PX4 FMU启动流程 2. 一、 nsh_newconsole

PX4 FMU启动流程 2. 一、 nsh_newconsole

PX4 FMU启动流程 2. 一、 nsh_newconsole

                                                                             -------- 转载请注明出处

                                                                             -------- 2014-11-27.冷月追风

                                                                             -------- email：merafour@163.com 

    这是一个 new函数。用来创建 stdio接口。

FAR struct console_stdio_s *nsh_newconsole(void)
{
  struct console_stdio_s *pstate = (struct console_stdio_s *)zalloc(sizeof(struct console_stdio_s));
  if (pstate)
    {
      /* Initialize the call table */

#ifndef CONFIG_NSH_DISABLEBG
      pstate->cn_vtbl.clone      = nsh_consoleclone;
      pstate->cn_vtbl.release    = nsh_consolerelease;
#endif
      pstate->cn_vtbl.write      = nsh_consolewrite;
      pstate->cn_vtbl.output     = nsh_consoleoutput;
      pstate->cn_vtbl.linebuffer = nsh_consolelinebuffer;
      pstate->cn_vtbl.redirect   = nsh_consoleredirect;
      pstate->cn_vtbl.undirect   = nsh_consoleundirect;
      pstate->cn_vtbl.exit       = nsh_consoleexit;

      /* (Re-) open the console input device */

#ifdef CONFIG_NSH_CONDEV
      pstate->cn_confd           = open(CONFIG_NSH_CONDEV, O_RDWR);
      if (pstate->cn_confd < 0)
        {
          free(pstate);
          return NULL;
        }

      /* Create a standard C stream on the console device */

      pstate->cn_constream = fdopen(pstate->cn_confd, "r+");
      if (!pstate->cn_constream)
        {
          close(pstate->cn_confd);
          free(pstate);
          return NULL;
        }
#endif

      /* Initialize the output stream */

      pstate->cn_outfd           = OUTFD(pstate);
      pstate->cn_outstream       = OUTSTREAM(pstate);
    }
  return pstate;
}

其实也就是填充了结构 “struct console_stdio_s”。这些接口基本上都可以通过函数名大致了解其作用。除了函数指针外还有两个比较特殊的指针：输出流。