ft_memmove: initial implementation

This was tricky to visualize, consider bringing pen and paper next time

Makefile

@@ -6,7 +6,7 @@
 #    By: kcolin <marvin@42.fr>                      +#+  +:+       +#+         #
 #                                                 +#+#+#+#+#+   +#+            #
 #    Created: 2024/10/14 13:43:59 by kcolin            #+#    #+#              #
-#    Updated: 2024/10/15 13:37:50 by kcolin           ###   ########.fr        #
+#    Updated: 2024/10/15 13:56:10 by kcolin           ###   ########.fr        #
 #                                                                              #
 # **************************************************************************** #
 
@@ -20,7 +20,8 @@ SOURCES = ft_isalpha.c \
 	ft_strlen.c \
 	ft_memset.c \
 	ft_bzero.c \
-	ft_memcpy.c
+	ft_memcpy.c \
+	ft_memmove.c
 OBJECTS = $(SOURCES:.c=.o)
 CC = gcc
 

ft_memmove.c

@@ -0,0 +1,46 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ft_memmove.c                                       :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: kcolin <marvin@42.fr>                      +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2024/10/15 13:57:12 by kcolin            #+#    #+#             */
+/*   Updated: 2024/10/15 14:12:15 by kcolin           ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "libft.h"
+
+/*
+ * case 1: dst overlaps at start of src. 
+ * src is before dst.
+ * copy back to front
+ *
+ * case 2: dst overlaps at beginning of src.
+ * src is after dst.
+ * copy front to back.
+ *
+ * case 3: dst and src do not overlap
+ * it doesn't matter how the data is copied
+ * merge with case 2
+ */
+void	*ft_memmove(void *dst, const void *src, t_size len)
+{
+	t_size	i;
+
+	if (dst >= src && dst <= (src + len))
+	{
+		i = len;
+		while (i > 0)
+		{
+			i--;
+			((char *)dst)[i] = ((char *)src)[i];
+		}
+	}
+	else
+	{
+		ft_memcpy(dst, src, len);
+	}
+	return (dst);
+}

libft.h

@@ -6,7 +6,7 @@
 /*   By: kcolin <marvin@42.fr>                      +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2024/10/15 10:11:54 by kcolin            #+#    #+#             */
-/*   Updated: 2024/10/15 13:37:25 by kcolin           ###   ########.fr       */
+/*   Updated: 2024/10/15 13:56:53 by kcolin           ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -26,5 +26,6 @@ t_size	ft_strlen(const char *s);
 void	*ft_memset(void *dest, int c, t_size len);
 void	ft_bzero(void *b, t_size len);
 void	*ft_memcpy(void *dst, const void *src, t_size len);
+void	*ft_memmove(void *dst, const void *src, t_size len);
 
 #endif