ronaldo.afonso@xxxxxxxxxxx wrote: > > > > Hello all, > > I'm trying to read data from a "tty" one character at a time. I'd like that > when a single byte was inputed on one side of my tty, it imediataly must be > read by my user space program on the otherside. It is not happening in my > environment and I belive the cause is a buffer in the tty driver. I'd like > to know if it could be happening, I mean, could a tty be buffering data > before send to user space, and if so, what can I do to inform the tty > driver not buffering data anymore? > Thanks. > > > ==================================================== > Ronaldo Z. Afonso > Software Engineering > Avocent Corporation, formerly Cyclades > ronaldo.afonso@xxxxxxxxxxx > Phone: 55 11 5033-3361 > Fax: 55 11 5033-3388 > www.avocent.com > ==================================================== > > - > : send the line "unsubscribe linux-c-programming" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Hi, This is a small demo I made some time ago. Should help. #include <stdlib.h> #include <stdio.h> #include <sys/time.h> #include <sys/types.h> #include <sys/select.h> #include <termios.h> #include <unistd.h> int main( void ) { fd_set read_fd; struct termios t; struct timeval tv; /* Since '0' is open()-ed to STDIN... let's use this */ /* "See" what the terminal knows */ tcgetattr( 0, &t ); /* "Tell" the terminal not to wait for EOL (Enter) */ t.c_lflag &= ~( ICANON ); /* This should be restored if not needed anymore */ tcsetattr( 0, TCSANOW, &t ); printf( "Waiting for ESC ...\n" ); while ( 1 ) { memset( &tv, 0, sizeof( tv ) ); tv.tv_sec = 1; /* These two below shold not be needed (should be outside the loop), but somehow the program won't work without them */ FD_ZERO( &read_fd ); FD_SET( 0, &read_fd ); /* Aaa... multiplexing for the penguins :-) */ if ( select( 1, &read_fd, NULL, NULL, &tv ) > 0 && FD_ISSET( 0, &read_fd ) ) { unsigned v = 0; /* Read what we've got so far */ read( 0, &v, sizeof( v ) ); /* Mask out the extra data and leave the character code */ v &= 0x7F; /* This has been deduced experimentaly :-) */ if ( v == 0x1b ) printf( "ESC!\n" ); } else { /* Do something */ printf( "Zum\n" ); } } return 0; } Enjoy, M.D. -- |_|0|_| |_|_|0| |0|0|0| -- This message was scanned for spam and viruses by BitDefender. For more information please visit http://www.bitdefender.com/ - : send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
