On Fri, Jan 04, 2008 at 02:14:37AM -0800, David Miller wrote:
> From: Matthias Goebl <[EMAIL PROTECTED]>
> Date: Thu, 3 Jan 2008 23:00:03 +0100
>
> > --- linux-2.6.23.12.orig/drivers/isdn/i4l/isdn_tty.c 2007-12-22
> > 21:13:49.000000000 +0100
> > +++ linux-2.6.23.12/drivers/isdn/i4l/isdn_tty.c 2007-12-26
> > 11:37:18.000000000 +0100
> > @@ -85,6 +85,8 @@
> >
> > tty_insert_flip_char(tty, DLE, 0);
> >
> > tty_insert_flip_char(tty, *dp++, 0);
> > }
> > + if (*dp == DLE)
> > +
> > tty_insert_flip_char(tty, DLE, 0);
> > last = *dp;
> > } else {
> > #endif
>
> I'm not sure this part is correct.
>
> Here, *dp will be assigned to 'last'.
The while (--l) {...} pushes+adds DLE for len-1 characters.
( while (l--) would process all len characters)
The last charater is assigned to "last" and pushed after the else block:
> The rest of the code (after the else block) then reads:
>
> if (info->emu.mdmreg[REG_CPPP] &
> BIT_CPPP)
> tty_insert_flip_char(tty, last,
> 0xFF);
> else
> tty_insert_flip_char(tty, last,
> TTY_NORMAL);
>
> which should push that character out to the TTY.
But this does not care about a DLE and doesn't escape that with another DLE.
> With your change we will push a DLE out twice in such a case,
> and that doesn't seem right.
For an audio data stream we have to escape DLE (ascii 16) by another DLE,
otherwise it is interpreted as command, as in Documentation/isdn/README.audio:
... escape sequences defined, all using DLE (0x10) as Escape char:...
<DLE><DLE> Escape sequence for DLE in data stream.
<DLE>0 Touchtone "0" received.
...
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