x86_string.c File Reference

Optimised string operations. More...

#include <string.h>
#include <config/defaults.h>

Go to the source code of this file.

Macros
#define	USE_GENERIC_MEMCPY_REVERSE   0

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
void *	__attribute__ ((noinline))
	Copy memory area. More...
void *	__memmove (void *dest, const void *src, size_t len)
	Copy (possibly overlapping) memory area. More...

Detailed Description

Optimised string operations.

Definition in file x86_string.c.

Macro Definition Documentation

USE_GENERIC_MEMCPY_REVERSE

#define USE_GENERIC_MEMCPY_REVERSE   0

Definition at line 39 of file x86_string.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

__attribute__()

void* __attribute__

(

(noinline)

)

Copy memory area.

Copy memory area backwards.

Parameters

dest	Destination address
src	Source address
len	Length

Return values

dest	Destination address

Definition at line 50 of file x86_string.c.

                                                            {
        void *edi = dest;
        const void *esi = src;
        int discard_ecx;

        /* We often do large dword-aligned and dword-length block
         * moves.  Using movsl rather than movsb speeds these up by
         * around 32%.
         */
        __asm__ __volatile__ ( "rep movsl"
                               : "=&D" ( edi ), "=&S" ( esi ),
                                 "=&c" ( discard_ecx )
                               : "0" ( edi ), "1" ( esi ), "2" ( len >> 2 )
                               : "memory" );
        __asm__ __volatile__ ( "rep movsb"
                               : "=&D" ( edi ), "=&S" ( esi ),
                                 "=&c" ( discard_ecx )
                               : "0" ( edi ), "1" ( esi ), "2" ( len & 3 )
                               : "memory" );
        return dest;
}

References __asm__(), __volatile__(), dest, discard_ecx, edi, esi, len, and src.

__memmove()

void* __memmove	(	void *	dest,
		const void *	src,
		size_t	len
	)

Copy (possibly overlapping) memory area.

Parameters

dest	Destination address
src	Source address
len	Length

Return values

dest	Destination address

Definition at line 117 of file x86_string.c.

                                                             {

        if ( dest <= src ) {
                return __memcpy ( dest, src, len );
        } else {
                return __memcpy_reverse ( dest, src, len );
        }
}

References __memcpy(), __memcpy_reverse(), dest, len, and src.