LXR linux/arch/mn10300/lib/memmove.S

   1/* MN10300 Optimised simple memory to memory copy, with support for overlapping
   2 * regions
   3 *
   4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5 * Written by David Howells (dhowells@redhat.com)
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public Licence
   9 * as published by the Free Software Foundation; either version
  10 * 2 of the Licence, or (at your option) any later version.
  11 */
  12#include <asm/cache.h>
  13
  14        .section .text
  15        .balign L1_CACHE_BYTES
  16
  17###############################################################################
  18#
  19# void *memmove(void *dst, const void *src, size_t n)
  20#
  21###############################################################################
  22        .globl  memmove
  23        .type   memmove,@function
  24memmove:
  25        # fall back to memcpy if dst < src to work bottom up
  26        cmp     d1,d0
  27        bcs     memmove_memcpy
  28
  29        # work top down
  30        movm    [d2,d3],(sp)
  31        mov     d0,(12,sp)
  32        mov     d1,(16,sp)
  33        mov     (20,sp),d2                      # count
  34        add     d0,d2,a0                        # dst end
  35        add     d1,d2,a1                        # src end
  36        mov     d0,e3                           # the return value
  37
  38        cmp     +0,d2
  39        beq     memmove_done                    # return if zero-length copy
  40
  41        # see if the three parameters are all four-byte aligned
  42        or      d0,d1,d3
  43        or      d2,d3
  44        and     +3,d3
  45        bne     memmove_1                       # jump if not
  46
  47        # we want to transfer as much as we can in chunks of 32 bytes
  48        add     -4,a1
  49        cmp     +31,d2
  50        bls     memmove_4_remainder             # 4-byte aligned remainder
  51
  52        add     -32,d2
  53        mov     +32,d3
  54
  55memmove_4_loop:
  56        mov     (a1),d0
  57        sub_sub +4,a1,+4,a0
  58        mov     d0,(a0)
  59        mov     (a1),d1
  60        sub_sub +4,a1,+4,a0
  61        mov     d1,(a0)
  62
  63        mov     (a1),d0
  64        sub_sub +4,a1,+4,a0
  65        mov     d0,(a0)
  66        mov     (a1),d1
  67        sub_sub +4,a1,+4,a0
  68        mov     d1,(a0)
  69
  70        mov     (a1),d0
  71        sub_sub +4,a1,+4,a0
  72        mov     d0,(a0)
  73        mov     (a1),d1
  74        sub_sub +4,a1,+4,a0
  75        mov     d1,(a0)
  76
  77        mov     (a1),d0
  78        sub_sub +4,a1,+4,a0
  79        mov     d0,(a0)
  80        mov     (a1),d1
  81        sub_sub +4,a1,+4,a0
  82        mov     d1,(a0)
  83
  84        sub     d3,d2
  85        bcc     memmove_4_loop
  86
  87        add     d3,d2
  88        beq     memmove_4_no_remainder
  89
  90memmove_4_remainder:
  91        # cut 4-7 words down to 0-3
  92        cmp     +16,d2
  93        bcs     memmove_4_three_or_fewer_words
  94        mov     (a1),d0
  95        sub_sub +4,a1,+4,a0
  96        mov     d0,(a0)
  97        mov     (a1),d1
  98        sub_sub +4,a1,+4,a0
  99        mov     d1,(a0)
 100        mov     (a1),e0
 101        sub_sub +4,a1,+4,a0
 102        mov     e0,(a0)
 103        mov     (a1),e1
 104        sub_sub +4,a1,+4,a0
 105        mov     e1,(a0)
 106        add     -16,d2
 107        beq     memmove_4_no_remainder
 108
 109        # copy the remaining 1, 2 or 3 words
 110memmove_4_three_or_fewer_words:
 111        cmp     +8,d2
 112        bcs     memmove_4_one_word
 113        beq     memmove_4_two_words
 114        mov     (a1),d0
 115        sub_sub +4,a1,+4,a0
 116        mov     d0,(a0)
 117memmove_4_two_words:
 118        mov     (a1),d0
 119        sub_sub +4,a1,+4,a0
 120        mov     d0,(a0)
 121memmove_4_one_word:
 122        mov     (a1),d0
 123        sub_sub +4,a1,+4,a0
 124        mov     d0,(a0)
 125
 126memmove_4_no_remainder:
 127        # check we copied the correct amount
 128        # TODO: REMOVE CHECK
 129        sub     e3,a0,d2
 130        beq     memmove_done
 131        break
 132        break
 133        break
 134
 135memmove_done:
 136        mov     e3,a0
 137        ret     [d2,d3],8
 138
 139        # handle misaligned copying
 140memmove_1:
 141        add     -1,a1
 142        add     -1,d2
 143        mov     +1,d3
 144        setlb                                   # setlb requires the next insns
 145                                                # to occupy exactly 4 bytes
 146
 147        sub     d3,d2
 148        movbu   (a1),d0
 149        sub_sub d3,a1,d3,a0
 150        movbu   d0,(a0)
 151        lcc
 152
 153        mov     e3,a0
 154        ret     [d2,d3],8
 155
 156memmove_memcpy:
 157        jmp     memcpy
 158
 159memmove_end:
 160        .size   memmove, memmove_end-memmove
 161