arch/xtensa/lib/memcopy.S

   1 /*
   2  * arch/xtensa/lib/hal/memcopy.S -- Core HAL library functions
   3  * xthal_memcpy and xthal_bcopy
   4  *
   5  * This file is subject to the terms and conditions of the GNU General Public
   6  * License.  See the file "COPYING" in the main directory of this archive
   7  * for more details.
   8  *
   9  * Copyright (C) 2002 - 2012 Tensilica Inc.
  10  */
  11
  12 #include <linux/linkage.h>
  13 #include <asm/asmmacro.h>
  14 #include <asm/core.h>
  15
  16 /*
  17  * void *memcpy(void *dst, const void *src, size_t len);
  18  *
  19  * This function is intended to do the same thing as the standard
  20  * library function memcpy() for most cases.
  21  * However, where the source and/or destination references
  22  * an instruction RAM or ROM or a data RAM or ROM, that
  23  * source and/or destination will always be accessed with
  24  * 32-bit load and store instructions (as required for these
  25  * types of devices).
  26  *
  27  * !!!!!!!  XTFIXME:
  28  * !!!!!!!  Handling of IRAM/IROM has not yet
  29  * !!!!!!!  been implemented.
  30  *
  31  * The (general case) algorithm is as follows:
  32  *   If destination is unaligned, align it by conditionally
  33  *     copying 1 and 2 bytes.
  34  *   If source is aligned,
  35  *     do 16 bytes with a loop, and then finish up with
  36  *     8, 4, 2, and 1 byte copies conditional on the length;
  37  *   else (if source is unaligned),
  38  *     do the same, but use SRC to align the source data.
  39  *   This code tries to use fall-through branches for the common
  40  *     case of aligned source and destination and multiple
  41  *     of 4 (or 8) length.
  42  *
  43  * Register use:
  44  *      a0/ return address
  45  *      a1/ stack pointer
  46  *      a2/ return value
  47  *      a3/ src
  48  *      a4/ length
  49  *      a5/ dst
  50  *      a6/ tmp
  51  *      a7/ tmp
  52  *      a8/ tmp
  53  *      a9/ tmp
  54  *      a10/ tmp
  55  *      a11/ tmp
  56  */
  57
  58         .text
  59
  60 /*
  61  * Byte by byte copy
  62  */
  63         .align  4
  64         .byte   0               # 1 mod 4 alignment for LOOPNEZ
  65                                 # (0 mod 4 alignment for LBEG)
  66 .Lbytecopy:
  67 #if XCHAL_HAVE_LOOPS
  68         loopnez a4, .Lbytecopydone
  69 #else /* !XCHAL_HAVE_LOOPS */
  70         beqz    a4, .Lbytecopydone
  71         add     a7, a3, a4      # a7 = end address for source
  72 #endif /* !XCHAL_HAVE_LOOPS */
  73 .Lnextbyte:
  74         l8ui    a6, a3, 0
  75         addi    a3, a3, 1
  76         s8i     a6, a5, 0
  77         addi    a5, a5, 1
  78 #if !XCHAL_HAVE_LOOPS
  79         bne     a3, a7, .Lnextbyte # continue loop if $a3:src != $a7:src_end
  80 #endif /* !XCHAL_HAVE_LOOPS */
  81 .Lbytecopydone:
  82         abi_ret_default
  83
  84 /*
  85  * Destination is unaligned
  86  */
  87
  88         .align  4
  89 .Ldst1mod2:     # dst is only byte aligned
  90         _bltui  a4, 7, .Lbytecopy       # do short copies byte by byte
  91
  92         # copy 1 byte
  93         l8ui    a6, a3,  0
  94         addi    a3, a3,  1
  95         addi    a4, a4, -1
  96         s8i     a6, a5,  0
  97         addi    a5, a5,  1
  98         _bbci.l a5, 1, .Ldstaligned     # if dst is now aligned, then
  99                                         # return to main algorithm
 100 .Ldst2mod4:     # dst 16-bit aligned
 101         # copy 2 bytes
 102         _bltui  a4, 6, .Lbytecopy       # do short copies byte by byte
 103         l8ui    a6, a3,  0
 104         l8ui    a7, a3,  1
 105         addi    a3, a3,  2
 106         addi    a4, a4, -2
 107         s8i     a6, a5,  0
 108         s8i     a7, a5,  1
 109         addi    a5, a5,  2
 110         j       .Ldstaligned    # dst is now aligned, return to main algorithm
 111
 112 ENTRY(__memcpy)
 113 WEAK(memcpy)
 114
 115         abi_entry_default
 116         # a2/ dst, a3/ src, a4/ len
 117         mov     a5, a2          # copy dst so that a2 is return value
 118 .Lcommon:
 119         _bbsi.l a2, 0, .Ldst1mod2       # if dst is 1 mod 2
 120         _bbsi.l a2, 1, .Ldst2mod4       # if dst is 2 mod 4
 121 .Ldstaligned:   # return here from .Ldst?mod? once dst is aligned
 122         srli    a7, a4, 4       # number of loop iterations with 16B
 123                                 # per iteration
 124         movi    a8, 3           # if source is not aligned,
 125         _bany   a3, a8, .Lsrcunaligned  # then use shifting copy
 126         /*
 127          * Destination and source are word-aligned, use word copy.
 128          */
 129         # copy 16 bytes per iteration for word-aligned dst and word-aligned src
 130 #if XCHAL_HAVE_LOOPS
 131         loopnez a7, .Loop1done
 132 #else /* !XCHAL_HAVE_LOOPS */
 133         beqz    a7, .Loop1done
 134         slli    a8, a7, 4
 135         add     a8, a8, a3      # a8 = end of last 16B source chunk
 136 #endif /* !XCHAL_HAVE_LOOPS */
 137 .Loop1:
 138         l32i    a6, a3,  0
 139         l32i    a7, a3,  4
 140         s32i    a6, a5,  0
 141         l32i    a6, a3,  8
 142         s32i    a7, a5,  4
 143         l32i    a7, a3, 12
 144         s32i    a6, a5,  8
 145         addi    a3, a3, 16
 146         s32i    a7, a5, 12
 147         addi    a5, a5, 16
 148 #if !XCHAL_HAVE_LOOPS
 149         bne     a3, a8, .Loop1  # continue loop if a3:src != a8:src_end
 150 #endif /* !XCHAL_HAVE_LOOPS */
 151 .Loop1done:
 152         bbci.l  a4, 3, .L2
 153         # copy 8 bytes
 154         l32i    a6, a3,  0
 155         l32i    a7, a3,  4
 156         addi    a3, a3,  8
 157         s32i    a6, a5,  0
 158         s32i    a7, a5,  4
 159         addi    a5, a5,  8
 160 .L2:
 161         bbsi.l  a4, 2, .L3
 162         bbsi.l  a4, 1, .L4
 163         bbsi.l  a4, 0, .L5
 164         abi_ret_default
 165 .L3:
 166         # copy 4 bytes
 167         l32i    a6, a3,  0
 168         addi    a3, a3,  4
 169         s32i    a6, a5,  0
 170         addi    a5, a5,  4
 171         bbsi.l  a4, 1, .L4
 172         bbsi.l  a4, 0, .L5
 173         abi_ret_default
 174 .L4:
 175         # copy 2 bytes
 176         l16ui   a6, a3,  0
 177         addi    a3, a3,  2
 178         s16i    a6, a5,  0
 179         addi    a5, a5,  2
 180         bbsi.l  a4, 0, .L5
 181         abi_ret_default
 182 .L5:
 183         # copy 1 byte
 184         l8ui    a6, a3,  0
 185         s8i     a6, a5,  0
 186         abi_ret_default
 187
 188 /*
 189  * Destination is aligned, Source is unaligned
 190  */
 191
 192         .align  4
 193 .Lsrcunaligned:
 194         _beqz   a4, .Ldone      # avoid loading anything for zero-length copies
 195         # copy 16 bytes per iteration for word-aligned dst and unaligned src
 196         __ssa8  a3              # set shift amount from byte offset
 197
 198 /* set to 1 when running on ISS (simulator) with the
 199    lint or ferret client, or 0 to save a few cycles */
 200 #define SIM_CHECKS_ALIGNMENT    1
 201 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
 202         and     a11, a3, a8     # save unalignment offset for below
 203         sub     a3, a3, a11     # align a3
 204 #endif
 205         l32i    a6, a3, 0       # load first word
 206 #if XCHAL_HAVE_LOOPS
 207         loopnez a7, .Loop2done
 208 #else /* !XCHAL_HAVE_LOOPS */
 209         beqz    a7, .Loop2done
 210         slli    a10, a7, 4
 211         add     a10, a10, a3    # a10 = end of last 16B source chunk
 212 #endif /* !XCHAL_HAVE_LOOPS */
 213 .Loop2:
 214         l32i    a7, a3,  4
 215         l32i    a8, a3,  8
 216         __src_b a6, a6, a7
 217         s32i    a6, a5,  0
 218         l32i    a9, a3, 12
 219         __src_b a7, a7, a8
 220         s32i    a7, a5,  4
 221         l32i    a6, a3, 16
 222         __src_b a8, a8, a9
 223         s32i    a8, a5,  8
 224         addi    a3, a3, 16
 225         __src_b a9, a9, a6
 226         s32i    a9, a5, 12
 227         addi    a5, a5, 16
 228 #if !XCHAL_HAVE_LOOPS
 229         bne     a3, a10, .Loop2 # continue loop if a3:src != a10:src_end
 230 #endif /* !XCHAL_HAVE_LOOPS */
 231 .Loop2done:
 232         bbci.l  a4, 3, .L12
 233         # copy 8 bytes
 234         l32i    a7, a3,  4
 235         l32i    a8, a3,  8
 236         __src_b a6, a6, a7
 237         s32i    a6, a5,  0
 238         addi    a3, a3,  8
 239         __src_b a7, a7, a8
 240         s32i    a7, a5,  4
 241         addi    a5, a5,  8
 242         mov     a6, a8
 243 .L12:
 244         bbci.l  a4, 2, .L13
 245         # copy 4 bytes
 246         l32i    a7, a3,  4
 247         addi    a3, a3,  4
 248         __src_b a6, a6, a7
 249         s32i    a6, a5,  0
 250         addi    a5, a5,  4
 251         mov     a6, a7
 252 .L13:
 253 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
 254         add     a3, a3, a11     # readjust a3 with correct misalignment
 255 #endif
 256         bbsi.l  a4, 1, .L14
 257         bbsi.l  a4, 0, .L15
 258 .Ldone: abi_ret_default
 259 .L14:
 260         # copy 2 bytes
 261         l8ui    a6, a3,  0
 262         l8ui    a7, a3,  1
 263         addi    a3, a3,  2
 264         s8i     a6, a5,  0
 265         s8i     a7, a5,  1
 266         addi    a5, a5,  2
 267         bbsi.l  a4, 0, .L15
 268         abi_ret_default
 269 .L15:
 270         # copy 1 byte
 271         l8ui    a6, a3,  0
 272         s8i     a6, a5,  0
 273         abi_ret_default
 274
 275 ENDPROC(__memcpy)
 276
 277 /*
 278  * void bcopy(const void *src, void *dest, size_t n);
 279  */
 280
 281 ENTRY(bcopy)
 282
 283         abi_entry_default
 284         # a2=src, a3=dst, a4=len
 285         mov     a5, a3
 286         mov     a3, a2
 287         mov     a2, a5
 288         j       .Lmovecommon    # go to common code for memmove+bcopy
 289
 290 ENDPROC(bcopy)
 291
 292 /*
 293  * void *memmove(void *dst, const void *src, size_t len);
 294  *
 295  * This function is intended to do the same thing as the standard
 296  * library function memmove() for most cases.
 297  * However, where the source and/or destination references
 298  * an instruction RAM or ROM or a data RAM or ROM, that
 299  * source and/or destination will always be accessed with
 300  * 32-bit load and store instructions (as required for these
 301  * types of devices).
 302  *
 303  * !!!!!!!  XTFIXME:
 304  * !!!!!!!  Handling of IRAM/IROM has not yet
 305  * !!!!!!!  been implemented.
 306  *
 307  * The (general case) algorithm is as follows:
 308  *   If end of source doesn't overlap destination then use memcpy.
 309  *   Otherwise do memcpy backwards.
 310  *
 311  * Register use:
 312  *      a0/ return address
 313  *      a1/ stack pointer
 314  *      a2/ return value
 315  *      a3/ src
 316  *      a4/ length
 317  *      a5/ dst
 318  *      a6/ tmp
 319  *      a7/ tmp
 320  *      a8/ tmp
 321  *      a9/ tmp
 322  *      a10/ tmp
 323  *      a11/ tmp
 324  */
 325
 326 /*
 327  * Byte by byte copy
 328  */
 329         .align  4
 330         .byte   0               # 1 mod 4 alignment for LOOPNEZ
 331                                 # (0 mod 4 alignment for LBEG)
 332 .Lbackbytecopy:
 333 #if XCHAL_HAVE_LOOPS
 334         loopnez a4, .Lbackbytecopydone
 335 #else /* !XCHAL_HAVE_LOOPS */
 336         beqz    a4, .Lbackbytecopydone
 337         sub     a7, a3, a4      # a7 = start address for source
 338 #endif /* !XCHAL_HAVE_LOOPS */
 339 .Lbacknextbyte:
 340         addi    a3, a3, -1
 341         l8ui    a6, a3, 0
 342         addi    a5, a5, -1
 343         s8i     a6, a5, 0
 344 #if !XCHAL_HAVE_LOOPS
 345         bne     a3, a7, .Lbacknextbyte # continue loop if
 346                                        # $a3:src != $a7:src_start
 347 #endif /* !XCHAL_HAVE_LOOPS */
 348 .Lbackbytecopydone:
 349         abi_ret_default
 350
 351 /*
 352  * Destination is unaligned
 353  */
 354
 355         .align  4
 356 .Lbackdst1mod2: # dst is only byte aligned
 357         _bltui  a4, 7, .Lbackbytecopy   # do short copies byte by byte
 358
 359         # copy 1 byte
 360         addi    a3, a3, -1
 361         l8ui    a6, a3,  0
 362         addi    a5, a5, -1
 363         s8i     a6, a5,  0
 364         addi    a4, a4, -1
 365         _bbci.l a5, 1, .Lbackdstaligned # if dst is now aligned, then
 366                                         # return to main algorithm
 367 .Lbackdst2mod4: # dst 16-bit aligned
 368         # copy 2 bytes
 369         _bltui  a4, 6, .Lbackbytecopy   # do short copies byte by byte
 370         addi    a3, a3, -2
 371         l8ui    a6, a3,  0
 372         l8ui    a7, a3,  1
 373         addi    a5, a5, -2
 374         s8i     a6, a5,  0
 375         s8i     a7, a5,  1
 376         addi    a4, a4, -2
 377         j       .Lbackdstaligned        # dst is now aligned,
 378                                         # return to main algorithm
 379
 380 ENTRY(__memmove)
 381 WEAK(memmove)
 382
 383         abi_entry_default
 384         # a2/ dst, a3/ src, a4/ len
 385         mov     a5, a2          # copy dst so that a2 is return value
 386 .Lmovecommon:
 387         sub     a6, a5, a3
 388         bgeu    a6, a4, .Lcommon
 389
 390         add     a5, a5, a4
 391         add     a3, a3, a4
 392
 393         _bbsi.l a5, 0, .Lbackdst1mod2   # if dst is 1 mod 2
 394         _bbsi.l a5, 1, .Lbackdst2mod4   # if dst is 2 mod 4
 395 .Lbackdstaligned:       # return here from .Lbackdst?mod? once dst is aligned
 396         srli    a7, a4, 4       # number of loop iterations with 16B
 397                                 # per iteration
 398         movi    a8, 3           # if source is not aligned,
 399         _bany   a3, a8, .Lbacksrcunaligned      # then use shifting copy
 400         /*
 401          * Destination and source are word-aligned, use word copy.
 402          */
 403         # copy 16 bytes per iteration for word-aligned dst and word-aligned src
 404 #if XCHAL_HAVE_LOOPS
 405         loopnez a7, .backLoop1done
 406 #else /* !XCHAL_HAVE_LOOPS */
 407         beqz    a7, .backLoop1done
 408         slli    a8, a7, 4
 409         sub     a8, a3, a8      # a8 = start of first 16B source chunk
 410 #endif /* !XCHAL_HAVE_LOOPS */
 411 .backLoop1:
 412         addi    a3, a3, -16
 413         l32i    a7, a3, 12
 414         l32i    a6, a3,  8
 415         addi    a5, a5, -16
 416         s32i    a7, a5, 12
 417         l32i    a7, a3,  4
 418         s32i    a6, a5,  8
 419         l32i    a6, a3,  0
 420         s32i    a7, a5,  4
 421         s32i    a6, a5,  0
 422 #if !XCHAL_HAVE_LOOPS
 423         bne     a3, a8, .backLoop1  # continue loop if a3:src != a8:src_start
 424 #endif /* !XCHAL_HAVE_LOOPS */
 425 .backLoop1done:
 426         bbci.l  a4, 3, .Lback2
 427         # copy 8 bytes
 428         addi    a3, a3, -8
 429         l32i    a6, a3,  0
 430         l32i    a7, a3,  4
 431         addi    a5, a5, -8
 432         s32i    a6, a5,  0
 433         s32i    a7, a5,  4
 434 .Lback2:
 435         bbsi.l  a4, 2, .Lback3
 436         bbsi.l  a4, 1, .Lback4
 437         bbsi.l  a4, 0, .Lback5
 438         abi_ret_default
 439 .Lback3:
 440         # copy 4 bytes
 441         addi    a3, a3, -4
 442         l32i    a6, a3,  0
 443         addi    a5, a5, -4
 444         s32i    a6, a5,  0
 445         bbsi.l  a4, 1, .Lback4
 446         bbsi.l  a4, 0, .Lback5
 447         abi_ret_default
 448 .Lback4:
 449         # copy 2 bytes
 450         addi    a3, a3, -2
 451         l16ui   a6, a3,  0
 452         addi    a5, a5, -2
 453         s16i    a6, a5,  0
 454         bbsi.l  a4, 0, .Lback5
 455         abi_ret_default
 456 .Lback5:
 457         # copy 1 byte
 458         addi    a3, a3, -1
 459         l8ui    a6, a3,  0
 460         addi    a5, a5, -1
 461         s8i     a6, a5,  0
 462         abi_ret_default
 463
 464 /*
 465  * Destination is aligned, Source is unaligned
 466  */
 467
 468         .align  4
 469 .Lbacksrcunaligned:
 470         _beqz   a4, .Lbackdone  # avoid loading anything for zero-length copies
 471         # copy 16 bytes per iteration for word-aligned dst and unaligned src
 472         __ssa8  a3              # set shift amount from byte offset
 473 #define SIM_CHECKS_ALIGNMENT    1       /* set to 1 when running on ISS with
 474                                          * the lint or ferret client, or 0
 475                                          * to save a few cycles */
 476 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
 477         and     a11, a3, a8     # save unalignment offset for below
 478         sub     a3, a3, a11     # align a3
 479 #endif
 480         l32i    a6, a3, 0       # load first word
 481 #if XCHAL_HAVE_LOOPS
 482         loopnez a7, .backLoop2done
 483 #else /* !XCHAL_HAVE_LOOPS */
 484         beqz    a7, .backLoop2done
 485         slli    a10, a7, 4
 486         sub     a10, a3, a10    # a10 = start of first 16B source chunk
 487 #endif /* !XCHAL_HAVE_LOOPS */
 488 .backLoop2:
 489         addi    a3, a3, -16
 490         l32i    a7, a3, 12
 491         l32i    a8, a3,  8
 492         addi    a5, a5, -16
 493         __src_b a6, a7, a6
 494         s32i    a6, a5, 12
 495         l32i    a9, a3,  4
 496         __src_b a7, a8, a7
 497         s32i    a7, a5,  8
 498         l32i    a6, a3,  0
 499         __src_b a8, a9, a8
 500         s32i    a8, a5,  4
 501         __src_b a9, a6, a9
 502         s32i    a9, a5,  0
 503 #if !XCHAL_HAVE_LOOPS
 504         bne     a3, a10, .backLoop2 # continue loop if a3:src != a10:src_start
 505 #endif /* !XCHAL_HAVE_LOOPS */
 506 .backLoop2done:
 507         bbci.l  a4, 3, .Lback12
 508         # copy 8 bytes
 509         addi    a3, a3, -8
 510         l32i    a7, a3,  4
 511         l32i    a8, a3,  0
 512         addi    a5, a5, -8
 513         __src_b a6, a7, a6
 514         s32i    a6, a5,  4
 515         __src_b a7, a8, a7
 516         s32i    a7, a5,  0
 517         mov     a6, a8
 518 .Lback12:
 519         bbci.l  a4, 2, .Lback13
 520         # copy 4 bytes
 521         addi    a3, a3, -4
 522         l32i    a7, a3,  0
 523         addi    a5, a5, -4
 524         __src_b a6, a7, a6
 525         s32i    a6, a5,  0
 526         mov     a6, a7
 527 .Lback13:
 528 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
 529         add     a3, a3, a11     # readjust a3 with correct misalignment
 530 #endif
 531         bbsi.l  a4, 1, .Lback14
 532         bbsi.l  a4, 0, .Lback15
 533 .Lbackdone:
 534         abi_ret_default
 535 .Lback14:
 536         # copy 2 bytes
 537         addi    a3, a3, -2
 538         l8ui    a6, a3,  0
 539         l8ui    a7, a3,  1
 540         addi    a5, a5, -2
 541         s8i     a6, a5,  0
 542         s8i     a7, a5,  1
 543         bbsi.l  a4, 0, .Lback15
 544         abi_ret_default
 545 .Lback15:
 546         # copy 1 byte
 547         addi    a3, a3, -1
 548         addi    a5, a5, -1
 549         l8ui    a6, a3,  0
 550         s8i     a6, a5,  0
 551         abi_ret_default
 552
 553 ENDPROC(__memmove)