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
  24 memmove:
  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
  55 memmove_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
  90 memmove_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
 110 memmove_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)
 117 memmove_4_two_words:
 118         mov     (a1),d0
 119         sub_sub +4,a1,+4,a0
 120         mov     d0,(a0)
 121 memmove_4_one_word:
 122         mov     (a1),d0
 123         sub_sub +4,a1,+4,a0
 124         mov     d0,(a0)
 125
 126 memmove_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
 135 memmove_done:
 136         mov     e3,a0
 137         ret     [d2,d3],8
 138
 139         # handle misaligned copying
 140 memmove_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
 156 memmove_memcpy:
 157         jmp     memcpy
 158
 159 memmove_end:
 160         .size   memmove, memmove_end-memmove