/* * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu> * Copyright (C) 2008-2009 PetaLogix * Copyright (C) 2007 John Williams * * Reasonably optimised generic C-code for memcpy on Microblaze * This is generic C code to do efficient, alignment-aware memcpy. * * It is based on demo code originally Copyright 2001 by Intel Corp, taken from * http://www.embedded.com/showArticle.jhtml?articleID=19205567 * * Attempts were made, unsuccessfully, to contact the original * author of this code (Michael Morrow, Intel). Below is the original * copyright notice. * * This software has been developed by Intel Corporation. * Intel specifically disclaims all warranties, express or * implied, and all liability, including consequential and * other indirect damages, for the use of this program, including * liability for infringement of any proprietary rights, * and including the warranties of merchantability and fitness * for a particular purpose. Intel does not assume any * responsibility for and errors which may appear in this program * not any responsibility to update it. */ #include <linux/types.h> #include <linux/stddef.h> #include <linux/compiler.h> #include <linux/module.h> #include <linux/string.h> #include <asm/system.h> #ifdef __HAVE_ARCH_MEMCPY void *memcpy(void *v_dst, const void *v_src, __kernel_size_t c) { const char *src = v_src; char *dst = v_dst; #ifndef CONFIG_OPT_LIB_FUNCTION /* Simple, byte oriented memcpy. */ while (c--) *dst++ = *src++; return v_dst; #else /* The following code tries to optimize the copy by using unsigned * alignment. This will work fine if both source and destination are * aligned on the same boundary. However, if they are aligned on * different boundaries shifts will be necessary. This might result in * bad performance on MicroBlaze systems without a barrel shifter. */ const uint32_t *i_src; uint32_t *i_dst; if (c >= 4) { unsigned value, buf_hold; /* Align the dstination to a word boundry. */ /* This is done in an endian independant manner. */ switch ((unsigned long)dst & 3) { case 1: *dst++ = *src++; --c; case 2: *dst++ = *src++; --c; case 3: *dst++ = *src++; --c; } i_dst = (void *)dst; /* Choose a copy scheme based on the source */ /* alignment relative to dstination. */ switch ((unsigned long)src & 3) { case 0x0: /* Both byte offsets are aligned */ i_src = (const void *)src; for (; c >= 4; c -= 4) *i_dst++ = *i_src++; src = (const void *)i_src; break; case 0x1: /* Unaligned - Off by 1 */ /* Word align the source */ i_src = (const void *) ((unsigned)src & ~3); /* Load the holding buffer */ buf_hold = *i_src++ << 8; for (; c >= 4; c -= 4) { value = *i_src++; *i_dst++ = buf_hold | value >> 24; buf_hold = value << 8; } /* Realign the source */ src = (const void *)i_src; src -= 3; break; case 0x2: /* Unaligned - Off by 2 */ /* Word align the source */ i_src = (const void *) ((unsigned)src & ~3); /* Load the holding buffer */ buf_hold = *i_src++ << 16; for (; c >= 4; c -= 4) { value = *i_src++; *i_dst++ = buf_hold | value >> 16; buf_hold = value << 16; } /* Realign the source */ src = (const void *)i_src; src -= 2; break; case 0x3: /* Unaligned - Off by 3 */ /* Word align the source */ i_src = (const void *) ((unsigned)src & ~3); /* Load the holding buffer */ buf_hold = *i_src++ << 24; for (; c >= 4; c -= 4) { value = *i_src++; *i_dst++ = buf_hold | value >> 8; buf_hold = value << 24; } /* Realign the source */ src = (const void *)i_src; src -= 1; break; } dst = (void *)i_dst; } /* Finish off any remaining bytes */ /* simple fast copy, ... unless a cache boundry is crossed */ switch (c) { case 3: *dst++ = *src++; case 2: *dst++ = *src++; case 1: *dst++ = *src++; } return v_dst; #endif } EXPORT_SYMBOL(memcpy); #endif /* __HAVE_ARCH_MEMCPY */