Fwd: xterm-basic's acsc definition

[Thomas Dickey]

This should have been addressed to the mailing list.

----- Forwarded Message -----
From: "Thomas Dickey" <dickey@his.com>
To: "Ingo Brückl" <ib@wupperonline.de>
Cc: "Thomas E. Dickey" <dickey@invisible-island.net>
Sent: Tuesday, July 7, 2020 6:46:03 PM
Subject: Re: xterm-basic's acsc definition

On Wed, Jul 08, 2020 at 12:01:12AM +0200, Ingo Brückl wrote:
> Thomas,
> 
> is there a reason why xterm-basic's acsc definition (xterm-357) lacks hh?
> (Actually all xterm acsc definitions do so.)

The acsc codes are used in curses.h; these are relevant:

#define ACS_CKBOARD     NCURSES_ACS('a') /* checker board (stipple) */
#define ACS_BOARD       NCURSES_ACS('h') /* board of squares */
#define ACS_LANTERN     NCURSES_ACS('i') /* lantern symbol */
#define ACS_BLOCK       NCURSES_ACS('0') /* solid square block */

xterm's acsc is based on vt100, which see this (xterm adds "i", for lantern):

        acsc: '``aaffggiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~',
              '``aaffggjjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~'.

The assignment for "a" is used; that is the only block-like character in
the vt100's repertoire.  The Linux console doesn't actually act like vt100
(see the attached pictures for vttest), but it's passable.  It also has
some graphic characters that a vt100 never had (see the pictures for tack).

-- 
Thomas E. Dickey <dickey@invisible-island.net>
https://invisible-island.net
ftp://ftp.invisible-island.net
-- 
Thomas E. Dickey <dickey@invisible-island.net>
http://invisible-island.net
ftp://ftp.invisible-island.net

tack-xterm.png
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tack-linux.png
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vttest-xterm.png
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vttest-linux.png
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