bsd/dev/munge.c

   1 /*
   2  * Coyright (c) 2005-2006 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <sys/cdefs.h>
  30 #include <sys/types.h>
  31 #include <sys/munge.h>
  32 #include <stdint.h>
  33
  34 /*
  35  * Refer to comments in bsd/sys/munge.h
  36  */
  37
  38 static inline __attribute__((always_inline)) void
  39 munge_32_to_64_unsigned(volatile uint64_t *dest, volatile uint32_t *src, int count);
  40
  41 void
  42 munge_w(void *args)
  43 {
  44         munge_32_to_64_unsigned(args, args, 1);
  45 }
  46
  47 void
  48 munge_ww(void *args)
  49 {
  50         munge_32_to_64_unsigned(args, args, 2);
  51 }
  52
  53 void
  54 munge_www(void *args)
  55 {
  56         munge_32_to_64_unsigned(args, args, 3);
  57 }
  58
  59 void
  60 munge_wwww(void *args)
  61 {
  62         munge_32_to_64_unsigned(args, args, 4);
  63 }
  64
  65 void
  66 munge_wwwww(void *args)
  67 {
  68         munge_32_to_64_unsigned(args, args, 5);
  69 }
  70
  71 void
  72 munge_wwwwww(void *args)
  73 {
  74         munge_32_to_64_unsigned(args, args, 6);
  75 }
  76
  77 void
  78 munge_wwwwwww(void *args)
  79 {
  80         munge_32_to_64_unsigned(args, args, 7);
  81 }
  82
  83 void
  84 munge_wwwwwwww(void *args)
  85 {
  86         munge_32_to_64_unsigned(args, args, 8);
  87 }
  88
  89 void
  90 munge_wl(void *args)
  91 {
  92         volatile uint64_t *out_args = (volatile uint64_t*)args;
  93         volatile uint32_t *in_args = (volatile uint32_t*)args;
  94
  95         out_args[1] = *(volatile uint64_t*)&in_args[1];
  96         out_args[0] = in_args[0];
  97 }
  98
  99 void
 100 munge_wwl(void *args)
 101 {
 102         volatile uint64_t *out_args = (volatile uint64_t*)args;
 103         volatile uint32_t *in_args = (volatile uint32_t*)args;
 104
 105         out_args[2] = *(volatile uint64_t*)&in_args[2];
 106         out_args[1] = in_args[1];
 107         out_args[0] = in_args[0];
 108 }
 109
 110 void
 111 munge_wwlw(void *args)
 112 {
 113         volatile uint64_t *out_args = (volatile uint64_t*)args;
 114         volatile uint32_t *in_args = (volatile uint32_t*)args;
 115
 116         out_args[3] = in_args[4];
 117         out_args[2] = *(volatile uint64_t*)&in_args[2];
 118         out_args[1] = in_args[1];
 119         out_args[0] = in_args[0];
 120 }
 121 void
 122 munge_wwlll(void *args)
 123 {
 124         volatile uint64_t *out_args = (volatile uint64_t*)args;
 125         volatile uint32_t *in_args = (volatile uint32_t*)args;
 126
 127         out_args[4] = *(volatile uint64_t*)&in_args[6];
 128         out_args[3] = *(volatile uint64_t*)&in_args[4];
 129         out_args[2] = *(volatile uint64_t*)&in_args[2];
 130         out_args[1] = in_args[1];
 131         out_args[0] = in_args[0];
 132 }
 133
 134 void
 135 munge_wwllww(void *args)
 136 {
 137         volatile uint64_t *out_args = (volatile uint64_t*)args;
 138         volatile uint32_t *in_args = (volatile uint32_t*)args;
 139
 140         out_args[5] = in_args[7];
 141         out_args[4] = in_args[6];
 142         out_args[3] = *(volatile uint64_t*)&in_args[4];
 143         out_args[2] = *(volatile uint64_t*)&in_args[2];
 144         out_args[1] = in_args[1];
 145         out_args[0] = in_args[0];
 146 }
 147
 148 void
 149 munge_wlw(void *args)
 150 {
 151         volatile uint64_t *out_args = (volatile uint64_t*)args;
 152         volatile uint32_t *in_args = (volatile uint32_t*)args;
 153
 154         out_args[2] = in_args[3];
 155         out_args[1] = *(volatile uint64_t*)&in_args[1];
 156         out_args[0] = in_args[0];
 157 }
 158
 159 void
 160 munge_wlww(void *args)
 161 {
 162         volatile uint64_t *out_args = (volatile uint64_t*)args;
 163         volatile uint32_t *in_args = (volatile uint32_t*)args;
 164
 165         out_args[3] = in_args[4];
 166         out_args[2] = in_args[3];
 167         out_args[1] = *(volatile uint64_t*)&in_args[1];
 168         out_args[0] = in_args[0];
 169 }
 170
 171 void
 172 munge_wlwwwll(void *args)
 173 {
 174         volatile uint64_t *out_args = (volatile uint64_t*)args;
 175         volatile uint32_t *in_args = (volatile uint32_t*)args;
 176
 177         out_args[6] = *(volatile uint64_t*)&in_args[8];
 178         out_args[5] = *(volatile uint64_t*)&in_args[6];
 179         out_args[4] = in_args[5];
 180         out_args[3] = in_args[4];
 181         out_args[2] = in_args[3];
 182         out_args[1] = *(volatile uint64_t*)&in_args[1];
 183         out_args[0] = in_args[0];
 184 }
 185
 186 void
 187 munge_wlwwwllw(void *args)
 188 {
 189         volatile uint64_t *out_args = (volatile uint64_t*)args;
 190         volatile uint32_t *in_args = (volatile uint32_t*)args;
 191
 192         out_args[7] = in_args[10];
 193         munge_wlwwwll(args);
 194 }
 195
 196 void
 197 munge_wlwwlwlw(void *args)
 198 {
 199         volatile uint64_t *out_args = (volatile uint64_t*)args;
 200         volatile uint32_t *in_args = (volatile uint32_t*)args;
 201
 202         out_args[7] = in_args[10];
 203         out_args[6] = *(volatile uint64_t*)&in_args[8];
 204         out_args[5] = in_args[7];
 205         out_args[4] = *(volatile uint64_t*)&in_args[5];
 206         out_args[3] = in_args[4];
 207         out_args[2] = in_args[3];
 208         out_args[1] = *(volatile uint64_t*)&in_args[1];
 209         out_args[0] = in_args[0];
 210 }
 211
 212 void
 213 munge_wll(void *args)
 214 {
 215         volatile uint64_t *out_args = (volatile uint64_t*)args;
 216         volatile uint32_t *in_args = (volatile uint32_t*)args;
 217
 218         out_args[2] = *(volatile uint64_t*)&in_args[3];
 219         out_args[1] = *(volatile uint64_t*)&in_args[1];
 220         out_args[0] = in_args[0];
 221 }
 222
 223 void
 224 munge_wlll(void *args)
 225 {
 226         volatile uint64_t *out_args = (volatile uint64_t*)args;
 227         volatile uint32_t *in_args = (volatile uint32_t*)args;
 228
 229         out_args[3] = *(volatile uint64_t*)&in_args[5];
 230         out_args[2] = *(volatile uint64_t*)&in_args[3];
 231         out_args[1] = *(volatile uint64_t*)&in_args[1];
 232         out_args[0] = in_args[0];
 233 }
 234
 235 void
 236 munge_wlllww(void *args)
 237 {
 238         volatile uint64_t *out_args = (volatile uint64_t*)args;
 239         volatile uint32_t *in_args = (volatile uint32_t*)args;
 240
 241         out_args[5] = in_args[8];
 242         out_args[4] = in_args[7];
 243         out_args[3] = *(volatile uint64_t*)&in_args[5];
 244         out_args[2] = *(volatile uint64_t*)&in_args[3];
 245         out_args[1] = *(volatile uint64_t*)&in_args[1];
 246         out_args[0] = in_args[0];
 247 }
 248
 249 void
 250 munge_wllll(void *args)
 251 {
 252         volatile uint64_t *out_args = (volatile uint64_t*)args;
 253         volatile uint32_t *in_args = (volatile uint32_t*)args;
 254
 255         out_args[4] = *(volatile uint64_t*)&in_args[7];
 256         out_args[3] = *(volatile uint64_t*)&in_args[5];
 257         out_args[2] = *(volatile uint64_t*)&in_args[3];
 258         out_args[1] = *(volatile uint64_t*)&in_args[1];
 259         out_args[0] = in_args[0];
 260 }
 261
 262 void
 263 munge_wllww(void *args)
 264 {
 265         volatile uint64_t *out_args = (volatile uint64_t*)args;
 266         volatile uint32_t *in_args = (volatile uint32_t*)args;
 267
 268         out_args[4] = in_args[6];
 269         out_args[3] = in_args[5];
 270         out_args[2] = *(volatile uint64_t*)&in_args[3];
 271         out_args[1] = *(volatile uint64_t*)&in_args[1];
 272         out_args[0] = in_args[0];
 273 }
 274
 275 void
 276 munge_wllwwll(void *args)
 277 {
 278         volatile uint64_t *out_args = (volatile uint64_t*)args;
 279         volatile uint32_t *in_args = (volatile uint32_t*)args;
 280
 281         out_args[6] = *(volatile uint64_t*)&in_args[9];
 282         out_args[5] = *(volatile uint64_t*)&in_args[7];
 283         out_args[4] = in_args[6];
 284         out_args[3] = in_args[5];
 285         out_args[2] = *(volatile uint64_t*)&in_args[3];
 286         out_args[1] = *(volatile uint64_t*)&in_args[1];
 287         out_args[0] = in_args[0];
 288 }
 289
 290 void
 291 munge_wwwlw(void *args)
 292 {
 293         volatile uint64_t *out_args = (volatile uint64_t*)args;
 294         volatile uint32_t *in_args = (volatile uint32_t*)args;
 295
 296         out_args[4] = in_args[5];
 297         out_args[3] = *(volatile uint64_t*)&in_args[3];
 298         out_args[2] = in_args[2];
 299         out_args[1] = in_args[1];
 300         out_args[0] = in_args[0];
 301 }
 302
 303 void
 304 munge_wwwlww(void *args)
 305 {
 306         volatile uint64_t *out_args = (volatile uint64_t*)args;
 307         volatile uint32_t *in_args = (volatile uint32_t*)args;
 308
 309         out_args[5] = in_args[6];
 310         out_args[4] = in_args[5];
 311         out_args[3] = *(volatile uint64_t*)&in_args[3];
 312         out_args[2] = in_args[2];
 313         out_args[1] = in_args[1];
 314         out_args[0] = in_args[0];
 315 }
 316
 317 void
 318 munge_wwwlwww(void *args)
 319 {
 320         volatile uint64_t *out_args = (volatile uint64_t*)args;
 321         volatile uint32_t *in_args = (volatile uint32_t*)args;
 322
 323         out_args[6] = in_args[7];
 324         out_args[5] = in_args[6];
 325         out_args[4] = in_args[5];
 326         out_args[3] = *(volatile uint64_t*)&in_args[3];
 327         out_args[2] = in_args[2];
 328         out_args[1] = in_args[1];
 329         out_args[0] = in_args[0];
 330 }
 331
 332 void
 333 munge_wwwl(void *args)
 334 {
 335         volatile uint64_t *out_args = (volatile uint64_t*)args;
 336         volatile uint32_t *in_args = (volatile uint32_t*)args;
 337
 338         out_args[3] = *(volatile uint64_t*)&in_args[3];
 339         out_args[2] = in_args[2];
 340         out_args[1] = in_args[1];
 341         out_args[0] = in_args[0];
 342 }
 343
 344 void
 345 munge_wwwwlw(void *args)
 346 {
 347         volatile uint64_t *out_args = (volatile uint64_t*)args;
 348         volatile uint32_t *in_args = (volatile uint32_t*)args;
 349
 350         out_args[5] = in_args[6];
 351         out_args[4] = *(volatile uint64_t*)&in_args[4];
 352         out_args[3] = in_args[3];
 353         out_args[2] = in_args[2];
 354         out_args[1] = in_args[1];
 355         out_args[0] = in_args[0];
 356 }
 357
 358 void
 359 munge_wwwwllww(void *args)
 360 {
 361         volatile uint64_t *out_args = (volatile uint64_t*)args;
 362         volatile uint32_t *in_args = (volatile uint32_t*)args;
 363
 364         out_args[7] = in_args[9];
 365         out_args[6] = in_args[8];
 366         out_args[5] = *(volatile uint64_t*)&in_args[6];
 367         out_args[4] = *(volatile uint64_t*)&in_args[4];
 368         out_args[3] = in_args[3];
 369         out_args[2] = in_args[2];
 370         out_args[1] = in_args[1];
 371         out_args[0] = in_args[0];
 372 }
 373
 374 void
 375 munge_wwwwl(void *args)
 376 {
 377         volatile uint64_t *out_args = (volatile uint64_t*)args;
 378         volatile uint32_t *in_args = (volatile uint32_t*)args;
 379
 380         out_args[4] = *(volatile uint64_t*)&in_args[4];
 381         out_args[3] = in_args[3];
 382         out_args[2] = in_args[2];
 383         out_args[1] = in_args[1];
 384         out_args[0] = in_args[0];
 385 }
 386
 387 void
 388 munge_wwwwwl(void *args)
 389 {
 390         volatile uint64_t *out_args = (volatile uint64_t*)args;
 391         volatile uint32_t *in_args = (volatile uint32_t*)args;
 392
 393         out_args[5] = *(volatile uint64_t*)&in_args[5];
 394         out_args[4] = in_args[4];
 395         out_args[3] = in_args[3];
 396         out_args[2] = in_args[2];
 397         out_args[1] = in_args[1];
 398         out_args[0] = in_args[0];
 399 }
 400
 401 void
 402 munge_wwwwwlww(void *args)
 403 {
 404         volatile uint64_t *out_args = (volatile uint64_t*)args;
 405         volatile uint32_t *in_args = (volatile uint32_t*)args;
 406
 407         out_args[7] = in_args[8];
 408         out_args[6] = in_args[7];
 409         out_args[5] = *(volatile uint64_t*)&in_args[5];
 410         out_args[4] = in_args[4];
 411         out_args[3] = in_args[3];
 412         out_args[2] = in_args[2];
 413         out_args[1] = in_args[1];
 414         out_args[0] = in_args[0];
 415 }
 416
 417 void
 418 munge_wwwwwllw(void *args)
 419 {
 420         volatile uint64_t *out_args = (volatile uint64_t*)args;
 421         volatile uint32_t *in_args = (volatile uint32_t*)args;
 422
 423         out_args[7] = in_args[9];
 424         out_args[6] = *(volatile uint64_t*)&in_args[7];
 425         out_args[5] = *(volatile uint64_t*)&in_args[5];
 426         out_args[4] = in_args[4];
 427         out_args[3] = in_args[3];
 428         out_args[2] = in_args[2];
 429         out_args[1] = in_args[1];
 430         out_args[0] = in_args[0];
 431 }
 432
 433 void
 434 munge_wwwwwlll(void *args)
 435 {
 436         volatile uint64_t *out_args = (volatile uint64_t*)args;
 437         volatile uint32_t *in_args = (volatile uint32_t*)args;
 438
 439         out_args[7] = *(volatile uint64_t*)&in_args[9];
 440         out_args[6] = *(volatile uint64_t*)&in_args[7];
 441         out_args[5] = *(volatile uint64_t*)&in_args[5];
 442         out_args[4] = in_args[4];
 443         out_args[3] = in_args[3];
 444         out_args[2] = in_args[2];
 445         out_args[1] = in_args[1];
 446         out_args[0] = in_args[0];
 447 }
 448
 449 void
 450 munge_wwwwwwl(void *args)
 451 {
 452         volatile uint64_t *out_args = (volatile uint64_t*)args;
 453         volatile uint32_t *in_args = (volatile uint32_t*)args;
 454
 455         out_args[6] = *(volatile uint64_t*)&in_args[6];
 456         out_args[5] = in_args[5];
 457         out_args[4] = in_args[4];
 458         out_args[3] = in_args[3];
 459         out_args[2] = in_args[2];
 460         out_args[1] = in_args[1];
 461         out_args[0] = in_args[0];
 462 }
 463
 464 void
 465 munge_wwwwwwlw(void *args)
 466 {
 467         volatile uint64_t *out_args = (volatile uint64_t*)args;
 468         volatile uint32_t *in_args = (volatile uint32_t*)args;
 469
 470         out_args[7] = in_args[8];
 471         out_args[6] = *(volatile uint64_t*)&in_args[6];
 472         out_args[5] = in_args[5];
 473         out_args[4] = in_args[4];
 474         out_args[3] = in_args[3];
 475         out_args[2] = in_args[2];
 476         out_args[1] = in_args[1];
 477         out_args[0] = in_args[0];
 478 }
 479
 480 void
 481 munge_wwwwwwll(void *args)
 482 {
 483         volatile uint64_t *out_args = (volatile uint64_t*)args;
 484         volatile uint32_t *in_args = (volatile uint32_t*)args;
 485
 486         out_args[7] = *(volatile uint64_t*)&in_args[8];
 487         out_args[6] = *(volatile uint64_t*)&in_args[6];
 488         out_args[5] = in_args[5];
 489         out_args[4] = in_args[4];
 490         out_args[3] = in_args[3];
 491         out_args[2] = in_args[2];
 492         out_args[1] = in_args[1];
 493         out_args[0] = in_args[0];
 494 }
 495
 496 void
 497 munge_wsw(void *args)
 498 {
 499         volatile uint64_t *out_args = (volatile uint64_t*)args;
 500         volatile uint32_t *in_args = (volatile uint32_t*)args;
 501
 502         out_args[2] = in_args[2];
 503         out_args[1] = (int64_t)(int)in_args[1]; /* Sign-extend */
 504         out_args[0] = in_args[0];
 505 }
 506
 507 void
 508 munge_wws(void *args)
 509 {
 510         volatile uint64_t *out_args = (volatile uint64_t*)args;
 511         volatile uint32_t *in_args = (volatile uint32_t*)args;
 512
 513         out_args[2] = (int64_t)(int)in_args[2]; /* Sign-extend */
 514         out_args[1] = in_args[1];
 515         out_args[0] = in_args[0];
 516 }
 517
 518 void
 519 munge_wwws(void *args)
 520 {
 521         volatile uint64_t *out_args = (volatile uint64_t*)args;
 522         volatile uint32_t *in_args = (volatile uint32_t*)args;
 523
 524         out_args[3] = (int64_t)(int)in_args[3]; /* Sign-extend */
 525         out_args[2] = in_args[2];
 526         out_args[1] = in_args[1];
 527         out_args[0] = in_args[0];
 528 }
 529
 530
 531 void
 532 munge_wwwsw(void *args)
 533 {
 534         volatile uint64_t *out_args = (volatile uint64_t*)args;
 535         volatile uint32_t *in_args = (volatile uint32_t*)args;
 536
 537         out_args[4] = in_args[4];
 538         out_args[3] = (int64_t)(int)in_args[3]; /* Sign-extend */
 539         out_args[2] = in_args[2];
 540         out_args[1] = in_args[1];
 541         out_args[0] = in_args[0];
 542 }
 543
 544 void
 545 munge_llllll(void *args __unused)
 546 {
 547         /* Nothing to do, already all 64-bit */
 548 }
 549
 550 void
 551 munge_ll(void *args __unused)
 552 {
 553         /* Nothing to do, already all 64-bit */
 554 }
 555
 556 void
 557 munge_l(void *args __unused)
 558 {
 559         /* Nothing to do, already all 64-bit */
 560 }
 561
 562 void
 563 munge_lw(void *args)
 564 {
 565         volatile uint64_t *out_args = (volatile uint64_t*)args;
 566         volatile uint32_t *in_args = (volatile uint32_t*)args;
 567
 568         out_args[1] = in_args[2];
 569         out_args[0] = *(volatile uint64_t*)&in_args[0];
 570 }
 571
 572 void
 573 munge_lwww(void *args)
 574 {
 575         volatile uint64_t *out_args = (volatile uint64_t*)args;
 576         volatile uint32_t *in_args = (volatile uint32_t*)args;
 577
 578         out_args[3] = in_args[4];
 579         out_args[2] = in_args[3];
 580         out_args[1] = in_args[2];
 581         out_args[0] = *(volatile uint64_t*)&in_args[0];
 582 }
 583
 584 void
 585 munge_lwwwwwww(void *args)
 586 {
 587         volatile uint64_t *out_args = (volatile uint64_t*)args;
 588         volatile uint32_t *in_args = (volatile uint32_t*)args;
 589
 590         out_args[7] = in_args[8];
 591         out_args[6] = in_args[7];
 592         out_args[5] = in_args[6];
 593         out_args[4] = in_args[5];
 594         out_args[3] = in_args[4];
 595         out_args[2] = in_args[3];
 596         out_args[1] = in_args[2];
 597         out_args[0] = *(volatile uint64_t*)&in_args[0];
 598 }
 599
 600 void
 601 munge_wwlww(void *args)
 602 {
 603         volatile uint64_t *out_args = (volatile uint64_t*)args;
 604         volatile uint32_t *in_args = (volatile uint32_t*)args;
 605
 606         out_args[4] = in_args[5];
 607         out_args[3] = in_args[4];
 608         out_args[2] = *(volatile uint64_t*)&in_args[2];
 609         out_args[1] = in_args[1];
 610         out_args[0] = in_args[0];
 611 }
 612
 613 void
 614 munge_wwlwww(void *args)
 615 {
 616         volatile uint64_t *out_args = (volatile uint64_t*)args;
 617         volatile uint32_t *in_args = (volatile uint32_t*)args;
 618
 619         out_args[5] = in_args[6];
 620         out_args[4] = in_args[5];
 621         out_args[3] = in_args[4];
 622         out_args[2] = *(volatile uint64_t*)&in_args[2];
 623         out_args[1] = in_args[1];
 624         out_args[0] = in_args[0];
 625 }
 626
 627 void
 628 munge_wlwwwl(void *args)
 629 {
 630         volatile uint64_t *out_args = (volatile uint64_t*)args;
 631         volatile uint32_t *in_args = (volatile uint32_t*)args;
 632
 633         out_args[5] = *(volatile uint64_t*)&in_args[6];
 634         out_args[4] = in_args[5];
 635         out_args[3] = in_args[4];
 636         out_args[2] = in_args[3];
 637         out_args[1] = *(volatile uint64_t*)&in_args[1];
 638         out_args[0] = in_args[0];
 639 }
 640
 641 void
 642 munge_wwlwwwl(void *args)
 643 {
 644         volatile uint64_t *out_args = (volatile uint64_t*)args;
 645         volatile uint32_t *in_args = (volatile uint32_t*)args;
 646
 647         out_args[6] = *(volatile uint64_t*)&in_args[7];
 648         out_args[5] = in_args[6];
 649         out_args[4] = in_args[5];
 650         out_args[3] = in_args[4];
 651         out_args[2] = *(volatile uint64_t*)&in_args[2];
 652         out_args[1] = in_args[1];
 653         out_args[0] = in_args[0];
 654 }
 655
 656 /*
 657  * Munge array of 32-bit values into an array of 64-bit values,
 658  * without sign extension.  Note, src and dest can be the same
 659  * (copies from end of array)
 660  */
 661 static inline __attribute__((always_inline)) void
 662 munge_32_to_64_unsigned(volatile uint64_t *dest, volatile uint32_t *src, int count)
 663 {
 664         int i;
 665
 666         for (i = count - 1; i >= 0; i--) {
 667                 dest[i] = src[i];
 668         }
 669 }