uclibc-ng/libc/string/i386/memmove.c

/*
 * This string-include defines all string functions as inline
 * functions. Use gcc. It also assumes ds=es=data space, this should be
 * normal. Most of the string-functions are rather heavily hand-optimized,
 * see especially strtok,strstr,str[c]spn. They should work, but are not
 * very easy to understand. Everything is done entirely within the register
 * set, making the functions fast and clean. String instructions have been
 * used through-out, making for "slightly" unclear code :-)
 *
 *		NO Copyright (C) 1991, 1992 Linus Torvalds,
 *		consider these trivial functions to be PD.
 */

/*
 * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
 *
 * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
 */

/*
 * Modified for uClibc by Erik Andersen <andersen@codepoet.org>
 * These make no attempt to use nifty things like mmx/3dnow/etc.
 * These are not inline, and will therefore not be as fast as
 * modifying the headers to use inlines (and cannot therefore
 * do tricky things when dealing with const memory).  But they
 * should (I hope!) be faster than their generic equivalents....
 *
 * More importantly, these should provide a good example for
 * others to follow when adding arch specific optimizations.
 *  -Erik
 */

#include <string.h>

#undef memmove
void attribute_hidden *__memmove(void *dest, const void *src, size_t n)
{
    int d0, d1, d2;
    if (dest<src)
	__asm__ __volatile__(
		"rep\n\t"
		"movsb"
		: "=&c" (d0), "=&S" (d1), "=&D" (d2)
		:"0" (n),"1" (src),"2" (dest)
		: "memory");
    else
	__asm__ __volatile__(
		"std\n\t"
		"rep\n\t"
		"movsb\n\t"
		"cld"
		: "=&c" (d0), "=&S" (d1), "=&D" (d2)
		:"0" (n),
		"1" (n-1+(const char *)src),
		"2" (n-1+(char *)dest)
		:"memory");
    return dest;
}

strong_alias(__memmove, memmove)