| /* |
| * 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 memmove. |
| * |
| * 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> |
| |
| #ifdef __HAVE_ARCH_MEMMOVE |
| #ifndef CONFIG_OPT_LIB_FUNCTION |
| void *memmove(void *v_dst, const void *v_src, __kernel_size_t c) |
| { |
| const char *src = v_src; |
| char *dst = v_dst; |
| |
| if (!c) |
| return v_dst; |
| |
| /* Use memcpy when source is higher than dest */ |
| if (v_dst <= v_src) |
| return memcpy(v_dst, v_src, c); |
| |
| /* copy backwards, from end to beginning */ |
| src += c; |
| dst += c; |
| |
| /* Simple, byte oriented memmove. */ |
| while (c--) |
| *--dst = *--src; |
| |
| return v_dst; |
| } |
| #else /* CONFIG_OPT_LIB_FUNCTION */ |
| void *memmove(void *v_dst, const void *v_src, __kernel_size_t c) |
| { |
| const char *src = v_src; |
| char *dst = v_dst; |
| const uint32_t *i_src; |
| uint32_t *i_dst; |
| |
| if (!c) |
| return v_dst; |
| |
| /* Use memcpy when source is higher than dest */ |
| if (v_dst <= v_src) |
| return memcpy(v_dst, v_src, c); |
| |
| /* 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. |
| */ |
| /* FIXME this part needs more test */ |
| /* Do a descending copy - this is a bit trickier! */ |
| dst += c; |
| src += c; |
| |
| if (c >= 4) { |
| unsigned value, buf_hold; |
| |
| /* Align the destination to a word boundry. */ |
| /* This is done in an endian independant manner. */ |
| |
| switch ((unsigned long)dst & 3) { |
| case 3: |
| *--dst = *--src; |
| --c; |
| case 2: |
| *--dst = *--src; |
| --c; |
| case 1: |
| *--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 + 4) & ~3); |
| |
| /* Load the holding buffer */ |
| buf_hold = *--i_src >> 24; |
| |
| for (; c >= 4; c -= 4) { |
| value = *--i_src; |
| *--i_dst = buf_hold << 8 | value; |
| buf_hold = value >> 24; |
| } |
| |
| /* Realign the source */ |
| src = (const void *)i_src; |
| src += 1; |
| break; |
| case 0x2: /* Unaligned - Off by 2 */ |
| /* Word align the source */ |
| i_src = (const void *) (((unsigned)src + 4) & ~3); |
| |
| /* Load the holding buffer */ |
| buf_hold = *--i_src >> 16; |
| |
| for (; c >= 4; c -= 4) { |
| value = *--i_src; |
| *--i_dst = buf_hold << 16 | value; |
| 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 + 4) & ~3); |
| |
| /* Load the holding buffer */ |
| buf_hold = *--i_src >> 8; |
| |
| for (; c >= 4; c -= 4) { |
| value = *--i_src; |
| *--i_dst = buf_hold << 24 | value; |
| buf_hold = value >> 8; |
| } |
| |
| /* Realign the source */ |
| src = (const void *)i_src; |
| src += 3; |
| break; |
| } |
| dst = (void *)i_dst; |
| } |
| |
| /* simple fast copy, ... unless a cache boundry is crossed */ |
| /* Finish off any remaining bytes */ |
| switch (c) { |
| case 4: |
| *--dst = *--src; |
| case 3: |
| *--dst = *--src; |
| case 2: |
| *--dst = *--src; |
| case 1: |
| *--dst = *--src; |
| } |
| return v_dst; |
| } |
| #endif /* CONFIG_OPT_LIB_FUNCTION */ |
| EXPORT_SYMBOL(memmove); |
| #endif /* __HAVE_ARCH_MEMMOVE */ |