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