<?php 

function strftime_ext($format = "", $timestamp = false){

    if ($timestamp >= 0 && $timestamp <= 2147480047){ 

        // between 1 Jan 1970 00:00:00 and 19 Jan 2038 03:14:07 GMT

        return strftime ($format, $timestamp);

    }

    

    $mappings = Array (

        Array ("start" => 1902, "end" => 1951, "map" => 1986), // 1902-1951 = 1986-2035

        Array ("start" => 1952, "end" => 1969, "map" => 1980), // 1952-1969 = 1980-1997

        Array ("start" => 2038, "end" => 2091, "map" => 1982), // 2038-2091 = 1982-2035

        //add additional mapping here

    );

    

    if ($timestamp < 0)    {

        $year = 1969;

        while ($timestamp < 0){

            $days = ($year % 4 == 0 && ($year % 100 > 0 || $year % 400 == 0)) ? 366 : 365;

            $timestamp += $days * 86400;

            $year--;

        }

    }    else {

        // if ($timestamp > 2147480047)

        $year = 2038;

        while ($timestamp > 0){

            $days = ($year % 4 == 0 && ($year % 100 > 0 || $year % 400 == 0)) ? 366 : 365;

            $timestamp -= $days * 86400;

            $year++;

        }

    }

    

    foreach ($mappings as $mapping) {

        if ($year >= $mapping["start"] && $year <= $mapping["end"])    {

            $find = Array ("%y", "%Y", "%D");

            $replace = Array (substr ($year, -2), $year, "%m/%d/" . substr ($year, -2));

            $format =& str_replace ($find, $replace, $format);

            $map_from_1970 = mktime (0, 0, 0, 1, 1, $mapping["map"]);

            return strftime ($format, $timestamp + $map_from_1970);

        }

    }

    

    return "strftime (): Year not mapped yet: " . $year;

}