component toggle2nist "toggle button to nist logic";

description
"""
Toggle2nist can be used with a momentary push button 
to control a device that has separate on and off inputs
and an is-on output. 

\[bu] On a rising edge on pin \\fIin\\fR when \\fIis-on\\fR is low: It sets \\fIon\\fR until \\fIis-on\\fR becomes high.

\[bu] On a rising edge on pin \\fIin\\fR when \\fIis-on\\fR is high: It sets \\fIoff\\fR until \\fIis-on\\fR becomes low.


       ┐     ┏─────xxxxxxxxxxxx┐           ┏─────xxxxxxxxxxxx┐     
.br
in   : └─────┛     xxxxxxxxxxxx└───────────┛     xxxxxxxxxxxx└─────
.br
       ┐     ┌───────────┐                                         
.br
on   : └─────┘           └─────────────────────────────────────────
       ┐                                   ┌───────────┐           
.br
off  : └───────────────────────────────────┘           └───────────
.br
       ┐                 ┌─────────────────────────────┐           
.br
is-on: └─────────────────┘                             └───────────

""";

pin in  bit in;
pin in  bit is_on;
pin out bit on;
pin out bit off;
variable int old_in;
variable int to_state=0;
function _ nofp;
license "GPL";
author "Anders Wallin";
;;
FUNCTION(_)  {
if (in!=old_in) /* a toggle has occurred */ {
    if (is_on) {   /* turn OFF if it's on */
        on=0;
        off=1;
        to_state=0;
    }
    else if (!is_on) { /* turn ON if it's off */
        on=1;
        off=0;
        to_state=1;
    }
}
else {
/* reset pins when we see the desired state */
    if (to_state==is_on) {
        on=0;
        off=0;
    }
}
old_in=in;
}