Richard Suchenwirth 2004-04-23: Yet another tiny fun project, here's how to convert a string of digits and some other characters to a multiline string that in a fixed-pitch font looks like a 7-segment LCD/LED display:
proc num->7seg string {
foreach i {a b c} {set $i " "}
array set 7segment {
0 {{ _ } {| |} {|_|}}
1 {{ } { |} { |}}
2 {{ _ } { _|} {|_ }}
3 {{ _ } { _|} { _|}}
4 {{ } {|_|} { |}}
5 {{ _ } {|_ } { _|}}
6 {{ _ } {|_ } {|_|}}
7 {{ _ } { |} { |}}
8 {{ _ } {|_|} {|_|}}
9 {{ _ } {|_|} { _|}}
- {{ } { _ } { }}
E {{ _ } {|_ } {|_ }}
r {{ } { _ } {| }}
o {{ } { _ } {|_|}}
A {{ _ } {|_|} {| |}}
B {{ } {|_ } {|_|}}
C {{ _ } {| } {|_ }}
D {{ } { _|} {|_|}}
F {{ _ } {|_ } {| }}
}
foreach char [split $string ""] {
if {$char eq "."} {
set c [string replace $c end end .]
} else {
foreach i {a b c} row $7segment($char) {
append $i $row " "
}
}
}
return $a\n$b\n$c
}
% num->7seg 12345.67890-Error_ _ _ _ _ _ _ _ _ | _| _| |_| |_ |_ | |_| |_| | | _ |_ _ _ _ _ | |_ _| | _|.|_| | |_| _| |_| |_ | | |_| |
MPJ: "Drive-by hacking" ... I added A,B,C,D,F so hex displays look right ;-)
RS: Thanks Mike, but that B is indistinguishable from 8, and D from 0... We'd have to use lowercase for these two:
B {{ } {|_ } {|_|}}
D {{ } { _|} {|_|}}% num->7seg 012345.6789ABCDEF _ _ _ _ _ _ _ _ _ _ _ _ | | | _| _| |_| |_ |_ | |_| |_| |_| |_ | _| |_ |_ |_| | |_ _| | _|.|_| | |_| _| | | |_| |_ |_| |_ |
MPJ: You're right; I just saw that on LCD hexa panel.
TV: Such things can also be applied to hardware LED display driven by the parallel port under tcl control, my routine wasn't as neatly defining the segments, just a list of decimal numbers...
FW: I thought of a (seemingly) clever way to store these characters, to make a little obfuscated puzzler, but the result is really not that much shorter, and not even as obfuscated as I had hoped. Ah well ;) It just replaces the "array set" construct with this:
foreach {char pc} [split "0o1\t2^3\[495s6w7I8\1779{_\20Evr\24o\27A}B7CfD Ft" ""] {
binary scan $pc B8 bin
set b2 ""
for {set i 1} {$i < 8} {incr i} {
append b2 [expr {[string index $bin $i] ? ([lsearch {1 3 6} $i] != -1 ? "_" : "|") : " "}]
}
set 7segment($char) [list " [string index $b2 0] " [string range $b2 1 3] [string range $b2 4 6]]
}