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On Wed, Nov 24, 2010 at 02:10:44PM -0500, Schwab,Wilhelm K wrote:
>
> The linux vm codes stop bits as follows: 0=1.5, 1=1, 2=2. I have long seen it (on Windows) expressed as
>
> ONESTOPBIT := 0.
> ONE5STOPBITS := 1.
> TWOSTOPBITS := 2.
The Windows and Unix SerialPlugin code the stop bits identically, although
on Unix the 1.5 setting apparently gets rounded up to 2. See man termios
for the reason.
Windows:
/* set stop bits */
switch(stopBitsType) {
case 0: dcb.StopBits = 1; break; /* 1.5 stop bits */
case 1: dcb.StopBits = 0; break; /* 1 stop bit */
case 2: dcb.StopBits = 2; break; /* 2 stop bits */
default: goto errExit;
}
Unix:
/* stopBits 0=1.5, 1=1, 2=2 */
/* I don't know how to get 1.5 stop bits. Oh well. So you get 2 instead */
#define MAX_STOP_BITS 2
/* c_cflag definitions */
static const unsigned int stopBitsDecode[MAX_STOP_BITS + 1] = { CSTOPB, 0, CSTOPB };
> Someone trying to write code that works across platforms will get snagged,
> at least if using the usual Windows definitions. Is this something that
> can/should be done better to make the stop bits as platform-neutral as
> possible? What would you change?
In the plugin, I would change nothing. In class SerialPlugin, I would
add some better method comments.
If I wanted my application code to be easier to understand for someone
accustomed to Windows headers, I might consider making ONESTOPBIT,
ONE5STOPBITS and TWOSTOPBITS be class variables somewhere in my
application. But that looks a bit silly, so I guess I just go with
the method comments and leave it at that.
Dave
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