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 */ 190