Process a PLAYPAL lump (https://doomwiki.org/wiki/PLAYPAL) extracted from a Doom-engine WAD and count the number of unique colors, optionally skipping unused palettes and truncating 8-bits colors to 6-bits - see https://www.doomworld.com/vb/post/1839737 for example results

playpal_total.php

#!/usr/bin/php -q
<?php
// count total number of unique colors used in palettes of Doom-engine games,
// optionally skipping unused palettes and truncating 8-bits colors to 6-bits
// by Frans P. de Vries (Xymph)

define('PALSIZE', 3 * 256);
define('USAGE', "usage: {$argv[0]} [-u] [-t] -d|-h|-x|-s PLAYPAL-file\n");

        // check options & file parameter
        $game = ''; // 'd' = doom, 'h' = heretic, 'x' = hexen, 's' = strife
        $unused = $truncate = false;
        while (isset($argv[1]) && $argv[1][0] == '-') {
                switch (substr($argv[1], 1)) {
                        case 'd':
                        case 'h':
                        case 'x':
                        case 's':
                                $game = substr($argv[1], 1);
                                break;
                        case 't':
                                $truncate = true;
                                break;
                        case 'u':
                                $unused = true;
                                break;
                        default:
                                echo USAGE;
                                exit(1);
                }
                unset($argv[1]);
                $argc--;
                $argv = array_merge($argv);
        }
        if ($game != '' && isset($argv[1]) && $argv[1] != '') {
                $pname = $argv[1];
        } else {
                echo USAGE;
                exit(1);
        }

        // check palette file
        $PALSETS = ($game == 'x' ? 28 : 14);
        if (!file_exists($pname)) {
                echo "$pname: No such PLAYPAL file\n";
                exit(1);
        }
        if (filesize($pname) != $PALSETS * PALSIZE) {
                echo "$pname: Invalid PLAYPAL size for this game\n";
                exit(1);
        }

        // process palette file
        if (($fp = @fopen($pname, 'rb')) === FALSE) {
                echo "$pname: Unable to open palette file\n";
                exit(1);
        }
        $palused = 0;
        // read all palettes and tally unique colors
        $colors = array();
        for ($palno = 0; $palno < $PALSETS; $palno++) {
                if (($palette = fread($fp, PALSIZE)) === FALSE) {
                        echo "$pname: Unable to read palette file\n";
                        exit(1);
                }
                // skip unused palettes?
                if ($unused &&
                    (($game != 'x' && ($palno == 1 || $palno == 9)) ||
                     ($game == 'h' && $palno == 13)))
                        continue;

                $palused++;
                // tally unique colors
                for ($i = 0; $i < PALSIZE; $i += 3)
                        // truncate to 6-bit colors?
                        if ($truncate)
                                $colors[ sprintf('%02X%02X%02X',
                                                 ord($palette[$i])   & 0xFC,
                                                 ord($palette[$i+1]) & 0xFC,
                                                 ord($palette[$i+2]) & 0xFC) ] = true;
                        else
                                $colors[ sprintf('%02X%02X%02X',
                                                 ord($palette[$i]),
                                                 ord($palette[$i+1]),
                                                 ord($palette[$i+2])) ] = true;
        }
        fclose($fp);

        // report results
        switch ($game) {
                case 'd':
                        echo "Doom";
                        break;
                case 'h':
                        echo "Heretic";
                        break;
                case 'x':
                        echo "Hexen";
                        break;
                case 's':
                        echo "Strife";
                        break;
        }
        echo " uses $palused palettes with " . count($colors) . " unique colors\n";

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