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x86: Import glibc memcpy implementation

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Taken from glibc version 2.14.90

--
Changes for v2:
 - None
This commit is contained in:
Graeme Russ 2011-12-27 22:46:39 +11:00
parent bfcc40bb09
commit b2c2a03842
2 changed files with 62 additions and 1 deletions
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2
arch/x86/include/asm/string.h
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@ -14,7 +14,7 @@ extern char * strrchr(const char * s, int c);
#undef __HAVE_ARCH_STRCHR
extern char * strchr(const char * s, int c);
#undef __HAVE_ARCH_MEMCPY
#define __HAVE_ARCH_MEMCPY
extern void * memcpy(void *, const void *, __kernel_size_t);
#undef __HAVE_ARCH_MEMMOVE

61
arch/x86/lib/string.c
View File

@ -85,3 +85,64 @@ void *memset(void *dstpp, int c, size_t len)
return dstpp;
}
#define OP_T_THRES 8
#define OPSIZ (sizeof(op_t))
#define BYTE_COPY_FWD(dst_bp, src_bp, nbytes) \
do { \
int __d0; \
asm volatile( \
/* Clear the direction flag, so copying goes forward. */ \
"cld\n" \
/* Copy bytes. */ \
"rep\n" \
"movsb" : \
"=D" (dst_bp), "=S" (src_bp), "=c" (__d0) : \
"0" (dst_bp), "1" (src_bp), "2" (nbytes) : \
"memory"); \
} while (0)
#define WORD_COPY_FWD(dst_bp, src_bp, nbytes_left, nbytes) \
do { \
int __d0; \
asm volatile( \
/* Clear the direction flag, so copying goes forward. */ \
"cld\n" \
/* Copy longwords. */ \
"rep\n" \
"movsl" : \
"=D" (dst_bp), "=S" (src_bp), "=c" (__d0) : \
"0" (dst_bp), "1" (src_bp), "2" ((nbytes) / 4) : \
"memory"); \
(nbytes_left) = (nbytes) % 4; \
} while (0)
void *memcpy(void *dstpp, const void *srcpp, size_t len)
{
unsigned long int dstp = (long int)dstpp;
unsigned long int srcp = (long int)srcpp;
/* Copy from the beginning to the end. */
/* If there not too few bytes to copy, use word copy. */
if (len >= OP_T_THRES) {
/* Copy just a few bytes to make DSTP aligned. */
len -= (-dstp) % OPSIZ;
BYTE_COPY_FWD(dstp, srcp, (-dstp) % OPSIZ);
/* Copy from SRCP to DSTP taking advantage of the known
* alignment of DSTP. Number of bytes remaining is put
* in the third argument, i.e. in LEN. This number may
* vary from machine to machine.
*/
WORD_COPY_FWD(dstp, srcp, len, len);
/* Fall out and copy the tail. */
}
/* There are just a few bytes to copy. Use byte memory operations. */
BYTE_COPY_FWD(dstp, srcp, len);
return dstpp;
}