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