// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Checksum a short ASCII message
// Not compiled or tested in-world
// Setup: Put in a spare prim you own. Edit MESSAGE, keeping it ASCII and at most two hundred characters, then touch.
// Stop / restore: Disable or remove the script. It only reports to its owner and does not change prim properties. Reset clears its temporary state.
// Notes: Rejects non-ASCII text to avoid confusing Unicode characters with bytes. This detects some accidental changes; it is not a secure signature or password hash.
// License: see LICENSE in this distribution.
// Original Incoprea example. MIT. Owner-only calculation; no scene changes.
string MESSAGE="panel=west;revision=7";
default
{
    touch_start(integer detectedCount)
    {
        if (llDetectedKey(0) != llGetOwner()) return;
        integer length=llStringLength(MESSAGE);
        if (length>200)
        {
            llOwnerSay("Keep the demonstration under 201 characters.");
            return;
        }
        integer first=0;
        integer second=0;
        integer i;
        for (i=0; i<length; ++i)
        {
            integer code=llOrd(MESSAGE,i);
            if (code>127 || code<0)
            {
                llOwnerSay("ASCII only for this byte-checksum example.");
                return;
            }
            first=(first+code)%255;
            second=(second+first)%255;
        }
        llOwnerSay("Fletcher-16 decimal checksum: "+(string)((second<<8)|first));
    }
    changed(integer change)
    {
        if (change & CHANGED_OWNER) llResetScript();
    }
}