#! perl -slw
use strict;
package SEIFA; #! Space Efficient, Inflexible Float Array

my %instances;

use constant	ARYREF	=> 0;
use constant	X_SIZE	=> 1;
use constant	Y_SIZE	=> 2;
sub new {
	my ($class, $x, $y, $init ) = @_;
	my $size = $x * $y;
	my $mem = pack('f', $init||'0.0') x $size;
	my $data = [ \$mem, $x, $y ];
	my $self = bless $data, $class;
	$instances{$self} = $data;
	return $self;
}

use constant	X		=> 1;
use constant	Y		=> 2;
sub seifa{
	my ($data, $x, $y) = ($instances{+shift}, shift, shift);
	my $pos = ($data->[X_SIZE] * $y * 4) + ($x * 4);
	return unpack 'f*', substr( ${$data->[ARYREF]}, $pos, 4) unless @_;
	return unpack 'f*', substr( ${$data->[ARYREF]}, $pos, @_ * 4) = pack 'f*', @_;
}

package main;
use vars qw[$X $Y];
use Benchmark::Timer; my $timer = Benchmark::Timer->new();

$X ||= 20; $Y ||= 20;

print 'Before'; <>;
$timer->start("allocate ${\($X * $Y)}");
my $matrix = SEIFA->new( $X, $Y, 1.0);
$timer->stop("allocate ${\($X * $Y)}");
print 'After'; <>;



$matrix->seifa( $X-1, 0, 3.1415926 );
$matrix->seifa( $X-1, $Y-1, 3.1415926 );

local $\;

for my $y (0 .. 5, '...', $Y-6 .. $Y-1) {
	print( "    ...    " x 8, $/), next if $y eq '...';
	for my $x (0 .. 3, '...', $X-3 .. $X-1) {
		print( '    ...  '), next if $x eq '...';
		$timer->start('write-read');
		my $value = $matrix->seifa($x, $y, "$y.$x");
		$timer->stop('write-read');
		printf '%9.4f, ',  $value;
	}
	print $/,
}

print $timer->report();

__END__
c:\test>230052 -X=4000 -Y=4000
Before

After

   0.0000,    0.1000,    0.2000,    0.3000,     ...     0.3997,    0.3998,    0.3999,
   1.0000,    1.1000,    1.2000,    1.3000,     ...     1.3997,    1.3998,    1.3999,
   2.0000,    2.1000,    2.2000,    2.3000,     ...     2.3997,    2.3998,    2.3999,
   3.0000,    3.1000,    3.2000,    3.3000,     ...     3.3997,    3.3998,    3.3999,
   4.0000,    4.1000,    4.2000,    4.3000,     ...     4.3997,    4.3998,    4.3999,
   5.0000,    5.1000,    5.2000,    5.3000,     ...     5.3997,    5.3998,    5.3999,
    ...        ...        ...        ...        ...        ...        ...        ...
3994.0000, 3994.1001, 3994.2000, 3994.3000,     ...  3994.3997, 3994.3999, 3994.3999,
3995.0000, 3995.1001, 3995.2000, 3995.3000,     ...  3995.3997, 3995.3999, 3995.3999,
3996.0000, 3996.1001, 3996.2000, 3996.3000,     ...  3996.3997, 3996.3999, 3996.3999,
3997.0000, 3997.1001, 3997.2000, 3997.3000,     ...  3997.3997, 3997.3999, 3997.3999,
3998.0000, 3998.1001, 3998.2000, 3998.3000,     ...  3998.3997, 3998.3999, 3998.3999,
3999.0000, 3999.1001, 3999.2000, 3999.3000,     ...  3999.3997, 3999.3999, 3999.3999,
1 trial of allocate 16000000 (4.467s total)
84 trials of write-read (20ms total), 238us/trial

c:\test>