firmware/target/arm/memmove-arm.S

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2006 Free Software Foundation, Inc.
  11  * This file was originally part of the GNU C Library
  12  * Contributed to glibc by MontaVista Software, Inc. (written by Nicolas Pitre)
  13  * Adapted for Rockbox by Daniel Ankers
  14  *
  15  * This program is free software; you can redistribute it and/or
  16  * modify it under the terms of the GNU General Public License
  17  * as published by the Free Software Foundation; either version 2
  18  * of the License, or (at your option) any later version.
  19  *
  20  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  21  * KIND, either express or implied.
  22  *
  23  ****************************************************************************/
  24
  25 #include "config.h"
  26
  27 /*
  28  * Endian independent macros for shifting bytes within registers.
  29  */
  30 #ifndef __ARMEB__
  31 #define pull            lsr
  32 #define push            lsl
  33 #else
  34 #define pull            lsl
  35 #define push            lsr
  36 #endif
  37
  38                 .text
  39
  40 /*
  41  * Prototype: void *memmove(void *dest, const void *src, size_t n);
  42  *
  43  * Note:
  44  *
  45  * If the memory regions don't overlap, we simply branch to memcpy which is
  46  * normally a bit faster. Otherwise the copy is done going downwards.
  47  */
  48
  49     .section    .icode,"ax",%progbits
  50
  51     .align      2
  52     .global     memmove
  53     .type       memmove,%function
  54
  55 memmove:
  56
  57                 subs    ip, r0, r1
  58                 cmphi   r2, ip
  59                 bls     memcpy
  60
  61                 stmfd   sp!, {r0, r4, lr}
  62                 add     r1, r1, r2
  63                 add     r0, r0, r2
  64                 subs    r2, r2, #4
  65                 blt     8f
  66                 ands    ip, r0, #3
  67                 bne     9f
  68                 ands    ip, r1, #3
  69                 bne     10f
  70
  71 1:              subs    r2, r2, #(28)
  72                 stmfd   sp!, {r5 - r8}
  73                 blt     5f
  74
  75 2:
  76 3:
  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
  82 5:              ands    ip, r2, #28
  83                 rsb     ip, ip, #32
  84                 addne   pc, pc, ip              @ C is always clear here
  85                 b       7f
  86 6:              nop
  87                 ldr     r3, [r1, #-4]!
  88                 ldr     r4, [r1, #-4]!
  89                 ldr     r5, [r1, #-4]!
  90                 ldr     r6, [r1, #-4]!
  91                 ldr     r7, [r1, #-4]!
  92                 ldr     r8, [r1, #-4]!
  93                 ldr     lr, [r1, #-4]!
  94
  95                 add     pc, pc, ip
  96                 nop
  97                 nop
  98                 str     r3, [r0, #-4]!
  99                 str     r4, [r0, #-4]!
 100                 str     r5, [r0, #-4]!
 101                 str     r6, [r0, #-4]!
 102                 str     r7, [r0, #-4]!
 103                 str     r8, [r0, #-4]!
 104                 str     lr, [r0, #-4]!
 105
 106 7:              ldmfd   sp!, {r5 - r8}
 107
 108 8:              movs    r2, r2, lsl #31
 109                 ldrneb  r3, [r1, #-1]!
 110                 ldrcsb  r4, [r1, #-1]!
 111                 ldrcsb  ip, [r1, #-1]
 112                 strneb  r3, [r0, #-1]!
 113                 strcsb  r4, [r0, #-1]!
 114                 strcsb  ip, [r0, #-1]
 115                 ldmfd   sp!, {r0, r4, pc}
 116
 117 9:              cmp     ip, #2
 118                 ldrgtb  r3, [r1, #-1]!
 119                 ldrgeb  r4, [r1, #-1]!
 120                 ldrb    lr, [r1, #-1]!
 121                 strgtb  r3, [r0, #-1]!
 122                 strgeb  r4, [r0, #-1]!
 123                 subs    r2, r2, ip
 124                 strb    lr, [r0, #-1]!
 125                 blt     8b
 126                 ands    ip, r1, #3
 127                 beq     1b
 128
 129 10:             bic     r1, r1, #3
 130                 cmp     ip, #2
 131                 ldr     r3, [r1, #0]
 132                 beq     17f
 133                 blt     18f
 134
 135
 136                 .macro  backward_copy_shift push pull
 137
 138                 subs    r2, r2, #28
 139                 blt     14f
 140
 141 11:             stmfd   sp!, {r5 - r9}
 142
 143 12:
 144 13:             ldmdb   r1!, {r7, r8, r9, ip}
 145                 mov     lr, r3, push #\push
 146                 subs    r2, r2, #32
 147                 ldmdb   r1!, {r3, r4, r5, r6}
 148                 orr     lr, lr, ip, pull #\pull
 149                 mov     ip, ip, push #\push
 150                 orr     ip, ip, r9, pull #\pull
 151                 mov     r9, r9, push #\push
 152                 orr     r9, r9, r8, pull #\pull
 153                 mov     r8, r8, push #\push
 154                 orr     r8, r8, r7, pull #\pull
 155                 mov     r7, r7, push #\push
 156                 orr     r7, r7, r6, pull #\pull
 157                 mov     r6, r6, push #\push
 158                 orr     r6, r6, r5, pull #\pull
 159                 mov     r5, r5, push #\push
 160                 orr     r5, r5, r4, pull #\pull
 161                 mov     r4, r4, push #\push
 162                 orr     r4, r4, r3, pull #\pull
 163                 stmdb   r0!, {r4 - r9, ip, lr}
 164                 bge     12b
 165
 166                 ldmfd   sp!, {r5 - r9}
 167
 168 14:             ands    ip, r2, #28
 169                 beq     16f
 170
 171 15:             mov     lr, r3, push #\push
 172                 ldr     r3, [r1, #-4]!
 173                 subs    ip, ip, #4
 174                 orr     lr, lr, r3, pull #\pull
 175                 str     lr, [r0, #-4]!
 176                 bgt     15b
 177
 178 16:             add     r1, r1, #(\pull / 8)
 179                 b       8b
 180
 181                 .endm
 182
 183
 184                 backward_copy_shift     push=8  pull=24
 185
 186 17:             backward_copy_shift     push=16 pull=16
 187
 188 18:             backward_copy_shift     push=24 pull=8
 189
 190