arch/microblaze/lib/memcpy.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 memcpy.
   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
  32 #include <linux/string.h>
  33
  34 #ifdef __HAVE_ARCH_MEMCPY
  35 #ifndef CONFIG_OPT_LIB_FUNCTION
  36 void *memcpy(void *v_dst, const void *v_src, __kernel_size_t c)
  37 {
  38         const char *src = v_src;
  39         char *dst = v_dst;
  40
  41         /* Simple, byte oriented memcpy. */
  42         while (c--)
  43                 *dst++ = *src++;
  44
  45         return v_dst;
  46 }
  47 #else /* CONFIG_OPT_LIB_FUNCTION */
  48 void *memcpy(void *v_dst, const void *v_src, __kernel_size_t c)
  49 {
  50         const char *src = v_src;
  51         char *dst = v_dst;
  52
  53         /* The following code tries to optimize the copy by using unsigned
  54          * alignment. This will work fine if both source and destination are
  55          * aligned on the same boundary. However, if they are aligned on
  56          * different boundaries shifts will be necessary. This might result in
  57          * bad performance on MicroBlaze systems without a barrel shifter.
  58          */
  59         const uint32_t *i_src;
  60         uint32_t *i_dst;
  61
  62         if (likely(c >= 4)) {
  63                 unsigned  value, buf_hold;
  64
  65                 /* Align the destination to a word boundary. */
  66                 /* This is done in an endian independent manner. */
  67                 switch ((unsigned long)dst & 3) {
  68                 case 1:
  69                         *dst++ = *src++;
  70                         --c;
  71                 case 2:
  72                         *dst++ = *src++;
  73                         --c;
  74                 case 3:
  75                         *dst++ = *src++;
  76                         --c;
  77                 }
  78
  79                 i_dst = (void *)dst;
  80
  81                 /* Choose a copy scheme based on the source */
  82                 /* alignment relative to destination. */
  83                 switch ((unsigned long)src & 3) {
  84                 case 0x0:       /* Both byte offsets are aligned */
  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 & ~3);
  95 #ifndef __MICROBLAZEEL__
  96                         /* Load the holding buffer */
  97                         buf_hold = *i_src++ << 8;
  98
  99                         for (; c >= 4; c -= 4) {
 100                                 value = *i_src++;
 101                                 *i_dst++ = buf_hold | value >> 24;
 102                                 buf_hold = value << 8;
 103                         }
 104 #else
 105                         /* Load the holding buffer */
 106                         buf_hold = (*i_src++ & 0xFFFFFF00) >> 8;
 107
 108                         for (; c >= 4; c -= 4) {
 109                                 value = *i_src++;
 110                                 *i_dst++ = buf_hold | ((value & 0xFF) << 24);
 111                                 buf_hold = (value & 0xFFFFFF00) >> 8;
 112                         }
 113 #endif
 114                         /* Realign the source */
 115                         src = (const void *)i_src;
 116                         src -= 3;
 117                         break;
 118                 case 0x2:       /* Unaligned - Off by 2 */
 119                         /* Word align the source */
 120                         i_src = (const void *) ((unsigned)src & ~3);
 121 #ifndef __MICROBLAZEEL__
 122                         /* Load the holding buffer */
 123                         buf_hold = *i_src++ << 16;
 124
 125                         for (; c >= 4; c -= 4) {
 126                                 value = *i_src++;
 127                                 *i_dst++ = buf_hold | value >> 16;
 128                                 buf_hold = value << 16;
 129                         }
 130 #else
 131                         /* Load the holding buffer */
 132                         buf_hold = (*i_src++ & 0xFFFF0000) >> 16;
 133
 134                         for (; c >= 4; c -= 4) {
 135                                 value = *i_src++;
 136                                 *i_dst++ = buf_hold | ((value & 0xFFFF) << 16);
 137                                 buf_hold = (value & 0xFFFF0000) >> 16;
 138                         }
 139 #endif
 140                         /* Realign the source */
 141                         src = (const void *)i_src;
 142                         src -= 2;
 143                         break;
 144                 case 0x3:       /* Unaligned - Off by 3 */
 145                         /* Word align the source */
 146                         i_src = (const void *) ((unsigned)src & ~3);
 147 #ifndef __MICROBLAZEEL__
 148                         /* Load the holding buffer */
 149                         buf_hold = *i_src++ << 24;
 150
 151                         for (; c >= 4; c -= 4) {
 152                                 value = *i_src++;
 153                                 *i_dst++ = buf_hold | value >> 8;
 154                                 buf_hold = value << 24;
 155                         }
 156 #else
 157                         /* Load the holding buffer */
 158                         buf_hold = (*i_src++ & 0xFF000000) >> 24;
 159
 160                         for (; c >= 4; c -= 4) {
 161                                 value = *i_src++;
 162                                 *i_dst++ = buf_hold | ((value & 0xFFFFFF) << 8);
 163                                 buf_hold = (value & 0xFF000000) >> 24;
 164                         }
 165 #endif
 166                         /* Realign the source */
 167                         src = (const void *)i_src;
 168                         src -= 1;
 169                         break;
 170                 }
 171                 dst = (void *)i_dst;
 172         }
 173
 174         /* Finish off any remaining bytes */
 175         /* simple fast copy, ... unless a cache boundary is crossed */
 176         switch (c) {
 177         case 3:
 178                 *dst++ = *src++;
 179         case 2:
 180                 *dst++ = *src++;
 181         case 1:
 182                 *dst++ = *src++;
 183         }
 184
 185         return v_dst;
 186 }
 187 #endif /* CONFIG_OPT_LIB_FUNCTION */
 188 EXPORT_SYMBOL(memcpy);
 189 #endif /* __HAVE_ARCH_MEMCPY */