Использовать void из 1.cpp в 2.cpp

void Hello();

void Hello()
{
    pD3DFont->PrintShadow( 1, 500, MENU_COLOR_DEFAULT, "Text" );
}

void cmd_n1(  )
{   
    clst = SetTimer(NULL,1,6000,(TIMERPROC)tick);
    clen = SetTimer(NULL,1,16000,(TIMERPROC)tick1);
    Hello();
}

addClientCommand( "cmd1", (int)cmd_n1);

void addClientCommand ( char *name, int function )

void addClientCommand ( char *name, int function )
{
    if ( name == NULL || function == NULL || g_Input == NULL )
        return;
 
    if ( g_Input->iCMDCount == (MAX_CLIENTCMDS-1) )
    {
        Log( "Error: couldn't initialize '%s'. Maximum command amount reached.", name );
        return;
    }
 
    if ( strlen(name) > 30 )
    {
        Log( "Error: command name '%s' was too long.", name );
        return;
    }
 
    if ( m0d_cmd_num < (MAX_CLIENTCMDS - 22) )
    {
        strncpy_s( m0d_cmd_list[m0d_cmd_num].cmd_name, name, sizeof(m0d_cmd_list[m0d_cmd_num].cmd_name)-1 );
        m0d_cmd_num++;
    }
    else
        Log( "m0d_cmd_list[] too short." );
 
    uint32_t    data = g_dwSAMP_Addr + SAMP_CHAT_INPUT_INFO_OFFSET;
    uint32_t    func = g_dwSAMP_Addr + FUNC_ADDCLIENTCMD;
    __asm mov eax, data
    __asm mov ecx, [eax]
    __asm push function
    __asm push name
    __asm call func
}

cmd_n1();

cmd_n1();