arch/arm/lib/memmove.S

   1 /*
   2  *  linux/arch/arm/lib/memmove.S
   3  *
   4  *  Author:     Nicolas Pitre
   5  *  Created:    Sep 28, 2005
   6  *  Copyright:  (C) MontaVista Software Inc.
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License version 2 as
  10  *  published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/linkage.h>
  14 #include <asm/assembler.h>
  15 #include <asm/unwind.h>
  16
  17                 .text
  18
  19 /*
  20  * Prototype: void *memmove(void *dest, const void *src, size_t n);
  21  *
  22  * Note:
  23  *
  24  * If the memory regions don't overlap, we simply branch to memcpy which is
  25  * normally a bit faster. Otherwise the copy is done going downwards.  This
  26  * is a transposition of the code from copy_template.S but with the copy
  27  * occurring in the opposite direction.
  28  */
  29
  30 ENTRY(memmove)
  31         UNWIND( .fnstart                        )
  32
  33                 subs    ip, r0, r1
  34                 cmphi   r2, ip
  35                 bls     memcpy
  36
  37                 stmfd   sp!, {r0, r4, lr}
  38         UNWIND( .fnend                          )
  39
  40         UNWIND( .fnstart                        )
  41         UNWIND( .save   {r0, r4, lr}            ) @ in first stmfd block
  42                 add     r1, r1, r2
  43                 add     r0, r0, r2
  44                 subs    r2, r2, #4
  45                 blt     8f
  46                 ands    ip, r0, #3
  47         PLD(    pld     [r1, #-4]               )
  48                 bne     9f
  49                 ands    ip, r1, #3
  50                 bne     10f
  51
  52 1:              subs    r2, r2, #(28)
  53                 stmfd   sp!, {r5 - r8}
  54         UNWIND( .fnend                          )
  55
  56         UNWIND( .fnstart                        )
  57         UNWIND( .save   {r0, r4, lr}            )
  58         UNWIND( .save   {r5 - r8}               ) @ in second stmfd block
  59                 blt     5f
  60
  61         CALGN(  ands    ip, r0, #31             )
  62         CALGN(  sbcnes  r4, ip, r2              )  @ C is always set here
  63         CALGN(  bcs     2f                      )
  64         CALGN(  adr     r4, 6f                  )
  65         CALGN(  subs    r2, r2, ip              )  @ C is set here
  66         CALGN(  rsb     ip, ip, #32             )
  67         CALGN(  add     pc, r4, ip              )
  68
  69         PLD(    pld     [r1, #-4]               )
  70 2:      PLD(    subs    r2, r2, #96             )
  71         PLD(    pld     [r1, #-32]              )
  72         PLD(    blt     4f                      )
  73         PLD(    pld     [r1, #-64]              )
  74         PLD(    pld     [r1, #-96]              )
  75
  76 3:      PLD(    pld     [r1, #-128]             )
  77 4:              ldmdb   r1!, {r3, r4, r5, r6, r7, r8, ip, lr}
  78                 subs    r2, r2, #32
  79                 stmdb   r0!, {r3, r4, r5, r6, r7, r8, ip, lr}
  80                 bge     3b
  81         PLD(    cmn     r2, #96                 )
  82         PLD(    bge     4b                      )
  83
  84 5:              ands    ip, r2, #28
  85                 rsb     ip, ip, #32
  86                 addne   pc, pc, ip              @ C is always clear here
  87                 b       7f
  88 6:              W(nop)
  89                 W(ldr)  r3, [r1, #-4]!
  90                 W(ldr)  r4, [r1, #-4]!
  91                 W(ldr)  r5, [r1, #-4]!
  92                 W(ldr)  r6, [r1, #-4]!
  93                 W(ldr)  r7, [r1, #-4]!
  94                 W(ldr)  r8, [r1, #-4]!
  95                 W(ldr)  lr, [r1, #-4]!
  96
  97                 add     pc, pc, ip
  98                 nop
  99                 W(nop)
 100                 W(str)  r3, [r0, #-4]!
 101                 W(str)  r4, [r0, #-4]!
 102                 W(str)  r5, [r0, #-4]!
 103                 W(str)  r6, [r0, #-4]!
 104                 W(str)  r7, [r0, #-4]!
 105                 W(str)  r8, [r0, #-4]!
 106                 W(str)  lr, [r0, #-4]!
 107
 108         CALGN(  bcs     2b                      )
 109
 110 7:              ldmfd   sp!, {r5 - r8}
 111         UNWIND( .fnend                          ) @ end of second stmfd block
 112
 113         UNWIND( .fnstart                        )
 114         UNWIND( .save   {r0, r4, lr}            ) @ still in first stmfd block
 115
 116 8:              movs    r2, r2, lsl #31
 117                 ldrneb  r3, [r1, #-1]!
 118                 ldrcsb  r4, [r1, #-1]!
 119                 ldrcsb  ip, [r1, #-1]
 120                 strneb  r3, [r0, #-1]!
 121                 strcsb  r4, [r0, #-1]!
 122                 strcsb  ip, [r0, #-1]
 123                 ldmfd   sp!, {r0, r4, pc}
 124
 125 9:              cmp     ip, #2
 126                 ldrgtb  r3, [r1, #-1]!
 127                 ldrgeb  r4, [r1, #-1]!
 128                 ldrb    lr, [r1, #-1]!
 129                 strgtb  r3, [r0, #-1]!
 130                 strgeb  r4, [r0, #-1]!
 131                 subs    r2, r2, ip
 132                 strb    lr, [r0, #-1]!
 133                 blt     8b
 134                 ands    ip, r1, #3
 135                 beq     1b
 136
 137 10:             bic     r1, r1, #3
 138                 cmp     ip, #2
 139                 ldr     r3, [r1, #0]
 140                 beq     17f
 141                 blt     18f
 142         UNWIND( .fnend                          )
 143
 144
 145                 .macro  backward_copy_shift push pull
 146
 147         UNWIND( .fnstart                        )
 148         UNWIND( .save   {r0, r4, lr}            ) @ still in first stmfd block
 149                 subs    r2, r2, #28
 150                 blt     14f
 151
 152         CALGN(  ands    ip, r0, #31             )
 153         CALGN(  sbcnes  r4, ip, r2              )  @ C is always set here
 154         CALGN(  subcc   r2, r2, ip              )
 155         CALGN(  bcc     15f                     )
 156
 157 11:             stmfd   sp!, {r5 - r9}
 158         UNWIND( .fnend                          )
 159
 160         UNWIND( .fnstart                        )
 161         UNWIND( .save   {r0, r4, lr}            )
 162         UNWIND( .save   {r5 - r9}               ) @ in new second stmfd block
 163
 164         PLD(    pld     [r1, #-4]               )
 165         PLD(    subs    r2, r2, #96             )
 166         PLD(    pld     [r1, #-32]              )
 167         PLD(    blt     13f                     )
 168         PLD(    pld     [r1, #-64]              )
 169         PLD(    pld     [r1, #-96]              )
 170
 171 12:     PLD(    pld     [r1, #-128]             )
 172 13:             ldmdb   r1!, {r7, r8, r9, ip}
 173                 mov     lr, r3, lspush #\push
 174                 subs    r2, r2, #32
 175                 ldmdb   r1!, {r3, r4, r5, r6}
 176                 orr     lr, lr, ip, lspull #\pull
 177                 mov     ip, ip, lspush #\push
 178                 orr     ip, ip, r9, lspull #\pull
 179                 mov     r9, r9, lspush #\push
 180                 orr     r9, r9, r8, lspull #\pull
 181                 mov     r8, r8, lspush #\push
 182                 orr     r8, r8, r7, lspull #\pull
 183                 mov     r7, r7, lspush #\push
 184                 orr     r7, r7, r6, lspull #\pull
 185                 mov     r6, r6, lspush #\push
 186                 orr     r6, r6, r5, lspull #\pull
 187                 mov     r5, r5, lspush #\push
 188                 orr     r5, r5, r4, lspull #\pull
 189                 mov     r4, r4, lspush #\push
 190                 orr     r4, r4, r3, lspull #\pull
 191                 stmdb   r0!, {r4 - r9, ip, lr}
 192                 bge     12b
 193         PLD(    cmn     r2, #96                 )
 194         PLD(    bge     13b                     )
 195
 196                 ldmfd   sp!, {r5 - r9}
 197         UNWIND( .fnend                          ) @ end of the second stmfd block
 198
 199         UNWIND( .fnstart                        )
 200         UNWIND( .save {r0, r4, lr}              ) @ still in first stmfd block
 201
 202 14:             ands    ip, r2, #28
 203                 beq     16f
 204
 205 15:             mov     lr, r3, lspush #\push
 206                 ldr     r3, [r1, #-4]!
 207                 subs    ip, ip, #4
 208                 orr     lr, lr, r3, lspull #\pull
 209                 str     lr, [r0, #-4]!
 210                 bgt     15b
 211         CALGN(  cmp     r2, #0                  )
 212         CALGN(  bge     11b                     )
 213
 214 16:             add     r1, r1, #(\pull / 8)
 215                 b       8b
 216         UNWIND( .fnend                          )
 217
 218                 .endm
 219
 220
 221                 backward_copy_shift     push=8  pull=24
 222
 223 17:             backward_copy_shift     push=16 pull=16
 224
 225 18:             backward_copy_shift     push=24 pull=8
 226
 227 ENDPROC(memmove)