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 CONFIG_OPT_LIB_FUNCTION
  34 void *memmove(void *v_dst, const void *v_src, __kernel_size_t c)
  35 {
  36         const char *src = v_src;
  37         char *dst = v_dst;
  38         const uint32_t *i_src;
  39         uint32_t *i_dst;
  40
  41         if (!c)
  42                 return v_dst;
  43
  44         /* Use memcpy when source is higher than dest */
  45         if (v_dst <= v_src)
  46                 return memcpy(v_dst, v_src, c);
  47
  48         /* The following code tries to optimize the copy by using unsigned
  49          * alignment. This will work fine if both source and destination are
  50          * aligned on the same boundary. However, if they are aligned on
  51          * different boundaries shifts will be necessary. This might result in
  52          * bad performance on MicroBlaze systems without a barrel shifter.
  53          */
  54         /* FIXME this part needs more test */
  55         /* Do a descending copy - this is a bit trickier! */
  56         dst += c;
  57         src += c;
  58
  59         if (c >= 4) {
  60                 unsigned  value, buf_hold;
  61
  62                 /* Align the destination to a word boundary. */
  63                 /* This is done in an endian independent manner. */
  64
  65                 switch ((unsigned long)dst & 3) {
  66                 case 3:
  67                         *--dst = *--src;
  68                         --c;
  69                         fallthrough;
  70                 case 2:
  71                         *--dst = *--src;
  72                         --c;
  73                         fallthrough;
  74                 case 1:
  75                         *--dst = *--src;
  76                         --c;
  77                 }
  78
  79                 i_dst = (void *)dst;
  80                 /* Choose a copy scheme based on the source */
  81                 /* alignment relative to destination. */
  82                 switch ((unsigned long)src & 3) {
  83                 case 0x0:       /* Both byte offsets are aligned */
  84
  85                         i_src  = (const void *)src;
  86
  87                         for (; c >= 4; c -= 4)
  88                                 *--i_dst = *--i_src;
  89
  90                         src  = (const void *)i_src;
  91                         break;
  92                 case 0x1:       /* Unaligned - Off by 1 */
  93                         /* Word align the source */
  94                         i_src = (const void *) (((unsigned)src + 4) & ~3);
  95 #ifndef __MICROBLAZEEL__
  96                         /* Load the holding buffer */
  97                         buf_hold = *--i_src >> 24;
  98
  99                         for (; c >= 4; c -= 4) {
 100                                 value = *--i_src;
 101                                 *--i_dst = buf_hold << 8 | value;
 102                                 buf_hold = value >> 24;
 103                         }
 104 #else
 105                         /* Load the holding buffer */
 106                         buf_hold = (*--i_src & 0xFF) << 24;
 107
 108                         for (; c >= 4; c -= 4) {
 109                                 value = *--i_src;
 110                                 *--i_dst = buf_hold |
 111                                                 ((value & 0xFFFFFF00) >> 8);
 112                                 buf_hold = (value  & 0xFF) << 24;
 113                         }
 114 #endif
 115                         /* Realign the source */
 116                         src = (const void *)i_src;
 117                         src += 1;
 118                         break;
 119                 case 0x2:       /* Unaligned - Off by 2 */
 120                         /* Word align the source */
 121                         i_src = (const void *) (((unsigned)src + 4) & ~3);
 122 #ifndef __MICROBLAZEEL__
 123                         /* Load the holding buffer */
 124                         buf_hold = *--i_src >> 16;
 125
 126                         for (; c >= 4; c -= 4) {
 127                                 value = *--i_src;
 128                                 *--i_dst = buf_hold << 16 | value;
 129                                 buf_hold = value >> 16;
 130                         }
 131 #else
 132                         /* Load the holding buffer */
 133                         buf_hold = (*--i_src & 0xFFFF) << 16;
 134
 135                         for (; c >= 4; c -= 4) {
 136                                 value = *--i_src;
 137                                 *--i_dst = buf_hold |
 138                                                 ((value & 0xFFFF0000) >> 16);
 139                                 buf_hold = (value & 0xFFFF) << 16;
 140                         }
 141 #endif
 142                         /* Realign the source */
 143                         src = (const void *)i_src;
 144                         src += 2;
 145                         break;
 146                 case 0x3:       /* Unaligned - Off by 3 */
 147                         /* Word align the source */
 148                         i_src = (const void *) (((unsigned)src + 4) & ~3);
 149 #ifndef __MICROBLAZEEL__
 150                         /* Load the holding buffer */
 151                         buf_hold = *--i_src >> 8;
 152
 153                         for (; c >= 4; c -= 4) {
 154                                 value = *--i_src;
 155                                 *--i_dst = buf_hold << 24 | value;
 156                                 buf_hold = value >> 8;
 157                         }
 158 #else
 159                         /* Load the holding buffer */
 160                         buf_hold = (*--i_src & 0xFFFFFF) << 8;
 161
 162                         for (; c >= 4; c -= 4) {
 163                                 value = *--i_src;
 164                                 *--i_dst = buf_hold |
 165                                                 ((value & 0xFF000000) >> 24);
 166                                 buf_hold = (value & 0xFFFFFF) << 8;
 167                         }
 168 #endif
 169                         /* Realign the source */
 170                         src = (const void *)i_src;
 171                         src += 3;
 172                         break;
 173                 }
 174                 dst = (void *)i_dst;
 175         }
 176
 177         /* simple fast copy, ... unless a cache boundary is crossed */
 178         /* Finish off any remaining bytes */
 179         switch (c) {
 180         case 4:
 181                 *--dst = *--src;
 182                 fallthrough;
 183         case 3:
 184                 *--dst = *--src;
 185                 fallthrough;
 186         case 2:
 187                 *--dst = *--src;
 188                 fallthrough;
 189         case 1:
 190                 *--dst = *--src;
 191         }
 192         return v_dst;
 193 }
 194 EXPORT_SYMBOL(memmove);
 195 #endif /* CONFIG_OPT_LIB_FUNCTION */