init.php

<?php

$xy = [];

$xy[] = [1,1,52,52];
$xy[] = [1,53,52,104];
$xy[] = [1,105,52,156];
$xy[] = [1,157,52,208];
$xy[] = [1,209,52,260];
$xy[] = [1,261,52,312];
$xy[] = [1,313,52,364];
$xy[] = [1,365,53,416];

$xy[] = [53,1,104,52];
$xy[] = [53,53,104,104];
$xy[] = [53,105,104,156];
$xy[] = [53,157,104,208];
$xy[] = [53,209,104,260];
$xy[] = [53,261,104,312];
$xy[] = [53,313,104,364];
$xy[] = [53,365,105,416];

$xy[] = [105,1,156,52];
$xy[] = [105,53,156,104];
$xy[] = [105,105,156,156];
$xy[] = [105,157,156,208];
$xy[] = [105,209,156,260];
$xy[] = [105,261,156,312];
$xy[] = [105,313,156,364];
$xy[] = [105,365,157,416];

$xy[] = [157,1,208,52];
$xy[] = [157,53,208,104];
$xy[] = [157,105,208,156];
$xy[] = [157,157,208,208];
$xy[] = [157,209,208,260];
$xy[] = [157,261,208,312];
$xy[] = [157,313,208,364];
$xy[] = [157,365,209,416];

$xy[] = [209,1,260,52];
$xy[] = [209,53,260,104];
$xy[] = [209,105,260,156];
$xy[] = [209,157,260,208];
$xy[] = [209,209,260,260];
$xy[] = [209,261,260,312];
$xy[] = [209,313,260,364];
$xy[] = [209,365,261,416];

$xy[] = [261,1,312,52];
$xy[] = [261,53,312,104];
$xy[] = [261,105,312,156];
$xy[] = [261,157,312,208];
$xy[] = [261,209,312,260];
$xy[] = [261,261,312,312];
$xy[] = [261,313,312,364];
$xy[] = [261,365,313,416];

$xy[] = [313,1,364,52];
$xy[] = [313,53,364,104];
$xy[] = [313,105,364,156];
$xy[] = [313,157,364,208];
$xy[] = [313,209,364,260];
$xy[] = [313,261,364,312];
$xy[] = [313,313,364,364];
$xy[] = [313,365,365,416];

$xy[] = [365,1,416,53];
$xy[] = [365,53,416,105];
$xy[] = [365,105,416,157];
$xy[] = [365,157,416,209];
$xy[] = [365,209,416,261];
$xy[] = [365,261,416,313];
$xy[] = [365,313,416,365];
$xy[] = [365,365,416,416];

$xyImploded = [];
foreach ($xy as $key => $val) {
    $xyImploded[] = implode('', $val);
}

$pieces = [ 'B', 'b', 'K', 'k', 'N', 'n', 'P', 'p', 'Q', 'q', 'R', 'r', ];