diff options
Diffstat (limited to 'arch/microblaze/lib/memmove.c')
| -rw-r--r-- | arch/microblaze/lib/memmove.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/arch/microblaze/lib/memmove.c b/arch/microblaze/lib/memmove.c new file mode 100644 index 0000000..d4e9f49 --- /dev/null +++ b/arch/microblaze/lib/memmove.c @@ -0,0 +1,175 @@ +/* + * 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, unsuccesfully, 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 +void *memmove(void *v_dst, const void *v_src, __kernel_size_t c) +{ + const char *src = v_src; + char *dst = v_dst; + +#ifdef CONFIG_OPT_LIB_FUNCTION + const uint32_t *i_src; + uint32_t *i_dst; +#endif + + 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); + +#ifndef CONFIG_OPT_LIB_FUNCTION + /* copy backwards, from end to beginning */ + src += c; + dst += c; + + /* Simple, byte oriented memmove. */ + 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. + */ + /* 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 +} +EXPORT_SYMBOL(memmove); +#endif /* __HAVE_ARCH_MEMMOVE */ |