arch/microblaze/lib/memmove.c

   1 /*
   2  * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
   3  * Copyright (C) 2008-2009 PetaLogix
   4  * Copyright (C) 2007 John Williams
   5  *
   6  * Reasonably optimised generic C-code for memcpy on Microblaze
   7  * This is generic C code to do efficient, alignment-aware memmove.
   8  *
   9  * It is based on demo code originally Copyright 2001 by Intel Corp, taken from
  10  * http://www.embedded.com/showArticle.jhtml?articleID=19205567
  11  *
  12  * Attempts were made, unsuccessfully, to contact the original
  13  * author of this code (Michael Morrow, Intel).  Below is the original
  14  * copyright notice.
  15  *
  16  * This software has been developed by Intel Corporation.
  17  * Intel specifically disclaims all warranties, express or
  18  * implied, and all liability, including consequential and
  19  * other indirect damages, for the use of this program, including
  20  * liability for infringement of any proprietary rights,
  21  * and including the warranties of merchantability and fitness
  22  * for a particular purpose. Intel does not assume any
  23  * responsibility for and errors which may appear in this program
  24  * not any responsibility to update it.
  25  */
  26
  27 #include <linux/export.h>
  28 #include <linux/types.h>
  29 #include <linux/stddef.h>
  30 #include <linux/compiler.h>
  31 #include <linux/string.h>
  32
  33 #ifdef __HAVE_ARCH_MEMMOVE
  34 #ifndef CONFIG_OPT_LIB_FUNCTION
  35 void *memmove(void *v_dst, const void *v_src, __kernel_size_t c)
  36 {
  37         const char *src = v_src;
  38         char *dst = v_dst;
  39
  40         if (!c)
  41                 return v_dst;
  42
  43         /* Use memcpy when source is higher than dest */
  44         if (v_dst <= v_src)
  45                 return memcpy(v_dst, v_src, c);
  46
  47         /* copy backwards, from end to beginning */
  48         src += c;
  49         dst += c;
  50
  51         /* Simple, byte oriented memmove. */
  52         while (c--)
  53                 *--dst = *--src;
  54
  55         return v_dst;
  56 }
  57 #else /* CONFIG_OPT_LIB_FUNCTION */
  58 void *memmove(void *v_dst, const void *v_src, __kernel_size_t c)
  59 {
  60         const char *src = v_src;
  61         char *dst = v_dst;
  62         const uint32_t *i_src;
  63         uint32_t *i_dst;
  64
  65         if (!c)
  66                 return v_dst;
  67
  68         /* Use memcpy when source is higher than dest */
  69         if (v_dst <= v_src)
  70                 return memcpy(v_dst, v_src, c);
  71
  72         /* The following code tries to optimize the copy by using unsigned
  73          * alignment. This will work fine if both source and destination are
  74          * aligned on the same boundary. However, if they are aligned on
  75          * different boundaries shifts will be necessary. This might result in
  76          * bad performance on MicroBlaze systems without a barrel shifter.
  77          */
  78         /* FIXME this part needs more test */
  79         /* Do a descending copy - this is a bit trickier! */
  80         dst += c;
  81         src += c;
  82
  83         if (c >= 4) {
  84                 unsigned  value, buf_hold;
  85
  86                 /* Align the destination to a word boundary. */
  87                 /* This is done in an endian independent manner. */
  88
  89                 switch ((unsigned long)dst & 3) {
  90                 case 3:
  91                         *--dst = *--src;
  92                         --c;
  93                 case 2:
  94                         *--dst = *--src;
  95                         --c;
  96                 case 1:
  97                         *--dst = *--src;
  98                         --c;
  99                 }
 100
 101                 i_dst = (void *)dst;
 102                 /* Choose a copy scheme based on the source */
 103                 /* alignment relative to dstination. */
 104                 switch ((unsigned long)src & 3) {
 105                 case 0x0:       /* Both byte offsets are aligned */
 106
 107                         i_src  = (const void *)src;
 108
 109                         for (; c >= 4; c -= 4)
 110                                 *--i_dst = *--i_src;
 111
 112                         src  = (const void *)i_src;
 113                         break;
 114                 case 0x1:       /* Unaligned - Off by 1 */
 115                         /* Word align the source */
 116                         i_src = (const void *) (((unsigned)src + 4) & ~3);
 117 #ifndef __MICROBLAZEEL__
 118                         /* Load the holding buffer */
 119                         buf_hold = *--i_src >> 24;
 120
 121                         for (; c >= 4; c -= 4) {
 122                                 value = *--i_src;
 123                                 *--i_dst = buf_hold << 8 | value;
 124                                 buf_hold = value >> 24;
 125                         }
 126 #else
 127                         /* Load the holding buffer */
 128                         buf_hold = (*--i_src & 0xFF) << 24;
 129
 130                         for (; c >= 4; c -= 4) {
 131                                 value = *--i_src;
 132                                 *--i_dst = buf_hold |
 133                                                 ((value & 0xFFFFFF00) >> 8);
 134                                 buf_hold = (value  & 0xFF) << 24;
 135                         }
 136 #endif
 137                         /* Realign the source */
 138                         src = (const void *)i_src;
 139                         src += 1;
 140                         break;
 141                 case 0x2:       /* Unaligned - Off by 2 */
 142                         /* Word align the source */
 143                         i_src = (const void *) (((unsigned)src + 4) & ~3);
 144 #ifndef __MICROBLAZEEL__
 145                         /* Load the holding buffer */
 146                         buf_hold = *--i_src >> 16;
 147
 148                         for (; c >= 4; c -= 4) {
 149                                 value = *--i_src;
 150                                 *--i_dst = buf_hold << 16 | value;
 151                                 buf_hold = value >> 16;
 152                         }
 153 #else
 154                         /* Load the holding buffer */
 155                         buf_hold = (*--i_src & 0xFFFF) << 16;
 156
 157                         for (; c >= 4; c -= 4) {
 158                                 value = *--i_src;
 159                                 *--i_dst = buf_hold |
 160                                                 ((value & 0xFFFF0000) >> 16);
 161                                 buf_hold = (value & 0xFFFF) << 16;
 162                         }
 163 #endif
 164                         /* Realign the source */
 165                         src = (const void *)i_src;
 166                         src += 2;
 167                         break;
 168                 case 0x3:       /* Unaligned - Off by 3 */
 169                         /* Word align the source */
 170                         i_src = (const void *) (((unsigned)src + 4) & ~3);
 171 #ifndef __MICROBLAZEEL__
 172                         /* Load the holding buffer */
 173                         buf_hold = *--i_src >> 8;
 174
 175                         for (; c >= 4; c -= 4) {
 176                                 value = *--i_src;
 177                                 *--i_dst = buf_hold << 24 | value;
 178                                 buf_hold = value >> 8;
 179                         }
 180 #else
 181                         /* Load the holding buffer */
 182                         buf_hold = (*--i_src & 0xFFFFFF) << 8;
 183
 184                         for (; c >= 4; c -= 4) {
 185                                 value = *--i_src;
 186                                 *--i_dst = buf_hold |
 187                                                 ((value & 0xFF000000) >> 24);
 188                                 buf_hold = (value & 0xFFFFFF) << 8;
 189                         }
 190 #endif
 191                         /* Realign the source */
 192                         src = (const void *)i_src;
 193                         src += 3;
 194                         break;
 195                 }
 196                 dst = (void *)i_dst;
 197         }
 198
 199         /* simple fast copy, ... unless a cache boundary is crossed */
 200         /* Finish off any remaining bytes */
 201         switch (c) {
 202         case 4:
 203                 *--dst = *--src;
 204         case 3:
 205                 *--dst = *--src;
 206         case 2:
 207                 *--dst = *--src;
 208         case 1:
 209                 *--dst = *--src;
 210         }
 211         return v_dst;
 212 }
 213 #endif /* CONFIG_OPT_LIB_FUNCTION */
 214 EXPORT_SYMBOL(memmove);
 215 #endif /* __HAVE_ARCH_MEMMOVE */