xref: /haiku/src/system/libroot/posix/string/memmove.c (revision 9642f7705b27e5c270c15fa526d14e1848c2c27d)

/*
 * Copyright 2001, Travis Geiselbrecht. All rights reserved.
 * Distributed under the terms of the NewOS License.
 */


#include <sys/types.h>
#include <string.h>

#if !_ASM_MEMCPY

typedef int word;

#define lsize sizeof(word)
#define lmask (lsize - 1)


void*
memmove(void* dest, void const* src, size_t count)
{
	char* d = (char*)dest;
	const char* s = (const char*)src;
	int len;

	if (count == 0 || dest == src)
		return dest;

	if ((long)d < (long)s) {
		if (((long)d | (long)s) & lmask) {
			// src and/or dest do not align on word boundary
			if ((((long)d ^ (long)s) & lmask) || (count < lsize))
				len = count; // copy the rest of the buffer with the byte mover
			else
				len = lsize - ((long)d & lmask); // move the ptrs up to a word boundary

			count -= len;
			for (; len > 0; len--)
				*d++ = *s++;
		}
		for (len = count / lsize; len > 0; len--) {
			*(word*)d = *(word*)s;
			d += lsize;
			s += lsize;
		}
		for (len = count & lmask; len > 0; len--)
			*d++ = *s++;
	} else {
		d += count;
		s += count;
		if (((long)d | (long)s) & lmask) {
			// src and/or dest do not align on word boundary
			if ((((long)d ^ (long)s) & lmask) || (count <= lsize))
				len = count;
			else
				len = ((long)d & lmask);

			count -= len;
			for (; len > 0; len--)
				*--d = *--s;
		}
		for (len = count / lsize; len > 0; len--) {
			d -= lsize;
			s -= lsize;
			*(word*)d = *(word*)s;
		}
		for (len = count & lmask; len > 0; len--)
			*--d = *--s;
	}

	return dest;
}

#if defined(__arm__)
void* __aeabi_memmove(void* dest, void const* src, size_t count)
	__attribute__((__alias__("memmove")));
#endif

#endif