feat: added memchr, memcmp, memmv and realloc

srcs/ft_memmv.c

@@ -0,0 +1,44 @@
+#include <stddef.h>
+#include <stdint.h>
+
+void *ft_memmove(void *dst, const void *src, size_t n)
+{
+    unsigned char *d = dst;
+    const unsigned char *s = src;
+
+    if (d == s || n == 0)
+        return dst;
+
+    if (d < s) {
+        while (((uintptr_t)d % sizeof(size_t)) && n) {
+            *d++ = *s++;
+            n--;
+        }
+        while (n >= sizeof(size_t)) {
+            *(size_t *)d = *(const size_t *)s;
+            d += sizeof(size_t);
+            s += sizeof(size_t);
+            n -= sizeof(size_t);
+        }
+        while (n--) {
+            *d++ = *s++;
+        }
+    } else {
+        d += n;
+        s += n;
+        while (n && ((uintptr_t)d % sizeof(size_t))) {
+            *(--d) = *(--s);
+            n--;
+        }
+        while (n >= sizeof(size_t)) {
+            d -= sizeof(size_t);
+            s -= sizeof(size_t);
+            *(size_t *)d = *(const size_t *)s;
+            n -= sizeof(size_t);
+        }
+        while (n--) {
+            *(--d) = *(--s);
+        }
+    }
+    return (dst);
+}