[asterisk-dev] "56k" in dahdi/system.conf [was Re: [svn-commits] mattf: tools/trunk r4818 - /tools/trunk/dahdi_cfg.c]

[Matthew Fredrickson]

Tzafrir Cohen wrote:
> Hi
> 
> On Sun, Aug 24, 2008 at 05:54:12AM -0000, SVN commits to the Digium repositories wrote:
>> Author: mattf
>> Date: Sun Aug 24 00:54:11 2008
>> New Revision: 4818
>>
>> URL: http://svn.digium.com/view/dahdi?view=rev&rev=4818
>> Log:
>> Add support for 56 KB HDLC as well as selectable rate in system.conf
>>
>> Modified:
>>     tools/trunk/dahdi_cfg.c
> 
> What does it mean? Where should it be used?
> 
> Something in the lines of:
> 
> (immedietly following the description of dacsrbs)
> 
> # 56k::
> #   Set a D-channel (which has already been set above as 'bchan',
> #   'hardhdlc' or 'nethdlc') to use 56kbps HDLC.
> 
> The name "56k" sounds strange and and maybe not descriptive enough.

It is basically a call that puts whatever channel that maybe running an 
HDLC encoder or decoder (nethdlc, dchan, mtp2, etc) into 56kbps HDLC mode.

> 
> Also:
> 
>> Modified: tools/trunk/dahdi_cfg.c
>> URL: http://svn.digium.com/view/dahdi/tools/trunk/dahdi_cfg.c?view=diff&rev=4818&r1=4817&r2=4818
>> ==============================================================================
>> --- tools/trunk/dahdi_cfg.c (original)
>> +++ tools/trunk/dahdi_cfg.c Sun Aug 24 00:54:11 2008
>> @@ -85,6 +85,8 @@
>>  static const char *sig[DAHDI_MAX_CHANNELS];		/* Signalling */
>>  
>>  static int slineno[DAHDI_MAX_CHANNELS];	/* Line number where signalling specified */
>> +
>> +static int fiftysixkhdlc[DAHDI_MAX_CHANNELS];
>>  
>>  static int spans=0;
>>  
>> @@ -646,6 +648,49 @@
>>  	return 0;
>>  }
>>  
>> +static int setfiftysixkhdlc(char *keyword, char *args)
>> +{
>> +	int res;
>> +
>> +	res = apply_channels(fiftysixkhdlc, args);
>> +	if (res <= 0)
>> +		return -1;
>> +
>> +	return 0;
>> +}
>> +
>> +static void apply_fiftysix(void)
>> +{
>> +	int x;
>> +	int rate;
>> +	int chanfd;
>> +
>> +	for (x = 1; x < DAHDI_MAX_CHANNELS; x++) {
>> +		chanfd = open("/dev/dahdi/channel", O_RDWR);
>> +		if (chanfd == -1) {
>> +			fprintf(stderr, "Couldn't open /dev/zap/channel\n");
>> +			exit(-1);
>> +		}
>> +
>> +		if (ioctl(chanfd, DAHDI_SPECIFY, &x)) {
>> +			continue;
>> +		}
>> +
>> +		if (fiftysixkhdlc[x]) {
>> +			printf("Setting channel %d to 56K mode (only valid on HDLC channels)\n", x);
>> +			rate = 56;
>> +		} else {
>> +			rate = 64;
>> +		}
>> +
>> +		if (ioctl(chanfd, DAHDI_HDLC_RATE, &rate)) {
>> +			fprintf(stderr, "Error setting HDLC rate\n");
>> +			exit(-1);
>> +		}
>> +		close(chanfd);
>> +	}
>> +}
>> +
>>  static int setechocan(char *keyword, char *args)
>>  {
>>  	int res;
>> @@ -1310,6 +1355,7 @@
>>  	{ "channel", rad_chanconfig },
>>  	{ "channels", rad_chanconfig },
>>  	{ "echocanceller", setechocan },
>> +	{ "56k", setfiftysixkhdlc },
>>  };
>>  
>>  static char *readline()
> 
> Here we are in the end of main()
> 
>> @@ -1586,5 +1632,6 @@
>>  		fprintf(stderr, "\n%d error(s) detected\n\n", errcnt);
>>  		exit(1);
>>  	}
>> +	apply_fiftysix();
>>  	exit(0);
>>  }
> 
> Why run this is a separate loop? Re-open /dev/dahdi/channel regardless
> of whether this directive was ever used.

Because if you previously had 56K HDLC enabled on a channel, and 
subsequently you change your system.conf to disable it, that is the only 
way it will be disabled.

The flag is a sticky flag, and is not reset when the channel is closed 
or anything like that.

> The loop above for applying configuration to channels is indeed not a
> pretty sight. 3 nesting levels can be easily removed from it (OK to
> commit that now?)
> 

Feel free to improve as you see fit :-)

Matthew Fredrickson
Digium, Inc.