)) {
276  struct vfp_double *vdp = &vdd;
277 
278  if (tm & VFP_NAN)
279  ret = vfp_propagate_nan(vdp, &vdm, NULL, fpscr);
280  else if (vdm.sign == 0) {
281  sqrt_copy:
282  vdp = &vdm;
283  ret = 0;
284  } else {
285  sqrt_invalid:
286  vdp = &vfp_double_default_qnan;
287  ret = FPSCR_IOC;
288  }
289  vfp_put_double(vfp_double_pack(vdp), dd);
290  return ret;
291  }
292 
293  /*
294  * sqrt(+/- 0) == +/- 0
295  */
296  if (tm & VFP_ZERO)
297  goto sqrt_copy;
298 
299  /*
300  * Normalise a denormalised number
301  */
302  if (tm & VFP_DENORMAL)
303  vfp_double_normalise_denormal(&vdm);
304 
305  /*
306  * sqrt(<0) = invalid
307  */
308  if (vdm.sign)
309  goto sqrt_invalid;
310 
311  vfp_double_dump("sqrt", &vdm);
312 
313  /*
314  * Estimate the square root.
315  */
316  vdd.sign = 0;
317  vdd.exponent = ((vdm.exponent - 1023) >> 1) + 1023;
319 
320  vfp_double_dump("sqrt estimate1", &vdd);
321 
322  vdm.significand >>= 1 + (vdm.exponent & 1);
323  vdd.significand += 2 + vfp_estimate_div128to64(vdm.significand, 0, vdd.significand);
324 
325  vfp_double_dump("sqrt estimate2", &vdd);
326 
327  /*
328  * And now adjust.
329  */
330  if ((vdd.significand & VFP_DOUBLE_LOW_BITS_MASK) <= 5) {
331  if (vdd.significand < 2) {
332  vdd.significand = ~0ULL;
333  } else {
334  u64 termh, terml, remh, reml;
335  vdm.significand <<= 2;
336  mul64to128(&termh, &terml, vdd.significand, vdd.significand);
337  sub128(&remh, &reml, vdm.significand, 0, termh, terml);
338  while ((s64)remh < 0) {
339  vdd.significand -= 1;
340  shift64left(&termh, &terml, vdd.significand);
341  terml |= 1;
342  add128(&remh, &reml, remh, reml, termh, terml);
343  }
344  vdd.significand |= (remh | reml) != 0;
345  }
346  }
347  vdd.significand = vfp_shiftright64jamming(vdd.significand, 1);
348 
349  return vfp_double_normaliseround(dd, &vdd, fpscr, 0, "fsqrt");
350 }
351 
352 /*
353  * Equal := ZC
354  * Less than := N
355  * Greater than := C
356  * Unordered := CV
357  */
358 static u32 vfp_compare(int dd, int signal_on_qnan, int dm, u32 fpscr)
359 {
360  s64 d, m;
361  u32 ret = 0;
362 
363  m = vfp_get_double(dm);
365  ret |= FPSCR_C | FPSCR_V;
366  if (signal_on_qnan || !(vfp_double_packed_mantissa(m) & (1ULL << (VFP_DOUBLE_MANTISSA_BITS - 1))))
367  /*
368  * Signalling NaN, or signalling on quiet NaN
369  */
370  ret |= FPSCR_IOC;
371  }
372 
373  d = vfp_get_double(dd);
375  ret |= FPSCR_C | FPSCR_V;
376  if (signal_on_qnan || !(vfp_double_packed_mantissa(d) & (1ULL << (VFP_DOUBLE_MANTISSA_BITS - 1))))
377  /*
378  * Signalling NaN, or signalling on quiet NaN
379  */
380  ret |= FPSCR_IOC;
381  }
382 
383  if (ret == 0) {
384  if (d == m || vfp_double_packed_abs(d | m) == 0) {
385  /*
386  * equal
387  */
388  ret |= FPSCR_Z | FPSCR_C;
389  } else if (vfp_double_packed_sign(d ^ m)) {
390  /*
391  * different signs
392  */
393  if (vfp_double_packed_sign(d))
394  /*
395  * d is negative, so d < m
396  */
397  ret |= FPSCR_N;
398  else
399  /*
400  * d is positive, so d > m
401  */
402  ret |= FPSCR_C;
403  } else if ((vfp_double_packed_sign(d) != 0) ^ (d < m)) {
404  /*
405  * d < m
406  */
407  ret |= FPSCR_N;
408  } else if ((vfp_double_packed_sign(d) != 0) ^ (d > m)) {
409  /*
410  * d > m
411  */
412  ret |= FPSCR_C;
413  }
414  }
415 
416  return ret;
417 }
418 
419 static u32 vfp_double_fcmp(int dd, int unused, int dm, u32 fpscr)
420 {
421  return vfp_compare(dd, 0, dm, fpscr);
422 }
423 
424 static u32 vfp_double_fcmpe(int dd, int unused, int dm, u32 fpscr)
425 {
426  return vfp_compare(dd, 1, dm, fpscr);
427 }
428 
429 static u32 vfp_double_fcmpz(int dd, int unused, int dm, u32 fpscr)
430 {
431  return vfp_compare(dd, 0, VFP_REG_ZERO, fpscr);
432 }
433 
434 static u32 vfp_double_fcmpez(int dd, int unused, int dm, u32 fpscr)
435 {
436  return vfp_compare(dd, 1, VFP_REG_ZERO, fpscr);
437 }
438 
439 static u32 vfp_double_fcvts(int sd, int unused, int dm, u32 fpscr)
440 {
441  struct vfp_double vdm;
442  struct vfp_single vsd;
443  int tm;
444  u32 exceptions = 0;
445 
446  vfp_double_unpack(&vdm, vfp_get_double(dm));
447 
448  tm = vfp_double_type(&vdm);
449 
450  /*
451  * If we have a signalling NaN, signal invalid operation.
452  */
453  if (tm == VFP_SNAN)
454  exceptions = FPSCR_IOC;
455 
456  if (tm & VFP_DENORMAL)
457  vfp_double_normalise_denormal(&vdm);
458 
459  vsd.sign = vdm.sign;
460  vsd.significand = vfp_hi64to32jamming(vdm.significand);
461 
462  /*
463  * If we have an infinity or a NaN, the exponent must be 255
464  */
465  if (tm & (VFP_INFINITY|VFP_NAN)) {
466  vsd.exponent = 255;
467  if (tm == VFP_QNAN)
468  vsd.significand |= VFP_SINGLE_SIGNIFICAND_QNAN;
469  goto pack_nan;
470  } else if (tm & VFP_ZERO)
471  vsd.exponent = 0;
472  else
473  vsd.exponent = vdm.exponent - (1023 - 127);
474 
475  return vfp_single_normaliseround(sd, &vsd, fpscr, exceptions, "fcvts");
476 
477  pack_nan:
478  vfp_put_float(vfp_single_pack(&vsd), sd);
479  return exceptions;
480 }
481 
482 static u32 vfp_double_fuito(int dd, int unused, int dm, u32 fpscr)
483 {
484  struct vfp_double vdm;
485  u32 m = vfp_get_float(dm);
486 
487  vdm.sign = 0;
488  vdm.exponent = 1023 + 63 - 1;
489  vdm.significand = (u64)m;
490 
491  return vfp_double_normaliseround(dd, &vdm, fpscr, 0, "fuito");
492 }
493 
494 static u32 vfp_double_fsito(int dd, int unused, int dm, u32 fpscr)
495 {
496  struct vfp_double vdm;
497  u32 m = vfp_get_float(dm);
498 
499  vdm.sign = (m & 0x80000000) >> 16;
500  vdm.exponent = 1023 + 63 - 1;
501  vdm.significand = vdm.sign ? -m : m;
502 
503  return vfp_double_normaliseround(dd, &vdm, fpscr, 0, "fsito");
504 }
505 
506 static u32 vfp_double_ftoui(int sd, int unused, int dm, u32 fpscr)
507 {
508  struct vfp_double vdm;
509  u32 d, exceptions = 0;
510  int rmode = fpscr & FPSCR_RMODE_MASK;
511  int tm;
512 
513  vfp_double_unpack(&vdm, vfp_get_double(dm));
514 
515  /*
516  * Do we have a denormalised number?
517  */
518  tm = vfp_double_type(&vdm);
519  if (tm & VFP_DENORMAL)
520  exceptions |= FPSCR_IDC;
521 
522  if (tm & VFP_NAN)
523  vdm.sign = 0;
524 
525  if (vdm.exponent >= 1023 + 32) {
526  d = vdm.sign ? 0 : 0xffffffff;
527  exceptions = FPSCR_IOC;
528  } else if (vdm.exponent >= 1023 - 1) {
529  int shift = 1023 + 63 - vdm.exponent;
530  u64 rem, incr = 0;
531 
532  /*
533  * 2^0 <= m < 2^32-2^8
534  */
535  d = (vdm.significand << 1) >> shift;
536  rem = vdm.significand << (65 - shift);
537 
538  if (rmode == FPSCR_ROUND_NEAREST) {
539  incr = 0x8000000000000000ULL;
540  if ((d & 1) == 0)
541  incr -= 1;
542  } else if (rmode == FPSCR_ROUND_TOZERO) {
543  incr = 0;
544  } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vdm.sign != 0)) {
545  incr = ~0ULL;
546  }
547 
548  if ((rem + incr) < rem) {
549  if (d < 0xffffffff)
550  d += 1;
551  else
552  exceptions |= FPSCR_IOC;
553  }
554 
555  if (d && vdm.sign) {
556  d = 0;
557  exceptions |= FPSCR_IOC;
558  } else if (rem)
559  exceptions |= FPSCR_IXC;
560  } else {
561  d = 0;
562  if (vdm.exponent | vdm.significand) {
563  exceptions |= FPSCR_IXC;
564  if (rmode == FPSCR_ROUND_PLUSINF && vdm.sign == 0)
565  d = 1;
566  else if (rmode == FPSCR_ROUND_MINUSINF && vdm.sign) {
567  d = 0;
568  exceptions |= FPSCR_IOC;
569  }
570  }
571  }
572 
573  pr_debug("VFP: ftoui: d(s%d)=%08x exceptions=%08x\n", sd, d, exceptions);
574 
575  vfp_put_float(d, sd);
576 
577  return exceptions;
578 }
579 
580 static u32 vfp_double_ftouiz(int sd, int unused, int dm, u32 fpscr)
581 {
582  return vfp_double_ftoui(sd, unused, dm, FPSCR_ROUND_TOZERO);
583 }
584 
585 static u32 vfp_double_ftosi(int sd, int unused, int dm, u32 fpscr)
586 {
587  struct vfp_double vdm;
588  u32 d, exceptions = 0;
589  int rmode = fpscr & FPSCR_RMODE_MASK;
590  int tm;
591 
592  vfp_double_unpack(&vdm, vfp_get_double(dm));
593  vfp_double_dump("VDM", &vdm);
594 
595  /*
596  * Do we have denormalised number?
597  */
598  tm = vfp_double_type(&vdm);
599  if (tm & VFP_DENORMAL)
600  exceptions |= FPSCR_IDC;
601 
602  if (tm & VFP_NAN) {
603  d = 0;
604  exceptions |= FPSCR_IOC;
605  } else if (vdm.exponent >= 1023 + 32) {
606  d = 0x7fffffff;
607  if (vdm.sign)
608  d = ~d;
609  exceptions |= FPSCR_IOC;
610  } else if (vdm.exponent >= 1023 - 1) {
611  int shift = 1023 + 63 - vdm.exponent; /* 58 */
612  u64 rem, incr = 0;
613 
614  d = (vdm.significand << 1) >> shift;
615  rem = vdm.significand << (65 - shift);
616 
617  if (rmode == FPSCR_ROUND_NEAREST) {
618  incr = 0x8000000000000000ULL;
619  if ((d & 1) == 0)
620  incr -= 1;
621  } else if (rmode == FPSCR_ROUND_TOZERO) {
622  incr = 0;
623  } else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vdm.sign != 0)) {
624  incr = ~0ULL;
625  }
626 
627  if ((rem + incr) < rem && d < 0xffffffff)
628  d += 1;
629  if (d > 0x7fffffff + (vdm.sign != 0)) {
630  d = 0x7fffffff + (vdm.sign != 0);
631  exceptions |= FPSCR_IOC;
632  } else if (rem)
633  exceptions |= FPSCR_IXC;
634 
635  if (vdm.sign)
636  d = -d;
637  } else {
638  d = 0;
639  if (vdm.exponent | vdm.significand) {
640  exceptions |= FPSCR_IXC;
641  if (rmode == FPSCR_ROUND_PLUSINF && vdm.sign == 0)
642  d = 1;
643  else if (rmode == FPSCR_ROUND_MINUSINF && vdm.sign)
644  d = -1;
645  }
646  }
647 
648  pr_debug("VFP: ftosi: d(s%d)=%08x exceptions=%08x\n", sd, d, exceptions);
649 
650  vfp_put_float((s32)d, sd);
651 
652  return exceptions;
653 }
654 
655 static u32 vfp_double_ftosiz(int dd, int unused, int dm, u32 fpscr)
656 {
657  return vfp_double_ftosi(dd, unused, dm, FPSCR_ROUND_TOZERO);
658 }
659 
660 
661 static struct op fops_ext[32] = {
662  [FEXT_TO_IDX(FEXT_FCPY)] = { vfp_double_fcpy, 0 },
663  [FEXT_TO_IDX(FEXT_FABS)] = { vfp_double_fabs, 0 },
664  [FEXT_TO_IDX(FEXT_FNEG)] = { vfp_double_fneg, 0 },
665  [FEXT_TO_IDX(FEXT_FSQRT)] = { vfp_double_fsqrt, 0 },
666  [FEXT_TO_IDX(FEXT_FCMP)] = { vfp_double_fcmp, OP_SCALAR },
667  [FEXT_TO_IDX(FEXT_FCMPE)] = { vfp_double_fcmpe, OP_SCALAR },
668  [FEXT_TO_IDX(FEXT_FCMPZ)] = { vfp_double_fcmpz, OP_SCALAR },
669  [FEXT_TO_IDX(FEXT_FCMPEZ)] = { vfp_double_fcmpez, OP_SCALAR },
670  [FEXT_TO_IDX(FEXT_FCVT)] = { vfp_double_fcvts, OP_SCALAR|OP_SD },
671  [FEXT_TO_IDX(FEXT_FUITO)] = { vfp_double_fuito, OP_SCALAR|OP_SM },
672  [FEXT_TO_IDX(FEXT_FSITO)] = { vfp_double_fsito, OP_SCALAR|OP_SM },
673  [FEXT_TO_IDX(FEXT_FTOUI)] = { vfp_double_ftoui, OP_SCALAR|OP_SD },
674  [FEXT_TO_IDX(FEXT_FTOUIZ)] = { vfp_double_ftouiz, OP_SCALAR|OP_SD },
675  [FEXT_TO_IDX(FEXT_FTOSI)] = { vfp_double_ftosi, OP_SCALAR|OP_SD },
676  [FEXT_TO_IDX(FEXT_FTOSIZ)] = { vfp_double_ftosiz, OP_SCALAR|OP_SD },
677 };
678 
679 
680 
681 
682 static u32
683 vfp_double_fadd_nonnumber(struct vfp_double *vdd, struct vfp_double *vdn,
684  struct vfp_double *vdm, u32 fpscr)
685 {
686  struct vfp_double *vdp;
687  u32 exceptions = 0;
688  int tn, tm;
689 
690  tn = vfp_double_type(vdn);
691  tm = vfp_double_type(vdm);
692 
693  if (tn & tm & VFP_INFINITY) {
694  /*
695  * Two infinities. Are they different signs?
696  */
697  if (vdn->sign ^ vdm->sign) {
698  /*
699  * different signs -> invalid
700  */
701  exceptions = FPSCR_IOC;
702  vdp = &vfp_double_default_qnan;
703  } else {
704  /*
705  * same signs -> valid
706  */
707  vdp = vdn;
708  }
709  } else if (tn & VFP_INFINITY && tm & VFP_NUMBER) {
710  /*
711  * One infinity and one number -> infinity
712  */
713  vdp = vdn;
714  } else {
715  /*
716  * 'n' is a NaN of some type
717  */
718  return vfp_propagate_nan(vdd, vdn, vdm, fpscr);
719  }
720  *vdd = *vdp;
721  return exceptions;
722 }
723 
724 static u32
725 vfp_double_add(struct vfp_double *vdd, struct vfp_double *vdn,
726  struct vfp_double *vdm, u32 fpscr)
727 {
728  u32 exp_diff;
729  u64 m_sig;
730 
731  if (vdn->significand & (1ULL << 63) ||
732  vdm->significand & (1ULL << 63)) {
733  pr_info("VFP: bad FP values in %s\n", __func__);
734  vfp_double_dump("VDN", vdn);
735  vfp_double_dump("VDM", vdm);
736  }
737 
738  /*
739  * Ensure that 'n' is the largest magnitude number. Note that
740  * if 'n' and 'm' have equal exponents, we do not swap them.
741  * This ensures that NaN propagation works correctly.
742  */
743  if (vdn->exponent < vdm->exponent) {
744  struct vfp_double *t = vdn;
745  vdn = vdm;
746  vdm = t;
747  }
748 
749  /*
750  * Is 'n' an infinity or a NaN? Note that 'm' may be a number,
751  * infinity or a NaN here.
752  */
753  if (vdn->exponent == 2047)
754  return vfp_double_fadd_nonnumber(vdd, vdn, vdm, fpscr);
755 
756  /*
757  * We have two proper numbers, where 'vdn' is the larger magnitude.
758  *
759  * Copy 'n' to 'd' before doing the arithmetic.
760  */
761  *vdd = *vdn;
762 
763  /*
764  * Align 'm' with the result.
765  */
766  exp_diff = vdn->exponent - vdm->exponent;
767  m_sig = vfp_shiftright64jamming(vdm->significand, exp_diff);
768 
769  /*
770  * If the signs are different, we are really subtracting.
771  */
772  if (vdn->sign ^ vdm->sign) {
773  m_sig = vdn->significand - m_sig;
774  if ((s64)m_sig < 0) {
775  vdd->sign = vfp_sign_negate(vdd->sign);
776  m_sig = -m_sig;
777  } else if (m_sig == 0) {
778  vdd->sign = (fpscr & FPSCR_RMODE_MASK) ==
779  FPSCR_ROUND_MINUSINF ? 0x8000 : 0;
780  }
781  } else {
782  m_sig += vdn->significand;
783  }
784  vdd->significand = m_sig;
785 
786  return 0;
787 }
788 
789 static u32
790 vfp_double_multiply(struct vfp_double *vdd, struct vfp_double *vdn,
791  struct vfp_double *vdm, u32 fpscr)
792 {
793  vfp_double_dump("VDN", vdn);
794  vfp_double_dump("VDM", vdm);
795 
796  /*
797  * Ensure that 'n' is the largest magnitude number. Note that
798  * if 'n' and 'm' have equal exponents, we do not swap them.
799  * This ensures that NaN propagation works correctly.
800  */
801  if (vdn->exponent < vdm->exponent) {
802  struct vfp_double *t = vdn;
803  vdn = vdm;
804  vdm = t;
805  pr_debug("VFP: swapping M <-> N\n");
806  }
807 
808  vdd->sign = vdn->sign ^ vdm->sign;
809 
810  /*
811  * If 'n' is an infinity or NaN, handle it. 'm' may be anything.
812  */
813  if (vdn->exponent == 2047) {
814  if (vdn->significand || (vdm->exponent == 2047 && vdm->significand))
815  return vfp_propagate_nan(vdd, vdn, vdm, fpscr);
816  if ((vdm->exponent | vdm->significand) == 0) {
817  *vdd = vfp_double_default_qnan;
818  return FPSCR_IOC;
819  }
820  vdd->exponent = vdn->exponent;
821  vdd->significand = 0;
822  return 0;
823  }
824 
825  /*
826  * If 'm' is zero, the result is always zero. In this case,
827  * 'n' may be zero or a number, but it doesn't matter which.
828  */
829  if ((vdm->exponent | vdm->significand) == 0) {
830  vdd->exponent = 0;
831  vdd->significand = 0;
832  return 0;
833  }
834 
835  /*
836  * We add 2 to the destination exponent for the same reason
837  * as the addition case - though this time we have +1 from
838  * each input operand.
839  */
840  vdd->exponent = vdn->exponent + vdm->exponent - 1023 + 2;
841  vdd->significand = vfp_hi64multiply64(vdn->significand, vdm->significand);
842 
843  vfp_double_dump("VDD", vdd);
844  return 0;
845 }
846 
847 #define NEG_MULTIPLY (1 << 0)
848 #define NEG_SUBTRACT (1 << 1)
849 
850 static u32
851 vfp_double_multiply_accumulate(int dd, int dn, int dm, u32 fpscr, u32 negate, char *func)
852 {
853  struct vfp_double vdd, vdp, vdn, vdm;
854  u32 exceptions;
855 
856  vfp_double_unpack(&vdn, vfp_get_double(dn));
857  if (vdn.exponent == 0 && vdn.significand)
858  vfp_double_normalise_denormal(&vdn);
859 
860  vfp_double_unpack(&vdm, vfp_get_double(dm));
861  if (vdm.exponent == 0 && vdm.significand)
862  vfp_double_normalise_denormal(&vdm);
863 
864  exceptions = vfp_double_multiply(&vdp, &vdn, &vdm, fpscr);
865  if (negate & NEG_MULTIPLY)
866  vdp.sign = vfp_sign_negate(vdp.sign);
867 
868  vfp_double_unpack(&vdn, vfp_get_double(dd));
869  if (negate & NEG_SUBTRACT)
870  vdn.sign = vfp_sign_negate(vdn.sign);
871 
872  exceptions |= vfp_double_add(&vdd, &vdn, &vdp, fpscr);
873 
874  return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, func);
875 }
876 
877 /*
878  * Standard operations
879  */
880 
881 /*
882  * sd = sd + (sn * sm)
883  */
884 static u32 vfp_double_fmac(int dd, int dn, int dm, u32 fpscr)
885 {
886  return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, 0, "fmac");
887 }
888 
889 /*
890  * sd = sd - (sn * sm)
891  */
892 static u32 vfp_double_fnmac(int dd, int dn, int dm, u32 fpscr)
893 {
894  return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_MULTIPLY, "fnmac");
895 }
896 
897 /*
898  * sd = -sd + (sn * sm)
899  */
900 static u32 vfp_double_fmsc(int dd, int dn, int dm, u32 fpscr)
901 {
902  return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_SUBTRACT, "fmsc");
903 }
904 
905 /*
906  * sd = -sd - (sn * sm)
907  */
908 static u32 vfp_double_fnmsc(int dd, int dn, int dm, u32 fpscr)
909 {
910  return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_SUBTRACT | NEG_MULTIPLY, "fnmsc");
911 }
912 
913 /*
914  * sd = sn * sm
915  */
916 static u32 vfp_double_fmul(int dd, int dn, int dm, u32 fpscr)
917 {
918  struct vfp_double vdd, vdn, vdm;
919  u32 exceptions;
920 
921  vfp_double_unpack(&vdn, vfp_get_double(dn));
922  if (vdn.exponent == 0 && vdn.significand)
923  vfp_double_normalise_denormal(&vdn);
924 
925  vfp_double_unpack(&vdm, vfp_get_double(dm));
926  if (vdm.exponent == 0 && vdm.significand)
927  vfp_double_normalise_denormal(&vdm);
928 
929  exceptions = vfp_double_multiply(&vdd, &vdn, &vdm, fpscr);
930  return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fmul");
931 }
932 
933 /*
934  * sd = -(sn * sm)
935  */
936 static u32 vfp_double_fnmul(int dd, int dn, int dm, u32 fpscr)
937 {
938  struct vfp_double vdd, vdn, vdm;
939  u32 exceptions;
940 
941  vfp_double_unpack(&vdn, vfp_get_double(dn));
942  if (vdn.exponent == 0 && vdn.significand)
943  vfp_double_normalise_denormal(&vdn);
944 
945  vfp_double_unpack(&vdm, vfp_get_double(dm));
946  if (vdm.exponent == 0 && vdm.significand)
947  vfp_double_normalise_denormal(&vdm);
948 
949  exceptions = vfp_double_multiply(&vdd, &vdn, &vdm, fpscr);
950  vdd.sign = vfp_sign_negate(vdd.sign);
951 
952  return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fnmul");
953 }
954 
955 /*
956  * sd = sn + sm
957  */
958 static u32 vfp_double_fadd(int dd, int dn, int dm, u32 fpscr)
959 {
960  struct vfp_double vdd, vdn, vdm;
961  u32 exceptions;
962 
963  vfp_double_unpack(&vdn, vfp_get_double(dn));
964  if (vdn.exponent == 0 && vdn.significand)
965  vfp_double_normalise_denormal(&vdn);
966 
967  vfp_double_unpack(&vdm, vfp_get_double(dm));
968  if (vdm.exponent == 0 && vdm.significand)
969  vfp_double_normalise_denormal(&vdm);
970 
971  exceptions = vfp_double_add(&vdd, &vdn, &vdm, fpscr);
972 
973  return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fadd");
974 }
975 
976 /*
977  * sd = sn - sm
978  */
979 static u32 vfp_double_fsub(int dd, int dn, int dm, u32 fpscr)
980 {
981  struct vfp_double vdd, vdn, vdm;
982  u32 exceptions;
983 
984  vfp_double_unpack(&vdn, vfp_get_double(dn));
985  if (vdn.exponent == 0 && vdn.significand)
986  vfp_double_normalise_denormal(&vdn);
987 
988  vfp_double_unpack(&vdm, vfp_get_double(dm));
989  if (vdm.exponent == 0 && vdm.significand)
990  vfp_double_normalise_denormal(&vdm);
991 
992  /*
993  * Subtraction is like addition, but with a negated operand.
994  */
995  vdm.sign = vfp_sign_negate(vdm.sign);
996 
997  exceptions = vfp_double_add(&vdd, &vdn, &vdm, fpscr);
998 
999  return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fsub");
1000 }
1001 
1002 /*
1003  * sd = sn / sm
1004  */
1005 static u32 vfp_double_fdiv(int dd, int dn, int dm, u32 fpscr)
1006 {
1007  struct vfp_double vdd, vdn, vdm;
1008  u32 exceptions = 0;
1009  int tm, tn;
1010 
1011  vfp_double_unpack(&vdn, vfp_get_double(dn));
1012  vfp_double_unpack(&vdm, vfp_get_double(dm));
1013 
1014  vdd.sign = vdn.sign ^ vdm.sign;
1015 
1016  tn = vfp_double_type(&vdn);
1017  tm = vfp_double_type(&vdm);
1018 
1019  /*
1020  * Is n a NAN?
1021  */
1022  if (tn & VFP_NAN)
1023  goto vdn_nan;
1024 
1025  /*
1026  * Is m a NAN?
1027  */
1028  if (tm & VFP_NAN)
1029  goto vdm_nan;
1030 
1031  /*
1032  * If n and m are infinity, the result is invalid
1033  * If n and m are zero, the result is invalid
1034  */
1035  if (tm & tn & (VFP_INFINITY|VFP_ZERO))
1036  goto invalid;
1037 
1038  /*
1039  * If n is infinity, the result is infinity
1040  */
1041  if (tn & VFP_INFINITY)
1042  goto infinity;
1043 
1044  /*
1045  * If m is zero, raise div0 exceptions
1046  */
1047  if (tm & VFP_ZERO)
1048  goto divzero;
1049 
1050  /*
1051  * If m is infinity, or n is zero, the result is zero
1052  */
1053  if (tm & VFP_INFINITY || tn & VFP_ZERO)
1054  goto zero;
1055 
1056  if (tn & VFP_DENORMAL)
1057  vfp_double_normalise_denormal(&vdn);
1058  if (tm & VFP_DENORMAL)
1059  vfp_double_normalise_denormal(&vdm);
1060 
1061  /*
1062  * Ok, we have two numbers, we can perform division.
1063  */
1064  vdd.exponent = vdn.exponent - vdm.exponent + 1023 - 1;
1065  vdm.significand <<= 1;
1066  if (vdm.significand <= (2 * vdn.significand)) {
1067  vdn.significand >>= 1;
1068  vdd.exponent++;
1069  }
1070  vdd.significand = vfp_estimate_div128to64(vdn.significand, 0, vdm.significand);
1071  if ((vdd.significand & 0x1ff) <= 2) {
1072  u64 termh, terml, remh, reml;
1073  mul64to128(&termh, &terml, vdm.significand, vdd.significand);
1074  sub128(&remh, &reml, vdn.significand, 0, termh, terml);
1075  while ((s64)remh < 0) {
1076  vdd.significand -= 1;
1077  add128(&remh, &reml, remh, reml, 0, vdm.significand);
1078  }
1079  vdd.significand |= (reml != 0);
1080  }
1081  return vfp_double_normaliseround(dd, &vdd, fpscr, 0, "fdiv");
1082 
1083  vdn_nan:
1084  exceptions = vfp_propagate_nan(&vdd, &vdn, &vdm, fpscr);
1085  pack:
1086  vfp_put_double(vfp_double_pack(&vdd), dd);
1087  return exceptions;
1088 
1089  vdm_nan:
1090  exceptions = vfp_propagate_nan(&vdd, &vdm, &vdn, fpscr);
1091  goto pack;
1092 
1093  zero:
1094  vdd.exponent = 0;
1095  vdd.significand = 0;
1096  goto pack;
1097 
1098  divzero:
1099  exceptions = FPSCR_DZC;
1100  infinity:
1101  vdd.exponent = 2047;
1102  vdd.significand = 0;
1103  goto pack;
1104 
1105  invalid:
1106  vfp_put_double(vfp_double_pack(&vfp_double_default_qnan), dd);
1107  return FPSCR_IOC;
1108 }
1109 
1110 static struct op fops[16] = {
1111  [FOP_TO_IDX(FOP_FMAC)] = { vfp_double_fmac, 0 },
1112  [FOP_TO_IDX(FOP_FNMAC)] = { vfp_double_fnmac, 0 },
1113  [FOP_TO_IDX(FOP_FMSC)] = { vfp_double_fmsc, 0 },
1114  [FOP_TO_IDX(FOP_FNMSC)] = { vfp_double_fnmsc, 0 },
1115  [FOP_TO_IDX(FOP_FMUL)] = { vfp_double_fmul, 0 },
1116  [FOP_TO_IDX(FOP_FNMUL)] = { vfp_double_fnmul, 0 },
1117  [FOP_TO_IDX(FOP_FADD)] = { vfp_double_fadd, 0 },
1118  [FOP_TO_IDX(FOP_FSUB)] = { vfp_double_fsub, 0 },
1119  [FOP_TO_IDX(FOP_FDIV)] = { vfp_double_fdiv, 0 },
1120 };
1121 
1122 #define FREG_BANK(x) ((x) & 0x0c)
1123 #define FREG_IDX(x) ((x) & 3)
1124 
1126 {
1127  u32 op = inst & FOP_MASK;
1128  u32 exceptions = 0;
1129  unsigned int dest;
1130  unsigned int dn = vfp_get_dn(inst);
1131  unsigned int dm;
1132  unsigned int vecitr, veclen, vecstride;
1133  struct op *fop;
1134 
1135  vecstride = (1 + ((fpscr & FPSCR_STRIDE_MASK) == FPSCR_STRIDE_MASK));
1136 
1137  fop = (op == FOP_EXT) ? &fops_ext[FEXT_TO_IDX(inst)] : &fops[FOP_TO_IDX(op)];
1138 
1139  /*
1140  * fcvtds takes an sN register number as destination, not dN.
1141  * It also always operates on scalars.
1142  */
1143  if (fop->flags & OP_SD)
1144  dest = vfp_get_sd(inst);
1145  else
1146  dest = vfp_get_dd(inst);
1147 
1148  /*
1149  * f[us]ito takes a sN operand, not a dN operand.
1150  */
1151  if (fop->flags & OP_SM)
1152  dm = vfp_get_sm(inst);
1153  else
1154  dm = vfp_get_dm(inst);
1155 
1156  /*
1157  * If destination bank is zero, vector length is always '1'.
1158  * ARM DDI0100F C5.1.3, C5.3.2.
1159  */
1160  if ((fop->flags & OP_SCALAR) || (FREG_BANK(dest) == 0))
1161  veclen = 0;
1162  else
1163  veclen = fpscr & FPSCR_LENGTH_MASK;
1164 
1165  pr_debug("VFP: vecstride=%u veclen=%u\n", vecstride,
1166  (veclen >> FPSCR_LENGTH_BIT) + 1);
1167 
1168  if (!fop->fn)
1169  goto invalid;
1170 
1171  for (vecitr = 0; vecitr <= veclen; vecitr += 1 << FPSCR_LENGTH_BIT) {
1172  u32 except;
1173  char type;
1174 
1175  type = fop->flags & OP_SD ? 's' : 'd';
1176  if (op == FOP_EXT)
1177  pr_debug("VFP: itr%d (%c%u) = op[%u] (d%u)\n",
1178  vecitr >> FPSCR_LENGTH_BIT,
1179  type, dest, dn, dm);
1180  else
1181  pr_debug("VFP: itr%d (%c%u) = (d%u) op[%u] (d%u)\n",
1182  vecitr >> FPSCR_LENGTH_BIT,
1183  type, dest, dn, FOP_TO_IDX(op), dm);
1184 
1185  except = fop->fn(dest, dn, dm, fpscr);
1186  pr_debug("VFP: itr%d: exceptions=%08x\n",
1187  vecitr >> FPSCR_LENGTH_BIT, except);
1188 
1189  exceptions |= except;
1190 
1191  /*
1192  * CHECK: It appears to be undefined whether we stop when
1193  * we encounter an exception. We continue.
1194  */
1195  dest = FREG_BANK(dest) + ((FREG_IDX(dest) + vecstride) & 3);
1196  dn = FREG_BANK(dn) + ((FREG_IDX(dn) + vecstride) & 3);
1197  if (FREG_BANK(dm) != 0)
1198  dm = FREG_BANK(dm) + ((FREG_IDX(dm) + vecstride) & 3);
1199  }
1200  return exceptions;
1201 
1202  invalid:
1203  return ~0;
1204 }