termios raw question

[Eric Norum]

If your code is looking for  '\n' to terminate the read, and the  
device is actually sending a '\r' then you'll never see an 'end-of- 
line' unless ICRNL is set.

i.e. if your code looks something like:
	for(;;) {
		read(fd,&c,1);
		if (c == '\n')
			break;
		buf[i++] = c;
	}
then you must have IRCNL set.....


On Feb 14, 2006, at 6:03 PM, Jennifer Averett wrote:

> I'm trying to use termios for reading/writing a raw data stream.
> I am using tcgetattr to get the attributes then setting:
>
>   termios_attr.c_iflag &= ~(IXON|IXANY|IXOFF);
>   termios_attr.c_oflag &= ~OPOST;
>   termios_attr.c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
>   termios_attr.c_cflag = CREAD;
>   termios_attr.c_cflag &= ~(CSIZE|PARENB);
>
>   Setting Baud rate in c_cflag based upon a table value
>   Setting bits per charachter in c_cflag based upon a table value
>   Setting parity in c_cflag based upon a table value
>   Setting number in c_cflag of stop bits based upon a table value
>   Settiing flow control in c_iflag based upon a table value
>
> Then I use tcsetattr to set the attribute.  I found a problem where  
> 0xd
> was being changed to a 0xa with this code and replaced the first  
> c_iflag
> setting with:
>
>   termios_attr.c_iflag &= ~(IXON|IXANY|IXOFF|ICRNL);
>
> However this causes a queue overflow when reading the device.  Does  
> anyone
> know if clearing ICRNL, would have the effect of hoarding input  
> characters
> and if so how to keep this from happening?  Any other suggestions  
> would be
> appreciated.
>
> Jennifer

-- 
Eric Norum <norume at aps.anl.gov>
Advanced Photon Source
Argonne National Laboratory
(630) 252-4793