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Date: Sat, 30 May 2009 08:33:55 +0100
Message-ID: <416096c60905300033g105ddd7elf96812b0d000f731@mail.gmail.com>
Subject: Re: emacs -nw keypad, tpu-edt.el, and C-h
From: Andy Koppe <andy DOT koppe AT gmail DOT com>
To: cygwin AT cygwin DOT com
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Christopher Faylor wrote:
>>Now of course if emacs can translate low-level console I/O as it sees
>>fit, then the Cygwin DLL could also be able to translate Backspace into
>>^? =C2=A0characters rather than ^H, in CYGWIN=3Dtty mode anyway. =C2=A0So=
 I had a
>>look at fhandler_console.cc. =C2=A0It already uses ReadConsoleInput(), so
>>mapping from VK_BACK to ^? =C2=A0might be fairly straightforward actually.
>
> And a patch would have been appreciated...

Sorry, I didn't think I understood the code enough for that.


> However, I have made the change to Cygwin to translate backspace to ^?.
> It will be in the next snapshot.

Great, thanks! Does this apply both with and without CYGWIN=3Dtty? And I
guess native console applications won't be affected by this?

The relevant termios default setting will need to change accordingly,
either by changing the definition of CERASE in include/sys/termios.h:

-#define CERASE	CTRL('H')
+#define CERASE	CDEL

Or by changing the initialisation in fhandler_termios.c:

-      tc->ti.c_cc[VERASE]	=3D CERASE;
+      tc->ti.c_cc[VERASE]	=3D CDEL;

The cygwin section in /etc/termcap doesn't have a kb entry, so luckily
no change needed there.

terminfo has an entry for backspace though:

$ tput -T cygwin kbs | cat -v
^H

So this has to to change as well:

+++ terminfo.src        2009-05-30 07:50:44.893933600 +0100
@@ -5221,7 +5221,7 @@
-       kbs=3D^H, kcub1=3D\E[D, kcud1=3D\E[B, kcuf1=3D\E[C, kcuu1=3D\E[A,
+       kbs=3D^?, kcub1=3D\E[D, kcud1=3D\E[B, kcuf1=3D\E[C, kcuu1=3D\E[A,

And then there are rxvt and xterm and their termcap and terminfo
entries as well ...

One more thing: with your change, Alt can be used to override ^? and
get ^H instead. Usually though, Ctrl is used as the modifier for this,
whereas Alt acts as Meta (i.e. it sends a ^[ prefix).

Andy

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