libft/ft_memmove.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_memmove.c                                       :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: kcolin <marvin@42.fr>                      +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/10/15 13:57:12 by kcolin            #+#    #+#             */
/*   Updated: 2024/10/22 12:15:04 by kcolin           ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "libft.h"
#include <stdlib.h>

/*
 * case 1: dest overlaps at start of src. 
 * src is before dest.
 * copy back to front
 *
 * case 2: dest overlaps at beginning of src.
 * src is after dest.
 * copy front to back.
 *
 * case 3: dest and src do not overlap
 * it doesn't matter how the data is copied
 * merge with case 2
 */
void	*ft_memmove(void *dest, const void *src, size_t n)
{
	size_t	i;

	if ((dest == NULL && src == NULL) && n > 0)
		return (dest);
	if (dest >= src && dest <= (src + n))
	{
		i = n;
		while (i > 0)
		{
			i--;
			((char *)dest)[i] = ((char *)src)[i];
		}
	}
	else
		ft_memcpy(dest, src, n);
	return (dest);
}

/*
#include <string.h>
#include <stdio.h>
#include "libft.h"

int	main(void)
{
	char	buf[27] = "abcdefghijklmnopqrstuvwxyz";
	char	buf2[27] = "abcdefghijklmnopqrstuvwxyz";

	printf("%p\n", ft_memmove(buf, buf+3, 6));
	printf("%s\n", buf);
	printf("%p\n", ft_memmove(buf+10, buf+8, 6));
	printf("%s\n", buf);
	printf("%p\n", ft_memmove(buf, buf+6, 6));
	printf("%s\n", buf);
	printf("%p\n", memmove(buf2, buf2+3, 6));
	printf("%s\n", buf2);
	printf("%p\n", memmove(buf2+10, buf2+8, 6));
	printf("%s\n", buf2);
	printf("%p\n", memmove(buf2, buf2+6, 6));
	printf("%s\n", buf2);
	printf("%p\n", ft_memmove(NULL, NULL, 6));
}
*/