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The Inspiring Journey Of Emma Kotos A Rising Star In The World Of Social Media Stgrm Live Strem 28 Jnury 2020 Ig Live's Tv is currently gaining attention. //标志fndelay可以保证read函数在端口上读不到字符的时候返回0 //fcntl (fd, f_setfl, 0); Description top fcntl () performs one of the operations described below on the open file descriptor fd.
The Inspiring Journey Of Emma Kotos A Rising Star In The World Of Social Media Stgrm Live Strem 28 Jnury 2020 Ig Live's Tv – //标志fndelay可以保证read函数在端口上读不到字符的时候返回0 //fcntl (fd, f_setfl, 0);
Description top fcntl () performs one of the operations described below on the open file descriptor fd. { if (fcntl (fd,f_setfl,fndelay) < 0) //非阻塞，覆盖前面open的属性 { printf (fcntl failed\n); } } else { if (fcntl. 打开后使用 fcntl 函数修改： fcntl (fd, f_setfl, 0)； //设为阻塞，即使前面在 open 串口设备时设置的是非阻塞的，这里设为阻塞后，以此为准 fcntl (fd,f_setfl,fndelay)//设为非阻塞，道.
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Certain of the operations below are. Fnonblock == o_nonblock fndelay == o_ndelay 所以 fndelay == fnonblock 上面设置非阻塞模式的方法归根结底就是要把文件状态加上o_nonblock一个. The operation is determined by op. 在打开串口成功后，使用fcntl (fd, f_setfl, fndelay)语句，可以使read函数立即返回而不阻塞。 fndelay选项使read函数在串口无字符时立即返回且为0。
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} else { printf (fcntl=%d\n,fcntl (fd,f_setfl,fndelay)); Fndelay 函数使read函数在端口没月字符存在的情况下，立刻返回0, 如果要恢复正常 (阻塞)状态,可以调用fcntl ()函数，不要fndelay参数,
