def xxx_memcpy(jitter):
    """
    #include <string.h>
    void *memcpy(void *dest, const void *src, size_t n);

    copies n bytes from memory area src to memory area dest.
    """
    ret_addr, args = jitter.func_args_systemv(['dest', 'src', 'n'])
    jitter.vm.set_mem(args.dest, jitter.vm.get_mem(args.src, args.n))
    return jitter.func_ret_systemv(ret_addr, args.dest)
