UART - Raspberry Pi Hardware Reference - page 107

Disabling ISTRIP prevents the kernel from stripping the high-order bit in the byte.
Disabling INLCR , ICRNL prevents the substitution of NL or CR characters (for input).
Disabling IGNCR prevents the kernel from deleting the CR character from the input stream.
Disabling IXON disables software flow control so that the characters XON and XOFF can be
read by the application program.
Looking at the output processing changes,

term.c_oflag &= ~OPOST;

we see that the following change applies:

Flag Description Setting

OPOST Enable output processing Disabled

This disables all output processing features with one flag.
Local processing includes both input and output. The following local processing
flags are changed:

term.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG| IEXTEN);

From this, we see that these local processing features are disabled:

Flag Description Setting

ECHO Echo input Disabled

ECHONL Echo NL even if !ECHO Disabled

ICANON Enable canonical mode Disabled

ISIG Generate signals Disabled

IEXTEN Enable input processing Disabled

Disabling ICANON means that all special nonsignal characters defined in c_cc are
disregarded (like VERASE ). Disabling ISIG means that there will be no signals sent to your
application for characters like VINTR . Disabling IEXTEN disables other c_cc character
processing like VEOL2 , VLNEXT , VREPRINT , VWERASE , and the IUCLC flag. Disabling ECHO and
ECHONL disables two aspects of character echoing.
Finally, the following control aspects are changed:

term.c_cflag &= ~ (CSIZE | PARENB);
term.c_cflag |= CS8;