#!/usr/bin/perl -w
use strict;

use HTTP::Date;
use Time::HiRes;
$\ ="\n";

my %month = (Jan => 0,
Feb => 31,
Mar => 59,
Apr => 90,
May => 120,
Jun => 151,
Jul => 181,
Aug => 212,
Sep => 243,
Oct => 273,
Nov => 304,
Dec => 334);
my %year = (1901 => -25202, 1902 => -24837, 1903 => -24472, 1904 => -24107, 1905 => -23741, 1906 => -23376,
            1907 => -23011, 1908 => -22646, 1909 => -22280, 1910 => -21915, 1911 => -21550, 1912 => -21185,
            1913 => -20819, 1914 => -20454, 1915 => -20089, 1916 => -19724, 1917 => -19358, 1918 => -18993,
            1919 => -18628, 1920 => -18263, 1921 => -17897, 1922 => -17532, 1923 => -17167, 1924 => -16802,
            1925 => -16436, 1926 => -16071, 1927 => -15706, 1928 => -15341, 1929 => -14975, 1930 => -14610,
            1931 => -14245, 1932 => -13880, 1933 => -13514, 1934 => -13149, 1935 => -12784, 1936 => -12419,
            1937 => -12053, 1938 => -11688, 1939 => -11323, 1940 => -10958, 1941 => -10592, 1942 => -10227,
            1943 => -9862, 1944 => -9497, 1945 => -9131, 1946 => -8766, 1947 => -8401, 1948 => -8036, 1949 => -7670,
            1950 => -7305, 1951 => -6940, 1952 => -6575, 1953 => -6209, 1954 => -5844, 1955 => -5479, 1956 => -5114,
            1957 => -4748, 1958 => -4383, 1959 => -4018, 1960 => -3653, 1961 => -3287, 1962 => -2922, 1963 => -2557,
            1964 => -2192, 1965 => -1826, 1966 => -1461, 1967 => -1096, 1968 => -731, 1969 => -365, 1970 => 0,
            1971 => 365, 1972 => 730, 1973 => 1096, 1974 => 1461, 1975 => 1826, 1976 => 2191, 1977 => 2557,
            1978 => 2922, 1979 => 3287, 1980 => 3652, 1981 => 4018, 1982 => 4383, 1983 => 4748, 1984 => 5113,
            1985 => 5479, 1986 => 5844, 1987 => 6209, 1988 => 6574, 1989 => 6940, 1990 => 7305, 1991 => 7670,
            1992 => 8035, 1993 => 8401, 1994 => 8766, 1995 => 9131, 1996 => 9496, 1997 => 9862, 1998 => 10227,
            1999 => 10592, 2000 => 10957, 2001 => 11323, 2002 => 11688, 2003 => 12053, 2004 => 12418, 2005 => 12784,
            2006 => 13149, 2007 => 13514, 2008 => 13879, 2009 => 14245, 2010 => 14610, 2011 => 14975, 2012 => 15340,
            2013 => 15706, 2014 => 16071, 2015 => 16436, 2016 => 16801, 2017 => 17167, 2018 => 17532, 2019 => 17897,
            2020 => 18262, 2021 => 18628, 2022 => 18993, 2023 => 19358, 2024 => 19723, 2025 => 20089, 2026 => 20454,
            2027 => 20819, 2028 => 21184, 2029 => 21550, 2030 => 21915, 2031 => 22280, 2032 => 22645, 2033 => 23011,
            2034 => 23376, 2035 => 23741, 2036 => 24106, 2037 => 24472, 2038 => 24837);

my $httpdate = 'Wed, 25 Aug 2010 09:56:38 GMT';

sub mytime {
my $year = substr($_[0],12,4);
my $days =  ($year-1970)*365+ # days in full year passed
        sprintf('%d', ($year-1970)/4)+ # add leap days in years passed
        $month{substr($_[0],8,3)}+ # add days in full months passed
        (substr($_[0],5,2)-1)+ #is doing a -1 to day of month needed?
        (((($year)%4) == 0 && (($month{substr($_[0],8,3)}+substr($_[0],5,2)) > 59))?1:0); #have we passed the leap day in the current year?
return $days*86400+(substr($_[0],17,2)*60*60)+(substr($_[0],20,2)*60)+substr($_[0],23,2); #hrs/mins/secs
}

sub mytime2 {
my $year = substr($_[0],12,4);
my $days =  ($year-1970)*365+ # days in full year passed
        ((($year-1970) - (($year-1970) % 4))/4)+ # add leap days in years passed
        $month{substr($_[0],8,3)}+ # add days in full months passed
        (substr($_[0],5,2)-1)+ #is doing a -1 to day of month needed?
        (((($year)%4) == 0 && (($month{substr($_[0],8,3)}+substr($_[0],5,2)) > 59))?1:0); #have we passed the leap day in the current year?
return  $days*86400+(substr($_[0],17,2)*60*60)+(substr($_[0],20,2)*60)+substr($_[0],23,2); #hrs/mins/secs
}

sub mytime3 { #yr table
my $year = substr($_[0],12,4);
my $days =  $year{$year}+ #use year day hash
        $month{substr($_[0],8,3)}+ # add days in full months passed
        (substr($_[0],5,2)-1)+ #is doing a -1 to day of month needed?
        (((($year)%4) == 0 && (($month{substr($_[0],8,3)}+substr($_[0],5,2)) > 59))?1:0); #have we passed the leap day in the current year?
return  $days*86400+(substr($_[0],17,2)*60*60)+(substr($_[0],20,2)*60)+substr($_[0],23,2); #hrs/mins/secs
}
sub mytime4 { #yr table and full substr caching
my $year = substr($_[0],12,4);
my $month = substr($_[0],8,3);
my $day = substr($_[0],5,2);
my $days =  $year{$year}+ #use year day hash
        $month{$month}+ # add days in full months passed
        ($day-1)+ #is doing a -1 to day of month needed?
        (((($year)%4) == 0 && (($month{$month}+$day) > 59))?1:0); #have we passed the leap day in the current year?
return  $days*86400+(substr($_[0],17,2)*60*60)+(substr($_[0],20,2)*60)+substr($_[0],23,2); #hrs/mins/secs
}
sub mytime5 { #year table and removed redundant year caching
my $days =  $year{substr($_[0],12,4)}+ #use year day hash
        $month{substr($_[0],8,3)}+ # add days in full months passed
        (substr($_[0],5,2)-1)+ #is doing a -1 to day of month needed?
        ((((substr($_[0],12,4))%4) == 0 && (($month{substr($_[0],8,3)}+substr($_[0],5,2)) > 59))?1:0); #have we passed the leap day in the current year?
return  $days*86400+(substr($_[0],17,2)*60*60)+(substr($_[0],20,2)*60)+substr($_[0],23,2); #hrs/mins/secs
}
my $t_a = Time::HiRes::time();
for (0 .. 100000) {mytime($httpdate);}
print 'with sprintf int '.(Time::HiRes::time()-$t_a)."\n";;

$t_a = Time::HiRes::time();
for (0 .. 100000) {mytime2($httpdate);}
print 'with algebra int '.(Time::HiRes::time()-$t_a)."\n";;

$t_a = Time::HiRes::time();
for (0 .. 100000) {mytime3($httpdate);}
print 'with yr table '.(Time::HiRes::time()-$t_a)."\n";;

$t_a = Time::HiRes::time();
for (0 .. 100000) {mytime4($httpdate);}
print 'with yr table and full substr caching '.(Time::HiRes::time()-$t_a)."\n";;

$t_a = Time::HiRes::time();
for (0 .. 100000) {mytime5($httpdate);}
print 'with yr table no cache '.(Time::HiRes::time()-$t_a)."\n";;

$t_a = Time::HiRes::time();
for (0 .. 100000) {str2time($httpdate);}
print 'with HTTP date '.(Time::HiRes::time()-$t_a)."\n";;

print "algorithm outputs";
print mytime($httpdate);
print mytime2($httpdate);
print mytime3($httpdate);
print mytime4($httpdate);
print mytime5($httpdate);
print str2time($httpdate);