libunix: add memmove()

libunix/Makefile

@@ -12,7 +12,7 @@ LIBRARY = libunix.a
 SOURCES = divsi3.S modsi3.S mulsi3.S udivsi3.S umodsi3.S free.c malloc.c \
 	  memcpy.c memset.c printf.c putchar.c puts.c read.c sprintf.c \
 	  strcpy.c strlen.c strncpy.c vsprintf.c write.c strcmp.c \
-	  strncmp.c strtol.c strdup.c
+	  strncmp.c strtol.c strdup.c memmove.c
 
 HEADERS =
 

libunix/memmove.c

@@ -0,0 +1,31 @@
+/*
+ *
+ * (c) 2025 Laurent Vivier <Laurent@Vivier.EU>
+ *
+ */
+
+#include <sys/types.h>
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+	unsigned char *d = dest;
+	const unsigned char *s = src;
+
+	if (d == s || n == 0)
+		return dest;
+
+	if (d < s)
+	{
+		while (n--)
+			*d++ = *s++;
+	}
+	else
+	{
+		d += n;
+		s += n;
+		while (n--)
+			*--d = *--s;
+	}
+
+	return dest;
+}